Molecules

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Open AccessArticle

Synthesis and Antiviral Activity of N-Phenylbenzamide Derivatives, a Novel Class of Enterovirus 71 Inhibitors

by Xing-Yue Ji, Hui-Qiang Wang, Lan-Hu Hao, Wei-Ying He, Rong-Mei Gao, Yan-Ping Li, Yu-Huan Li, Jian-Dong Jiang and Zhuo-Rong Li

Molecules 2013, 18(3), 3630-3640; https://doi.org/10.3390/molecules18033630 - 21 Mar 2013

Cited by 22 | Viewed by 7592

Abstract

A series of novel N-phenylbenzamide derivatives were synthesized and their anti-EV 71 activities were assayed in vitro. Among the compounds tested, 3-amino-N-(4-bromophenyl)-4-methoxybenzamide (1e) was active against the EV 71 strains tested at low micromolar concentrations, with IC [...] Read more.

A series of novel N-phenylbenzamide derivatives were synthesized and their anti-EV 71 activities were assayed in vitro. Among the compounds tested, 3-amino-N-(4-bromophenyl)-4-methoxybenzamide (1e) was active against the EV 71 strains tested at low micromolar concentrations, with IC₅₀ values ranging from 5.7 ± 0.8–12 ± 1.2 μM, and its cytotoxicity to Vero cells (TC₅₀ = 620 ± 0.0 μM) was far lower than that of pirodavir (TC₅₀ = 31 ± 2.2 μM). Based on these results, compound 1e is a promising lead compound for the development of anti-EV 71 drugs. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

Efficient Synthesis and Anti-Fungal Activity of Oleanolic Acid Oxime Esters

by Hanqing Zhao, Minjie Zhou, Lifeng Duan, Wei Wang, Jianjun Zhang, Daoquan Wang and Xiaomei Liang

Molecules 2013, 18(3), 3615-3629; https://doi.org/10.3390/molecules18033615 - 21 Mar 2013

Cited by 52 | Viewed by 8218

Abstract

In order to develop potential glucosamine-6-phosphate synthase inhibitors and anti-fungal agents, twenty five oleanolic acid oxime esters were synthesized in an efficient way. The structures of the new compounds were confirmed by MS, HRMS, ¹H-NMR and ¹³C-NMR. Preliminary studies based on [...] Read more.

In order to develop potential glucosamine-6-phosphate synthase inhibitors and anti-fungal agents, twenty five oleanolic acid oxime esters were synthesized in an efficient way. The structures of the new compounds were confirmed by MS, HRMS, ¹H-NMR and ¹³C-NMR. Preliminary studies based on means of the Elson-Morgan method indicated that many compounds exhibited some inhibitory activity of glucosamine-6-phosphate synthase (GlmS), and the original fungicidal activities results showed that some of the compounds exhibited good fungicidal activities towards Sclerotinia sclerotiorum (Lib.) de Bary, Rhizoctonia solani Kuhn and Botrytis cinerea Pers at the concentration of 50 µg/mL. These compounds would thus merit further study and development as antifungal agents. Full article

(This article belongs to the Special Issue Triterpenes and Triterpenoids 2013)

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Open AccessArticle

Synthesis and Characterization of Celecoxib Derivatives as Possible Anti-Inflammatory, Analgesic, Antioxidant, Anticancer and Anti-HCV Agents

by Ş. Güniz Küçükgüzel, İnci Coşkun, Sevil Aydın, Göknur Aktay, Şule Gürsoy, Özge Çevik, Özlem Bingöl Özakpınar, Derya Özsavcı, Azize Şener, Neerja Kaushik-Basu, Amartya Basu and Tanaji T. Talele

Molecules 2013, 18(3), 3595-3614; https://doi.org/10.3390/molecules18033595 - 21 Mar 2013

Cited by 44 | Viewed by 11058

Abstract

A series of novel N-(3-substituted aryl/alkyl-4-oxo-1,3-thiazolidin-2-ylidene)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamides 2a–e were synthesized by the addition of ethyl a-bromoacetate and anhydrous sodium acetate in dry ethanol to N-(substituted aryl/alkylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoro-methyl)-1H-pyrazol-1-yl]benzene sulfonamides 1a–e, which were synthesized by the [...] Read more.

A series of novel N-(3-substituted aryl/alkyl-4-oxo-1,3-thiazolidin-2-ylidene)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamides 2a–e were synthesized by the addition of ethyl a-bromoacetate and anhydrous sodium acetate in dry ethanol to N-(substituted aryl/alkylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoro-methyl)-1H-pyrazol-1-yl]benzene sulfonamides 1a–e, which were synthesized by the reaction of alkyl/aryl isothiocyanates with celecoxib. The structures of the isolated products were determined by spectral methods and their anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV NS5B RNA-dependent RNA polymerase (RdRp) activities evaluated. The compounds were also tested for gastric toxicity and selected compound 1a was screened for its anticancer activity against 60 human tumor cell lines. These investigations revealed that compound 1a exhibited anti-inflammatory and analgesic activities and further did not cause tissue damage in liver, kidney, colon and brain compared to untreated controls or celecoxib. Compounds 1c and 1d displayed modest inhibition of HCV NS5B RdRp activity. In conclusion, N-(ethylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (1a) may have the potential to be developed into a therapeutic agent. Full article

(This article belongs to the Special Issue Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry)

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Open AccessArticle

Design, Synthesis and Evaluation of 3-(2-Aminoheterocycle)-4-benzyloxyphenylbenzamide Derivatives as BACE-1 Inhibitors

by Shihao Shangguan, Fei Wang, Yong Liao, Haiping Yu, Jia Li, Wenhai Huang, Haihong Hu, Lushan Yu, Yongzhou Hu and Rong Sheng

Molecules 2013, 18(3), 3577-3594; https://doi.org/10.3390/molecules18033577 - 20 Mar 2013

Cited by 6 | Viewed by 6477

Abstract

Three series of 3-(2-aminoheterocycle)-4-benzyloxyphenylbenzamide derivatives, 2-aminooxazoles, 2-aminothiazoles, and 2-amino-6H-1,3,4-thiadizines were designed, synthesized and evaluated as β-secretase (BACE-1) inhibitors. Preliminary structure-activity relationships revealed that the existence of a 2-amino-6H-1,3,4-thiadizine moiety and α-naphthyl group were favorable for BACE-1 inhibition. Among [...] Read more.

