Diterpene Glycosides and Polyketides from <i>Xylotumulus gibbisporus</i>

Abstract

Four new tetracyclic diterpene glycosides, namely, sordarins C–F (<b>1</b>–<b>4</b>), and three new γ-lactone polyketides, namely, xylogiblactones A–C (<b>5</b>–<b>7</b>), along with sordarin were isolated from the ethyl acetate extracts of the fermented broths of <i>Xylotumulus gibbisporus</i> YMJ863. The structures of <b>1</b>–<b>7</b> were elucidated on the basis of spectroscopic data analyses. The configurations of <b>1</b>–<b>4</b> were deduced by NOESY, molecular modeling, and comparison with the literature. The relative configurations of <b>5</b>–<b>7</b> were deduced by X-ray crystallographic analysis of <b>5</b>. Compounds <b>1</b>–<b>5</b> and sordarin were evaluated in an antifungal assay using <i>Candida albicans</i> ATCC 18804, <i>C. albicans</i> ATCC MYA-2876, and <i>Saccharomyces cerevisiae</i> ATCC 2345, and only sordarin exhibited significant antifungal activities against these fungal strains, with MIC values of 64.0, 32.0, and 32.0 μg/mL, respectively. The effect of compounds <b>1</b>–<b>7</b> and sordarin on the inhibition of NO production in lipopolysaccharide-activated murine macrophages was also evaluated. Compounds <b>2</b> and sordarin inhibited NO production with IC₅₀ values of 327.2 ± 46.6 and 157.1 ± 24.1 μM, respectively