Antifouling steroids from the South China Sea gorgonian coral Subergorgia suberosa

Two new unusual cholestane derivatives, pentacyclic steroid 16,22-epoxy-20 beta,23S-dihydroxycholest-1-ene-3-one (1) and 20 beta,23S-dihydroxycholest-1-ene-3,22-dione (2), along with two new pregnane derivatives, 15 beta,17 alpha-dihydroxypregna-4,6-diene-3,20-dione (3) and 11 alpha-hydroxypregna-4-ene-3,6, 20-trione (4), were isolated from the South China Sea gorgonian coral Subergorgia suberosa. Their structures were established based on the extensive analyses of 2D NMR, IR, and HRMS. Antifouling tests against Balanus amphitrite larvae settlement indicated that 1 and 2 exhibited inhibitory effect with EC50 values of 5.3, and 14.5 mu g/mL, respectively. (C) 2013 Elsevier Inc. All rights reserved.