Sterols sources

Gagosian, R.B., J.K. Volkman, and G.E. Nigrelli. 1983. The use of sediment traps to determine sterol sources in coastal sediments off Peru. Pp. 369-379 in Advances in Organic Geochemistry 1981, M. Bjoroy et al., eds., New York John Wiley and Sons. 

Fig. 34. 3. Structures of selected sterols. Sources animal - lanosterol, cholesterol and ergosterol (also microbial) plant - all others. (From Warner, K., Su, C, and White, P.J. "Role of Antioxidants and Polymerization Inhibitors in Protecting Frying Oils" in Frying Technology and Practices, M.K. Gupta, K. Warner, and P.J. White (Eds.), pp. 37-49, AOCS Press, Champaign, IL 2004. With permission.)...

Benecol also received FDA approval for its cholesterol-lowering stanol ester ingredient, a hydrogenated sterol sourced from wood pulp. Approval was originally delayed when the FDA ruled that it could not be labelled as a dietary supplement and would have to undergo the same safety procedures as regular food products. 

Domain 0.5 - 1.0 pg/ml Miminal amount of sterol necessary for sustained growth of cells without other sterol sources. Cell cone.=ca.0.3 pg/mg d.w. cells... 

Bulk 15 ug/ml Expandable pool of free sterol in absence of other sterol sources. Cell cone.=0.3 to 3.0 ug/mg d.w. 

The quaHty, ie, level of impurities, of the fats and oils used in the manufacture of soap is important in the production of commercial products. Fats and oils are isolated from various animal and vegetable sources and contain different intrinsic impurities. These impurities may include hydrolysis products of the triglyceride, eg, fatty acid and mono/diglycerides proteinaceous materials and particulate dirt, eg, bone meal and various vitamins, pigments, phosphatides, and sterols, ie, cholesterol and tocopherol as weU as less descript odor and color bodies. These impurities affect the physical properties such as odor and color of the fats and oils and can cause additional degradation of the fats and oils upon storage. For commercial soaps, it is desirable to keep these impurities at the absolute minimum for both storage stabiHty and finished product quaHty considerations. 

Initial steroid research involved isolation of sterols and bile acids from natural sources. DeFourcroy is generally credited with the discovery of cholesterol [57-88-5] (2) in 1789 (3). In 1848, choHc acid [81-25-4] (3) was isolated from the saponification of ox bile and its elementary composition deterrnined as... 

Again, the answer should be fairly obvious. The potential therapeutic value of the steroid hormones makes these of tremendous commercial value. The commercial market for these is of the order of hundreds of millions of dollars per year. There is no comparable market for sterols and bile salts. We are faced with the interesting situation, therefore, that sterols are relatively abundant in natural sources but of relatively low commercial value, whilst steroids occur naturally at very low concentrations but are of great commercial value. Although there are tremendous variations amongst different products, steroids with desirable properties command market prices that are (ten to one thousand fold) greater than their sterol counterparts. 

Herbal products used for the relief of menopausal symptoms are purported to act by a number of different mechanisms. Phytoestrogens are plant sterols that are structurally similar to human and animal estrogen. Soy protein is a common source of phytoestrogens and can be found in products such as tofu, soy milk, soy flour, and tempeh. Various studies have demonstrated conflicting results as to the efficacy of... 

Marine organisms frequently contain a complex mixture of sterols. The biosynthetic origin of these compounds is complicated by the fact that there are four possible sources. The sources by which marine invertebrates may obtain sterols, first described by Goad [3], are (1) de novo biosynthesis, (2) assimilation from diet, (3) modification of dietary sterols and (4) assimilation of symbiont-produced sterols or sterol precursors. In any examination of the biosynthetic origin(s) of sterols one must consider all of these factors needless to say, a complex picture is emerging. 

In more recent studies the use of HPLC allowed isolation and counting of individual sterols after administration of labelled precursors. The sterols isolated from mantles and viscera of the nudibranch Doris verrucosa were identified as cholestanol, cholesterol, 24-dehydrocholesterol and 7-dehydrocholesterol [103]. After injection of dl-[2-14C]-mevalonic acid DBED salt, cholesterol (57) and 7-dehydrocholesterol (58) were isolated as the acetates by reversed phase HPLC. Both sterols were found significantly labelled specific radioactivity associated with 7-dehydrocholesterol was higher by one order of magnitude than that associated with cholesterol. This fact would indicate either that the reduction of the A1 double bond of 7-dehydrocholesterol to afford cholesterol occurs at a low rate, or that the cholesterol found in D. verrucosa comes partly from a dietary source. 

The active vitamins are produced by conversion of provitamins by ultraviolet light. Ergosterol, a yeast sterol, is converted to its active form, ergocalciferol (vitamin D2), and 7-dehydrocholesterol, which is found in many natural foods and is also synthesized in man, is converted to cholecalciferol (vitamin D3). Fish liver oils are virtually the only source of vitamin D3 in nature. The most active form of vitamin D3 is 1,25-dihydroxycholecalciferol and this is produced by the hydroxylation of cholecalciferol at position 25 in the liver and then at position 1 in the kidney. 

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