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Molecules, Volume 24, Issue 2 (January-2 2019) – 162 articles

Cover Story (view full-size image): Caribou and moose meats or antlers were observed to be rich in functional lipids, i.e., fatty acid esters of hydroxy fatty acids (FAHFAs), diglycerides (DGs), and monoacetyldiglycerides (MAcDGs). Emerging evidence suggests that these are new classes of functional lipids that have been demonstrated to have potential application in pharmaceuticals and functional food formulations in managing and preventing metabolic or inflammatory diseases including obesity, type 2 diabetes, sepsis, and rheumatoid arthritis. In this study, we demonstrated that moose and caribou meat or antlers are significant sources of polyunsaturaed FAHFAs and 1,3-DGs molecular species. Increasing access to and knowledge of the presence of these functional lipids in foods will enhance their intake in the diet with potential implications in improving personal and population health. View this paper.
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19 pages, 1559 KiB  
Article
Dual Geometry Schemes in Tetrel Bonds: Complexes between TF4 (T = Si, Ge, Sn) and Pyridine Derivatives
by Wiktor Zierkiewicz, Mariusz Michalczyk, Rafał Wysokiński and Steve Scheiner
Molecules 2019, 24(2), 376; https://doi.org/10.3390/molecules24020376 - 21 Jan 2019
Cited by 28 | Viewed by 4791
Abstract
When an N-base approaches the tetrel atom of TF4 (T = Si, Ge, Sn) the latter molecule deforms from a tetrahedral structure in the monomer to a trigonal bipyramid. The base can situate itself at either an axial or equatorial position, leading [...] Read more.
When an N-base approaches the tetrel atom of TF4 (T = Si, Ge, Sn) the latter molecule deforms from a tetrahedral structure in the monomer to a trigonal bipyramid. The base can situate itself at either an axial or equatorial position, leading to two different equilibrium geometries. The interaction energies are considerably larger for the equatorial structures, up around 50 kcal/mol, which also have a shorter R(T··N) separation. On the other hand, the energy needed to deform the tetrahedral monomer into the equatorial structure is much higher than the equivalent deformation energy in the axial dimer. When these two opposite trends are combined, it is the axial geometry which is somewhat more stable than the equatorial, yielding binding energies in the 8–34 kcal/mol range. There is a clear trend of increasing interaction energy as the tetrel atom grows larger: Si < Ge < Sn, a pattern which is accentuated for the binding energies. Full article
(This article belongs to the Special Issue σ and π Holes: A New Class of Non-Covalent Interactions)
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14 pages, 2844 KiB  
Article
Design and Synthesis of a Fluorescent Probe with a Large Stokes Shift for Detecting Thiophenols and Its Application in Water Samples and Living Cells
by Hua Liu, Chuanlong Guo, Shuju Guo, Lijun Wang and Dayong Shi
Molecules 2019, 24(2), 375; https://doi.org/10.3390/molecules24020375 - 21 Jan 2019
Cited by 10 | Viewed by 4611
Abstract
A turn-on florescent probe (probe-KCP) was developed for highly selective detection of thiophenols based on a donor-excited photo-induced electron transfer mechanism. Herein, the synthesis of the probe, a chalcone derivative, through a simple straightforward combination of a carbazole-chalcone fluorophore with a 2,4-dinitrophenyl functional [...] Read more.
A turn-on florescent probe (probe-KCP) was developed for highly selective detection of thiophenols based on a donor-excited photo-induced electron transfer mechanism. Herein, the synthesis of the probe, a chalcone derivative, through a simple straightforward combination of a carbazole-chalcone fluorophore with a 2,4-dinitrophenyl functional group. In a kinetic study of the probe-KCP for thiophenols, the probe displayed a short response time (~30 min) and significant fluorescence enhancement. In selection and competition experiments, the probe-KCP exhibited excellent selectivity for thiophenols over glutathione (GSH), cysteine (Cys), sodium hydrosulfide (NaSH), and ethanethiol (C2H5SH) in addition to common anions and metal ions. Using the designed probe, we successfully monitored and quantified thiophenols, which are highly toxic. This turn-on fluorescence probe features a remarkably large Stokes shift (130 nm) and a short response time (30 min), and it is highly selective and sensitive (~160-fold) in the detection of thiophenols, with marked fluorescence in the presence of thiophenols. probe-KCP responds to thiophenols with a good range of linearity (0–15 μM) and a detection limit of 28 nM (R2 = 0.9946) over other tested species mentioned including aliphatic thiols, thiophenol analogues, common anions, and metal ions. The potential applications of this carbazole-chalcone fluorescent probe was successfully used to determine of thiophenols in real water samples and living cells with good performance and low cytotoxicity. Therefore, this probe has great potential application in environment and biological samples. Full article
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16 pages, 1146 KiB  
Article
A Comprehensive and Rapid Quality Evaluation Method of Traditional Chinese Medicine Decoction by Integrating UPLC-QTOF-MS and UFLC-QQQ-MS and Its Application
by Yinfang Chen, Riyue Yu, Li Jiang, Qiyun Zhang, Bingtao Li, Hongning Liu and Guoliang Xu
Molecules 2019, 24(2), 374; https://doi.org/10.3390/molecules24020374 - 21 Jan 2019
Cited by 12 | Viewed by 5099
Abstract
Decoction is one of the oldest forms of traditional Chinese medicine and it is widely used in clinical practice. However, the quality evaluation and control of traditional decoction is a challenge due to the characteristics of complicated constituents, water as solvent, and temporary [...] Read more.
Decoction is one of the oldest forms of traditional Chinese medicine and it is widely used in clinical practice. However, the quality evaluation and control of traditional decoction is a challenge due to the characteristics of complicated constituents, water as solvent, and temporary preparation. ShenFu Prescription Decoction (SFPD) is a classical prescription for preventing and treating many types of cardiovascular disease. In this article, a comprehensive and rapid method for quality evaluation and control of SFPD was developed, via qualitative and quantitative analysis of the major components by integrating ultra-high-performance liquid chromatography equipped with quadrupole time-of-flight mass spectrometry and ultra-fast-performance liquid chromatography equipped with triple quadrupole mass spectrometry. Consequently, a total of 39 constituents were tentatively identified in qualitative analysis, of which 21 compounds were unambiguously confirmed by comparing with reference substances. We determined 13 important constituents within 7 min by multiple reaction monitoring. The validated method was applied for determining five different proportion SFPDs. It was found that different proportions generated great influence on the dissolution of constituents. This may be one of the mechanisms for which different proportions play different synergistic effects. Therefore, the developed method is a fast and useful approach for quality evaluation of SFPD. Full article
(This article belongs to the Special Issue Qualitative and Quantitative Analysis of Bioactive Natural Products 2018)
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12 pages, 4048 KiB  
Article
Protective Effects of Astragaloside IV against LPS-Induced Endometritis in Mice through Inhibiting Activation of the NF-κB, p38 and JNK Signaling Pathways
by Fengge Wang, Shuxiong Chen, Liang Deng, Lu Chen, Yuwen Huang, Meng Tian, Chunjin Li and Xu Zhou
Molecules 2019, 24(2), 373; https://doi.org/10.3390/molecules24020373 - 21 Jan 2019
Cited by 32 | Viewed by 4543
Abstract
Endometritis, inflammation of the endometrium, is a common reproductive obstacle disease that can lead to infertility in female animals. Astragaloside IV (AS IV), one of the major and active components of the Astragalus membranaceus (Fisch.) Bunge, is known for its anti-inflammatory effects. In [...] Read more.
