Isolation and Identification of Xanthone, Benzofuran, and Spirolactone Derivatives from Dinemasporium parastrigosum KT4144 and Their Plausible Biosynthetic Pathways.

Abstract

The structurally distinct dinemaxanthones A (1) and B (2), dinemafuran (3), and dinemaspirone (4) were isolated from the fungus Dinemasporium parastrigosum KT4144. Their structures were elucidated primarily through spectroscopic analyses and validated via NMR chemical shift calculations. These analyses revealed that while the density functional theory (DFT) functional ωB97X-D, which has previously yielded reliable results, tends to overestimate van der Waals interactions in highly conformationally flexible compounds, leading to increased chemical shift deviations between the calculated and experimental data. In contrast, the more traditional B3LYP functional more accurately reproduced their conformational distributions, yielding more preferable results. Additionally, electron circular dichroism (ECD) spectral computations established the absolute configurations of 1-4. Structural characterization indicated that these metabolites belong to the xanthone family of fungal natural products. Genome sequence analysis of the producer strain provided insights into their biosynthetic origins, suggesting a pathway from the common intermediate monodictyphenone (6) to compounds 1-4.