Metabolism of long-chain alcohols in cell suspension cultures of soya and rape

Comparison of the concentrations of long-chain alcohols (policosanol) in three Tunisian peanut varieties (Arachis hypogaea L.)

Policosanol (PC) is a mixture of high molecular weight aliphatic primary alcohols. Literature about the contents and compositions of PC derived from peanut varieties is scarce. Total PC composition and content in whole peanut grain samples from three varieties of peanut (two cultivars, AraC and AraT, and a wild one, AraA) were identified using a gas chromatograph system coupled with a mass spectrophotometer. The results show that, qualitatively, 21 components of peanut aliphatic alcohols were identified (C14-C30). Besides (C18=), the results exhibited a previously unreported mixture of PC compositions in the peanuts: the unsaturated PC (UPC), which are (C20=), (C21=), (C22=), and (C24=). The main components of total PC in Tunisian peanut kernels are docosanol (C22), (Z)-octadec-9-en-1-ol (C18=), hexadecanol (C16), and octadecanol (C18). Quantitatively, the total PC content of the whole peanut samples varied from 11.18 to 54.19 mg/100 g of oil and was higher than those of beeswax and whole sugar cane, which are sources of dietary supplements containing policosanol.

Biosynthesis and biotransformation of ether lipids

Some naturally occurring as well as synthetic ether lipids are biologically active. In certain cases, the effects of these substances are enhanced, in others, they are inhibited by compounds that were isolated from natural sources or prepared by chemical synthesis. The biotransformation of natural or "unnatural" ether lipids in microorganisms, plant or animal tissue also can lead to substances that elicit biological effects. The production of such compounds through various biotechnological techniques is a field wide open for future exploration. In addition to animal cell cultures, plant cell cultures may become useful tools in biomedical studies concerned with ether lipids.

Formation of complex ether lipids from 1-O-alkylglycerols in cell suspension cultures of rape

Photomixotrophic cell suspension cultures of rape, Brassica napus, were incubated with rac-1-O-[1'-(14)C]hexadecylglycerol. Radioactivity was incorporated predominantly into choline glycerophospholipids. Prolonged incubation led also to considerable proportions of labeled ethanolamine glycerophospholipids. In addition to these ionic lipids,isomeric hexadecylacylglycerols as well as hexadecyldiacylglycerols were formed. About a third of the hexadecylglycerol supplied as substrate was cleaved within 48 h incubation. The palmitic acid formed by oxidative cleavage of the substrate was incorporated predominantly into choline glycerophospholipids, ethanolamine glycerophospholipids, and triacylglycerols. Incubation of an equimolar mixture of homologous saturated rac-1-O-[1'(14)C]alkylglycerols (C14, C16, C18, C20) with rape cells showed that alkylglycerols with alkyl moieties having 16 and 18 carbon atoms were incorporated preferentially. Incubation of labeled hexadecyglycerol with a homogenate of rape cells led also predominantly to choline glycerophospholipids; highest yields were obtained at pH 7. Neither the 1-O-alkyl moieties in choline glycerophospholipis nor those in ethanolamine glycerophospholipids were desaturated to 1-O-alk-1'-enylmoieties. The results of these experiments led to the following conclusions: (1) The acylation of 1-O-alkylglycerols to isomeric alkylacylglycerols is catalyzed by two acyltransferases differing in their specificity with regard to the chain length of the alkyl moiety in the substrate. (2) CDP-Choline: diacylglycerol cholinephosphotransferase and CDP-ethanolamine: diacylglycerol ethanolaminephosphotransferase are two enzymes differing in various respects. Cholinephosphotransferase exhibits a much higher affinity for 1-O-alkyl-2-O-acylglycerols than ethanolaminephosphotransferase. The two enzymes show marked differences with regard to their specificity for 1-O-alkyl-2-O-acylglycerols differing in the chain lengths of their alkyl moieties.