Antioxidant activities and simultaneous HPLC-DAD profiling of polyphenolic compounds from Moringa oleifera Lam. leaves grown in Bangladesh

Moringa oleifera Lam. has been used as a traditional medicine for the treatment of several diseases. In this study, the antioxidant activity and simultaneous HPLC profiling of polyphenolic compounds in 80% ethanol and water extracts of M. oleifera tender and mature leaves available in Bangladesh were investigated. The 80% ethanol extract of M. oleifera tender leaves contained high concentration and more amount of 3,4- dihydroxybenzoic acid, (-) epicatechin and rosmarinic acid (201.32±1.94, 213.08±1.96 and 133.84±1.42 mg/100 g of dry extract, respectively) than that of mature leaves (82.55±1.09, 141.86±1.10 and 16.23±0.76 mg/100 g of dry extract, respectively). On the other hand, the water extract of M. oleifera tender leaves contained a high concentration of catechin hydrate, trans-ferulic acid and quercetin (530.05±1.91, 166.38±0.90 and 771.74±1.34 mg/100 g of dry extract, respectively) than that of mature leaves (207.21±0.90, 62.42±0.45 and 483.25±1.04 mg/100 g of dry extract, respectively). It was also found that 3,4-dihydroxybenzoic acid, catechol, p-coumaric acid and trans-cinnamic acid were detected only in 80% ethanol extract of M. oleifera leaves but syringic acid was identified in the water extract. In DPPH free radical scavenging activity test, IC₅₀ values of 80% ethanol extract of tender leaves (EETL), 80% ethanol extract of mature leaves (EEML), water extract of tender leaves (WETL) and water extract of mature leaves (WEML) were found to be moderately significant (105.50±1.05, 115.00±1.14, 216.00±1.34 and 269.50±1.56 μg/mL, respectively) when compared to the IC₅₀ value of ascorbic acid, 3.32±0.07 μg/mL. The polyphenolic compounds are responsible for antioxidant activity. On the basis of the present study, it can be suggested that the leaves show antioxidant activity and it’s contained a significant amount and different types of polyphenolic compounds. Standardized polyphenolic compounds from M. oleifera leaves could be used as a better source of natural antioxidant supplement.