Abstract
Chromatographic separation of a marine algal-derived endophytic fungus Penicillium chrysogenum AD-1540, which was isolated from the inner tissue of the marine red alga Grateloupia turuturu, yielded two new benzophenone derivatives, chryxanthones A and B (compounds 1 and 2, respectively). Their structures were undoubtedly determined by comprehensive analysis of spectroscopic data (1D/2D NMR and HRESIMS). The relative and absolute configurations were assigned by analysis of the coupling constants and time-dependent density functional theory (TDDFT) calculations of their electronic circular dichroism (ECD) spectra, respectively. Both compounds possessed an unusual dihydropyran ring (ring D) fused to an aromatic ring, rather than the commonly occurring prenyl moiety, and a plausible biosynthetic pathway was postulated. The cytotoxicities of compounds 1 and 2 were evaluated against six human cell lines, and both of the compounds demonstrated weak to moderate cytotoxicities with IC50 values ranging from 20.4 to 46.4 μM. These new compounds further demonstrate the potential of marine-derived fungi as an untapped source of pharmaceutical components with unique properties that could be developed as drug candidates.
Highlights
Marine-derived fungi, which are recognized as frontier resources for drug candidate discovery, are prolific sources of bioactive secondary metabolites with unique structures [1]
The unique features of the marine environment result in distinct structures of the secondary metabolites secreted by marine-derived fungi from those produced by terrestrial microorganisms [2]
During our unremitting search for novel natural products from marine-derived fungi [8,9], an endophytic strain P. chrysogenum isolated from the marine red alga Grateloupia turuturu was chemically investigated
Summary
Marine-derived fungi, which are recognized as frontier resources for drug candidate discovery, are prolific sources of bioactive secondary metabolites with unique structures [1]. Secondary metabolites isolated from marine-derived fungi are considered as an untapped resource in the search for novel lead compounds and/or new drugs [3]. Two new benzophenone derivatives, namely, chryxanthone A (1) and B (2), were benzophenone derivatives, namely, chryxanthone A (1) and B (2), were obtained. We report the details of the isolation, structure elucidation, and cytotoxic structure elucidation, and cytotoxic activities of these new polyketides, providing a foundation for activities of these new polyketides, providing a foundation for further exploration of their further exploration of their pharmaceutical properties as novel drug candidates.
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