In the studies on the chemical constituents of octocoral Nephthea columnaris, collected off the coast of Southern Taiwan, had led to the isolation of 11 metabolites, including ten sterols, columnaristerols A-C (1-3), litosterol (4), 24-methylene-cholesterol (5), 24-methylene-cholest-5-ene-3β,7α-diol (6), 5α,8α-epidioxy-24-methylcholesta-6,24(28)-dien-3β-ol (7), 4α-methylergosta-22(E),24(28)-dien-3β-ol (8), 24-methylcholesta-5,24(28)-diene-3β,19-diol-7-one (9), 5,6-epoxylitosterol (10), and one cembranoid, 2β-hydroxy-11α,12β-epoxynephthenol (11). Among these natural products, columnaristerols A-C (1-3) are new sterols and sterol 8 (4α-methylergosta-22(E),24(28)-dien-3β-ol) was first being reported from a natural source. The structures of above metabolites were determined by spectroscopic methods. Columnaristerol A (1) was proven to be a rare natural 19-norsterol possessing a 10β-hydroxy group and this compound was found to exhibit cytotoxic effects toward MOLT-4 and SUP-T1 cells.
Fig. 1
