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6.2.1.2.2.4 Steroids
The steroids are found in association with fat. All of the steroids have a similar cyclic nucleus resembling phenanthrene (rings A, B and C) to which a cyclopentane ring (D) is attached. The parent substance is cyclopentano-perhydrophenanthrene.
Steroid nucleus (cyclopentano-perhydrophenanthrene) Steroids play many physiologically important roles. Cholesterol is probably the best known steroid. It is of significance because it is the precursor of a large number of equally important steroids which include the bile acids, adrenocortical hormones, sex hormones, D vitamins, cardiac glycosides, sitosterols of the plant kingdom, and some alkaloids. Cholesterol is found is cell membrane, nerve, brain tissue, and in all fluids. Ergosterol is a plant steroid used for the synthesis of vitamin D.
Cholesterol |