Guanahanolide A, a Meroterpenoid with a Sesterterpene Skeleton from Coral-Derived <i>Streptomyces</i> sp.

A meroterpenoid, guanahanolide A (1), was purified from a fermentation extract of Streptomyces sp. RKBH-B7. The planar structure of guanahanolide A (1) was elucidated by NMR spectroscopy, revealing a meroterpenoid comprised of an unprecedented sesterterpene skeleton. Upon determination of the relative configuration of 1 through X-ray crystallography, its absolute configuration was unambiguously assigned using Mosher ester analysis. Guanahanolide A (1) showed moderate cytotoxicity against human cancer cell lines MCF-7, HTB-26, and HCT-116.从链霉菌属（Streptomyces）菌株RKBH-B7的发酵提取物中纯化得到一种杂萜类（meroterpenoid）化合物胍哈内酯A（1）。通过核磁共振波谱法（NMR spectroscopy）阐明了胍哈内酯A（1）的平面结构，结果显示其具有前所未有的二倍半萜（sesterterpene）骨架。通过X射线晶体衍射法（X-ray crystallography）确定该化合物的相对构型后，采用莫斯酯分析法（Mosher ester analysis）明确归属了其绝对构型。胍哈内酯A（1）对人类癌细胞系MCF-7、HTB-26及HCT-116具有中等强度的细胞毒性。