Endometritis, inflammation of the endometrium, is a common reproductive obstacle disease that can lead to infertility in female animals. Astragaloside IV (AS IV), one of the major and active components of the Astragalus membranaceus (Fisch.) Bunge, is known for its anti-inflammatory effects. In the present study, the effects and mechanisms of AS IV on lipopolysaccharide (LPS)-induced endometritis were investigated using a mouse model. Female mice were prepared with AS IV (0.01 mg/g) by gavage for six days before being stimulated with LPS. The results showed that the histopathological changes, levels of inflammatory cytokines (IL-1β and TNF-α), concentration of NO, and myeloperoxidase (MPO) activity in LPS-induced uteri were attenuated significantly by pretreatment with AS IV. Furthermore, LPS-induced activations of NF-κB, p38, and JNK signal pathways were suppressed by pretreatment with AS IV. In conclusion, the data provided new evidence that AS IV effectively attenuates LPS-induced endometritis through inhibition of TLR4-mediated NF-κB, p38, and JNK signaling pathways, implying that AS IV might become a promising potential anti-inflammatory agent for endometritis and other inflammatory diseases. Full article
(This article belongs to the Special Issue Anti-Inflammatory Activity of Natural Products)
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26 pages, 7646 KiB  
Article
Functionalization of the Chalcone Scaffold for the Discovery of Novel Lead Compounds Targeting Fungal Infections
by Francesca Bonvicini, Giovanna A. Gentilomi, Francesca Bressan, Silvia Gobbi, Angela Rampa, Alessandra Bisi and Federica Belluti
Molecules 2019, 24(2), 372; https://doi.org/10.3390/molecules24020372 - 21 Jan 2019
Cited by 14 | Viewed by 3932
Abstract
The occurrence of invasive fungal infections represents a substantial threat to human health that is particularly serious in immunocompromised patients. The limited number of antifungal agents, devoid of unwanted toxic effects, has resulted in an increased demand for new drugs. Herein, the chalcone [...] Read more.
The occurrence of invasive fungal infections represents a substantial threat to human health that is particularly serious in immunocompromised patients. The limited number of antifungal agents, devoid of unwanted toxic effects, has resulted in an increased demand for new drugs. Herein, the chalcone framework was functionalized to develop new antifungal agents able to interfere with cell growth and with the infection process. Thus, a small library of chalcone-based analogues was evaluated in vitro against C. albicans ATCC 10231 and a number of compounds strongly inhibited yeast growth at non-cytotoxic concentrations. Among these, 5 and 7 interfered with the expression of two key virulence factors in C. albicans pathogenesis, namely, hyphae and biofilm formation, while 28 emerged as a potent and broad spectrum antifungal agent, enabling the inhibition of the tested Candida spp. and non-Candida species. Indeed, these compounds combine two modes of action by selectively interfering with growth and, as an added value, weakening microbial virulence. Overall, these compounds could be regarded as promising antifungal candidates worthy of deeper investigation. They also provide a chemical platform through which to perform an optimization process, addressed at improving potency and correcting liabilities. Full article
(This article belongs to the Special Issue Chalcone: A Privileged Structure in Medicinal Chemistry)
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14 pages, 2830 KiB  
Article
Comparison of the Inhibitory Activities of 5,6-Dihydroergosterol Glycoside α- and β-Anomers on Skin Inflammation
by Tae Kyun Kim, Young Kyoung Cho, HoonGyu Park, Tae Hoon Lee and Hakwon Kim
Molecules 2019, 24(2), 371; https://doi.org/10.3390/molecules24020371 - 21 Jan 2019
Cited by 5 | Viewed by 3318
Abstract
Chronic skin inflammatory diseases, such as atopic dermatitis, are associated with a dysfunctional skin barrier due to an increase in various inflammatory stimuli, for instance inflammatory cytokines and chemokines. In particular, CCL17 and CCL22 expression is increased in patients with chronic skin inflammation. [...] Read more.
Chronic skin inflammatory diseases, such as atopic dermatitis, are associated with a dysfunctional skin barrier due to an increase in various inflammatory stimuli, for instance inflammatory cytokines and chemokines. In particular, CCL17 and CCL22 expression is increased in patients with chronic skin inflammation. In this study, we synthesized several α- and β-anomers of dihydroergosterol (DHE)-glycosides and assessed their effects on CCL17 and CCL22 expression. We confirmed that the β-anomers of DHE-glycosides were superior to α-anomers of DHE-glycosides in inhibiting CCL17 and CCL22 mRNA and protein expression. In addition, we determined that DHE-glycoside β-anomers showed strong inhibitory activity towards pro-inflammatory cytokine mRNA and protein expression, including that of TNF-α, IL-6, and IL-1β- in stimulated HaCaT cells. These results imply that DHE-glycoside α- and β-anomers should be separated during synthesis of drugs for chronic skin inflammation. Our results also suggest that β-anomers of DHE-glycosides may play an important role as new drugs for chronic skin inflammation because of their ability to inhibit the skin inflammatory biomarker proteins CCL17 and CCL22. Full article
(This article belongs to the Special Issue Application of Organic Synthesis to Bioactive Compounds)
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25 pages, 2380 KiB  
Review
Role of Intestinal Microbiota in the Bioavailability and Physiological Functions of Dietary Polyphenols
by Kyuichi Kawabata, Yasukiyo Yoshioka and Junji Terao
Molecules 2019, 24(2), 370; https://doi.org/10.3390/molecules24020370 - 21 Jan 2019
Cited by 435 | Viewed by 17939
Abstract
Polyphenols are categorized as plant secondary metabolites, and they have attracted much attention in relation to human health and the prevention of chronic diseases. In recent years, a considerable number of studies have been published concerning their physiological function in the digestive tract, [...] Read more.
Polyphenols are categorized as plant secondary metabolites, and they have attracted much attention in relation to human health and the prevention of chronic diseases. In recent years, a considerable number of studies have been published concerning their physiological function in the digestive tract, such as their prebiotic properties and their modification of intestinal microbiota. It has also been suggested that several hydrolyzed and/or fission products, derived from the catabolism of polyphenols by intestinal bacteria, exert their physiological functions in target sites after transportation into the body. Thus, this review article focuses on the role of intestinal microbiota in the bioavailability and physiological function of dietary polyphenols. Monomeric polyphenols, such as flavonoids and oligomeric polyphenols, such as proanthocyanidins, are usually catabolized to chain fission products by intestinal bacteria in the colon. Gallic acid and ellagic acid derived from the hydrolysis of gallotannin, and ellagitannin are also subjected to intestinal catabolism. These catabolites may play a large role in the physiological functions of dietary polyphenols. They may also affect the microbiome, resulting in health promotion by the activation of short chain fatty acids (SCFA) excretion and intestinal immune function. The intestinal microbiota is a key factor in mediating the physiological functions of dietary polyphenols. Full article
(This article belongs to the Special Issue Bioactive Plant Compounds for Sustainable Health)
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15 pages, 1565 KiB  
Article
Competition between Second-Generation Ethanol and Bioelectricity using the Residual Biomass of Sugarcane: Effects of Uncertainty on the Production Mix
by Lucio Guido Tapia Carpio and Fábio Simone de Souza
Molecules 2019, 24(2), 369; https://doi.org/10.3390/molecules24020369 - 21 Jan 2019
Cited by 17 | Viewed by 4490
Abstract
Several economies around the world are using second-generation (2G) ethanol produced from agricultural residues, like sugarcane straw and bagasse, as a sustainable solution to replace petroleum products. Since first-generation (1G) ethanol uses the sugars of sugarcane, an integrated 1G–2G production would enable the [...] Read more.