Three series of 3-(2-aminoheterocycle)-4-benzyloxyphenylbenzamide derivatives, 2-aminooxazoles, 2-aminothiazoles, and 2-amino-6H-1,3,4-thiadizines were designed, synthesized and evaluated as β-secretase (BACE-1) inhibitors. Preliminary structure-activity relationships revealed that the existence of a 2-amino-6H-1,3,4-thiadizine moiety and α-naphthyl group were favorable for BACE-1 inhibition. Among the synthesized compounds, 5e exhibited the most potent BACE-1 inhibitory activity, with an IC₅₀ value of 9.9 μΜ and it exhibited high brain uptake potential in Madin-Darby anine kidney cell lines (MDCK) and a Madin-Darby canine kidney-multidrug resistance 1 (MDCK-MDR1) model. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

Synthesis and Biological Activity of Substituted Urea and Thiourea Derivatives Containing 1,2,4-Triazole Moieties

by Bedia Kocyigit-Kaymakcioglu, Ahmet Ozgur Celen, Nurhayat Tabanca, Abbas Ali, Shabana I. Khan, Ikhlas A. Khan and David E. Wedge

Molecules 2013, 18(3), 3562-3576; https://doi.org/10.3390/molecules18033562 - 19 Mar 2013

Cited by 68 | Viewed by 9527

Abstract

A series of novel thiourea and urea derivatives containing 1,2,4-triazole moieties were synthesized and evaluated for their antifungal and larvicidal activity. Triazole derivatives 3a–e and 4a–e were synthesized by reacting thiocarbohydrazide with thiourea and urea compounds 1a–e [...] Read more.

A series of novel thiourea and urea derivatives containing 1,2,4-triazole moieties were synthesized and evaluated for their antifungal and larvicidal activity. Triazole derivatives 3a–e and 4a–e were synthesized by reacting thiocarbohydrazide with thiourea and urea compounds 1a–e and 2a–e, respectively, in a 130–140 °C oil bath. The proposed structures of all the synthesized compounds were confirmed using elemental analysis, UV,IR, ¹H-NMR and mass spectroscopy. All compounds were evaluated for antifungal activity against plant pathogens, larvicidal and biting deterrent activity against the mosquito Aedes aegypti L. and in vitro cytotoxicity and anti-inflammatory activity against some human cell lines. Phomopis species were the most sensitive fungi to these compounds. Compounds 1b, 1c, 3a and 4e demonstrated selectively good activity against Phomopis obscurans and only 1b and 4e showed a similar level of activity against P. viticola. Compound 3d, with a LD₅₀ value of 67.9 ppm, followed by 1c (LD₅₀ = 118.8 ppm) and 3e (LD₅₀ = 165.6 ppm), showed the highest toxicity against Aedes aegypti larvae. Four of these compounds showed biting deterrent activity greater than solvent control, with the highest activity being seen for 1c, with a proportion not biting (PNB) value of 0.75, followed by 1e, 2b and 1a. No cytotoxicity was observed against the tested human cancer cell lines. No anti-inflammatory activity was observed against NF-kB dependent transcription induced by phorbol myristate acetate (PMA) in human chondrosarcoma cells. Full article

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Open AccessArticle

Cyclic versus Hemi-Bastadins. Pleiotropic Anti-Cancer Effects: from Apoptosis to Anti-Angiogenic and Anti-Migratory Effects

by Véronique Mathieu, Nathalie Wauthoz, Florence Lefranc, Hendrik Niemann, Karim Amighi, Robert Kiss and Peter Proksch

Molecules 2013, 18(3), 3543-3561; https://doi.org/10.3390/molecules18033543 - 19 Mar 2013

Cited by 18 | Viewed by 5969

Abstract

Bastadins-6, -9 and -16 isolated from the marine sponge Ianthella basta displayed in vitro cytostatic and/or cytotoxic effects in six human and mouse cancer cell lines. The in vitro growth inhibitory effects of these bastadins were similar in cancer cell lines sensitive to [...] Read more.

Bastadins-6, -9 and -16 isolated from the marine sponge Ianthella basta displayed in vitro cytostatic and/or cytotoxic effects in six human and mouse cancer cell lines. The in vitro growth inhibitory effects of these bastadins were similar in cancer cell lines sensitive to pro-apoptotic stimuli versus cancer cell lines displaying various levels of resistance to pro-apoptotic stimuli. While about ten times less toxic than the natural cyclic bastadins, the synthetically derived 5,5'-dibromohemibastadin-1 (DBHB) displayed not only in vitro growth inhibitory activity in cancer cells but also anti-angiogenic properties. At a concentration of one tenth of its in vitro growth inhibitory concentration, DBHB displayed actual antimigratory effects in mouse B16F10 melanoma cells without any sign of cytotoxicity and/or growth inhibition. The serum concentration used in the cell culture media markedly influenced the DBHB-induced antimigratory effects in the B16F10 melanoma cell population. We are currently developing a specific inhalation formulation for DBHB enabling this compound to avoid plasmatic albumin binding through its direct delivery to the lungs to combat primary as well as secondary (metastases) tumors. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

Terminalia chebula Extract Protects OGD-R Induced PC12 Cell Death and Inhibits LPS Induced Microglia Activation

by Bhakta Prasad Gaire, Nirmala Jamarkattel-Pandit, Donghun Lee, Jungbin Song, Ji Young Kim, Juyeon Park, Soyoung Jung, Ho-Young Choi and Hocheol Kim

Molecules 2013, 18(3), 3529-3542; https://doi.org/10.3390/molecules18033529 - 19 Mar 2013

Cited by 26 | Viewed by 13552

Abstract

Terminalia chebula, native to Southeast Asia, is a popular medicinal plant in Ayurveda. It has been previously reported to have strong antioxidant and anti-inflammatory efficacy. In this study, we aimed to investigate if fruit extract from T. chebula might protect neuronal cells [...] Read more.

