Metabolites from the co-culture of nigranoic acid and Umbelopsis dimorpha SWUKD3.1410, an endophytic fungus from Kadsura angustifolia

Abstract

The ability of the endophytic fungus Umbelopsis dimorpha SWUKD3.1410 to transform the triterpene nigranoic acid (3, 4-secocycloarta-4(28), 24-(Z)-diene-3, 26-dioic acid; 1) was investigated. Co-culture of nigranoic acid with U. dimorpha SWUKD3.1410 yielded six major products, including a new triterpene (2) and 5 known compounds (3–7). Their structures were identified by the extensive 1D, 2D NMR and HR-ESI-MS Data analysis, and by comparison with those reported data. Among them, 2–4 were transformed from nigranoic acid (1), while 5–7 were derived from the culture medium stimulated by the substrate. On the basis of the structures of 2–4, it was proposed that the transformative process probably involved isomerase and hydroxylase, in which the former was rare in fungi. Additionally, all the compounds (1–7) were evaluated for their cytotoxic activity. As a result, compounds 1, 3–5 exhibited weak cytotoxicity against the tested cell lines, while others showed no cytotoxicity.

Keywords:

• Endophytic fungus
• Umbelopsis dimorpha
• nigranoic acid
• microbial transformation
• structural identification
• cytotoxicity