Alternarias G and H: Benzoxepine Derivatives from the Endophytic Fungus <i>Alternaria</i> sp. HJT-Y7.

Abstract

Alternaria G (<b>1</b>), a benzoxepine dimer with an unprecedented 6/7-7/6 tetracyclic skeleton, and a benzoxepine monomer, alternaria H (<b>2</b>), were successfully isolated from the fungus Alternaria sp. HJT-Y7. Structural determination was accomplished through comprehensive spectroscopic data interpretation, supported by electronic circular dichroism calculations, and quantum-chemical NMR calculations with DP4+ probability analyses. Genomic exploration uncovered a candidate biosynthetic gene cluster <i>(aln</i>) putatively responsible for their assembly, from which a plausible biosynthetic route was proposed. Notably, <b>1</b> significantly inhibited nitric oxide production in LPS-stimulated RAW 264.7 macrophages.