Terminalia chebula, native to Southeast Asia, is a popular medicinal plant in Ayurveda. It has been previously reported to have strong antioxidant and anti-inflammatory efficacy. In this study, we aimed to investigate if fruit extract from T. chebula might protect neuronal cells against ischemia and related diseases by reduction of oxidative damage and inflammation in rat pheochromocytoma cells (PC12) using in vitro oxygen-glucose deprivation followed by reoxygenation (OGD-R) ischemia and hydrogen peroxide (H₂O₂) induced cell death. Cell survival was evaluated by a 2-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Free radical scavenging, lipid peroxidation and nitric oxide inhibition were measured by diphenyl-1-picrylhydrazyl (DPPH), thiobarbituric acid (TBA) and Griess reagent, respectively. We found that T. chebula extract: (1) increases the survival of cells subjected to OGD-R by 68%, and H₂O₂ by 91.4%; (2) scavenges the DPPH free radical by 96% and decreases malondialdehyde (MDA) levels from 237.0 ± 15.2% to 93.7 ± 2.2%; (3) reduces NO production and death rate of microglia cells stimulated by lipopolysaccharide (LPS). These results suggest that T. chebula extract has the potential as a natural herbal medicine, to protect the cells from ischemic damage and the possible mechanism might be the inhibition of oxidative and inflammatory processes. Full article

(This article belongs to the Section Natural Products Chemistry)

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Open AccessReview

Technologies for the Synthesis of mRNA-Encoding Libraries and Discovery of Bioactive Natural Product-Inspired Non-Traditional Macrocyclic Peptides

by Kenichiro Ito, Toby Passioura and Hiroaki Suga

Molecules 2013, 18(3), 3502-3528; https://doi.org/10.3390/molecules18033502 - 18 Mar 2013

Cited by 53 | Viewed by 15384

Abstract

In this review, we discuss emerging technologies for drug discovery, which yields novel molecular scaffolds based on natural product-inspired non-traditional peptides expressed using the translation machinery. Unlike natural products, these technologies allow for constructing mRNA-encoding libraries of macrocyclic peptides containing non-canonical sidechains and [...] Read more.

In this review, we discuss emerging technologies for drug discovery, which yields novel molecular scaffolds based on natural product-inspired non-traditional peptides expressed using the translation machinery. Unlike natural products, these technologies allow for constructing mRNA-encoding libraries of macrocyclic peptides containing non-canonical sidechains and N-methyl-modified backbones. The complexity of sequence space in such libraries reaches as high as a trillion (>10¹²), affording initial hits of high affinity ligands against protein targets. Although this article comprehensively covers several related technologies, we discuss in greater detail the technical development and advantages of the Random non-standard Peptide Integration Discovery (RaPID) system, including the recent identification of inhibitors against various therapeutic targets. Full article

(This article belongs to the Special Issue Chemical Protein and Peptide Synthesis)

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Open AccessArticle

Synthesis, Bioevaluation and Structural Study of Substituted Phthalazin-1(2H)-ones Acting as Antifungal Agents

by Marcos Derita, Esther Del Olmo, Bianca Barboza, Ana Esther García-Cadenas, José Luis López-Pérez, Sebastián Andújar, Daniel Enriz, Susana Zacchino and Arturo San Feliciano

Molecules 2013, 18(3), 3479-3501; https://doi.org/10.3390/molecules18033479 - 18 Mar 2013

Cited by 13 | Viewed by 7045

Abstract

Twenty-five polysubstituted phthalazinone derivatives were synthesized and tested for their antifungal activity against a panel of pathogenic and clinically important yeasts and filamentous fungi. Among them, the compound 4-(4-chlorobenzyl)-2-methylphthalazin-1(2H)-one (5) exhibited a remarkable antifungal activity against standardised strains of [...] Read more.

Twenty-five polysubstituted phthalazinone derivatives were synthesized and tested for their antifungal activity against a panel of pathogenic and clinically important yeasts and filamentous fungi. Among them, the compound 4-(4-chlorobenzyl)-2-methylphthalazin-1(2H)-one (5) exhibited a remarkable antifungal activity against standardised strains of dermatophytes and Cryptococcus neoformans, as well as against some clinical isolates. A physicochemical study performed on compound 5 revealed its conformational and electronic characteristics, providing us with useful data for the future design of novel related antifungal analogues. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

The Ameliorative Effects of L-2-Oxothiazolidine-4-Carboxylate on Acetaminophen-Induced Hepatotoxicity in Mice

by Jiwon Choi, Kwang-Hyun Park, Sung Zoo Kim, Jun Ho Shin and Seon-Il Jang

Molecules 2013, 18(3), 3467-3478; https://doi.org/10.3390/molecules18033467 - 18 Mar 2013

Cited by 19 | Viewed by 7249

Abstract

The aim of the study was to investigate the ameliorative effects and the mechanism of action of L-2-oxothiazolidine-4-carboxylate (OTC) on acetaminophen (APAP)-induced hepatotoxicity in mice. Mice were randomly divided into six groups: normal control group, APAP only treated group, APAP + 25 mg/kg [...] Read more.

