Steroids and derivatives

Certain compounds related to steroids and derived from plants are now known to lower total blood cholesterol when used in dietary forms approved by the FDA. Called phytostanols and phytosterols, these patented compounds act by inhibiting intestinal absorption of dietary cholesterol. They are marketed as food in the form of edible spreads. An example of a phytostanol is shown here. 

Farnesol pyrophosphate is an immediate precursor of squalene, the key intermediate in steroid and triterpenoid biogenesis, which arises from the coupling of two farnesol pyrophosphate molecules or of C,s units derived therefrom. The numerous types of sesquiter-penoid carbon skeletons represent various modes of cyclization of farnesol (sometimes with rearrangement) and it is probable that farnesol pyrophosphate is also the source of these compounds. 

Other examples of irreversible derivatization on treatment with iodine have been described for phenohc steroids (estrone derivatives [256]), morphine [257] and 23 other pharmaceuticals [258]. These reactions are probably favored by the presence of silica gel as stationary phase and by the influence of light. 

Note Monohydroxybenzene derivatives and vicinal hydroxymethoxybenzene derivatives do not react under these conditions but can be made visible by spraying afterwards with Folin-Qocalteu s reagent [1]. Flavonoids, anthraquinone derivatives and a-nitroso-B-naphthol yield a red color with alkalis alone [1]. Steroids and aromatic amines do not react [1]. 

For instance, trenbolone fluoresces yellow [12] and the qinoxalone derivative of pyruvic acid yellow-green [18]. In the case of steroids and Digitalis glycosides it is possible to differentiate on the basis of various fluorescence colors [8, 9, 15]. 

Steroid and stilbene derivatives e.g. rrans-stilbene metabolites [16]... 

Precursor and derived lipids These include fatty acids, glycerol, steroids, other alcohols, fatty aldehydes, and ketone bodies (Chapter 22), hydrocarbons, hpid-soluble vitamins, and hormones. 

The pentose phosphate pathway is an alternative route for the metabolism of glucose. It does not generate ATP but has two major functions (1) The formation of NADPH for synthesis of fatty acids and steroids and (2) the synthesis of ribose for nucleotide and nucleic acid formation. Glucose, fructose, and galactose are the main hexoses absorbed from the gastrointestinal tract, derived principally from dietary starch, sucrose, and lactose, respectively. Fructose and galactose are converted to glucose, mainly in the liver. 

FIGURE 7.41 Demethylation of angular methyl groups (a) in steroids and related compounds, (b) in lanos-terol derivative and (c) summary of reactions for the formation of CHjO. 

Cyclodextrins as chemically banded layers [102] or mobile phase additives [103-105] have been used successfully to resolve a wide variety of alkaloids, steroids and dansyl- and naphthylamide-amino acid derivatives. The low solubility in aqueous solution and f high cost of cyclodextrins restricted the use of these additives > initially. These limitations were overcome by the availability of ... 

Cyclic diethylsilylene and di-tert.-butylsilylene derivatives have been used to protect diol groups in steroids and prostanoids [539-541]. N,0-bis(diethylhydrogensilyl)trifluoro-methylacetamide simultaneously converts Isolated hydroxyl groups to the diethyllu ogensilyl ether allowing a single step derivatization toVp used for the analysis of corticosteriods. 

With severe colitis, there is a much greater reliance on parenteral steroids and surgical procedures. Sulfasalazine or mesalamine derivatives have not been proven beneficial for treatment of severe colitis. 

T.R. Sharp, M. Sutton, A. Ferguson and K.N. Marsh, Electron impact mass spectra of steroids Androstanes and derivatives. Presented at the 37th ASMS Conference on Mass Spectrometry and Allied Topics, Miami Beach, FL, 21-26 May 1989. 

Gas iromatography (GC) Gas-Liquid (GLC) Gas, e.g. N2, H2, He Liquid-film coated on solid support Gases and adequately volatile liquids (mol. wt. <300) of adequate thermal stability, e.g. hydrocarbons and their derivatives, solvents, inorganic gases, essential oils, some steroids and vitamins. 

Shoppee, C. W. Steroids and the Walden Inversion. Part II. Derivatives of d5-Cholestene and zl5-Androstene. J. chem. Soc. [London] 1946, 1147. 203- Siegel, S., and C. G. Bergstrom The Effect of a Cyclopropyl Group on a Displacement Reaction at an Adjacent Saturated Carbon Atom. I. The Ethanolysis of Cyclopropylmethyl Benzenesulfonate. J. Amer. chem. Soc. 74, 145 (1952). 

The fruit of a number of solanaceous plants, including tomato Lycopersicon esculentum), potato Solanum tuberosum) and eggplant Solarium melongena esculentum), have cholinesterase-inhibiting effects (Krasowski et al. 1997). They contain solanaceous glycoalkaloids o-solanine and o-chaconine, which are triglycosides of solanidine, a steroidal alkaloid derived from cholesterol. They are the only plant chemicals known to inhibit both acetlycholinesterase and butyrylcholinesterase, both in vitro and in vivo. 

Steroids are derived bio synthetically from cholesterol. They play multiple roles in human physiology sex characteristics, control of inflammation, embryo implantation, and control of salt and water balance. Cholesterol itself is an indispensable constituent of biological membranes. 

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