Identification and Characterization of Anthocyanins in Yard-Long Beans (Vigna unguiculata ssp sesquipedalis L.) by High-Performance Liquid Chromatography with Diode Array Detection and Electrospray Ionization/Mass Spectrometry (HPLC-DAD-ESI/MS) Analysis

Anthocyanins play an important role in physiological functions related to human health. The objective of this study was to investigate the profiles of anthocyanins in the immature purple pods and black seeds of yard-long beans (Vigna unguiculata ssp. sesquipedalis L.) using high-performance liquid chromatography (HPLC) with diode array detection and electrospray ionization/mass spectrometry (DAD-ESI/MS) analysis. The individual anthocyanins were identified by comparing their mass spectrometric data and retention times. In the purple pods, five individual anthocyanins were identified: delphinidin-3-O-glucoside (2), cyanidin-3-O-sambubioside (4), cyanidin-3-O-glucoside (5), pelargonidin-3-O-glucoside (7), and peonidin-3-O-glucoside (8). From the black seed coat of the yard-long beans, seven anthocyanins were identified, including delphinidin-3-O-galactoside (1), cyanidin-3-O-galactoside (3), petunidin-3-O-glucoside (6), and malvidin-3-O-glucoside (9), together with compounds 2, 5, and 8. In this study, we report for the first time anthocyanin profiles for the pod and seed coat of yard-long beans.