Several economies around the world are using second-generation (2G) ethanol produced from agricultural residues, like sugarcane straw and bagasse, as a sustainable solution to replace petroleum products. Since first-generation (1G) ethanol uses the sugars of sugarcane, an integrated 1G–2G production would enable the production of more ethanol from the same amount of sugarcane without leading to increased use of arable land. The ethanol production process is complex, involving different high-energy consumption operations such as evaporation and distillation. The economic competitiveness of this process depends heavily on the amount of thermal and electrical energy produced using sugarcane straw and bagasse as input. Thus, the objective of this study was to use the mean-variance methodology to determine the optimal allocation of residual sugarcane biomass between 2G ethanol and bioelectricity productions, with simultaneous objectives of maximizing the return and minimizing the risk for investors of this sector. In this paper, four scenarios are analyzed. The first one is the base scenario that represents the current state of production costs and investments. scenarios 2, 3, and 4 considered four cuts of 10%, 20%, and 40% in the production cost of ethanol 2G, respectively. The results show the optimum biomass allocations and the growth rates of returns as a function of risk growth. It can be concluded that from scenario 4, the production of 2G ethanol becomes financially advantageous for the investor, presenting greater returns with smaller risks. Full article
(This article belongs to the Special Issue Biorefinery and Biomass Conversion and Utilization)
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31 pages, 4817 KiB  
Article
Next-Generation Sequencing Reveals the Role of Epigallocatechin-3-Gallate in Regulating Putative Novel and Known microRNAs Which Target the MAPK Pathway in Non-Small-Cell Lung Cancer A549 Cells
by Vaishali Bhardwaj and Abul Kalam Azad Mandal
Molecules 2019, 24(2), 368; https://doi.org/10.3390/molecules24020368 - 21 Jan 2019
Cited by 40 | Viewed by 5999
Abstract
Lung cancer constitutes 85% of non-small cell lung cancer diagnosed cases. MicroRNAs are novel biomarkers that are capable of modulating multiple oncogenic pathways. Epigallocatechin-3-gallate (EGCG) is a potent chemopreventive and chemotherapeutic agent for cancer. We aimed to identify important known and putative novel [...] Read more.
Lung cancer constitutes 85% of non-small cell lung cancer diagnosed cases. MicroRNAs are novel biomarkers that are capable of modulating multiple oncogenic pathways. Epigallocatechin-3-gallate (EGCG) is a potent chemopreventive and chemotherapeutic agent for cancer. We aimed to identify important known and putative novel microRNAs modulated by EGCG in A549 cells using next-generation sequencing and identify their gene targets. Preliminary analysis revealed an IC50 value of 309 μM with G0/G1 phase arrest at 40 μM EGCG treatment. MicroRNA profiling identified 115 known and 4 putative novel microRNAs in 40 μM and 134 known and 3 putative novel microRNAs in 100 μM EGCG-treated A549 cells. The top 10 up-expressed microRNAs were similar between the untreated control and EGCG-treated A549 cells. An up-expression in oncogenic microRNAs, which belong to broadly conserved seed families, were observed in untreated control and EGCG-treated A549 cells. Kyoto Encyclopedia of Genes and Genomes and Protein Analysis Through Evolutionary Relationships pathway analyses of the validated microRNA targeting genes strengthened the hypothesis that EGCG treatment can modulate microRNAs that play a significant role in the MAPK signaling pathway. Expression profile of microRNAs was validation by quantitative real time PCR of randomly selected microRNAs. This study identified signature microRNAs that can be used as novel biomarkers for lung cancer diagnosis. Full article
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14 pages, 2200 KiB  
Article
Effects of Betaine on LPS-Stimulated Activation of Microglial M1/M2 Phenotypes by Suppressing TLR4/NF-κB Pathways in N9 Cells
by Hui Shi, Xiao-Long Wang, Hong-Feng Quan, Lin Yan, Xiu-Ying Pei, Rui Wang and Xiao-Dong Peng
Molecules 2019, 24(2), 367; https://doi.org/10.3390/molecules24020367 - 21 Jan 2019
Cited by 80 | Viewed by 6389
Abstract
Microglia mediate multiple facets of neuroinflammation. They can be phenotypically divided into a classical phenotype (pro-inflammatory, M1) or an alternative phenotype (anti-inflammatory, M2) with different physiological characteristics and biological functions in the inflammatory process. Betaine has been shown to exert anti-inflammatory effects. In [...] Read more.
Microglia mediate multiple facets of neuroinflammation. They can be phenotypically divided into a classical phenotype (pro-inflammatory, M1) or an alternative phenotype (anti-inflammatory, M2) with different physiological characteristics and biological functions in the inflammatory process. Betaine has been shown to exert anti-inflammatory effects. In this study, we aimed to verify the anti-inflammatory effects of betaine and elucidate its possible molecular mechanisms of action in vitro. Lipopolysaccharide (LPS)-activated microglial cells were used as an inflammatory model to study the anti-inflammatory efficacy of betaine and explore its mechanism of regulating microglial polarisation by investigating the morphological changes and associated inflammatory changes. Cytokine and inflammatory mediator expression was also measured by ELISA, flow cytometry, immunofluorescence, and western blot analysis. Toll-like receptor (TLR)-myeloid differentiation factor 88 (Myd88)-nuclear factor-kappa B (NF-κB) p65, p-NF-κB p65, IκB, p-IκB, IκB kinase (IKK), and p-IKK expression was determined by western blot analysis. Betaine significantly mitigated the production of pro-inflammatory cytokines and increased the release of anti-inflammatory cytokines. It promoted the conversion of the microglia from M1 to M2 phenotype by decreasing the expression of inducible nitric oxide synthase and CD16/32 and by increasing that of CD206 and arginase-1. Betaine treatment inhibited the TLR4/NF-κB pathways by attenuating the expression of TLR4-Myd88 and blocking the phosphorylation of IκB and IKK. In conclusion, betaine could significantly alleviate LPS-induced inflammation by regulating the polarisation of microglial phenotype; thus, it might be an effective therapeutic agent for neurological disorders. Full article
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15 pages, 348 KiB  
Review
Roles of Phenolic Compounds in the Reduction of Risk Factors of Cardiovascular Diseases
by Mariane Lutz, Eduardo Fuentes, Felipe Ávila, Marcelo Alarcón and Iván Palomo
Molecules 2019, 24(2), 366; https://doi.org/10.3390/molecules24020366 - 21 Jan 2019
Cited by 82 | Viewed by 7269
Abstract
The population is now living longer during the period classified as “elderly” (60 years and older), exhibiting multimorbidity associated to the lengthening of the average life span. The dietary intake of phenolic compounds (PC) may affect the physiology, disease development and progression during [...] Read more.
