AppliedChem, Volume 3, Issue 1 (March 2023) – 12 articles

Climate change has been associated with intensified harmful algal blooms (HABs). Some harmful microalgae produce toxins that accumulate in food webs, adversely affecting the environment, public health and economy. Ocean acidification (OA) is a major consequence of high anthropogenic CO₂ emissions. The carbon chemistry and pH of aquatic ecosystems have been significantly altered as a result. The impacts of climate change on the metabolisms of microalgae, especially toxin biosynthesis, remain largely unknown. This hinders the optimization of HAB mitigation for changed climate conditions. To bridge this knowledge gap, previous studies on the effects of ocean acidification on toxin biosynthesis in microalgae were reviewed. There was no solid conclusion for the toxicity change of saxitoxin-producing dinoflagellates from the genus Alexandrium after high CO₂ treatment. Increased domoic acid content was observed in the diatom Pseudo-nitzschia. The brevetoxin content of Karenia brevis remained largely unchanged. The underlying regulatory mechanisms that account for the different toxicity levels observed have not been elucidated. Metabolic flux analysis is useful for investigating the carbon allocations of toxic microalgae under OA and revealing related metabolic pathways for toxin biosynthesis. Gaining knowledge of the responses of microalgae in high CO₂ conditions will allow the better risk assessment of HABs in the future. Full article

This work is concerned with polyethylene terephthalate (PET) saponification by different potassium compounds in various polyols as well as biodiesel’s main by-product, crude glycerol. It was established that reaction conditions (initial PET/K+ molar ratio, reaction time, etc.) could control the molecular weight of obtained oligomeric products. In ethylene glycol, depolymerization proceeds rapidly, and already at 10–30 min, PET is completely dissolved in the reaction mixture with the formation of liquid oligomers. Then, these oligomers react with potassium compounds, and after 200 min of the process, there are only solid, low-molecular-weight products (dipotassium terephthalate, monomers, and dimers). At the same time, PET saponification in pure glycerol is less effective, and solid polyether flakes could not fully decompose even after 200 min of the process. Crude glycerol takes the middle position between pure polyols. Based on the obtained data, an improved kinetic model was developed, and rate constants were estimated. This model takes into account PET saponification by potassium salts as well as direct PET glycolysis. Ethylene glycol is formed in situ by transesterification between fatty acid ethylene glycol esters and glycerol in the case of pure and crude glycerol. Full article

Drug addiction is a disease that is characterized by a compulsion, a desire to take different substances permanently or for a certain period of time. Numerous negative incidents, such as crimes, work accidents and traffic accidents, are related to using illegal substances. Therefore, urine drug cassette tests have become a screening tool. However, considering legal consequences of test result, the question arises of their performance and reliability. On this account, the main objective of this study was to evaluate the sensitivity and specificity of urine drug tests available on the commercial pharmaceutical market. Evaluated tests were immersed in synthetic urine diluent spiked with amphetamine at various concentrations also containing potentially interfering substances such as caffeine, paracetamol and acetylsalicylic acid, and after a certain period of time, it was observed whether the result was as expected. The reference method used in this study was high-performance liquid chromatography. The obtained results confirmed the declared cut-off as well as specificity of rapid diagnostic tests. Full article

