New Naturally Occurring Compounds from Sarcophyton trocheliophorum

Abstract

Corals are rich sources of secondary metabolites used as chemical defense compounds against predators. The production of diverse metabolites has characterized soft corals belonging to the genus Sarcophyton. However, phenolic compounds are slightly rare in soft corals. Through a further bioassay-guided fractionation for the chloroform-soluble extract of soft coral Sarcophyton trocheliophorum, collected from the Red Sea, three closely related phenolic compounds: 2,4-di-tert-butyl-6-nitro-phenol (1), 2,4-di-tert-butyl-phenol (2), and 2,4-bis(1-methyl-1-phenylethyl)-phenol (3), along with the wax tricosyldocosanoiate (4) were isolated herein for the first time from nature in addition to cholesterol. Structures of the isolated compounds 1-4 were identified by NMR spectroscopy (1H, 13C, 1H,1H COSY, HMQC and HMBC) and mass spectrometry (EI, HRESI-MS) for the first time so far. The antimicrobial activities of the soft coral extract, along with the isolated compounds, were evaluated against Staphylococcus aureus, Bacillus subtilis ATCC6051, Streptomyces viridochromogenes Tü 57, Escherichia coli, Mucor miehei Tü 284, Candida albicans, and the green alga Chlorella vulgaris. The crude extract exhibited a moderate activity against Streptomyces viridochromogenes Tü 57 (12 mm) at a concentration of 400 µg/disc, while the reported compounds 1-4 showed no activity against the reported test microorganisms at a concentration of 40 µg/disc.