The population is now living longer during the period classified as “elderly” (60 years and older), exhibiting multimorbidity associated to the lengthening of the average life span. The dietary intake of phenolic compounds (PC) may affect the physiology, disease development and progression during the aging process, reducing risk factors of age related diseases. The aim of this review is to briefly describe some of the possible effects of a series of PC on the reduction of risk factors of the onset of cardiovascular diseases, considering their potential mechanisms of action. The main actions described for PC are associated with reduced platelet activity, anti-inflammatory effects, and the protection from oxidation to reduce LDL and the generation of advanced glycation end products. Preclinical and clinical evidence of the physiological effects of various PC is presented, as well as the health claims approved by regulatory agencies. Full article
(This article belongs to the Special Issue New Frontiers on the Metabolism, Bioavailability and Health Effects of Phenolic Compounds II)
11 pages, 1901 KiB  
Article
Stability of Principal Hydrolysable Tannins from Trapa taiwanensis Hulls
by Ching-Chiung Wang, Hsyeh-Fang Chen, Jin-Yi Wu and Lih-Geeng Chen
Molecules 2019, 24(2), 365; https://doi.org/10.3390/molecules24020365 - 21 Jan 2019
Cited by 13 | Viewed by 4431
Abstract
The fruit and hulls of the water caltrop (Trapa taiwanensis Nakai) are used as hepatoprotective herbal tea ingredients in Taiwan. The stability of hydrolysable tannins in herbal drinks has rarely been reported. In the present study, two hydrolysable tannins, tellimagrandin II (TGII) [...] Read more.
The fruit and hulls of the water caltrop (Trapa taiwanensis Nakai) are used as hepatoprotective herbal tea ingredients in Taiwan. The stability of hydrolysable tannins in herbal drinks has rarely been reported. In the present study, two hydrolysable tannins, tellimagrandin II (TGII) and 1,2,3,4,6-pentagalloylglucopyranose (PGG), were isolated from water caltrop hulls. The stability of the two compounds was evaluated by treatment with various pH buffer solutions, simulated gastric fluid and intestinal fluid, different temperatures, and photo-irradiation at 352 nm in different solvents. Results showed that TGII and PGG were more stable in a pH 2.0 buffer solution (with 91.88% remaining) and in a water solution with 352 nm irradiation (with 95% remaining). TGII and PGG were more stable in methanol or ethanol solutions (with >93.69% remaining) than in an aqueous solution (with <43.52% remaining) at 100 °C. In simulated gastric fluid, more than 96% of the hydrolysable tannins remained after incubation at 37 °C for 4 h. However, these hydrolysable tannins were unstable in simulated intestinal fluid, as after incubation at 37 °C for 9 h, the content of TGII had decreased to 31.40% and of PGG to 12.46%. The synthetic antioxidants, butyl hydroxy anisole (BHA), di-butyl hydroxy toluene (BHT), and propyl gallate, did not exhibit photoprotective effects on these hydrolysable tannins. However, catechin, a natural antioxidant, displayed a weak photoprotective effect. Ascorbic acid had a short-term thermal-protective effect but not a long-term protective effect. The different stability properties of hydrolysable tannins in solutions can be used in the development of related herbal teas in the future. Full article
(This article belongs to the Special Issue Special Issue Dedicated to Late Professor Takuo Okuda, “Tannins and Related Polyphenols Revisited: Chemistry, Biochemistry and Biological Activities”)
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14 pages, 2197 KiB  
Article
Highly Efficient Synthesis of Substituted 3,4-Dihydropyrimidin-2-(1H)-ones (DHPMs) Catalyzed by Hf(OTf)4: Mechanistic Insights into Reaction Pathways under Metal Lewis Acid Catalysis and Solvent-Free Conditions
by Rui Kong, Shuai-Bo Han, Jing-Ying Wei, Xiao-Chong Peng, Zhen-Biao Xie, Shan-Shan Gong and Qi Sun
Molecules 2019, 24(2), 364; https://doi.org/10.3390/molecules24020364 - 21 Jan 2019
Cited by 32 | Viewed by 5209
Abstract
In our studies on the catalytic activity of Group IVB transition metal Lewis acids, Hf(OTf)4 was identified as a highly potent catalyst for ”one-pot, three-component” Biginelli reaction. More importantly, it was found that solvent-free conditions, in contrast to solvent-based conditions, could dramatically [...] Read more.
In our studies on the catalytic activity of Group IVB transition metal Lewis acids, Hf(OTf)4 was identified as a highly potent catalyst for ”one-pot, three-component” Biginelli reaction. More importantly, it was found that solvent-free conditions, in contrast to solvent-based conditions, could dramatically promote the Hf(OTf)4-catalyzed formation of 3,4-dihydro-pyrimidin-2-(1H)-ones. To provide a mechanistic explanation, we closely examined the catalytic effects of Hf(OTf)4 on all three potential reaction pathways in both “sequential bimolecular condensations” and “one-pot, three-component” manners. The experimental results showed that the synergistic effects of solvent-free conditions and Hf(OTf)4 catalysis not only drastically accelerate Biginelli reaction by enhancing the imine route and activating the enamine route but also avoid the formation of Knoevenagel adduct, which may lead to an undesired byproduct. In addition, 1H-MMR tracing of the H-D exchange reaction of methyl acetoacetate in MeOH-d4 indicated that Hf(IV) cation may significantly accelerate ketone-enol tautomerization and activate the β-ketone moiety, thereby contributing to the overall reaction rate. Full article
(This article belongs to the Special Issue Advances in One-Pot Reaction)
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15 pages, 5885 KiB  
Article
Compounding MgCl2·6H2O with NH4Al(SO4)2·12H2O or KAl(SO4)2·12H2O to Obtain Binary Hydrated Salts as High-Performance Phase Change Materials
by Wanchun Sun, Yan Zhou, Jinxin Feng, Xiaoming Fang, Ziye Ling and Zhengguo Zhang
Molecules 2019, 24(2), 363; https://doi.org/10.3390/molecules24020363 - 21 Jan 2019
Cited by 20 | Viewed by 7259
Abstract
Developing phase change materials (PCMs) with suitable phase change temperatures and high latent heat is of great significance for accelerating the development of latent heat storage technology to be applied in solar water heating (SWH) systems. The phase change performances of two mixtures, [...] Read more.
Developing phase change materials (PCMs) with suitable phase change temperatures and high latent heat is of great significance for accelerating the development of latent heat storage technology to be applied in solar water heating (SWH) systems. The phase change performances of two mixtures, NH4Al(SO4)2·12H2O-MgCl2·6H2O (mixture-A) and KAl(SO4)2·12H2O-MgCl2·6H2O (mixture-B), were investigated in this paper. Based on the DSC results, the optimum contents of MgCl2·6H2O in mixture-A and mixture-B were determined to be 30 wt%. It is found that the melting points of mixture-A (30 wt% MgCl2·6H2O) and mixture-B (30 wt% MgCl2·6H2O) are 64.15 °C and 60.15 °C, respectively, which are suitable for SWH systems. Moreover, two mixtures have high latent heat of up to 192.1 kJ/kg and 198.1 kJ/kg as well as exhibit little supercooling. After 200 cycles heating-cooling experiments, the deviations in melting point and melting enthalpy of mixture-A are only 1.51% and 1.20%, respectively. Furthermore, the XRD patterns before and after the cycling experiments show that mixture-A possesses good structure stability. These excellent thermal characteristics make mixture-A show great potential for SWH systems. Full article
(This article belongs to the Special Issue Phase Change Materials)
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8 pages, 1644 KiB  
Communication
Methyl Salicylate Enhances Flavonoid Biosynthesis in Tea Leaves by Stimulating the Phenylpropanoid Pathway
by Xin Li, Li-Ping Zhang, Lan Zhang, Peng Yan, Golam Jalal Ahammed and Wen-Yan Han
Molecules 2019, 24(2), 362; https://doi.org/10.3390/molecules24020362 - 21 Jan 2019
Cited by 60 | Viewed by 5930
Abstract
The phytohormone salicylic acid (SA) is a secondary metabolite that regulates plant growth, development and responses to stress. However, the role of SA in the biosynthesis of flavonoids (a large class of secondary metabolites) in tea (Camellia sinensis L.) remains largely unknown. [...] Read more.
