(±)-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, C-13 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 (IC50) values of 2.89 +/- 0.17 mu mol/L and 4.47 +/- 0.26 mu mol/L, respectively. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

(+/-)-Pyriindolin with a rare molecular backbone was isolated from Streptomyces albolongus EA12432. Its constitution and relative configuration were determined by spectroscopic analyses and probability analysis, while the absolute configurations of optically pure samples were identified by HPLC separation and ECD calculations. The compounds exhibited moderate cytotoxicity.