Two New Indole Derivatives from the Beibu Gulf Coral-Derived Fungus Pestalotiopsis microspora GXIMD 02530.

Two new indole derivatives (1 and 2), along with fourteen known indole and polyketide compounds, were characterized from the Beibu Gulf coral-derived fungus Pestalotiopsis microspora GXIMD 02530. Their structures and absolute configurations were determined by comprehensive spectroscopic analysis, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction. Structurally, furoindolin A (1) was obtained as a rare racemic 6/5/5 tricyclic indole derivative incorporating a dihydrofuranone ring, which was further separated into a pair of enantiomers by chiral chromatographic resolution. Compounds (±)-1, 3, 4, and 6-12 exhibited inhibition of LPS-induced NF-κB luciferase activities. Phomopsilactone (10) displayed antibacterial activities against Staphylococcus epidermidis, Bacillus subtilis, and Staphylococcus aureus, with MIC values of 15.6, 31.25, and 62.5 μg/mL, respectively. Our findings would expand the chemical variety of indole derivatives and highlight furoindolin A (+)-1 as a promising chemical template for further biosynthetic and anti-inflammatory pharmacological investigation.