The aim of the study was to investigate the ameliorative effects and the mechanism of action of L-2-oxothiazolidine-4-carboxylate (OTC) on acetaminophen (APAP)-induced hepatotoxicity in mice. Mice were randomly divided into six groups: normal control group, APAP only treated group, APAP + 25 mg/kg OTC, APAP + 50 mg/kg OTC, APAP + 100 mg/kg OTC, and APAP + 100 mg/kg N-acetylcysteine (NAC) as a reference control group. OTC treatment significantly reduced serum alanine aminotransferase and aspartate aminotransferase levels in a dose dependent manner. OTC treatment was markedly increased glutathione (GSH) production and glutathione peroxidase (GSH-px) activity in a dose dependent manner. The contents of malondialdehyde and 4-hydroxynonenal in liver tissues were significantly decreased by administration of OTC and the inhibitory effect of OTC was similar to that of NAC. Moreover, OTC treatment on APAP-induced hepatotoxicity significantly reduced the formation of nitrotyrosin and terminal deoxynucleotidyl transferase dUTP nick end labeling positive areas of liver tissues in a dose dependent manner. Furthermore, the activity of caspase-3 in liver tissues was reduced by administration of OTC in a dose dependent manner. The ameliorative effects of OTC on APAP-induced liver damage in mice was similar to that of NAC. These results suggest that OTC has ameliorative effects on APAP-induced hepatotoxicity in mice through anti-oxidative stress and anti-apoptotic processes. Full article

(This article belongs to the Special Issue Antioxidants 2012)

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Open AccessArticle

Bioactive Pregnane Steroids from a South China Sea Gorgonian Carijoa sp.

by Hong-Ying Zhao, Chang-Lun Shao, Zhi-Yong Li, Lei Han, Fei Cao and Chang-Yun Wang

Molecules 2013, 18(3), 3458-3466; https://doi.org/10.3390/molecules18033458 - 15 Mar 2013

Cited by 25 | Viewed by 5987

Abstract

A new pregnane steroid, 1, and three known analogues 2–4, have been isolated from a gorgonian Carijoa sp. collected from the South China Sea. The planar structure and relative configuration of 1 were elucidated from comprehensive spectroscopic data. Its [...] Read more.

A new pregnane steroid, 1, and three known analogues 2–4, have been isolated from a gorgonian Carijoa sp. collected from the South China Sea. The planar structure and relative configuration of 1 were elucidated from comprehensive spectroscopic data. Its absolute configuration was determined by application of the modified Mosher method. Compounds 1, 3 and 4 exhibited cytotoxicity against the human hepatoma cell line Bel-7402, with IC₅₀ values of 9.33, 11.02 and 18.68 µM, respectively. Additionally, compound 1 exhibited promising antibacterial activity against Pseudomona puido, with a MIC value of 31 nM, which is approximately 5-fold more potent than ciprofloxacin (MIC = 156 nM). Full article

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Open AccessArticle

Article Synthesis and Trypanocidal Activity of Novel 2,4,5-Triaryl-N-Hydroxylimidazole Derivatives

by Ramon Borges Da Silva, Vanessa Brandão Loback, Kelly Salomão, Solange Lisboa De Castro, James L. Wardell, Solange M. S. V. Wardell, Thadeu Estevam Moreira Maramaldo Costa, Carmen Penido, Maria Das Graças Muller Oliveira De Henriques, Samir Aquino Carvalho, Edson Ferreira Da Silva and Carlos Alberto Manssour Fraga

Molecules 2013, 18(3), 3445-3457; https://doi.org/10.3390/molecules18033445 - 15 Mar 2013

Cited by 27 | Viewed by 6098

Abstract

Herein, we report the design, synthesis and trypanocidal activity of some novel trisubstituted imidazole derivatives. These heterocyclic derivatives were structurally planned by exploring the concept of molecular hybridisation between two arylhydrazones derived from megazol, which has potent trypanocidal activity. The trypanocidal activity of [...] Read more.

Herein, we report the design, synthesis and trypanocidal activity of some novel trisubstituted imidazole derivatives. These heterocyclic derivatives were structurally planned by exploring the concept of molecular hybridisation between two arylhydrazones derived from megazol, which has potent trypanocidal activity. The trypanocidal activity of these triarylimidazole derivatives was evaluated against infective trypomastigote forms of T. cruzi and the derivative 2'-(4-bromophenyl)-1-methyl-5'-phenyl-1H,3'H-2,4'-biimidazol-3'-ol showed moderate biological activity (IC₅₀ = 23.9 µM) when compared to benznidazole, a standard trypanocidal drug. These compounds did not present cytotoxic effects at concentrations near the trypanocidal IC₅₀, being considered a good starting point for the development of new anti-Chagas drug candidates. Full article

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Open AccessComment

Remarks on Sasidharan et al. “Evaluation of the Hepatoprotective Effects of Lantadene A, a Pentacyclic Triterpenoid of Lantana Plants against Acetaminophen-induced Liver Damage”. Molecules 2012, 17, 13937-13947

by Manu Sharma

Molecules 2013, 18(3), 3442-3444; https://doi.org/10.3390/molecules18033442 - 14 Mar 2013

Cited by 1 | Viewed by 5461

Abstract

An article by Sasidharan et al. recently published in the journal Molecules [1] claimed to show the hepatoprotective effects of lantadene A against acetaminophen-induced liver damage in mice. While reading this paper, I came across certain points that need to be clarified and [...] Read more.

An article by Sasidharan et al. recently published in the journal Molecules [1] claimed to show the hepatoprotective effects of lantadene A against acetaminophen-induced liver damage in mice. While reading this paper, I came across certain points that need to be clarified and taken up in the interest of science and other scientists working in this area. Full article

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Open AccessArticle

Use of Mixed Micelles for Presentation of Building Blocks in a New Combinatorial Discovery Methodology: Proof-of-Concept Studies

by Roger New, Gurpal S. Bansal, Michael Bogus, Kasia Zajkowska, Steffen Rickelt and Istvan Toth

Molecules 2013, 18(3), 3427-3441; https://doi.org/10.3390/molecules18033427 - 14 Mar 2013

Cited by 6 | Viewed by 5812

Abstract

We describe a new method of combinatorial screening in which building blocks, instead of being linked together chemically, are placed on the surface of nanoparticles. Two- or three-dimensional structures form on the surface of these particles through the close approach of different building [...] Read more.

