Bioactive Alpha-Pyrone and Phenolic Glucosides from the Marine-Derived Metarhizium sp. P2100.

Glycoside compounds have attracted great interest due to their remarkable and multifarious bioactivities. In this study, four hitherto unknown 4-methoxy--D-glucosyl derivatives were obtained and identified from the marine-derived fungus sp. P2100, including three alpha-pyrone glycosides (-) and one phenolic glycoside (). Their planar structures were elucidated by comprehensive spectroscopic analysis, including 1D/2D NMR and HRESIMS. The absolute configurations of - were determined by a single-crystal X-ray crystallographic experiment, a comparison of the experimental, and a calculated electronic circular dichroism (ECD) spectra, respectively. Compounds and are a pair of rare epimeric pyranoside glycosides at C-7 with a core of aglycone as 2-pyrone. Compounds - exhibited weak anti-inflammatory activities. In particular, compounds - displayed inhibitory activities against -amylase, showing a potential for the development of a new -amylase inhibitor for controlling diabetes.