Isolation, Stereochemical Study, and Cytotoxic Activity of Isobenzofuran Derivatives From a Marine Streptomyces sp.

A new 1,3-dihydroisobenzofuran derivative (1), together with its epimer (2), was isolated from marine Streptomyces sp. W007. The structure of the two compounds was established by extensive spectroscopic analysis and comparison with reported data. The absolute configurations of 1 and 2 were determined by a combination of experimental and computational means, including J-coupling analysis and nuclear Overhauser effect spectroscopy (NOESY) spectra, nuclear magnetic resonance (NMR) calculations, electronic circular dichroism (ECD), and optical rotation (OR) calculations. Compound 1 had no cytotoxicity against human lung adenocarcinoma cell line A549, while compound 2 exhibited weak activity, suggesting that the biological activity depends on the configuration of a single chirality center. Chirality 27:82-87, 2015. (c) 2014 Wiley Periodicals, Inc.