We describe a new method of combinatorial screening in which building blocks, instead of being linked together chemically, are placed on the surface of nanoparticles. Two- or three-dimensional structures form on the surface of these particles through the close approach of different building blocks, with sufficient flexibility to be able to adapt and interact with putative binding sites in biological systems. The particles assemble without the need for formation of chemical bonds, so libraries comprised of many structures can be prepared rapidly, with large quantities of material available for testing. Screening methods can include solid and solution-phase binding assays, or tissue culture models, for example looking for structures which can change the behaviour of cells in a disease-modifying manner. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

Differences in the Phenolic Composition and Antioxidant Properties between Vitis coignetiae and Vitis vinifera Seeds Extracts

by Stanisław Weidner, Anna Rybarczyk, Magdalena Karamać, Angelika Król, Agnieszka Mostek, Joanna Grębosz and Ryszard Amarowicz

Molecules 2013, 18(3), 3410-3426; https://doi.org/10.3390/molecules18033410 - 14 Mar 2013

Cited by 34 | Viewed by 8659

Abstract

Phenolic compounds were extracted from European and Japanese grapevine species (Vitis vinifera and V. coignetiae) seeds using 80% methanol or 80% acetone. The total content of phenolic compounds was determined utilizing Folin-Ciocalteu’s phenol reagent, while the content of tannins was assayed [...] Read more.

Phenolic compounds were extracted from European and Japanese grapevine species (Vitis vinifera and V. coignetiae) seeds using 80% methanol or 80% acetone. The total content of phenolic compounds was determined utilizing Folin-Ciocalteu’s phenol reagent, while the content of tannins was assayed by the vanillin and BSA precipitation methods. Additionally, the DPPH free radical and ABTS cation radical scavenging activities and the reduction power of the extracts were measured. The HPLC method was applied to determine the phenolic compounds, such as phenolic acids and catechins. The seeds contained large amounts of tannins and gallic acid and observable quantities of catechins, p-coumaric, ferulic and caffeic acids. The dominant form of phenolic acids in the extracts was the ester-bound form. The content of total phenolics was higher in the European grape V. vinifera seeds, which also contained more tannins, catechins and phenolic acids, except for caffeic acid. Extracts from V. vinifera seeds showed better radical scavenger properties and stronger reducing power. The total contents of phenolic compounds and tannins in acetone extracts were higher than in methanolic extracts. Acetone extracts also exhibited stronger antiradical properties as well as stronger reducing power. Full article

(This article belongs to the Special Issue Antioxidants 2012)

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Open AccessReview

Synthesis of Peptide Radiopharmaceuticals for the Therapy and Diagnosis of Tumor Diseases

by Mazen Jamous, Uwe Haberkorn and Walter Mier

Molecules 2013, 18(3), 3379-3409; https://doi.org/10.3390/molecules18033379 - 14 Mar 2013

Cited by 80 | Viewed by 12902

Abstract

Despite the advances in molecular biology and biochemistry, the prognosis of patients suffering from tumor diseases remains poor. The limited therapeutic success can be explained by the insufficient performance of the common chemotherapeutic drugs that lack the ability to specifically target tumor tissues. [...] Read more.

Despite the advances in molecular biology and biochemistry, the prognosis of patients suffering from tumor diseases remains poor. The limited therapeutic success can be explained by the insufficient performance of the common chemotherapeutic drugs that lack the ability to specifically target tumor tissues. Recently peptide radiopharmaceuticals have been developed that enable the concurrent imaging and therapy of tumors expressing a specific target. Here, with a special emphasis on the synthesis of the building blocks required for the complexation of metallic radioisotopes, the requirements to the design and synthesis of radiolabeled peptides for clinical applications are described. Full article

(This article belongs to the Special Issue Chemical Protein and Peptide Synthesis)

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Open AccessReview

Diosgenone Synthesis, Anti-Malarial Activity and QSAR of Analogues of This Natural Product

by Adriana Pabón, Gustavo Escobar, Esteban Vargas, Víctor Cruz, Rafael Notario, Silvia Blair and Fernando Echeverri

Molecules 2013, 18(3), 3356-3378; https://doi.org/10.3390/molecules18033356 - 14 Mar 2013

Cited by 20 | Viewed by 9102

Abstract

Solanum nudum Dunal steroids have been reported as being antimalarial compounds; however, their concentration in plants is low, meaning that the species could be threatened by over-harvesting for this purpose. Swern oxidation was used for hemisynthesis of diosgenone (one of the most active [...] Read more.

Solanum nudum Dunal steroids have been reported as being antimalarial compounds; however, their concentration in plants is low, meaning that the species could be threatened by over-harvesting for this purpose. Swern oxidation was used for hemisynthesis of diosgenone (one of the most active steroidal sapogenin diosgenin compounds). Eighteen structural analogues were prepared; three of them were found to be more active than diosgenone (IC₅₀ 27.9 μM vs. 10.1 μM, 2.9 μM and 11.3 μM). The presence of a 4-en-3-one grouping in the A-ring of the compounds seems to be indispensable for antiplasmodial activity; progesterone (having the same functional group in the steroid A-ring) has also displayed antiplasmodial activity. Quantitative correlations between molecular structure and bioactivity were thus explored in diosgenone and several derivatives using well-established 3D-QSAR techniques. The models showed that combining electrostatic (70%) and steric (30%) fields can explain most variance regarding compound activity. Malarial parasitemia in mice became reduced by oral administration of two diosgenone derivatives. Full article

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Open AccessReview

Advances in Click Chemistry for Single-Chain Nanoparticle Construction

by Ana Sanchez-Sanchez, Irma Pérez-Baena and José A. Pomposo

Molecules 2013, 18(3), 3339-3355; https://doi.org/10.3390/molecules18033339 - 14 Mar 2013

Cited by 110 | Viewed by 10641

Abstract

Single-chain polymeric nanoparticles are artificial folded soft nano-objects of ultra-small size which have recently gained prominence in nanoscience and nanotechnology due to their exceptional and sometimes unique properties. This review focuses on the current state of the investigations of click chemistry techniques for [...] Read more.

