Chromatographic profiling of bioactive polyphenolic compounds and antioxidant evaluation of ethnobotanical leafy vegetables (Amaranthus spinosus and Glinus oppositifolius) from the hilly regions of Bangladesh

Amaranthus spinosus and Glinus oppositifolius are leafy vegetables commonly consumed by indigenous populations in the Bandarban hill tracts of Bangladesh due to their distinct sensory characteristics and therapeutic properties. This study aimed to analyze the bioactive polyphenolic compounds in ethanolic extracts of both plants using HPLC-DAD and evaluate their antioxidant potential. Results revealed that G. oppositifolius had higher total flavonoid content, total phenolic content, total antioxidant activity and IC50 values compared to A. spinosus. However, A. spinosus exhibited a higher total tannin content. The chromatographic analysis identified various bioactive compounds, including gallic acid, epicatechin, quercetin, catechin, rutin hydrate, kaempferol, caffeic acid, and ferulic acid in A. spinosus. Similarly, G. oppositifolius contained gallic acid, epicatechin, quercetin, catechin, rutin hydrate, caffeic acid, trans-ferulic acid, rosmarinic acid, trans cinnamic acid, and vanillin. These polyphenol-rich extracts possess significant antioxidant and anti-inflammatory properties, making them promising candidates for nutraceuticals, functional foods, and industrial applications.