Lipase-catalysed kinetic resolution of 1-O-alkylglycerols by sequential transesterification

Synthesis, characterization, antibacterial and antifungal activities of 1-O-alkylglycerols

1-O-alkylglycerols are a class of natural existing lipids with broad biological activities. However, their use in food or agricultural fields remains to be investigated, especially for their antimicrobial activity. In this work, three 1-O-alkylglycerols, 1-O-octanylglycerol (C8Gly1), 1-O-dodecylglycerol (C12Gly1), and 1-O-hexadecylglycerol (C16Gly1), were synthesized in the isolated yields of 71.3-89.8 % and characterized by 1H NMR, 13C NMR, FITR, mass spectra, and HPLC-ESLD. The critical micelle concentration (CMC) of 1-O-alkylglycerols was determined to be 1.65 mmol/L (C8Gly1), 0.33 mmol/L (C12Gly1), and 0.23 mmol/L (C16Gly1) using the pyrene method. C12Gly1 and C16Gly1 had similar surface tensions that are lower than C8Gly1. C8Gly1 can form micelles in aqueous solution with excellent nano-dispersed uniformity and stability. Furthermore, C8Gly1 and C12Gly1 not only displayed good antibacterial activity against Staphylococcus aureus, but they also inhibited the growth of Botryosphaeria dothidea, Monilia fructigena, and Phytophthora capsicum at 400 μg/mL. Thus, the C8Gly1 and C12Gly1 can serve as novel antimicrobial agents in food preservation.

Synthesis of natural 1-O-alkylglycerols: a study on the chemoselective opening of the epoxide ring by onium quaternary salts (N and P) and ionic liquids

A chemoselective route for the synthesis of 1-O-alkylglycerols chimyl (1), batyl (2), and selachyl (3) is reported.

High enantioselective Novozym 435-catalyzed esterification of (R,S)-flurbiprofen monitored with a chiral stationary phase

Lipases form Candida rugosa and Candida antarctica were tested for their application in the enzymatic kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification. Successful chromatographic separation with well-resolved peaks of (R)- and (S)-flurbiprofen and their esters was achieved in one run on chiral stationary phases by high-performance liquid chromatography (HPLC). In this study screening of enzymes was performed, and Novozym 435 was selected as an optimal catalyst for obtaining products with high enantiopurity. Additionally, the influence of organic solvents (dichloromethane, dichloroethane, dichloropropane, and methyl tert-butyl ether), primary alcohols (methanol, ethanol, n-propanol, and n-butanol), reaction time, and temperature on the enantiomeric ratio and conversion was tested. The high values of enantiomeric ratio (E in the range of 51.3-90.5) of the esterification of (R,S)-flurbiprofen were obtained for all tested alcohols using Novozym 435, which have a great significance in the field of biotechnological synthesis of drugs. The optimal temperature range for the performed reactions was from 37 to 45 °C. As a result of the optimization, (R)-flurbiprofen methyl ester was obtained with a high optical purity, eep = 96.3 %, after 96 h of incubation. The enantiomeric ratio of the reaction was E = 90.5 and conversion was C = 35.7 %.

Ether lipids

The naturally occurring 1-O-alkyl-sn-glycerols and their methoxylated congeners, 1-O-(2'-methoxyalkyl)-sn-glycerols, are biologically active compounds, ubiquitously found in nature as diacyl glyceryl ether lipids and phosphoether lipids. The chief objective of this article is to provide a comprehensive and up to date review on such ether lipids. The occurrence and distribution of these compounds in nature are extensively reviewed, their chemical structure and molecular variety, their biosynthesis and chemical synthesis and, finally, their various biological effects are described and discussed. An unprecedented biosynthesis of the 2'-methoxylated alkylglycerols is proposed. The first synthesis of enantiopure (Z)-(2'R)-1-O-(2'-methoxyhexadec-4'-enyl)-sn-glycerol, the most prevalent 2'-methoxylated type alkylglycerol present in cartilaginous fish, is described. It was accomplished by a highly convergent five step process.

Membrane plasmalogen composition and cellular cholesterol regulation: a structure activity study

Background

Disrupted cholesterol regulation leading to increased circulating and membrane cholesterol levels is implicated in many age-related chronic diseases such as cardiovascular disease (CVD), Alzheimer's disease (AD), and cancer. In vitro and ex vivo cellular plasmalogen deficiency models have been shown to exhibit impaired intra- and extra-cellular processing of cholesterol. Furthermore, depleted brain plasmalogens have been implicated in AD and serum plasmalogen deficiencies have been linked to AD, CVD, and cancer.

Results

Using plasmalogen deficient (NRel-4) and plasmalogen sufficient (HEK293) cells we investigated the effect of species-dependent plasmalogen restoration/augmentation on membrane cholesterol processing. The results of these studies indicate that the esterification of cholesterol is dependent upon the amount of polyunsaturated fatty acid (PUFA)-containing ethanolamine plasmalogen (PlsEtn) present in the membrane. We further elucidate that the concentration-dependent increase in esterified cholesterol observed with PUFA-PlsEtn was due to a concentration-dependent increase in sterol-O-acyltransferase-1 (SOAT1) levels, an observation not reproduced by 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibition.

Conclusion

The present study describes a novel mechanism of cholesterol regulation that is consistent with clinical and epidemiological studies of cholesterol, aging and disease. Specifically, the present study describes how selective membrane PUFA-PlsEtn enhancement can be achieved using 1-alkyl-2-PUFA glycerols and through this action reduce levels of total and free cholesterol in cells.