Characterization of bioactive compounds in unripe edible pods of cluster bean [Cyamopsis tetragonoloba (Taub)] for vegetable purpose

Abstract

In today’s era of climate change, hunger, sustainable agriculture and nutritional security are the pressing needs. Climate-resilient and nutritionally dense crops can be a way to overcome the perpetuating global crisis. Cluster bean, commonly known as guar, is a legume crop that is well-adapted to diverse climatic conditions. Its immature pods are commonly consumed as a vegetable in many parts of the world. The present study was designed to investigate the bioactive compounds, i.e. total phenols, flavonoids and antioxidant activity in two genotypes of cluster bean. The total phenols and flavonoids were evaluated by colorimetry and an improved high-performance liquid chromatography (HPLC) method. Antioxidant activity was determined based on the ability to scavenge free radicals using the DPPH assay. An acidic methanolic extract of AG112 genotype showed the presence of high phenolic (293.25 mg GAE / 100 g) and flavonoid content (20.24 mg QE/100 g) compared to 289.93 mg GAE / 100 g and 17.85 mg QE/100 g in HG-365 genotype, respectively. The highest DPPH activity was observed in AG112 (42%) compared to 34.39% in HG-365 genotype. HPLC analysis of polyphenolic compounds showed the presence of 2,3 dihydroxy benzoic acid, vanillic acid, rutin, sinapic acid and quercetin as major polyphenolic compounds in guar pods. The results indicated that cluster bean possesses high bioactive potential when consumed as a vegetable in the form of immature edible pods, thereby providing good justification for its increased cultivation and consumption.