Isolation, Stereochemical Study, and Antioxidant Activity of Benzofuranone Derivatives from a Mangrove-derived Fungus Eurotium rubrum MA-150.

Abstract

Enantiomers of a 2-benzofuran-1(3H)-one derivative [(-)- and (+)-] and four known analogs () were isolated and identified from the culture extract of Eurotium rubrum MA-150, a fungus obtained from the mangrove-derived rizospheric soil. Their structures were established by detailed interpretation of nuclear magnetic resonance (NMR) data and the structure of (±)- was confirmed by single-crystal X-ray diffraction analysis. The absolute configuration of the enantiomers (-)- and (+)- was determined by means of online high-performance liquid chromatography - electronic circular dichroism (HPLC-ECD) measurements and time-dependent Density Functional Theory - electronic circular dichroism (TDDFT-ECD) calculations. Compounds (±)- as well as and exhibited potent DPPH radical scavenging activities with IC50 values of 1.23, 2.26, and 3.99 μg/mL, respectively. Chirality 28:581-584, 2016. © 2016 Wiley Periodicals, Inc.