Abstract
A new dimeric isocoumarin, bireticulol, was isolated from the terrestrial Streptomyces sp. and characterized as a 5-5' dimer of reticulol. In addition, reticulol and 8-hydroxy-6,7-dimethoxy-3-methyl isocoumarin, together with other known polyketides piericidin A, 2'-(2-hydroxyphenyl)-2,4'-bibenzoxazole-4-carboxylic acid methyl ester (UK-1) and 3-benzyl-4-hydroxy-5-methyldihydrofuran-2-one were also obtained. Bireticulol exhibited cytotoxic effects against KB (human epidermoid carcinoma, ATCC CCL-17) and NCI-H187 (human small cell lung cancer, ATCC CRL-5804) cell lines with IC50 values of 24.4 and 8.31 mu g ml(-1), respectively. The Journal of Antibiotics (2011) 64, 267-270; doi:10.1038/ja.2010.171; published online 12 January 2011
