Abstract
Five new compounds, including a benzopyran ribonic glycoside, daldiniside A (1), two isocoumarin ribonic glycosides, daldinisides B (2) and C (3), and two alkaloids, 1-(3-indolyl)-2R,3-dihydroxypropan-1-one (4) and 3-ethyl-2,5-pyrazinedipropanoic acid (5), along with five known compounds (6–10), were isolated from the EtOAc extract of the marine-associated fungus, Daldinia eschscholzii. Their structures were elucidated by extensive physicochemical and spectroscopic properties, besides comparison with literature data. The absolute configurations of compounds 1–3 were corroborated by chemical transformation, GC analysis and X-ray crystallographic analysis. Meanwhile, the absolute configuration of compound 4 and the planar structure of compound 6 were also determined based on the X-ray diffraction analysis. The cytotoxicity of compounds 1–10, antifungal and anti-HIV activities of compounds 1–5 and the in vitro assay for glucose consumption of compounds 1–3 were done in the anti-diabetic model, whereas none showed obvious activity.
Highlights
Marine fungi are known as a rich source of structurally diverse and biologically active secondary metabolites, including polyketides, steroids, terpenes and alkaloids
Column chromatography was performed on silica gel (100–200 mesh and 200–300 mesh, Qingdao Marine Chemical Inc., Qingdao, China), RP-C18 silica gel (50 μm, YMC, Kyoto, Japan) and Sephadex LH-20 (Pharmacia Biotech AB, Uppsala, Sweden)
The strain of fungus D. eschscholzii was isolated from the branches of Scaevola sericea Vahl, collected from the mangrove forest nature reserve in Haikou, Hainan province, China
Summary
Marine fungi are known as a rich source of structurally diverse and biologically active secondary metabolites, including polyketides, steroids, terpenes and alkaloids. Bioactive natural products obtained from the marine-derived fungi have attracted the rising attention of organic chemists for discovering new drugs [1]. Daldinia eschscholzii was well-known to produce abundant polyketides as a mantis-associated fungus [3,4], which motivated us to investigate the secondary metabolites produced by the marine-associated fungus, D. eschscholzii. As part of our ongoing research for structurally unique and bioactive natural products from the D. eschscholzii, we obtained a new benzopyran ribonic glycoside (1), two new isocoumarin ribonic glycosides (2 and 3). Two new alkaloids (4 and 5), together with five known derivatives (6–10) from the scaled-up fermentation of the D. eschscholzii. We describe the isolation, structural elucidation and biological evaluations of these compounds
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