The phytohormone salicylic acid (SA) is a secondary metabolite that regulates plant growth, development and responses to stress. However, the role of SA in the biosynthesis of flavonoids (a large class of secondary metabolites) in tea (Camellia sinensis L.) remains largely unknown. Here, we show that exogenous methyl salicylate (MeSA, the methyl ester of SA) increased flavonoid concentration in tea leaves in a dose-dependent manner. While a moderate concentration of MeSA (1 mM) resulted in the highest increase in flavonoid concentration, a high concentration of MeSA (5 mM) decreased flavonoid concentration in tea leaves. A time-course of flavonoid concentration following 1 mM MeSA application showed that flavonoid concentration peaked at 2 days after treatment and then gradually declined, reaching a concentration lower than that of control after 6 days. Consistent with the time course of flavonoid concentration, MeSA enhanced the activity of phenylalanine ammonia-lyase (PAL, a key enzyme for the biosynthesis of flavonoids) as early as 12 h after the treatment, which peaked after 1 day and then gradually declined upto 6 days. qRT-PCR analysis of the genes involved in flavonoid biosynthesis revealed that exogenous MeSA upregulated the expression of genes such as CsPAL, CsC4H, Cs4CL, CsCHS, CsCHI, CsF3H, CsDFR, CsANS and CsUFGT in tea leaves. These results suggest a role for MeSA in modulating the flavonoid biosynthesis in green tea leaves, which might have potential implications in manipulating the tea quality and stress tolerance in tea plants. Full article
(This article belongs to the Special Issue Polyphenols in Crops, Medicinal and Wild Edible Plants: From Their Metabolism to Their Benefits for Human Health)
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12 pages, 3518 KiB  
Article
Solution Combustion Synthesis of Cr2O3 Nanoparticles and the Catalytic Performance for Dehydrofluorination of 1,1,1,3,3-Pentafluoropropane to 1,3,3,3-Tetrafluoropropene
by Haili Wang, Wenfeng Han, Xiliang Li, Bing Liu, Haodong Tang and Ying Li
Molecules 2019, 24(2), 361; https://doi.org/10.3390/molecules24020361 - 20 Jan 2019
Cited by 23 | Viewed by 4810
Abstract
Cr2O3 nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr2O3 and Cr2O3 prepared by a precipitation method were also included for comparison. [...] Read more.
Cr2O3 nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr2O3 and Cr2O3 prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr2O3 catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH3-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF3CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr2O3 prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr2O3 and commercial Cr2O3, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr2O3, Cr2O3-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr2O3 prepared by SCS after reaction was not detected, indicating high resistance to sintering. Full article
(This article belongs to the Special Issue Nanomaterials for Catalysis)
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11 pages, 1012 KiB  
Article
Development and Validation of a LC–MS/MS-Based Assay for Quantification of Free and Total Omega 3 and 6 Fatty Acids from Human Plasma
by Vlad Serafim, Diana-Andreea Tiugan, Nicoleta Andreescu, Alexandra Mihailescu, Corina Paul, Iulian Velea, Maria Puiu and Mihai Dinu Niculescu
Molecules 2019, 24(2), 360; https://doi.org/10.3390/molecules24020360 - 20 Jan 2019
Cited by 49 | Viewed by 8918
Abstract
Few high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods have been developed for the full quantitation of fatty acids from human plasma without derivatization. Therefore, we propose a method that requires fewer sample preparation steps, which can be used for the quantitation of several [...] Read more.
Few high-performance liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods have been developed for the full quantitation of fatty acids from human plasma without derivatization. Therefore, we propose a method that requires fewer sample preparation steps, which can be used for the quantitation of several polyunsaturated fatty acids in human plasma. The method offers rapid, accurate, sensitive, and simultaneous quantification of omega 3 (α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and omega 6 fatty acids (arachidonic and linoleic acids) using high-performance LC-MS/MS. The selected fatty acids were analysed in lipid extracts from both free and total forms. Chromatographic separation was achieved using a reversed phase C18 column with isocratic flow using ammonium acetate for improving negative electrospray ionization (ESI) response. Mass detection was performed in multiple reaction monitoring (MRM) mode, and deuterated internal standards were used for each target compound. The limits of quantification were situated in the low nanomolar range, excepting linoleic acid, for which the limit was in the high nanomolar range. The method was validated according to the U.S. Department of Health and Human Services guidelines, and offers a fast, sensitive, and reliable quantification of selected omega 3 and 6 fatty acids in human plasma. Full article
(This article belongs to the Section Analytical Chemistry)
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40 pages, 3852 KiB  
Review
Traditional Uses, Botany, Phytochemistry, Pharmacology, Pharmacokinetics and Toxicology of Xanthium strumarium L.: A Review
by Wenxiang Fan, Linhong Fan, Chengyi Peng, Qing Zhang, Li Wang, Lin Li, Jiaolong Wang, Dayong Zhang, Wei Peng and Chunjie Wu
Molecules 2019, 24(2), 359; https://doi.org/10.3390/molecules24020359 - 19 Jan 2019
Cited by 91 | Viewed by 13232
Abstract
Xanthium strumarium L. (Asteraceae) is a common and well-known traditional Chinese herbal medicine usually named Cang-Er-Zi, and has been used for thousands of years in China. The purpose of this paper is to summarize the progress of modern research, and provide a systematic [...] Read more.
Xanthium strumarium L. (Asteraceae) is a common and well-known traditional Chinese herbal medicine usually named Cang-Er-Zi, and has been used for thousands of years in China. The purpose of this paper is to summarize the progress of modern research, and provide a systematic review on the traditional usages, botany, phytochemistry, pharmacology, pharmacokinetics, and toxicology of the X. strumarium. Moreover, an in-depth discussion of some valuable issues and possible development for future research on this plant is also given. X. strumarium, as a traditional herbal medicine, has been extensively applied to treat many diseases, such as rhinitis, nasal sinusitis, headache, gastric ulcer, urticaria, rheumatism bacterial, fungal infections and arthritis. Up to now, more than 170 chemical constituents have been isolated and identified from X. strumarium, including sesquiterpenoids, phenylpropenoids, lignanoids, coumarins, steroids, glycosides, flavonoids, thiazides, anthraquinones, naphthoquinones and other compounds. Modern research shows that the extracts and compounds from X. strumarium possess wide-ranging pharmacological effects, including anti- allergic rhinitis (AR) effects, anti-tumor effects, anti-inflammatory and analgesic effects, insecticide and antiparasitic effects, antioxidant effects, antibacterial and antifungal effects, antidiabetic effects, antilipidemic effects and antiviral effects. However, further research should focus on investigating bioactive compounds and demonstrate the mechanism of its detoxification, and more reasonable quality control standards for X. strumarium should also be established. Full article
(This article belongs to the Section Natural Products Chemistry)
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21 pages, 4680 KiB  
Article
Tripleurin XIIc: Peptide Folding Dynamics in Aqueous and Hydrophobic Environment Mimic Using Accelerated Molecular Dynamics
by Chetna Tyagi, Tamás Marik, András Szekeres, Csaba Vágvölgyi, László Kredics and Ferenc Ötvös
Molecules 2019, 24(2), 358; https://doi.org/10.3390/molecules24020358 - 19 Jan 2019
Cited by 10 | Viewed by 4706
Abstract
Peptaibols are a special class of fungal peptides with an acetylated N-terminus and a C-terminal 1,2-amino alcohol along with non-standard amino acid residues. New peptaibols named tripleurins were recently identified from a strain of the filamentous fungal species Trichoderma pleuroti, which [...] Read more.
