Betalains from Amaranthus tricolor L.

Abstract

Betalains in Amaranthus tricolor leaf were identified by means of reversed phase high-performance liquid chromatography (HPLC) and Liquid chromatography-Mass spectrometry (LC-MS). In addition to the known compound red-violet amaranthin, two yellow pigments were detected in Amaranthus tricolor. A novel betaxanthin, methyl derivative of arginine betaxanthin was identified on the basis of UV-Vis spectra and mass spectrometric characteristics, as well as by comparison with literature data, which to the best of our knowledge has not been reported in Amaranthus tricolor. Amaranthin was the major betacyanin pigment present in Amaranthus tricolor although methylated arginine betaxanthin, a novel betaxanthin hitherto not observed naturally and betalamic acid were also present. The identified compounds were then evaluated for alpha-amylase inhibitory potential using Bernfeld method. Amaranthin and betaxanthin did not show alpha-amylase inhibitory activity. Betalamic acid displayed significant alpha-amylase inhibitory activity compared to that of a reference standard, acarbose.