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 IC50 values ranging from 0.19 to 2.12 mu M.