Characterization and identification of bioactive polyphenols in the trapa bispinosa roxb. Pericarp extract

Abstract

In this study, we present the isolation and characterization of the structure of six gallotan-nins (1–6), three ellagitannins (7–9), a neolignan glucoside (10), and three related polyphenolic compounds (gallic acid, 11 and 12) from Trapa bispinosa Roxb. pericarp extract (TBE). Among the isolates, the structure of compound 10 possessing a previously unclear absolute configuration was unam-biguously determined through nuclear magnetic resonance and circular dichroism analyses. The α-glucosidase activity and glycation inhibitory effects of the isolates were evaluated. Decarboxylated rugosin A (8) showed an α-glucosidase inhibitory activity, while hydrolyzable tannins revealed stronger antiglycation activity than that of the positive control. Furthermore, the identification and quantification of the TBE polyphenols were investigated by high-performance liquid chromatog-raphy coupled to ultraviolet detection and electrospray ionization mass spectrometry analysis, in-dicating the predominance of gallic acid, ellagic acid, and galloyl glucoses showing marked anti-glycation properties. These findings suggest that there is a potential food industry application of polyphenols in TBE as a functional food with antidiabetic and antiglycation activities.