Increasing prospective phytochemical investigations and biological activities on Pueraria lobata and Trifolium pratense flowers exhibited their nutritional (food industry) pharmaceutical (anticancer, anti-inflammatory, anti-microbial, etc.) potentials. Previous studies paid great attention to the screening of isoflavones profile from phytochemicals. This study, in contrast, aimed at identifying the flavonoids from Pueraria lobata flowers or kudzu flower (KF) and Trifolium pratense flowers or red clover (RC) flowers and determining their cytotoxic activities on normal; (HEK-293) and cancer cell lines; human glioblastoma (A-172), osteosarcoma (HOS), embryonic rhabdomyosarcoma (Rd), lung carcinoma (A-549) and liver carcinoma (HepG2). The phytochemical screening using a high-performance liquid chromatography-diode array detector coupled with quadrupole time-of-flight mass spectrometry (HPLC-DAD-Q-TOF/MS) showed that 15 flavonoids, including isoflavones, flavones, flavonols, and flavanones, were identified in KF and 8 flavonoids, including isoflavones and flavonols, were found in RC. Nevertheless, the majority of flavonoid chemical constituents in KF or RC were found to be isoflavones (66.6%) and (62.5%), respectively. HPLC-DAD analysis following eco-friendly extraction of phytochemicals showed that KF contains mainly daidzein and genistein, while RC contains primarily formononetin and biochanin A. Cytotoxic activities evaluated according to IC₅₀ values exhibited the most pronounced dose-dependent antiproliferative effect of KF and RC extracts were against HOS and Rd cancer cell lines, respectively. Accordingly, the morphological observation carried out using acridine orange/ethidium bromide and Giemsa stains revealed apoptotic activities and cell death in HOS and Rd cell lines when subjected to KF or RC extracts. Cytotoxic activities and apoptotic changes were pronounced among all cancer cell lines except for the control cells (HEK-293). Additionally, various polyphenols and flavonoids were identified and quantified in KF and RC extracts and exhibited potent radical scavenging activities. Overall, this study suggests that KF and RC could be valuable edible sources of flavonoids. The comprehensive flavonoid profiles for KF and RC may explain their remarkable biological activities and contribution to inducing antioxidant and cytotoxic activities against cancer cell lines. Full article

Nuts are dry, single-seeded fruits with a combination of beneficial compounds that aid in disease prevention and treatment. The aims of this research are to evaluate the total antioxidant activity (AI) by ferric reducing antioxidant power (FRAP) assay, fatty acids by acid-catalyzed esterification method, and minerals by inductively coupled plasma optical emission (ICP-OE) spectrometer in hazelnuts, pistachios, and almond seeds and skins. Considering total AI, the results demonstrated that the highest activity was found in hazelnut and pistachio skin. The results considering minerals demonstrated that manganese, zinc, and iron levels are high in almond and hazelnut skins, copper is dominant in pistachio skin and hazelnut seed, and selenium is high in pistachio and almond skins and seed. Finally, the results showed palmitic acid is present in almond skin and pistachio seed, palmitoleic acid is high in almond and pistachio skins, and stearic acid is present in almond and hazelnut skins. Oleic acid was found in hazelnut seeds and their skin, linoleic acid in almond skin and pistachio seeds, and α-linolenic acid in almond and pistachio skins. In conclusion, hazelnut, pistachio, and almond skins are a great source of antioxidants, minerals, and healthy fatty acids, making them useful for nutraceutical development. Full article

This paper discusses the historical beginnings and the current state of knowledge of the synthesis of organosilicon compounds and chlorine derivatives of silicon. The key importance of these compounds for modern industry, including the semiconductor industry (photovoltaic cells, microprocessors, memory chips and many other electronic elements) is highlighted. Significant environmental threats related to the production of these compounds and the research challenges aimed at their elimination are discussed. The complexity of the catalytic mechanism of direct reaction of silicon with CH₃Cl and alcohols is presented in an accessible way. In the last part of the work, the directions of the development of direct synthesis technology in line with the principles of green chemistry are indicated. Full article

To deal with climate emergency and reduce environmental impact, agro-industrial wastes are gradually gaining interest and are being used for new products and applications. The large production of watermelons represents an opportunity because of the many byproducts that can be transformed into innovative and valuable foodstuffs. In this study, we examined the lycopene-rich whole dietary fiber (WDF) obtained from the watermelon pomace of a peculiar cultivar, Gavina^® (Oristano, Italy) a seedless fruit from Sardinia (Italy). The volatile chemical composition of the WDF was investigated using Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). The aim was to follow the evolution of the Volatile Organic Compounds (VOCs) fraction during storage and verify its stability over time. Since watermelon is an excellent source of carotenoids, their byproducts were the most abundant VOCs of the freshly prepared samples, but their overall abundance decreased significantly during storage. The opposite trend was observed for acids and aldehydes, whose increase over time is related to amino acid degradation. Freshly prepared WDF can be used in the food industry as an antioxidant-rich dietary fiber that imparts a characteristic and pleasant aroma. Over time, its aroma profile and carotenoid content change considerably, reducing its health properties and limiting its potential application as a natural flavor. Full article

