Plants, sterol identification

Bouvier-Nave, R, Husselstein, T., Desprez, T. and Benveniste, R (1997) Identification of cDNAs encoding sterol methyl-transferases involved in the second methylation step of plant sterol biosynthesis. Eur.. Biochem., 246,518-29. 

Pascal, S., Taton, M. and Rahier, A. (1993) Plant sterol biosynthesis. Identification and characterization of two distinct microsomal oxidative enzymatic systems involved in sterol C4-demethylation. /. Biol. Chem., 268,11639-54. 

PLANT STEROL BIOSYNTHESIS IDENTIFICATION AND CHARACTERIZATION OF A -STEROL C5(6)-DESATURASE... 

Taton, M. and Rahier, A. (1996) Plant sterol biosynthesis Identification and characterization of... 

Plant Sterol Biosynthesis Identification and Characterization of A " -Sterol C5(6)-Desaturase. 

Pascal S, Taton M and Rahier A. Plant sterol biosynthesis. Identification of a NADPH dependent sterone reductase involved in sterol-4-demethylation. Arch. Biochem. Biophys. 1994 312 000-000. 

Prior to lipid extraction, plants and spores were lyophilized. Sterols were extracted and analysed by the method described by Costet-Corio and Benveniste (1988), except that the saponifiable matter, containing total fatty acids, was adjusted to a pH of one by adding HCl before being extracted three times with hexane. These extracts were pooled and dried. Fatty acids and sterols were quantified by gas chromatography (GC). Fatty acid and sterols identifications were made by comparing retention times respectively to methyl heptadecanoate (17 0) and cholesterol as internal standards. All sterols isolated were identified by GC / mass spectrometry. 

The fatty/waxy products contained the lipophilic substances, including fatty oils, waxes, resins and colorants. Valuable pharmacological effects were proved for some minor constituents of these products (e.g. triterpenes, diterpenes, sterols and carotenoids). Thin layer chromatography and on-line UV-VIS spectroscopy were used for the quick identification and quantity determination of these compounds using authentic samples as standards. The SFE method proved favorable in terras of both extraction yield and speed of carotenoids. The CO2 extracts of the lavandin, clary sage and thyme have been enriched in triterpenic compounds (a-es P-amyrin, oleanic acid, ursolic acid, etc.) and phytosterols. Both free and esterified triterpenoids were present in the extracts of the different samples. Furthermore camosol and other diterpenes were detected in the SFE extract of Lamiaceae plants. The fatty acid composition was only slightly different for extracts obtained by SFE and conventional hexane extraction. 

A24(25)-COmp0und, which is then reduced to give the saturated sterol side-chain. This route is further supported by a recent identification of stigmasta-7,24-dien-3/3-ol in higher plants.167 A similar pathway of alkylation operates for the biosynthesis of clionasterol [(24S)-(95)] from cycloartenol in the yellow-green alga Monodus subter-raneus, with the exception that direct reduction of a A24(28)-sterol [cf. (98)], rather than isomerization and then reduction, appears to occur.168... 

Agrawal, P. K. Bishnoi, V. Studies on Indian medical plants. 42. Sterol and taraxastane derivatives from Artemisia annua and a rational approach based upon C-13 NMR for the identification of skeletal type of amorphane sesquiterpenoids. Indian J. Chem., 1996, 35B 86-88. 

Preparative HPLC was used to separate sterols and triterpene alcohols from the unsaponifiable matter in plant oils from Camellia weiningensis L., Brassica juncea L., and Microula sikkimensis. The isolated compounds were acetylated and further purified by AgN03-impregnated silica gel preparative thin layer chromatography (TLC). The identification was done by IR and MS. 

With the manufacture and use of steroids in pharmaceutical and contraceptive preparations increasing steadily, the quantities appearing in rivers and other natural waters are beginning to be a cause for concern. A report has now appeared on the identification and estimation of steroids in water. With 500 references, it is a useful source of information on analytical methods. The extent of interference by various cholestane derivatives in cholesterol determinations has been evaluated. Of five methods examined, none is wholly specific to cholesterol. Poor reproducibility in steroid solubility determinations can result from adsorption by filter papers. The g.l.c. retention times of an extensive series of sterols have been measured on four different stationary phases, in order to devise methods for the separation of particular mixtures. Some mixtures of saturated compounds with the corresponding unsaturated A -, A -, A -, A -, or A -sterols could not be separated, but A -, A -, and some dienic derivatives are easily separable from their isomers. The results were applied in the examination of sterols in sunflower and other plant oils. The... 

There is a growing interest in sterols and their derivatives in plants. The subject has been reviewed by Grunwald (1975a) Mudd and Garcia (1975) and by Eichenbeiger (1977). Much has been done on identification and biosynthesis, but some aspects of these studies require further elucidation, such as the subcellular sites of biosynthesis. In other respects the study of sterol derivatives in plants is in its infancy very little is known about function and metabolic turnover. 

The order Caryophyllales is composed of 12 families (Fig. 1) and was selected for a chemosystematic analysis of sterols based on early reports of 24-alkyl-A7-sterols in three families i.e. Spinacia (Chenopodiaceae), Lophocereus (Cactaceae) and Phytolacca (Phytolaccaceae) . Phytosterol structure and composition was analyzed with respect to each plant s taxonomic assignment. Isolation, identification methods, taxonomic classification, nomenclature systems and tribal arrangements are presented elsewhere only mature photosynthetic tissue was analyzed to avoid... 

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