Single-chain polymeric nanoparticles are artificial folded soft nano-objects of ultra-small size which have recently gained prominence in nanoscience and nanotechnology due to their exceptional and sometimes unique properties. This review focuses on the current state of the investigations of click chemistry techniques for highly-efficient single-chain nanoparticle construction. Additionally, recent progress achieved for the use of well-defined single-chain nanoparticles in some promising fields, such as nanomedicine and catalysis, is highlighted. Full article

(This article belongs to the Collection Advances in Click Chemistry)

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Open AccessReview

Relationship between Mood Change, Odour and Its Physiological Effects in Humans While Inhaling the Fragrances of Essential Oils as well as Linalool and Its Enantiomers

by Yoshiaki Sugawara, Asami Shigetho, Mai Yoneda, Tomoko Tuchiya, Tomomi Matumura and Miki Hirano

Molecules 2013, 18(3), 3312-3338; https://doi.org/10.3390/molecules18033312 - 13 Mar 2013

Cited by 25 | Viewed by 11080

Abstract

Humans can detect and discriminate a vast number of odours. The number perceived as distinguishable is estimated to be more than ten thousand. Humans are capable of distinguishing even slight alterations in the structure of an odorous molecule. A pair of enantiomers of [...] Read more.

Humans can detect and discriminate a vast number of odours. The number perceived as distinguishable is estimated to be more than ten thousand. Humans are capable of distinguishing even slight alterations in the structure of an odorous molecule. A pair of enantiomers of an odorant, which possess the same molecular structures except for the chiral position, can trigger profoundly different odour perceptions. How precisely can humans and their olfactory system detect and discriminate such a great variety of odours and such subtle differences in the molecular structures? In a series of studies, we have attempted to examine the relationship between mood change, odour and its physiological effects, by focusing on the possible verbal and non-verbal changes in humans induced by smelling the fragrances of essential oils as well as linalool and its enantiometric isomers. In this article, we provide an overview of our recent verbal and non-verbal studies. We then discuss how our findings may contribute to the assessment of psychophysiological responses of essential oils as well as how our research can contribute to the study of human chemoreception science, by shedding light on the sophistication of the olfactory system in its ability to detect and discriminate odors. Full article

(This article belongs to the Special Issue Flavors and Fragrances)

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Open AccessReview

Selenium in the Environment, Metabolism and Involvement in Body Functions

by Youcef Mehdi, Jean-Luc Hornick, Louis Istasse and Isabelle Dufrasne

Molecules 2013, 18(3), 3292-3311; https://doi.org/10.3390/molecules18033292 - 13 Mar 2013

Cited by 535 | Viewed by 28906

Abstract

Selenium (Se34 79) is a metalloid which is close to sulfur (S) in terms of properties. The Se concentration in soil varies with type, texture and organic matter content of the soil and with rainfall. Its assimilation by plants is influenced [...] Read more.

Selenium (Se34 79) is a metalloid which is close to sulfur (S) in terms of properties. The Se concentration in soil varies with type, texture and organic matter content of the soil and with rainfall. Its assimilation by plants is influenced by the physico-chemical properties of the soil (redox status, pH and microbial activity). The presence of Se in the atmosphere is linked to natural and anthropogenic activities. Selenoproteins, in which selenium is present as selenocysteine, present an important role in many body functions, such as antioxidant defense and the formation of thyroid hormones. Some selenoprotein metabolites play a role in cancer prevention. In the immune system, selenium stimulates antibody formation and activity of helper T cells, cytotoxic T cells and Natural Killer (NK) cells. The mechanisms of intestinal absorption of selenium differ depending on the chemical form of the element. Selenium is mainly absorbed in the duodenum and caecum by active transport through a sodium pump. The recommended daily intake of selenium varies from 60 μg/day for women, to 70 μg/day for men. In growing ruminants the requirements are estimated at 100 μg/kg dry matter and 200 μg/Kg for pregnant or lactating females. A deficiency can cause reproductive disorders in humans and animals. Full article

(This article belongs to the Special Issue Selenium and Tellurium Chemistry)

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Open AccessArticle

The Interactions of Oxygen with Small Gold Clusters on Nitrogen-Doped Graphene

by Xin Chen, Shaorui Sun, Fan Li, Xiayan Wang and Dingguo Xia

Molecules 2013, 18(3), 3279-3291; https://doi.org/10.3390/molecules18033279 - 13 Mar 2013

Cited by 17 | Viewed by 8184

Abstract

By means of density functional theory, the adsorption properties of O₂ molecule on both isolated and N-graphene supported gold clusters have been studied. The N-graphene is modeled by a C₆₅NH₂₂ cluster of finite size. The results indicate that the [...] Read more.

By means of density functional theory, the adsorption properties of O₂ molecule on both isolated and N-graphene supported gold clusters have been studied. The N-graphene is modeled by a C₆₅NH₂₂ cluster of finite size. The results indicate that the catalytic activity and the O₂ adsorption energies of odd-numbered Au clusters are larger than those of adjacent even-numbered ones. The O₂ molecule is in favor of bonding to the bridge sites of odd-numbered Au clusters, whereas for odd-numbered ones, the end-on adsorption mode is favored. The perpendicular adsorption orientation on N-graphene is preferred than the parallel one for Au₂, Au₃ and Au₄ clusters, while for Au₅, Au₆ and Au₇, the parallel ones are favored. When O₂ is adsorbed on N-graphene supported Au clusters, the adsorption energies are largely increased compared with those on gas-phase ones. The increased adsorption energies would significantly facilitate the electron transfer from Au d-orbital to π* orbital of O₂, which would further weakening the O–O bond and therefore enhancing the catalytic activity. The carbon atoms on N-graphene could anchor the clusters, which could make them more difficult to structural distortion, therefore enhance their stability. Full article

(This article belongs to the Special Issue Computational Chemistry)

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Open AccessArticle

Design, Synthesis and Biological Evaluation of N-Sulfonyl Homoserine Lactone Derivatives as Inhibitors of Quorum Sensing in Chromobacterium violaceum

by Mingming Zhao, Yingying Yu, Yuhui Hua, Fan Feng, Yigang Tong, Xiaohong Yang, Junhai Xiao and Hongrui Song

Molecules 2013, 18(3), 3266-3278; https://doi.org/10.3390/molecules18033266 - 13 Mar 2013

Cited by 20 | Viewed by 6357

Abstract

A novel series of N-sulfonyl homoserine lactone derivatives 5a–l has been designed, synthesized and evaluated for quorum sensing inhibitory activities towards violacein production. Of the compounds synthesized, compound 5h was found to possess an excellent level of enantiopurity (99.2% e.e.). [...] Read more.