Methylated indoles could be potentially interesting components for hydrogen (H₂) storage based on the Liquid Organic Hydrogen Carrier (LOHC) approach. It is likely that the methylated forms will preserve the beneficial thermochemical characteristics of indole compared to homocyclic LOHCs. At the same time, 1-methyl-indole is expected to have a higher stability than indole in the reactive cycle of hydrogenation and dehydrogenation. This study investigates whether the expectations regarding reaction thermodynamics and stability are justified. To this end, the chemical equilibria of the hydrogenation (+H₂)/dehydrogenation (−H₂) reactions of the indole/octahydroindole LOHC system was determined experimentally over a wide range of temperature, pressure, and hydrogen:feedstock ratio. Reaction thermodynamics were calculated from the relationship between temperature and equilibrium constant. In addition, the formation enthalpies of the species involved in the reaction have been determined experimentally utilizing combustion calorimetry. Further validation has been achieved using high-level quantum chemical methods. The evaluation confirms both hypotheses: (1) 1-methyl-indole exhibits less decomposition during reaction as is the case for the indole system. Hence, an improved stability of methylated LOHC molecules can be concluded; (2) The enthalpy of reaction for H₂ release from octahydro-1-methyl-indole is estimated from the equilibrium experiments and calorimetric measurements to be about +55.6 kJ mol(H₂)⁻¹ for reaction in the liquid phase at standard conditions. This is comparable to the values observed for octahydro-indole. Full article

The concentration region at which the solvent is formed during in situ solvent formation microextraction is determined by varying the concentrations of the two components required to form a solvent. In particular, a solvent is formed in situ during ion-associate phase (IAP) microextraction by mixing an aqueous solution with an organic cation and an organic anion. In this study, benzethonium chloride (BenCl) and sodium ethylbenzenesulfonate (NaEBS) were employed as the organic cation and anion sources of model IAPs to thoroughly investigate the in situ solvent formation. Additionally, the formation of the IAPs and the solvent via centrifugation of the formed ion associates was examined. We demonstrated that ion associates are formed when the product of [EBS] and [Ben] is greater than the solubility product and [EBS] is greater than [Ben]. The highest extraction of polycyclic aromatic hydrocarbons (PAHs) was achieved with an amount of NaEBS 40 times greater than that of BenCl. A higher hydrophobicity in the IAP extraction of PAHs, estrogens, and pesticides facilitated extraction into the IAP. Full article

Agricultural operations and the processing sector generate dust laden with endotoxin in the workplace. Endotoxin, a pro-inflammatory agent, has adverse effects on health, especially in the lungs, as exposure to endotoxin reduces lung function capacity. Endotoxin exposure to workers and its harmful impact on the health of agricultural workers needs to be studied in detail for future interventions to reduce exposure to endotoxin. The review can help to identify the analytical methods used to determine endotoxin exposure in agriculture. A detailed study of the research articles published in the last two decades related to agriculture and allied fields was carried out. In the agricultural sector, Pantoea agglomerans, a Gram-negative bacterium, was predominantly present. The filters were stored at a temperature of −20 °C, and E. coli 055: B5 was the predominately used standard to analyze the endotoxin. The quantitative kinetic Limulus Amebocyte Lysate test was the most common detection method for quantifying endotoxin. Control strategies to reduce endotoxin exposure are also emphasized in this review. Full article

Celery (Apium graveolens L.) is a well- known plant and at the basis of the culinary tradition of different populations. In Italy, several celery ecotypes, presenting unique peculiarities, are grown by small local producers, and they need to be characterized, in order to be protected and safeguarded. The present work aims at developing a fast and non-destructive method for the discrimination of a common celery (the "Elne" celery) from a typical celery of Abruzzo (Central Italy). The proposed strategy is based on the use of an e-eye tool which allows the collection of images used to infer colorgrams. Initially, a principal component analysis model was used to investigate the trends and outliers in the data. Then, the classification between the common celery (Elne class) and celery from Torricella Peligna (Torricella class) was achieved by a discriminant analysis, conducted by sequential preprocessing through orthogonalization (SPORT) and sequential and orthogonalized covariance selection (SO-CovSel) and by a class-modelling method called soft independent modelling of class analogies (SIMCAs). Among these, the highest accuracy was provided by the strategies, based on the discriminant classifiers, both of which provided a total accuracy of 82% in the external validation. Full article