PROXIMATE COMPOSITION AND HPLC-DAD ANALYSIS OF BIOACTIVE POLYPHENOLS IN LEAFY VEGETABLES CONSUMED IN THE DIET FOUND IN SOUTHERN PART OF BANGLADESH

Abstract

Four leafy vegetables, Phyla nodiflora, Amaranthus spinosus, Amaranthus viridis and Chenopodium album usually consumed by the Southern people of Bangladesh. In this study, we tested proximate composition and antioxidant potential of four leafy vegetables and further HPLC content of bioactive polyphenols in the most promising vegetable. The results revealed that they are rich in protein (12-17g/100g), carbohydrate (10- 20 g/100g) and fibre (29 - 44 g/100 g). The ash, glucose, sucrose and xylose contents were found within the ranges of 14-20 g/100 g, 35-77 mg/100 g, 32.79-68.72 mg/100 g and 3.79-7.71 mg/100 g, respectively. All the vegetables showed a lower content of lipid (0.73 – 1.47 g/100 g) and higher moisture content (81-85 g/100 g). The methanolic extracts of the vegetables were found to possess notable amount of total phenolic (11-60 mg GAE/g), total flavonoid (365-565 mg QE/g) and tannin content (28-49 mg TAE/g). All the samples showed significant DPPH free radical scavenging (IC50 53-1097 µg/ml) and hydrogen peroxide scavenging activity (IC50 41-96 µg/ml). Out of these four species, C. album was found to be the most promising leafy vegetable because of its high protein and fibre content, low lipid content and good antioxidant activities. HPLC-DAD analysis revealed the presence of 3,4-dihydroxy benzoic acid, catechol, vanillic acid, syringic acid, rutin hydrate, p-coumaric acid, trans-ferulic acid, rosmarinic acid and quercetin in C. album. The results of this study provide evidence for the importance of these leafy vegetables in improving the nutritional and health status of Southern rural people of Bangladesh.