Rimsi Saxena

Green beans contain high concentration of polyphenols, carotenoids, ascorbic acids, tocopherol and flavonoids which fight against oxidative damage. Free radicals have been implicated in the pathogenesis of most diseases. Thus, the consumption of dietary antioxidants from vegetables and fruits is beneficial in preventing these diseases. The present study was undertaken to evaluate antioxidant potential of ethanolic extracts of four different species of green beans. Ethanolic extract of Phaseolus vulgaris (french bean), Vicia faba (broad bean), Cyamopsis tetragonoloba (cluster bean) and Vigna unguiculata (cowpea) were studied for antioxidant properties by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, H2O2 decomposition, reducing power ability assay. Total phenolic content was measured by Folin Coilteau reaction and flavonoid contents were determined by AlCl3 assay. Efforts were made to study the iron chelation. Total phenol content ranged from 17.00 ± 0.004 to 53± 0.007 µg GAE/mg while total flavonoid ranged 22 ± 0.003 to 36 ± 0.006 µg QE/ mg. All the extracts scavenged DPPH radical, decomposed H2O2 and had significant reducing potential. The IC50 for DPPH scavenging activity was highest for Vigna unguiculata as 2.27 ± 0.19 mg/ml while lowest for Vicia faba as 0.18± 0.02 mg/ml. All the extracts chelated Fe2+ form of iron but not Fe3+. A positive and strong correlation (r2 = 0.9) between total phenolic content & antioxidant activity suggests that green beans have enormous potential to enhance antioxidant capacity of our daily food supply and may provide health benefits in oxidative stress as neutraceuticals.

The present study was undertaken to evaluate the total antioxidant potential of four different varieties of green beans namely Phaseolus vulgaris (french beans), Vicia faba (broad beans), Cyamopsis tetragonoloba (cluster beans) and Vigna unguiculata (cowpea beans) in both fresh and processed condition (microwave assisted). The total phenolic and flavonoid contents were determined by Folin Coilteaus and AlCl3 assay respectively. The antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, hydrogen peroxide(H2O2) decomposition and reducing power assay. Efforts were also made to study the interaction of beans with metal ions. Total phenolic content ranged from 105.00 ± 0.021 to 300.00 ± 0.009 µg GAE.g-1  (Gallic acid equivalent) of extract and flavonoid content ranged from 55.00 ± 0.017 to 550.00 ± 0.050 µg QE.g-1 (Quercitin equivalent) of extract. All the extracts scavenged DPPH radical and decomposed H2O2. The reducing potential was found to be highest in Cyamopsis tetragonoloba followed by Vigna unguiculata, Vicia faba and Phaseolus vulgaris. Good correlation of phenolic content was observed with reducing power ability ( r2 = 0.743) and DPPH radical scavenging property (r2 = 0.694). The extracts chelated both the ionic forms of iron Fe2+ and Fe3+ but the affinity towards Fe3+ was higher. Green beans can be considered as a potential source of antioxidants. Fresh extracts were found to have higher antioxidant potential as compared to processed extracts.