Abstract
The 7α-methyl analog (II) of 3β-hydroxy-5α-cholest-8(14)-en-15-one (I) was prepared by chemical synthesis and evaluated with respect to its effects on HMG-CoA reductase activity in CHO-K1 cells and on serum cholesterol levels in rats. The 7α-methyl substitution had no detectable effect on the potency of I in lowering HMG-CoA reductase activity in the cultured cells. In contrast, the 7α-methyl substitution had a marked effect on the action of I in the suppression of food consumption in rats. Whereas II was less potent than I in lowering serum cholesterol levels in rats, it did so at dosage levels at which only slight or moderate effects on food consumption were observed. Full 1H and 13C-NMR assignments for II and intermediates in its synthesis have been presented. Conformational analysis, based on 1H- 1H coupling constants, NMR shieldings and force-field calculations, indicated that the 7α-methyl substitution had virtually no effect on the conformation of the 15-ketosterol apart from minor distortions of ring B.
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