Sterols 3-sitosterol

The value of the sterol fraction (— 24.88%o, Table 1) and the presence of the C29 sterol, (3-sitosterol in dominant amounts relative to other sterols, would imply terrestrial contribution to the organic carbon (Huang and Meinschein, 1976 Venkatesan et al, 1987). This value is also within the range of determined by Pearson et al. (2000) for sterols such as cholesterol, 27 and C28 and many other sterols from the surface sediments of Santa Barbara (SBB, 0-1 cm) and SM basins (0-5.5 cm). They did not find any depletion in the C29 sterols as would be expected from a significant terrigenous inputs and concluded that these sediments do not contain a quantitatively significant terrestrial component. Similar conclusion may not be applicable to our sample which comes from a much deeper horizon than their study. 

The practical development of plant sterol drugs as cholesterol-lowering agents will depend both on structural features of the sterols themselves and on the form of the administered agent. For example, the unsaturated sterol sitosterol is poorly absorbed in the human intestine, whereas sitostanol, the saturated analog, is almost totally unabsorbable. In addition, there is evidence that plant sterols administered in a soluble, micellar form (see page 261 for a description of micelles) are more effective in blocking cholesterol absorption than plant sterols administered in a solid, crystalline form. 

Soya (soybean) Glycine max (Leguminosae/ Fabaceae) seed 18-20 linoleic (44-62%), oleic (19-30), palmitic (7-14), a-linolenic (4-11), stearic (1-5) food oil, dietary supplement, carrier oil (aromatherapy) Soya oil contains substantial amounts of the sterols sitosterol and stigmasterol (see page 256)... 

Among various sterols, sitosterol was predominant in nutmeg. Other sterols reported... 

Aniseed oil contains 0.7% sterols. Sitosterol and stigmasterol were identified as the major components (Zlatanov and Ivanov, 1995). Aniseed also contains coumarins and glycosides. 

Plant sterols, also called phytosterols, have been reported to include over 250 different sterols and related compounds in various terrestrial and marine materials (Akihisa et al., 1991). Sitosterol, stigmasterol, and campesterol are the commonly consumed plant sterols. The predominant sterol class in vegetable oils is 4-desmethyl sterols. Sitosterol usually contributes more than 50% of desmethyl sterols. The other most significant desmethyl sterols include campesterol, stigmasterol, A5-avenasterol, A7-avenasterol, and A7-stigmastenol. Brassicasterol is a typical sterol for rapeseed and other Cruciferae. Stanol occurs in significant amounts in com bran and fiber oil (Piironen, et al., 2000). 

Fermentation of a mixture of soy sterols, sitosterol, stigmasterol and traces of related compounds with Microbacteria sp. produces androstenedione (1-6). Relatively recent patents describe the production of the steroid from phytoserols from various crude vegetable oils, bypassing the need for prior isolation of the phytosterol fraction. 

Major sterols Sitosterol and others Cholesterol via None... 

Fig. 2. Biosynthesis of typical plant sterols. Boxed sterols are probable precursors of various brassinosteroids. Among these sterols, sitosterol, stigmasterol, campesterol, 24-epicampesterol and cholesterol are the most common end-of-pathway sterols in plants. Italic letters refer to the lesions in the biosynthesis mutants of Arabidopsis (dim) and pea (Ikb).

All defects can be picked up by a careful analysis of plasma cholesterol and its precursors by GC-MS. Following the saponification of cholesterol esters, the cholesterol(s) are extracted and derivatized to form trimethylsi-lyl ethers. The levels of all precursors are very low in controls, less than 1 pmol/l. Only few artefactual increases are known such as the increase of plant sterols (sitosterol) following the administration of intralipid, and the accumulation of 7- and 8-dehydrocholesterol following haloperidol drug treatment. 

In most higher plants, sterols are present as a mixture of A -sterols. Sitosterol, stigmasterol and 24-methylcholesterol are usually cited as the typical plant sterols (Fig.l). These sterols are concentrated mainly in the plasma membrane (PM) (1). Using sterol biosynthesis inhibitors, we have shown that it is possible to obtain plant cell suspensions or whole plants with a completely modified sterol profile (2,3). Such plants constitute most suitable material for studying structural and functional roles of sterols, which are still largely unknown. 

Other constiments present in clove buds include glucosides of sterols (sitosterol, stig-masterol, and campesterol), crategolic acid methyl ester, oleanolic acid, quercetin, eugeniin, kaempferol, rhamnetin, about 6% protein, 20% lipids, 61% carbohydrates, vitamins, and others (jiangsu marsh). 

Elder leaf contains sambunigrin (a cyano-genic glucoside) at 0.042% concentration, according to one source choline rutin and quercetin sterols (sitosterol, stigmasterol, and campesterol) triterpenes (a- and P-amyrin palmitates, oleanohc acid, and ursohc acid) alkanes (mainly -nonacosane and... 

Root contains 0.19-0.39% alkaloids, mainly quinoline type (dictamnine, skimmianine, preskimmianine, isodictamnine, dasycarpa-mine, y-fagarine (8-methoxydictamnine), iso-maculosindine, trigonelline, choline, etc.) lactones (dictamnolactone, obaculactone or limonin, rutaevin, fraxinellone, etc.) sterols (sitosterol and campesterol) saponins and volatile oil. Fraxinellone has antifertility (anti-implantation) activities. ... 

Small amounts of sitostanol and campestanol, which are 5,6-saturated analogues of the main 4-desmethyl sterols (sitosterol and campesterol), occur in plant materials such as coniferous trees (pine, spruce) and certain grains (rye, wheat and corn/maize). 

In milk fat, cholesterol is associated with Hpoproteins in the milk fat globule. It is also a component of animal membranes and controls rigidity and permeabihty of the membranes. Cholesterol has interesting surface properties and can occur in Hquid crystalline forms. Plants contain sterols such as P-sitosterol [83-46-5] (4b) or stigmasterol [83-48-7] (4c). Their functions in plant metaboHsm are not yet well understood. Analysis of sterols has proven useful for detection of adulteration of edible fats (9). 

Bacterial removal of sterol side chains is carried out by a stepwise P-oxidation, whereas the degradation of the perhydrocyclopentanophenanthrene nucleus is prevented by metaboHc inhibitors (54), chemical modification of the nucleus (55), or the use of bacterial mutants (11,56). P-Sitosterol [83-46-5] (10), a plant sterol, has been used as a raw material for the preparation of 4-androstene-3,17-dione [63-05-8] (13) and related compounds using selected mutants of the P-sitosterol-degrading bacteria (57) (Fig. 2). 

Processing Raw Materials. Along with the aforementioned chemical methods of processing steroid raw materials, microbial transformations have been and are used in a number of commercial degradation processes. The microbial degradation of the C17 side chain of the two most common sterols, cholesterol (2) and P-sitosterol (41), is a principal commercial method for the preparation of starting materials in Japan and the... 

The rate of side-chain cleavage of sterols is limited by the low solubiUty of substrates and products and thek low transport rates to and from cells. Cyclodextrins have been used to increase the solubiUties of these compounds and to assist in thek cellular transport. Cyclodextrins increase the rate and selectivity of side-chain cleavage of both cholesterol and P-sitosterol with no effect on cell growth. Optimal conditions have resulted in enhancement of molar yields of androsta-l,4-diene-3,17-dione (92) from 35—40% to >80% in the presence of cyclodextrins (120,145,146,155). 

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