Cytotoxic cholesta-1,4-dien-3-one derivatives from soft coral Nephthea sp.

Five new steroids, (12 beta, 22R)-12-acetoxy-22-hydroxy-cholesta-1,4-dien-3-one (1), (12 beta, 22R)-12-hydroxy-22-acetoxy-cholesta-1, 4-dien-3-one (2), (12 beta, 22R)-12, 22-diacetoxy-cholesta-1, 4-dien-3-one (3), (22R)-18, 22-diacetoxy-cholesta-1, 4-dien-3-one (4), (20R, 22R)-20-hydroxy-22-acetoxy-cholesta-1, 4-dien-3-one (5), and one known steroid astrogorgol N (6), were isolated from soft coral Nephthea sp. Their structures were established by spectroscopic analysis (1D, 2D NMR, HRMS) and comparisons of their spectral data with those of related steroids. The absolute configuration at C-22 of 1 was determined to be R by Mosher's analysis. All isolated compounds exhibited cytotoxic activity against HeLa cells with IC50 values ranged from 7.51 +/- 0.22 to 18.72 +/- 0.78 mu g/mL. (C) 2013 Elsevier Inc. All rights reserved.