Peptaibols are a special class of fungal peptides with an acetylated N-terminus and a C-terminal 1,2-amino alcohol along with non-standard amino acid residues. New peptaibols named tripleurins were recently identified from a strain of the filamentous fungal species Trichoderma pleuroti, which is known to cause green mould disease on cultivated oyster mushrooms. To understand the mode of action of these peptaibols, the three-dimensional structure of tripleurin (TPN) XIIc, an 18-mer peptide, was elucidated using an enhanced sampling method, accelerated MD, in water and chloroform solvents. Non-standard residues were parameterized by the Restrained Electrostatic Potential (RESP) charge fitting method. The dihedral distribution indicated towards a right-handed helical formation for TPN XIIc in both solvents. Dihedral angle based principal component analysis revealed a propensity for a slightly bent, helical folded conformation in water solvent, while two distinct conformations were revealed in chloroform: One that folds into highly bent helical structure that resembles a beta-hairpin and another with an almost straight peptide backbone appearing as a rare energy barrier crossing event. The hinge-like movement of the terminals was also observed and is speculated to be functionally relevant. The convergence and efficient sampling is addressed using Cartesian PCA and Kullback-Leibler divergence methods. Full article
(This article belongs to the Special Issue Molecular Simulation of Protein Structure, Dynamics and Interactions)
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10 pages, 2505 KiB  
Article
Rare Earth Hydroxide as a Precursor for Controlled Fabrication of Uniform β-NaYF4 Nanoparticles: A Novel, Low Cost, and Facile Method
by Lili Xu, Man Wang, Qing Chen, Jiajia Yang, Wubin Zheng, Guanglei Lv, Zewei Quan and Chunxia Li
Molecules 2019, 24(2), 357; https://doi.org/10.3390/molecules24020357 - 19 Jan 2019
Cited by 5 | Viewed by 4353
Abstract
In recent years, rare earth doped upconversion nanocrystals have been widely used in different fields owing to their unique merits. Although rare earth chlorides and trifluoroacetates are commonly used precursors for the synthesis of nanocrystals, they have certain disadvantages. For example, rare earth [...] Read more.
In recent years, rare earth doped upconversion nanocrystals have been widely used in different fields owing to their unique merits. Although rare earth chlorides and trifluoroacetates are commonly used precursors for the synthesis of nanocrystals, they have certain disadvantages. For example, rare earth chlorides are expensive and rare earth trifluoroacetates produce toxic gases during the reaction. To overcome these drawbacks, we use the less expensive rare earth hydroxide as a precursor to synthesize β-NaYF4 nanoparticles with multiform shapes and sizes. Small-sized nanocrystals (15 nm) can be obtained by precisely controlling the synthesis conditions. Compared with the previous methods, the current method is more facile and has lower cost. In addition, the defects of the nanocrystal surface are reduced through constructing core–shell structures, resulting in enhanced upconversion luminescence intensity. Full article
(This article belongs to the Special Issue Smart and Functional Polymers)
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15 pages, 2264 KiB  
Article
Discrimination of Structural and Immunological Features of Polysaccharides from Persimmon Leaves at Different Maturity Stages
by Young-Ran Song, Ah-Ram Han, Tae-Gyu Lim, Ji-Hyun Kang and Hee-Do Hong
Molecules 2019, 24(2), 356; https://doi.org/10.3390/molecules24020356 - 19 Jan 2019
Cited by 10 | Viewed by 3449
Abstract
In this study, we investigated changes in the structural and immunological features of polysaccharides (S1-PLE0, S2-PLE0, and S3-PLE0) extracted from persimmon leaves at three different growth stages. Physicochemical analyses revealed that their chemical compositions, molecular weight distributions, and linkage types differed. High-performance size-exclusion [...] Read more.
In this study, we investigated changes in the structural and immunological features of polysaccharides (S1-PLE0, S2-PLE0, and S3-PLE0) extracted from persimmon leaves at three different growth stages. Physicochemical analyses revealed that their chemical compositions, molecular weight distributions, and linkage types differed. High-performance size-exclusion chromatograms showed that the molecular weights of the polysaccharides increased during successive growth stages. In addition, seasonal variation of persimmon leaves affected the sugar compositions and glycosidic linkages in the polysaccharides. S2-PLE0 was composed of comparatively more galactose, arabinose, rhamnose, xylose, and galacturonic acid, showing the presence of β-glucopyranoside linkages. Significant differences also occurred in their immunostimulatory effects on RAW264.7 macrophages, with respect to which their activities could be ordered as S2-PLE0 > S3-PLE0 > S1-PLE0. Evidently, S2-PLE0 showed the greatest immunostimulatory activity by enhancing the phagocytic capacity and promoting nitric oxide (NO) and cytokines secretion through the upregulation of their gene expression in macrophages. These results suggest that differences in the structural features of polysaccharides according to the different maturity of persimmon leaves might impact their immunostimulatory properties. The results also provide a basis for optimizing persimmon leaf cultivation strategies for food and medical uses of the polysaccharides. Full article
(This article belongs to the Special Issue Herbal Carbohydrates: Chemistry, Biology and Application)
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35 pages, 18059 KiB  
Review
Recent Developments in the Functionalization of Betulinic Acid and Its Natural Analogues: A Route to New Bioactive Compounds
by Joana L. C. Sousa, Carmen S. R. Freire, Armando J. D. Silvestre and Artur M. S. Silva
Molecules 2019, 24(2), 355; https://doi.org/10.3390/molecules24020355 - 19 Jan 2019
Cited by 80 | Viewed by 8797
Abstract
Betulinic acid (BA) and its natural analogues betulin (BN), betulonic (BoA), and 23-hydroxybetulinic (HBA) acids are lupane-type pentacyclic triterpenoids. They are present in many plants and display important biological activities. This review focuses on the chemical transformations used to functionalize BA/BN/BoA/HBA in order [...] Read more.
Betulinic acid (BA) and its natural analogues betulin (BN), betulonic (BoA), and 23-hydroxybetulinic (HBA) acids are lupane-type pentacyclic triterpenoids. They are present in many plants and display important biological activities. This review focuses on the chemical transformations used to functionalize BA/BN/BoA/HBA in order to obtain new derivatives with improved biological activity, covering the period since 2013 to 2018. It is divided by the main chemical transformations reported in the literature, including amination, esterification, alkylation, sulfonation, copper(I)-catalyzed alkyne-azide cycloaddition, palladium-catalyzed cross-coupling, hydroxylation, and aldol condensation reactions. In addition, the synthesis of heterocycle-fused BA/HBA derivatives and polymer‒BA conjugates are also addressed. The new derivatives are mainly used as antitumor agents, but there are other biological applications such as antimalarial activity, drug delivery, bioimaging, among others. Full article
(This article belongs to the Section Organic Chemistry)
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18 pages, 4163 KiB  
Article
Selective Targeting of the Interconversion between Glucosylceramide and Ceramide by Scaffold Tailoring of Iminosugar Inhibitors
by Cécile Baudoin-Dehoux, Tessa Castellan, Frédéric Rodriguez, Arnaud Rives, Fabien Stauffert, Virginie Garcia, Thierry Levade, Philippe Compain and Yves Génisson
Molecules 2019, 24(2), 354; https://doi.org/10.3390/molecules24020354 - 19 Jan 2019
Cited by 5 | Viewed by 4841
Abstract
A series of simple C-alkyl pyrrolidines already known as cytotoxic inhibitors of ceramide glucosylation in melanoma cells can be converted into their corresponding 6-membered analogues by means of a simple ring expansion. This study illustrated how an isomerisation from iminosugar pyrrolidine toward [...] Read more.
