Cholesterol purification

Saponins. Although the hypocholesterolemic activity of saponins has been known since the 1950s, thek low potency and difficult purification sparked Htde interest in natural saponins as hypolipidemic agents. Synthetic steroids (292, 293) that are structurally related to saponins have been shown to lower plasma cholesterol in a variety of different species (252). Steroid (292) is designated CP-88,818 [99759-19-0]. The hypocholesterolemic agent CP-148,623 [150332-35-7] (293) is not absorbed into the systemic ckculation and does not inhibit enzymes involved in cholesterol synthesis, release, or uptake. Rather, (293) specifically inhibits cholesterol absorption into the intestinal mucosa (253). As of late 1996, CP-148,623 is in clinical trials as an agent that lowers blood concentrations of cholesterol (254). 

Cholesterol [57-88-5] M 386.7, m 148.9-149.4 , [a]D -35 (hexane). Crystd from ethyl acetate, EtOH or isopropyl ether/MeOH. [Hiromitsu and Kevan J Am Chem Soc 109 4501 I987. For extensive details of purification through the dibromide, see Fieser [J Am Chem SoclS 5421 1953] and Schwenk and Werthessen [Arch Biochem Biophys 40 334 7952], and by repeated crystn from acetic acid, see Fieser [J Am Chem Soc 75 4395 1953]. 

Material melting at 140-141° (p. 45) is satisfactory. The presence of a trace of cholesterol is not objectionable since this is converted into acidic products which are removed in the course of the purification. 

Extraction of Aesculus hippocastanum L. (horse-chestnut) and purification on cation-exchanger (H -form), resp. precipitation with cholesterol. 

Doukyu N, R Aono (1998) Purification of extracellular cholesterol oxidase with high activity in the presence of organic solvents from Pseudomonas sp. strain ST-200. Appl Environ Microbiol 64 1929-1932. 

Sometimes natural fine chemicals are by-products in bulk products refining. Examples are (a) lecithin and steroids in vegetable oil refining (b) betaine, pectin and raffinose in sugar manufacture (c) quinic acid in quinine extraction of the bark of Cinchona trees (d) chitin and the red pigment asthaxanthin in lobster and shrimp processing and (e) lanolin, lanosterol and cholesterol in sheep wool purification. 

D. J. S. Riley, E. M. Kyger, C. A. Spilburg, L. G. Lange, Pancreatic Cholesterol Esterases. 2. Purification and Characterization of Human Pancreatic Fatty Acid Ethyl Esterase Synthase , Biochemistry 1990, 29, 3848-3852. 

F2. Fielding, C. J., and Fielding, P. E., Purification and substrate specificity of lecithin-cholesterol acyltransferase from hiunan plasma. FEBS (Fed. Eur. Biochem. Soc.), Lett. 15, 355-358 (1971). 

R2. Ritter, M. C., and Dempsey, M. E., Purification and characterization of a naturally occurring activator of cholesterol biosynthesis from A -cholestadienol and other precursors. Biochem. Biophys. Res. Cmnmun. 38, 921-929 (1970). 

Applications of cation and anion resins are varied and include purification of sugar, identification of drugs and biomacromolecules, concentration of uranium, calcium therapy to help increase the amount of calcium in our bones (i.e., increase the bone density), and use as therapeutic agents for the control of bile acid and gastric acidity. In the latter use, a solid polyamide (Colestid) is diluted and taken with orange juice, which facilitates removal of bile acids from the body. This removal helps the body to produce more bile acid from cholesterol, thus effectively reducing the cholesterol level. 

Purification of cholesterol through the dibromide completely eliminates cholestanol, 7-dehydrocholesterol, and latho-sterol (A7-cholestenol). The first crop of material from methanol-ether is also free from cerebrosterol (24-hydroxycholesterol) and 25-hydroxycholesterol, a product of autoxidation present in cholesterol that has been stored in the crystalline state for a few years with access to air. When material of highest purity is desired, only first-crop dibromide should be employed, since de-bromination of second-crop material gives sterol melting at 146-147° and giving a positive Beilstein test. 

Membrane plasmapheresis is also the first step for treatment of pathological plasma in the case of autoimmune diseases, as the patient retains his own red blood cells while his plasma is replaced by an albumin solution or fresh frozen plasma obtained from donors (plasma exchange therapy). Other more selective plasma purification techniques consist in eliminating pathologic immunoglobulins or LDL cholesterol familial hypercholesterolemia, either by a secondary filtration, chemical adsorption or immunoadsorption. A description of various applications of plasmapheresis can be found in the book edited by Smit Sibinga and Rater [15]. 

W. Momsen and H. Brockman. Purification and characterization of cholesterol esterase from porcine pancreas. Bfachim. Btopkys. Acta 456 103 (1977). 

B36. Bloj, B., and Zilversmit, D. B., Rat liver proteins capable of transferring phosphatidyl-ethanolamine Purification and transfer activity for other phospholipids and cholesterol, J. Biol. Chem. 252, 1613-1619 (1977). 

C14. Chung, J., Abano, D., Fless, G., and Scanu, A. M., Purification and properties of lecithin cholesterol acyltransferase (LCAT) from human sera. Circulation 56 (Suppl. Ill), 185 (1977). 

K15. Kitabatake, K., Piran, U., Kamio, Y., Doi, Y., and Nishida, T., Purification of human plasma lecithin cholesterol acyltransferase and its specificity towards the acyl acceptor. Biochim. Biophys. Acta 573, 145-154 (1979). 

Petit, P.R., Sauvaire, Y.D., Hillaire-Buys, D.M., Leconte, O.M., Baissac, Y.G., Ponsin, G.R. and Ribes, G.R. (1995) Steroid saponins from fenugreek seeds extraction, purification, and pharmacological investigation on feeding behavior and plasma cholesterol. Steroids 60(1 0), 674-680. 

Ulberth, F., Buchgraber, M. 2002. Extraction and purification of cholesterol oxidation products. In Cholesterol and Phytosterol Oxidation Products Analysis, Occurrence, and Biological Effects (F. Guardiola, P.C. Dutta, R. Codony, G.P. Savage, eds.), pp. 26-49, AOCS Press, Champaign, IL. 387-392. 

HMG-CoA reductase, the enzyme that catalyses the formation of mevalonate [MVA, (2)] from HMG by an irreversible reaction that is considered rate-limiting with respect to the formation of cholesterol, has received much attention. Details of the purification of the enzyme from chicken liver and baker s yeast are available,15 and the solubilized enzyme from rat liver microsomes is readily and reversibly inactivated at temperatures below 19°C.16 Cold-inactivation is an uncommon phenomenon, and all the enzymes that have been found to exhibit this behaviour have been soluble proteins. Native HMG-CoA reductase is a particulate enzyme that is probably bound to protein or lipid of the microsomal membrane, although it is not known whether the solubilized enzyme contains a lipid component. Microsomal reductase is not cold-sensitive, and the cold-inactivation of the solubilized enzyme can be completely prevented by addition to the preparation of NADP+ or (more effectively) of NAD PH.17... 

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