Halichoblelide D, a New Elaiophylin Derivative with Potent Cytotoxic Activity from Mangrove-Derived Streptomyces sp. 219807

During our search for interesting bioactive secondary metabolites from mangrove actinomycetes, the strain Streptomyces sp. 219807 which produced a high elaiophylin yield of 4486 mg/L was obtained. A new elaiophylin derivative, halichoblelide D (1), along with seven known analogues 2–8 was isolated and identified from the culture broth. Their chemical structures were determined by detailed analysis of 1D and 2D NMR and HRMS data. The absolute configuration of halichoblelide D (1) was confirmed by comparing the CD spectrum with those of the reported analogues. Compounds 1–7 exhibited potent cytotoxic activities against HeLa and MCF-7 cells with IC(50) values ranging from 0.19 to 2.12 μM.