A series of simple C-alkyl pyrrolidines already known as cytotoxic inhibitors of ceramide glucosylation in melanoma cells can be converted into their corresponding 6-membered analogues by means of a simple ring expansion. This study illustrated how an isomerisation from iminosugar pyrrolidine toward piperidine could invert their targeting from glucosylceramide (GlcCer) formation toward GlcCer hydrolysis. Thus, we found that the 5-membered ring derivatives did not inhibit the hydrolysis reaction of GlcCer catalysed by lysosomal β-glucocerebrosidase (GBA). On the other hand, the ring-expanded C-alkyl piperidine isomers, non-cytotoxic and inactive regarding ceramide glucosylation, revealed to be potent inhibitors of GBA. A molecular docking study showed that the positions of the piperidine ring of the compound 6b and its analogous 2-O-heptyl DIX 8 were similar to that of isofagomine. Furthermore, compound 6b promoted mutant GBA enhancements over 3-fold equivalent to that of the related O-Hept DIX 8 belonging to one of the most potent iminosugar-based pharmacological chaperone series reported to date. Full article
(This article belongs to the Special Issue Small Molecule Drug Design)
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9 pages, 2197 KiB  
Article
Deep-Blue and Hybrid-White Organic Light Emitting Diodes Based on a Twisting Carbazole-Benzofuro[2,3-b]Pyrazine Fluorescent Emitter
by Chen-Chao Huang, Miao-Miao Xue, Fu-Peng Wu, Yi Yuan, Liang-Sheng Liao and Man-Keung Fung
Molecules 2019, 24(2), 353; https://doi.org/10.3390/molecules24020353 - 19 Jan 2019
Cited by 20 | Viewed by 4951
Abstract
A novel deep-blue fluorescent emitter was designed and synthesized. The external quantum efficiency (ηEQE) of the blue-emitting, doped, organic light-emitting diode (OLED) was as high as 4.34%. The device also exhibited an excellent color purity with Commission Internationale de l’Eclairage (CIE) [...] Read more.
A novel deep-blue fluorescent emitter was designed and synthesized. The external quantum efficiency (ηEQE) of the blue-emitting, doped, organic light-emitting diode (OLED) was as high as 4.34%. The device also exhibited an excellent color purity with Commission Internationale de l’Eclairage (CIE) coordinates of x = 0.15 and y = 0.05. In addition, the triplet energy had a value of 2.7 eV, which is rare for an emitter with deep-blue emission, which makes it a preferred choice for high-performance white OLEDs. By optimizing the device architectures, the color of hybrid-white OLEDs could be tunable from warm white to cool white using the aforementioned material as a bifunctional material. That is, the ηEQE of the hybrid warm-white OLED is 20.1% with a CIE x and y of 0.46 and 0.48 and the ηEQE of the hybrid cool-white OLED is 9% with a CIE x and y of 0.34 and 0.33. Full article
(This article belongs to the Special Issue Organic Light Emitting Diodes II)
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17 pages, 3450 KiB  
Article
Synthesis and Gelling Abilities of Polyfunctional Cyclohexane-1,2-dicarboxylic Acid Bisamides: Influence of the Hydroxyl Groups
by Bernat Pi-Boleda, María Campos, Marta Sans, Antonio Basavilbaso, Ona Illa, Vicenç Branchadell, Juan Carlos Estévez and Rosa M. Ortuño
Molecules 2019, 24(2), 352; https://doi.org/10.3390/molecules24020352 - 19 Jan 2019
Cited by 2 | Viewed by 4440
Abstract
New enantiomerically pure C16-alkyl diamides derived from trihydroxy cyclohexane-1,2-dicarboxylic acid have been synthesized from (−)-shikimic acid. The hydroxyl groups in these compounds are free or, alternatively, they present full or partial protection. Their gelling abilities towards several solvents have been tested [...] Read more.
New enantiomerically pure C16-alkyl diamides derived from trihydroxy cyclohexane-1,2-dicarboxylic acid have been synthesized from (−)-shikimic acid. The hydroxyl groups in these compounds are free or, alternatively, they present full or partial protection. Their gelling abilities towards several solvents have been tested and rationalized by means of the combined use of Hansen solubility parameters, scanning electron microscopy (SEM), and circular dichroism (CD), as well as computational calculations. All the results allowed us to account for the capability of each type of organogelator to interact with different solvents and for the main mode of aggregation. Thus, compounds with fully protected hydroxyl groups are good organogelators for methanol and ethanol. In contrast, a related compound bearing three free hydroxyl groups is insoluble in water and polar solvents including alcohols but it is able to gelate some low-polarity solvents. This last behavior can be justified by strong hydrogen bonding between molecules of organogelator, which competes advantageously with polar solvent interactions. As an intermediate case, an organogelator with two free hydroxyl groups presents an ambivalent ability to gelate both apolar and polar solvents by means of two aggregation patterns. These involve hydrogen bonding interactions of the unprotected hydroxyl groups in apolar solvents and intermolecular interactions between amide groups in polar ones. Full article
(This article belongs to the Section Organic Chemistry)
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27 pages, 2288 KiB  
Review
Peptide-Based Drug-Delivery Systems in Biotechnological Applications: Recent Advances and Perspectives
by Diego Tesauro, Antonella Accardo, Carlo Diaferia, Vittoria Milano, Jean Guillon, Luisa Ronga and Filomena Rossi
Molecules 2019, 24(2), 351; https://doi.org/10.3390/molecules24020351 - 19 Jan 2019
Cited by 189 | Viewed by 13144
Abstract
Peptides of natural and synthetic sources are compounds operating in a wide range of biological interactions. They play a key role in biotechnological applications as both therapeutic and diagnostic tools. They are easily synthesized thanks to solid-phase peptide devices where the amino acid [...] Read more.
Peptides of natural and synthetic sources are compounds operating in a wide range of biological interactions. They play a key role in biotechnological applications as both therapeutic and diagnostic tools. They are easily synthesized thanks to solid-phase peptide devices where the amino acid sequence can be exactly selected at molecular levels, by tuning the basic units. Recently, peptides achieved resounding success in drug delivery and in nanomedicine smart applications. These applications are the most significant challenge of recent decades: they can selectively deliver drugs to only pathological tissues whilst saving the other districts of the body. This specific feature allows a reduction in the drug side effects and increases the drug efficacy. In this context, peptide-based aggregates present many advantages, including biocompatibility, high drug loading capacities, chemical diversity, specific targeting, and stimuli responsive drug delivery. A dual behavior is observed: on the one hand they can fulfill a structural and bioactive role. In this review, we focus on the design and the characterization of drug delivery systems using peptide-based carriers; moreover, we will also highlight the peptide ability to self-assemble and to actively address nanosystems toward specific targets. Full article
(This article belongs to the Special Issue Molecules for Biotechnologies)
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18 pages, 2281 KiB  
Article
Inhibition of T Cell Receptor Activation by Semi-Synthetic Sesquiterpene Lactone Derivatives and Molecular Modeling of Their Interaction with Glutathione and Tyrosine Kinase ZAP-70
by Andrei I. Khlebnikov, Igor A. Schepetkin, Anarkul S. Kishkentaeva, Zhanar R. Shaimerdenova, Gayane A. Atazhanova, Sergazy M. Adekenov, Liliya N. Kirpotina and Mark T. Quinn
Molecules 2019, 24(2), 350; https://doi.org/10.3390/molecules24020350 - 19 Jan 2019
Cited by 5 | Viewed by 4744
Abstract
A variety of natural compounds have been shown to modulate T cell receptor (TCR) activation, including natural sesquiterpene lactones (SLs). In the present studies, we evaluated the biological activity of 11 novel semi-synthetic SLs to determine their ability to modulate TCR activation. Of [...] Read more.
