Zahramycins A-B, two new steroids from the coral Sarcophyton trocheliophorum

Abstract

Two new poly-hydroxy steroids, zahramycins A (1) and B (2), have been isolated from the polar fraction of the extract of the coral Sarcophyton trocheliophorum. Compound 1 was confirmed to bear an oxirane ring at C-5 and C-6, while 2 has a keto-hydroxy sterol structure. The known DNA primary metabolites uracil, thymine, adenine, uridine, 2'-deoxyuridine, and thymidine were also isolated and identified. Structures of the new sterols 1 and 2 were confirmed by NMR (H, C, 1H-1hcosy, HMQC, HMBC, and NOESY) spectroscopy, mass spectrometry (EI, ESI, and HRMS), and by comparison with related structures. The antimicrobial and cytotoxic activities of compounds 1 and 2 along with that of the coral extract were also determined. Zahramycin B (2) showed high (15 mm) and moderate (12 mm) antibacterial activity against Staphylococcus aureus and Bacillus subtilis, and fungus Pythium ultimum (12mm), while zahramycin A (1) and the crude extract of Sarcophyton trocheliophorum were inactive. Both steroids and the crude extract of Sarcophyton trocheliophorum showed no cytotoxicity. © 2013 Verlag der Zeitschrift fur Naturforschung, Tubingen • http://znaturforsch.com.