Xylanilyticolides A-C, Three New Compounds from Cultures of the Actinomycete Promicromonospora xylanilytica YIM 61515.

Three new lactones, xylanilyticolides A-C (1-3), were isolated from cultures of the actinomycete Promicromonospora xylanilytica YIM 61515. Their structures were elucidated by 1D and 2D NMR spectroscopic data in conjunction with HRESIMS analysis. Compound 1 exhibited potent cytotoxicities against five human cancer cell lines HL-60, A-549, SMMC-7721, MCF-7 and SW480 with the IC50 values of 3.9, 15.2, 11.2, 5.9, and 4.7 μM, respectively.