Phytosterol(redirected from phytostearin)
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a plant sterol released from the unsaponified parts of plant lipides. In contrast to animal sterols, such as cholesterol, the side chain in phytosterols is unsaturated and contains not eight carbon atoms but nine or ten. Most phytosterols are optically active crystalline substances with physical and chemical properties similar to those of other sterols.
The most common phytosterols include (β-sitosterol (C29H50O) and stigmasterol (C29H48O), which are released by cotton-seed, soybean, and other oils and from the by-products of the sulfate process in the cellulose industry. Isomers of stigmasterol are α-spinasterol (from spinach), fucosterol (from fungi), brassicasterol (C28H46O; from cabbage), and campesterol (C28H48O; from cabbage). Ergosterol is also a phytosterol.
Phytosterols are found in plants in free form, as well as in compounds with carbohydrates or fatty acids or with both. In some plants, β-sitosterol, like cholesterol, serves as the precursor to progesterone. Stigmasterol serves as a vitamin for guinea pigs (antiankylosis factor). Phytosterols also include certain C28 and C29 sterols from ferns and conifers that induce molting in insects (ecdysones).
Phytosterols are used in the pharmaceutical industry for the synthesis of steroid preparations.
REFERENCESHeftman, E. Biokhimiia steroidov. Moscow, 1972. (Translated from English.)
Heftmann, E. “Biochemistry of Plant Steroids.” Annual Review of Plant Physiology, 1963, vol. 14.
Bean, G. A. “Phytosterols.” Advances in Lipid Research, 1973, vol. 11.
E. P. SEREBRIAKOV