Abstract
Seeking a strategy for triggering the cryptic natural product biosynthesis to yield novel compounds in the plant-associated fungus Xylaria sp., the effect of culture conditions on metabolite production was investigated. A shift in the production of five known cytochalasin-type analogues 1–5 to six new α-pyrone derivatives, xylapyrones A–F (compounds 6–11), from a solid to a liquid medium was observed. These compounds were identified by analysis of 1D and 2D NMR and HRMS data. Compounds 1–3 showed moderate cytotoxicity against HepG2 and Caski cancer cell lines with IC50 values ranging from 25 to 63 μM and compounds 4–11 were found to be inactive, with IC50 values >100 μM.
Highlights
Natural products from microorganisms are a vital source for innovative therapeutic agents and drug leads [1]
Cytochalasin-type compounds have been reported as promising lead compounds for anticancer drug discovery that reduce the proliferation of different cancer cell lines such as P388, A549 and KB cells [10,11]. α-Pyrone natural products are widespread in Nature and have a broad spectrum of biological activities [13]
The literature [14,15,16] has suggested that structural variations of the side chains attached to α-pyrones ring may make significant differences to the cytotoxicity, which is worth further investigation
Summary
Natural products from microorganisms are a vital source for innovative therapeutic agents and drug leads [1]. Only a minority of pathway genes is expressed under standardized laboratory conditions and many valuable compounds are overlooked. In order to exploit the full metabolic potential of microorganisms, many regulatory strategies to activate cryptic pathways to facilitate the discovery of new natural products through modification of culture conditions [5], external cues [6], stress [7], co-cultures [8] and genomic approaches [9] were described in the literature. This paper describes the isolation, structure elucidation, and cytotoxic activities of the isolated compounds 1–11 (Figure 1)
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