PHYTOCHEMICALS, TOTAL PHENOLIC CONTENTS AND ANTIOXIDANT ACTIVITIES OF WATER AND ETHANOL EXTRACTS FROM INCA PEANUT (Plukenetia volubilis L.) LEAVES

Abstract

Inca peanut leaves (Plukenetia volubilis L.) is generally consumed in form of tea but there is less research which study about bioactivity of Inca peanut leaves cultivated in Thailand. The objectives of this study were to evaluate the phytochemical constituents, total phenolic contents and antioxidant activities of Inca peanut leaves. The fresh leaves and dried leaves were extracted by water (30°C), warm water (60°C), ethanol 95% (30°C) and warm ethanol​ 95% (60°C). It was found that dried leaves extracted with warm water (DW60) provided the highest percentage yield (19.01±0.43%w/w). The phytochemical screening of the extracts revealed the presence of phenols, flavonoids and alkaloids in all extracts. The main minerals in Inca peanut leaves were calcium, silicon and potassium. Dried leaves extracted with warm ethanol (60°C) (DE60) showed the highest (p<0.05) amount of total phenolic contents (22.05±1.20 mg GAE/g DW). The antioxidant activities were analyzed by ABTS radical cation scavenging activity and DPPH radical scavenging activity. It was found that DW 60 exhibited the highest ABTS radical cation scavenging activity (193.07±6.14 mg AEAC/g DW, IC50 3.07±0.91 µg/ml) while DE60 exhibited the highest DPPH radical scavenging activity (27.27±0.71 mg AEAC/g DW, IC50 119.81±4.35 µg/ml). Thus, the results of this work can be concluded that dried leaves extract obtained by warm water and warm ethanol 95% are suitable for further use as antioxidant for prevention and management of free radicals mediated oxidative stress.