A novel series of N-sulfonyl homoserine lactone derivatives 5a–l has been designed, synthesized and evaluated for quorum sensing inhibitory activities towards violacein production. Of the compounds synthesized, compound 5h was found to possess an excellent level of enantiopurity (99.2% e.e.). The results indicated that compounds bearing an ortho substituent on their phenyl ring exhibited excellent levels of inhibitory activity against violacein production. Compounds 5h and 5k in particular, with IC₅₀ values of 1.64 and 1.66 µM, respectively, were identified as promising lead compounds for further structural modification. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle

Inhibition of Telomerase Activity by Oleanane Triterpenoid CDDO-Me in Pancreatic Cancer Cells is ROS-Dependent

by Dorrah Deeb, Xiaohua Gao, Yongbo Liu, Nadimpalli R. S. Varma, Ali S. Arbab and Subhash C. Gautam

Molecules 2013, 18(3), 3250-3265; https://doi.org/10.3390/molecules18033250 - 13 Mar 2013

Cited by 43 | Viewed by 8149

Abstract

Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a synthetic derivative of oleanolic acid, a triterpene, with apoptosis-inducing activity in a wide range of cancer cells. Induction of apoptosis by CDDO-Me is associated with the generation of reactive oxygen species (ROS) and inhibition of telomerase activity. In the [...] Read more.

Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a synthetic derivative of oleanolic acid, a triterpene, with apoptosis-inducing activity in a wide range of cancer cells. Induction of apoptosis by CDDO-Me is associated with the generation of reactive oxygen species (ROS) and inhibition of telomerase activity. In the present study, we investigated the role of ROS in inhibition of telomerase by CDDO-me. Treatment of MiaPaCa-2 and Panc-1 pancreatic cancer cell lines with CDDO-Me induced the production of hydrogen peroxide and superoxide anions and inhibited the telomerase activity. Pretreatment of cells with N-acetylcycsteine, a general purpose antioxidant or overexpression of glutathione peroxidase (GPx) or superoxide dismutase-1 (SOD-1) blocked the telomerase inhibitory activity of CDDO-Me. Furthermore, blocking ROS generation also prevented the inhibition of hTERT gene expression, hTERT protein production and expression of a number of hTERT–regulatory proteins by CDDO-Me (e.g., c-Myc, Sp1, NF-κB and p-Akt). Data also showed that Akt plays an important role in the activation of telomerase activity. Together, these data suggest that inhibition of telomerase activity by CDDO-Me is mediated through a ROS-dependent mechanism; however, more work is needed to fully understand the role of ROS in down-regulation of hTERT gene and hTERT-regulatory proteins by CDDO-Me. Full article

(This article belongs to the Special Issue Triterpenes and Triterpenoids 2013)

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Open AccessArticle

Antioxidant Activity of Extracts of Momordica Foetida Schumach. et Thonn.

by Rosaria Acquaviva, Claudia Di Giacomo, Luca Vanella, Rosa Santangelo, Valeria Sorrenti, Ignazio Barbagallo, Carlo Genovese, Silvana Mastrojeni, Salvatore Ragusa and Liliana Iauk

Molecules 2013, 18(3), 3241-3249; https://doi.org/10.3390/molecules18033241 - 13 Mar 2013

Cited by 23 | Viewed by 7679

Abstract

Momordica foetida Schumach. et Thonn. (Cucurbitaceae) is a perennial climbing herb with tendrils, found in swampy areas in Central Uganda. Antidiabetic and antilipogenic activities were reported for some Momordica species, however the mechanism of action is still unknown. Oxidative stress may represent an [...] Read more.

Momordica foetida Schumach. et Thonn. (Cucurbitaceae) is a perennial climbing herb with tendrils, found in swampy areas in Central Uganda. Antidiabetic and antilipogenic activities were reported for some Momordica species, however the mechanism of action is still unknown. Oxidative stress may represent an important pathogenic mechanism in obesity-associated metabolic syndrome. The present study evaluated free radical scavenging capacity of different concentrations of aqueous, methanolic and dichloromethane leaf extracts of Momordica foetida Schumach. et Thonn. and the ability of these extracts to inhibit in vitro plasma lipid peroxidation; in addition, healthy human adipose mesenchymal stem cell cultures were used in order to test the hypothesis that these extracts may affect adipocyte differentiation. Results obtained in this study suggested that aqueous extract might be useful in preventing metabolic syndrome. Full article

(This article belongs to the Special Issue Antioxidants 2012)

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Open AccessArticle

Synthesis and Antimicrobial Activity of Novel Substituted Ethyl 2-(Quinolin-4-yl)-propanoates

by M. Akram Khan, Keith Miller, Kim Drummond Rainsford and Yong Zhou

Molecules 2013, 18(3), 3227-3240; https://doi.org/10.3390/molecules18033227 - 13 Mar 2013

Cited by 4 | Viewed by 6999

Abstract

Substituted 4-hydroxyquinolines were synthesized from anilines and diethyl 2-(ethoxymethylene)malonate by the Gould-Jacobs reaction via cyclization of the intermediate anilinomethylenemalonate followed by hydrolysis and decarboxylation. The 4-hydroxyquinolines reacted with phosphorous oxychloride to form 4-chloroquinolines, which reacted on heating with diethyl sodiomethylmalonate in DMF to [...] Read more.

Substituted 4-hydroxyquinolines were synthesized from anilines and diethyl 2-(ethoxymethylene)malonate by the Gould-Jacobs reaction via cyclization of the intermediate anilinomethylenemalonate followed by hydrolysis and decarboxylation. The 4-hydroxyquinolines reacted with phosphorous oxychloride to form 4-chloroquinolines, which reacted on heating with diethyl sodiomethylmalonate in DMF to yield moderate yields of substituted ethyl 2-(quinolin-4-yl)propanoates, many of which showed potent antimicrobial activity against Helicobacter pylori. Full article

(This article belongs to the Section Organic Chemistry)

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Open AccessReview

Click-to-Chelate: Development of Technetium and Rhenium-Tricarbonyl Labeled Radiopharmaceuticals

by Christiane A. Kluba and Thomas L. Mindt

Molecules 2013, 18(3), 3206-3226; https://doi.org/10.3390/molecules18033206 - 12 Mar 2013

Cited by 88 | Viewed by 11762

Abstract

The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) enables the simultaneous synthesis and conjugation of [...] Read more.

