Sterol plant

Note Values do not add up to 100% in every case, because there are components other than protein, phospholipids, and sterol plants, for example, have high levels of glycolipids. 

Most of the unsaponifiables in vegetable and animal fats are sterols. The animal fats contain predominantly cholesterol, and most vegetable fats contain only traces of this sterol. Plant sterols, collectively called phytosterols, are made up mainly of sitosterols and stigmasterol, but some individual vegetable fats contain additional phytosterols. The pattern of typical sterols has been suggested as useful in detecting the adulteration of one oil with another (2). 

P-Sitosterol (sterol) Plant membranes 4- Cortisol induction by stress [membrane fluidity 4- stressful exercise-induced immunosuppression]... 

Bouvier-Nave, R and Benveniste, P. (1995) Sterol acyl transferase and steryl ester hydrolase activities in a tobacco mutant which overproduces sterols. Plant Sci, 110, 11-9. 

Plant sterol and a pulp and paper industry effluent Plant sterol Plant sterol Plant sterol... 

Fujita S, Ohnishi T, Watanabe B, Yokota T, Takatsuto S, Fujioka S, Yoshida S, Sakata K, Mizutani M (2006) Arabidopsis CYP90B1 catalyses the early C-22 hydroxylalion of C27, Cjg and C29 sterols. Plant J 45 765-774... 

Although names and properties of thousands of hydrocarbons and their variously oxidized and rearranged derivatives have been compiled and catalogued (variously complete catalogues that are incomplete when published), the exact number of terpenes (Cio), sesquiterpenes (C15), diterpenes (C20), sesterpenes (C25), triterpenes (C30), carotenoids (C40), and varieties of rubber (e.g., laytex and gutta-percha) is unknown. Similarly, tomes have been written on the subject, and the discussion of these compounds here will end with an introduction to the triterpenes because these serve as sources of steroids (animal) and sterols (plants). 

Parameter Cholesterol Plant sterols Plant stanols... 

As well as the free triterpenes and sterols, plant cells often accumulate significant quantities of triterpene derivatives such as glycosides (as shown above by the ginsenosides and... 

The ancestors of these A"-sterol plants may have given rise to the Cactaceae and parts of the Chenopodiaceae. Likewise the A -sterol producing families may have arizen from A -sterol ancestors in the Phytolaccaceae. The 248-alkyl-A -sterols in the Caryophyllaceae would support its more basal assignment since 243-ethyl sterols occur in lower photosynthetic organismsl>2. A careful systematic analysis of additional species in this order will provide further insight into the significance of sterol structural and compositional data with respect to chemotaxonomy. 

The path from squalene (114) to the corresponding oxide and thence to lanosterol [79-63-0] (126), C qH qO, cholesterol [57-88-5] (127), and cycloartenol [469-38-5] (128) (Fig. 6) has been demonstrated in nonphotosynthetic organisms. It has not yet been demonstrated that there is an obligatory path paralleling the one known for generation of plant sterols despite the obvious stmctural relationships of, for example, cycloartenol (128), C qH qO, to cyclobuxine-D (129), C25H42N2O. The latter, obtained from the leaves of Buxus sempervirens E., has apparentiy found use medicinally for many disorders, from skin and venereal diseases to treatment of malaria and tuberculosis. In addition to cyclobuxine-D [2241-90-9] (129) from the Buxaceae, steroidal alkaloids are also found in the Solanaceae, Apocynaceae, and LiUaceae. 

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). 

Figure 8 illustrates one of the processing schemes used for separating various components in a hydrocarbon-containing plant. Acetone extraction removes the polyphenols, glycerides, and sterols, and benzene extraction removes the hydrocarbons. If the biomass species in question contain low concentrations of the nonhydrocarbon components, exclusive of the carbohydrate and protein fractions, direct extraction of the hydrocarbons with benzene or a similar solvent might be preferred. 

G. Haug and H. Hoffman, eds., Chemisty of Plant Protection, Hoi 1 Sterol Biosynthesis Inhibitors andMnti-Feeding Compounds, Springer-Vedag, Berlin, 1986. 

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). 

Table 2. Occurrence of the Provitamins D in Selected Plants and Animals, Parts per Thousand of Total Sterol...

It is important to note that diet is a complex mixture that contain compounds with varying activity. Chemical stimulators of colon cancer growth include bile acids, 1,2-diglycerides and prostaglandins which stem from consumption of fat. In contrast, fruits and vegetables contain substances such as carotenoids, flavonoids and fibre, which may inhibit cancer cell growth, and the risk of colon cancer appears to be mirrored by the ratio of plant sterols to cholesterol in the... 

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. 

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