Effect of thermal treatment on phenolic content, antioxidant, and -amylase inhibition activities of Moringa stenopetala leaves

Abstract

Moringa stenopetala is a socioeconomic valued tree that is widely available and cultivated in Southern part of Ethiopia. The leaves have been traditionally used as a food source with high nutritional and medicinal values. The present work was carried out to evaluate the effect of thermal treatment on the total phenolic content, total flavonoid content, antioxidant activities and α-amylase inhibition of aqueous leaf extracts obtained from M. stenopetala during maceration and different decoction time interval (5, 10 and 15 min). The total phenolic and flavonoid contents were determined by the Folinciocalteu and aluminum chloride methods, respectively whereas antioxidant activities were determined by 2,2-diphenyl-1-picryl-hydrazyl(DPPH) radical scavenging, reducing power, phosphomolybdenum and ferrous ion chelating assays and α-amylase inhibition potential was determined using 3,5-dinitrosalicylic acid method. Total phenolic and total flavonoid contents ranged from 34. .930), respectively with total phenolic content but ferrous ion chelating activity were found to be weakly correlated (R 2 =0.481). Based on present investigation, it could be concluded that major lose of total phenolic content, antioxidant and α-amylase inhibition activities of the crude leaf extracts of M. stenopetala leaves were observed at decoction time for 15 min. Therefore, to maintain the total phenolic content, antioxidant and α-amylase inhibition activities of leaves, cooking practice should be at the optimum decoction time (5-10 min).

Comparative Analyses of the Antimicrobial, Antioxidant, and Phytochemical Composition of Two Species of Moringa in Ghana

“…It was previously reported that the IC50 value for the radical scavenging activity of M. stenopetala leaves powder was 59.5 g/mL after two weeks of extraction with 100% methanol [35]. For the aqueous decoction of M. stenopetala leaves powder, [36] found an IC50 value of 41.5 g/mL. M. olifiera had an IC50 of 62.94 g/mL when extracted with 70% ethanol, 122 g/mL when extracted with 50% methanol for three days, and 78.15 g/mL when extracted with aqueous decoction for five minutes [37].…”