The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (bio)molecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications. Full article

(This article belongs to the Collection Advances in Click Chemistry)

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Open AccessArticle

Volatiles, A Glutarimide Alkaloid and Antimicrobial Effects of Croton pullei (Euphorbiaceae)

by Rosana N. S. Peixoto, Giselle M. S. P. Guilhon, Maria Das Graças B. Zoghbi, Isabella S. Araújo, Ana Paula T. Uetanabaro, Lourivaldo S. Santos and Davi Do S. B. Brasil

Molecules 2013, 18(3), 3195-3205; https://doi.org/10.3390/molecules18033195 - 12 Mar 2013

Cited by 12 | Viewed by 6100

Abstract

Chemical investigation of Croton pullei (Euphorbiaceae) collected in the Brazilian Amazon region was revisited. The chemical composition of the essential oils of leaves and stems was analyzed by GC/MS. It was found that both the oils comprise mainly terpenes, among which linalool was [...] Read more.

Chemical investigation of Croton pullei (Euphorbiaceae) collected in the Brazilian Amazon region was revisited. The chemical composition of the essential oils of leaves and stems was analyzed by GC/MS. It was found that both the oils comprise mainly terpenes, among which linalool was the major one (24.90 and 39.72%, respectively). Phytochemical investigation of the stem methanol extract led to the isolation of a new natural product from the glutarimide alkaloid group named N-[2,6-dioxo-1-(2-phenylethyl)-3-piperidinyl]-acetamide, confirming that C. pullei is a rich source of this class of alkaloids. The hexane and methanol extracts of the stems of C. pullei showed moderate antibacterial and antifungal activity and the highest inhibition was observed when the methanol extract was tested against Staphylococcus aureus CCMB 262 and CCMB 263. Full article

(This article belongs to the Section Natural Products Chemistry)

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Open AccessCommunication

The Toxicological Assessment of Cyclopentyl Methyl Ether (CPME) as a Green Solvent

by Kiyoshi Watanabe

Molecules 2013, 18(3), 3183-3194; https://doi.org/10.3390/molecules18033183 - 11 Mar 2013

Cited by 83 | Viewed by 11493

Abstract

Cyclopentyl methyl ether (CPME) has been used in chemical synthesis as an alternative to hazardous solvents. According to some earlier investigation by others, CPME has low acute or subchronic toxicity with moderate irritation and negative mutagenicity and negative skin sensitization (Local Lymph Node [...] Read more.

Cyclopentyl methyl ether (CPME) has been used in chemical synthesis as an alternative to hazardous solvents. According to some earlier investigation by others, CPME has low acute or subchronic toxicity with moderate irritation and negative mutagenicity and negative skin sensitization (Local Lymph Node Assay). Calculated Permitted Daily Exposure (PDE) value of CPME obtained by our 28-day oral toxicity test is 1.5 mg/day, and CPME is thus assumed to be a class 2 equivalent solvent in the ICH (International Conference on Harmonization) Harmonized Tripartite Guideline Q3C (R5). Wide synthetic utility and a detailed toxicity study suggest CPME as a green and sustainable solvent of choice for modern chemical transformations. Full article

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Open AccessReview

Dynamic Motion and Rearranged Molecular Shape of Heme in Myoglobin: Structural and Functional Consequences

by Saburo Neya

Molecules 2013, 18(3), 3168-3182; https://doi.org/10.3390/molecules18033168 - 11 Mar 2013

Cited by 8 | Viewed by 7734

Abstract

Myoglobin, a simple oxygen binding protein, was reconstituted with various types of synthetic hemes to manipulate the heme-globin interactions. From the paramagnetic NMR analysis, small heme was found to rotate rapidly about the iron-histidine bond upon. This is a novel and typical example [...] Read more.

Myoglobin, a simple oxygen binding protein, was reconstituted with various types of synthetic hemes to manipulate the heme-globin interactions. From the paramagnetic NMR analysis, small heme was found to rotate rapidly about the iron-histidine bond upon. This is a novel and typical example for the fluctuation of protein. The dynamic NMR analysis indicated that the 360° rotational rate of a small heme was 1,400 s⁻¹ at room temperature. The X-ray analyses revealed that the tertiary structure of globin containing the smallest heme was closely similar to that of native protein despite extensive destruction of the specific heme-globin interactions. The functional analyses of O₂ binding showed that the loose heme-globin contacts do not significantly affect the oxygen binding. On the other hand, the rearrangement of tetrapyrrole array and the non-planar deformation in porphyrin ring significantly affect the functional properties of myoglobin. These results, taken together, indicate that the essential factors to regulate the myoglobin function are hidden under the molecular shape of prosthetic group rather than in the nonbonded heme-globin contacts. Full article

(This article belongs to the Special Issue Macrocyclic Chemistry)

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Open AccessArticle

Synthesis and Characterization of the in Situ Bulk Polymerization of PMMA Containing Graphene Sheets Using Microwave Irradiation

by Mohammad A. Aldosari, Ali A. Othman and Edreese H. Alsharaeh

Molecules 2013, 18(3), 3152-3167; https://doi.org/10.3390/molecules18033152 - 11 Mar 2013

Cited by 97 | Viewed by 9200

Abstract

Polymethylmethacrylate–graphene (PMMA/RGO) nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the [...] Read more.

Polymethylmethacrylate–graphene (PMMA/RGO) nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH), the product was reduced via microwave irradiation (MWI) to obtain R-(GO-PMMA) composites. In the second approach, a mixture of graphite sheets (RGO) and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA) composites. The composites were characterized by FTIR, ¹H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI. Full article

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Molecules, Volume 18, Issue 3 (March 2013) – 82 articles , Pages 2458-3640

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