(+)-/(-)-Prunomarin A and (+)-pestalactone B, three new isocoumarin derivatives from the endophytic fungus Phomopsis prunorum

Three pairs of isocoumarin enantiomers, (+/-)-prunomarin A (1), (+/-)-pestalactone B (2), and (+/-)-3, including three new compounds, (+)-/(-)-1 and (+)-2, were isolated from the endophytic fungus Phomopsis prunorum (F4-3). These enantiomeric pairs were existed as partial racemates and were achieved by chiral-HPLC separation. Their structures were elucidated by comprehensive spectroscopic data, X-ray diffraction, and ECD analysis. Compounds (+/-)-1 represented the first examples of naturally occurring sulfoxide-containing isocoumarin derivatives. Compound 1 showed anti-inflammatory activity for NO production with an IC50 value of 84.2 mu M. Compounds (+)-/(-)-3 exhibited strong phytotoxicity against Amaranthus retroflexus. (C) 2021 Elsevier Ltd. All rights reserved.