Comparative analysis of metabolites and bioactivities of Alpinia nelumboides leaves, pseudostems and rhizomes

Alpinia nelumboides Nob. Tanaka, T. T. K. Van & V. Hoang is a member of the family Zingiberaceae. Alpinia spp. are often used in traditional medicine. Limited data regarding phytochemicals and biological activities of this species are found in the available literature. This study aimed to identify pigments and phenolics in its leaves, pseudo-stems and rhizomes using high-performance liquid chromatography and spectrophotometry. Besides, free radical scavenging properties of acetonic extracts from the plant were assessed. The levels of chlorophyll a and b in the A. nelumboides leaves were approximately 3 time higher in the rhizomes. Among the phenolics examined, epicatechin was the most abundant compound, with an average concentrations ranging from 12.26—61.23 mg/g extract. The leaf extract exerted the strongest activity to scavenge ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radicals (IC50 = 339.46 ± 10.18 µg/mL) while the rhizome extract showed the most potent capacity to neutralize DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals (IC50 = 149.56 ± 2.37 µg/mL). These results provide a better understanding of the phenolic components of A. nelumboides and its potential health-promoting activities.