Abstract
Two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together, with seven known metabolites (3 and 8–13) were obtained from the crude extract of the mangrove-derived fungus Hypoxylon sp. The structures of the new compounds were elucidated on the basis of 1- and 2-dimensional (1D/2D) nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analysis. The absolute configurations of compounds 1, 2, 4, 5, and 7 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra, and the absolute configurations of C-4′ in 6 and C-9 in 7 were determined by [Rh2(OCOCF3)4]-induced ECD spectra. Compound 1 showed moderate α-glucosidase inhibitory activities with IC50 values of 741.5 ± 2.83 μM. Compounds 6 and 11 exhibited DPPH scavenging activities with IC50 values of 15.36 ± 0.24 and 3.69 ± 0.07 μM, respectively.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The absolute configuration of C-4 was further determined by a comparison of tal and calculated electronic circular dichroism (ECD) spectra
All compounds were tested for antibacterial activities against three pathogenic bacteria (S. aureus CGMCC1.2465, B. subtilis ATCC6663, and E. coli CGMCC1.2340) in 96-well microplates, according to the method of Fan et al [31]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Hypoxylon species are widespread in terrestrial and marine environments, and chemical investigations of some Hypoxylon spp. have afforded a variety of natural products, such as azaphilones, diterpenes, sporothriolide derivatives, and various aromatic compounds, which exhibited antibacterial, antifungal, and cytotoxic activities [13,14,15,16,17,18]. The fungus was fermented on rice medium for 30 days and subsequently extracted by EtOAc to afford the organic extract. Fractionations of this extract were performed, leading to the isolation of two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together with seven known metabolites, penicichrysogene B (3) [19] penicimarin. Tion, structure elucidation and bioactivities of these compounds are reported
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