A variety of natural compounds have been shown to modulate T cell receptor (TCR) activation, including natural sesquiterpene lactones (SLs). In the present studies, we evaluated the biological activity of 11 novel semi-synthetic SLs to determine their ability to modulate TCR activation. Of these compounds, α -epoxyarglabin, cytisinyl epoxyarglabin, 1 β ,10 α -epoxyargolide, and chloroacetate grosheimin inhibited anti-CD3-induced Ca2+ mobilization and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in Jurkat T cells. We also found that the active SLs depleted intracellular glutathione (GSH) in Jurkat T cells, supporting their reactivity towards thiol groups. Because the zeta-chain associated tyrosine kinase 70 kDa (ZAP-70) is essential for TCR signaling and contains a tandem SH2 region that is highly enriched with multiple cysteines, we performed molecular docking of natural SLs and their semi-synthetic derivatives into the ZAP-70 binding site. The docking showed that the distance between the carbon atom of the exocyclic methylene group and the sulfur atom in Cys39 of the ZAP-70 tandem SH2 module was 3.04–5.3 Å for active compounds. Furthermore, the natural SLs and their derivatives could be differentiated by their ability to react with the Cys39 SH-group. We suggest that natural and/or semi-synthetic SLs with an α -methylene- γ -lactone moiety can specifically target GSH and the kinase site of ZAP-70 and inhibit the initial phases of TCR activation. Full article
(This article belongs to the Section Medicinal Chemistry)
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13 pages, 987 KiB  
Article
The Synthesis of 3H-Labelled 8-Azido-N6-Benzyladenine and Related Compounds for Photoaffinity Labelling of Cytokinin-Binding Proteins
by David. S. Letham, Xue-Dong Zhang and Charles H. Hocart
Molecules 2019, 24(2), 349; https://doi.org/10.3390/molecules24020349 - 18 Jan 2019
Cited by 3 | Viewed by 4176
Abstract
The biology of the group of plant hormones termed cytokinins is reviewed to reveal areas where further studies of cytokinin-binding proteins could be significant. Such areas include: inhibition of human tumour cell growth by cytokinin ribosides, the role of cytokinins in the development [...] Read more.
The biology of the group of plant hormones termed cytokinins is reviewed to reveal areas where further studies of cytokinin-binding proteins could be significant. Such areas include: inhibition of human tumour cell growth by cytokinin ribosides, the role of cytokinins in the development of diverse micro-organisms including the cyanobacteria and Mycobacterium tuberculosis, the very rapid responses of plant cells to exogenous cytokinins, and other aspects of cytokinin plant biology. Photoaffinity labelling (PAL) coupled to the recent advances in HPLC of proteins and mass spectral analysis and sequencing of proteins, may have relevance to these areas. To facilitate PAL, we present experimental details for two methods for synthesis of 8-azido-N6-benzyladenine, which has the azido affinity group in the preferred position of the purine ring. Synthesis from [2-3H]adenosine yielded the above-mentioned PAL reagent with 3H in the purine ring and also gave labelled 9-riboside and 8-azido-N6,9-dibenzyladenine. 8-Azido-N6-benzyladenine was also prepared from 6,8-dichloropurine by a facile synthesis, which would allow a label to be sited in the benzyl group where substituents can also be introduced to vary cytokinin activity. The use of inactive cytokinin analogues in assessing the significance of PAL is discussed. Full article
(This article belongs to the Section Bioorganic Chemistry)
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13 pages, 2697 KiB  
Article
Revealing the Presence of a Symbolic Sequence Representing Multiple Nucleotides Based on K-Means Clustering of Oligonucleotides
by Byoungsang Lee, So Yeon Ahn, Charles Park, James J. Moon, Jung Heon Lee, Dan Luo, Soong Ho Um and Seung Won Shin
Molecules 2019, 24(2), 348; https://doi.org/10.3390/molecules24020348 - 18 Jan 2019
Cited by 1 | Viewed by 3711
Abstract
In biological systems, a few sequence differences diversify the hybridization profile of nucleotides and enable the quantitative control of cellular metabolism in a cooperative manner. In this respect, the information required for a better understanding may not be in each nucleotide sequence, but [...] Read more.
In biological systems, a few sequence differences diversify the hybridization profile of nucleotides and enable the quantitative control of cellular metabolism in a cooperative manner. In this respect, the information required for a better understanding may not be in each nucleotide sequence, but representative information contained among them. Existing methodologies for nucleotide sequence design have been optimized to track the function of the genetic molecule and predict interaction with others. However, there has been no attempt to extract new sequence information to represent their inheritance function. Here, we tried to conceptually reveal the presence of a representative sequence from groups of nucleotides. The combined application of the K-means clustering algorithm and the social network analysis theorem enabled the effective calculation of the representative sequence. First, a “common sequence” is made that has the highest hybridization property to analog sequences. Next, the sequence complementary to the common sequence is designated as a ‘representative sequence’. Based on this, we obtained a representative sequence from multiple analog sequences that are 8–10-bases long. Their hybridization was empirically tested, which confirmed that the common sequence had the highest hybridization tendency, and the representative sequence better alignment with the analogs compared to a mere complementary. Full article
(This article belongs to the Section Medicinal Chemistry)
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15 pages, 1572 KiB  
Review
Peptides for Skin Protection and Healing in Amphibians
by Ilaria Demori, Zeinab El Rashed, Viola Corradino, Annamaria Catalano, Leila Rovegno, Linda Queirolo, Sebastiano Salvidio, Emanuele Biggi, Matteo Zanotti-Russo, Laura Canesi, Alessandro Catenazzi and Elena Grasselli
Molecules 2019, 24(2), 347; https://doi.org/10.3390/molecules24020347 - 18 Jan 2019
Cited by 58 | Viewed by 15867
Abstract
Amphibian skin is not to be considered a mere tegument; it has a multitude of functions related to respiration, osmoregulation, and thermoregulation, thus allowing the individuals to survive and thrive in the terrestrial environment. Moreover, amphibian skin secretions are enriched with several peptides, [...] Read more.
Amphibian skin is not to be considered a mere tegument; it has a multitude of functions related to respiration, osmoregulation, and thermoregulation, thus allowing the individuals to survive and thrive in the terrestrial environment. Moreover, amphibian skin secretions are enriched with several peptides, which defend the skin from environmental and pathogenic insults and exert many other biological effects. In this work, the beneficial effects of amphibian skin peptides are reviewed, in particular their role in speeding up wound healing and in protection from oxidative stress and UV irradiation. A better understanding of why some species seem to resist several environmental insults can help to limit the ongoing amphibian decline through the development of appropriate strategies, particularly against pathologies such as viral and fungal infections. Full article
(This article belongs to the Section Bioorganic Chemistry)
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