Micaryolanes A and B, Two New Caryolane-Type Sesquiterpenoids from Marine Streptomyces sp. AH25

Caryolanes, known as β-caryophyllene alcohols, are widely occurring sesquiterpenes in plants. From the cultures of marine Streptomyces sp. AH25, two new caryolane sesquiterpenes, micaryolanes A and B (1 and 2), together with caryolan-1,9β-diol (3) were isolated. Their structures were elucidated by extensive analyses of HR-MS and NMR spectroscopic data. The absolute configurations were assigned via the CD data of the in situ formed [Rh₂ (OCOCF₃ )₄ ] complex and supported by comparison of experimental and calculated specific rotation values. Compounds 1-3 exhibited no activities against Hep3B or MG-63 cell lines or against Gram-positive and Gram-negative bacteria. The results not only enriched the caryolane family, but also proved bacteria as a productive source of terpene metabolites.