- Synthesis of new C-19-functionalized cholesterols
-
A series of new derivatives of cholesterol bearing polar functional groups on carbon-19 were synthesized, including 19-oximino-, 19-amino-, 19- (methylimino)-, 19-(methylamino)-, 19-mercapto-, and 19-(methylthio) cholesterol, and 3β-hydroxycholest-5-en-19-oic acid, as well as an unusual cyclosterol, 5,19-cyclocholest-6-en-3β-ol.
- Mathai, Mary S.,Pascal Jr., Robert A.
-
p. 244 - 247
(2007/10/02)
-
- Biosynthetic studies of marine lipids. 39.1 19-norsterols: The course of c-19 methyl elimination
-
The biosynthesis of 19-norstanols in the Mediterranean sponge, Axinella polypoides, was investigated through the use of radiotracer experiments. It was found that the conversion of cholesterol (7) to 19-nor-5α-chotestan-3β-ol (8) involved oxidation at C-3 with the distribution of the abstracted hydride from the 3α-position of dietary cholesterol into all of the 19-norstanols of the native mixture. Furthermore, while the efficiency of conversion of Δ5-19-oxygenated sterol precursors 19-hydroxycholesterol (9) and 3β-hydroxycholest-5-en-19-oic acid (10) to 8 was low, the efficiency of the conversion of 19-hydroxycholest-4-en-3-one (23) to 8 was high, suggesting that the principal pathway for 19-norstanol biosynthesis involves oxidative isomerization of a dietary Δ5-3β-hydroxy sterol to the δ4-3-ketone before oxidation at C-19. It was also shown that the conversion of cholesterol to 19-nor-5α-cholestan-3β-ol involves the stereospecific loss of the 4β-hydrogen atom. It was further determined that the biological demethylation pathway is suppressed for dietary sterols bearing an unconventional configuration at C-20 in the hydrocarbon side chain.
- Rabinowitz, Michael H.,Djerassi, Carl
-
p. 304 - 317
(2007/10/02)
-