(±)-Pyriindolin with a 2,2'-bipyridine-spiro[furan-3,3'-indoline]chimeric skeleton from the endophytic Streptomyces albolongus EA12432

(±)-Pyriindolin(1)with a rare molecular backbone formed by fusing a 2,2'-bipyridine nucleus into a spiro[furan-3,3'-indoline]skeleton,was isolated from the Streptomyces albolongus EA12432.The constitution and the relative configuration of(±)-1 were determined by extensive spectroscopic analyses,^(13)C calculation and DP4+probability analysis.The absolute configurations of optically pure(+)-1 and(-)-1 which were obtained after a chiral high performance liquid chromatography(HPLC)separation were further identified by electronic circular dichroism(ECD)calculations.(+)-and(-)-Pyriindolins displayed moderate cytotoxicity against HCT-116 cell line with the half-maximal inhibitory concentration(IC_(50))values of 2.89±0.17μmol/L and 4.47±0.26μmol/L,respectively.