Heterogeneous Biocatalytic Processes of the Low-Temperature Synthesis of Esters: Selection of Organic Solvent

Processes of the low-temperature enzymatic synthesis of esters in nonaqueous media of organic solvents with participation of heterogeneous biocatalysts synthesized by the adsorption immobilization of a recombinant lipase from Thermomyces lanuginosus (Pichia pastoris producer) on macroporous carbon aerogel were investigated. The esterification reaction was conducted using individual organic solvents of different polarity, such as nonpolar ones (lоgP > 2.5) – hexadecane, hexane and toluene, and polar solvents (lоgP < 1) – diethyl ether, tert-butanol and acetone, as well as their binary mixtures of different composition, for example, a mixture of hexane with diethyl ether having the composition 1 : (1/5÷3, vol. fr.). The effect of the solvent and co-solvent nature on the properties of synthesized biocatalysts, namely the enzymatic activity and operational stability, was studied in the batch esterification of heptanoic acid (C7:0) by alcohols, particularly the polar substrates – ethanol and n-butanol, or nonpolar alcohols – n-octanol and n-hexadecanol. Activity of the synthesized biocatalysts was found to depend to a great extent on polarity of both the solvents used in the reaction and the alcohol substrates. The maximum activity of 400 EA·g–1 was observed in a medium of nonpolar and nonviscous hexane (lоgP = 2.9), whereas the minimum activity of 4 EA·g–1 – in acetone (lоgP = 0.4); esterification of heptanoic acid in the presence of tert-butanol (lоgP = 0.6) virtually did not proceed. The activity of biocatalysts was shown to depend nonmonotonically on the lоgP value of individual solvent. In the binary mixtures of organic solvents, such as hexane/diethyl ether, biocatalytic activity linearly increased with an increase in lоgPmixture; in addition, biocatalysts exhibited the maximum operational stability.

Impact of Drying Method on the Evaluation of Fatty Acids and Their Derived Volatile Compounds in ‘Thompson Seedless’ Raisins

Air- and sun-dried raisins from Thompson Seedless (TS) grapes were analyzed under GC/MS to evaluate fatty acids (FAs) and their derived volatile compounds, coming from unsaturated fatty acids oxidation. A total of 16 FAs were identified in TS raisins, including 10 saturated fatty acids (SFAs) and 6 unsaturated fatty acids (USFAs). The contents of C18:0, C15:0, and C16:0 among SFAs and C18:3, C18:2 and C18:1 in USFAs were significantly higher. Furthermore, USFAs such as C16:1 and C20:1 were only identified in air-dried raisins. The principal component analysis showed the increased content of FAs and FA-derived compounds were in air-dried and sun-dried raisins, respectively. Among FA-derived compounds, 2-pentyl furan, 3-octen-2-one, 1-hexanol and heptanoic acid were more potent. This study shows that air-drying is more favorable for the production of fatty acids (SFAs and USFAs), whereas sun-drying is more advantageous in terms of fatty acid-derived volatiles.

Flexible polyurethanes, renewable fuels, and flavorings from a microalgae oil waste stream

To achieve sustainably-sourced polymers from algae, azelaic acid was prepared from an algae oil waste stream and converted into a flexible polyurethane foam. The heptanoic acid co-product was converted into both a flavoring and a renewable solvent.

Exploring Molecular Docking Studies of Alanine Racemase Inhibitors from Elettaria cardamomum

Background: Enterococcus faecalis has attracted much attention in recent times due to its increased virulence in hospital-acquired infections. Cardamom which is an exotic spice in food items can be proposed for its antimicrobial potential. In the present study, alanine racemase (AlaR) of the bacteria was considered as inhibitors’ target due to its crucial role in cell wall synthesis. Methods: GC-MS analysis of Cardamom extract was performed and the identified phytochemicals were docked against AlaR using AutoDock 4.0. Top score ligands were further subjected to Absorption, Distribution, Metabolism, Excretion (ADME) analysis. Results & Conclusion: Molecular docking studies reveal that among 85 phytoligands, ricinoleic acid, bombykol, 1,8- cineole, heptanoic acid, and linalool showed significant interaction to the enzyme with an energy of -7.81, -7.57, -7.03, -7.02 and -7 kcal/mol, respectively, as compared to its substrate (ΔG Alanine: -5.03 kcal/mol). Among all the five lead compounds, 1,8- cineole, heptanoic acid, and linalool exhibited high bioactivity score on druglikeliness. This enabled us to conclude that the compounds 1,8- cineole, heptanoic acid and linalool would be useful antibacterial agents against E. faecalis infections.

Occurrence and source apportionment of perfluoroalkyl acids (PFAAs) in the atmosphere in China

Perfluoroalkyl acids (PFAAs) are a form of toxic pollutant that can be transported across the globe and accumulated in the bodies of wildlife and humans. A nationwide geographical investigation considering atmospheric PFAAs was conducted in China, which provides an excellent chance to investigate their occurences, spatial trends, and potential sources. The total concentrations of thirteen PFAAs were 6.19–292.6 pg/m3, with an average value of 39.8 ± 28.1 pg/m3, which were higher than other urban levels but lower than point source measurements. Perfluorooctanoic acid (PFOA) was the dominant PFAAs (20.6 %), followed by perfluoro–hexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS), and perfluoro–heptanoic acid (PFPeA). An increasing seasonal trend of PFAAs concentrations was shown as summer

Two solvent-induced variable host–guest two-dimensional binary frameworks mediated by hydrogen bonding

Two-dimensional binary hydrogen-bonded organic frameworks constructed from 1,3,5-benzenetricarboxylic acid (TMA) and 4,4′-biphenyldicarboxylic acid (BDA) on highly oriented pyrolytic graphite (HOPG) were investigated by scanning tunneling microscopy (STM) in heptanoic acid and octanoic acid solvents.