In vitro antioxidant potential and phytochemical profiling of Melastoma malabathricum leaf water extract

Abstract

Melastoma malabathricum is one of the medicinal plants plated in West Kalimantan, Indonesia. Its leaves extraction using organic solvents revealed bioactive compounds and antioxidant activity. However, the antioxidant activity, toxicity, and chemical profile of water extract of M. malabathricum leaves are still unknown. This study aimed to determine extraction conditions that provide water extract of M. malabathricum with the highest antioxidant activity and the lowest toxicity. The extraction conditions were conducted at different water temperatures (25 ± 2 ºC and 90 ± 2 ºC), concentrations (10 and 5 g leaves/100 mL water), and extraction time (15, 30, and 45 minutes). Data analysis was performed by one-way ANOVA followed by Duncan's test (p < 0.05). The result showed that M. malabathricum leaves of 5g/100 mL extracted with hot water (90 ± 2 ºC) for 15 minutes showed the highest antioxidant activity (IC50 2.13 ± 19.20 ppm), which was higher than vitamin C (IC50 4.32 ± 0.16 ppm), and low toxicity (LC50 333.06 ± 99.45 ppm). Six compounds namely, 4-O-caffeoylquinic acid, quercimeritin, digiprolactone, 3-O-trans-coumaroylquinic acid, norbergenin, and arteamisinin were identified for the first time in the water extract of M. malabathricum leaves. These compounds, individually or extracted from other ingredients, have previously been reported to have antioxidant activity.