Study on the scavenging DPPH radical inhibitory activity of some medicinal plants collected at Ma Da forest, Dong Nai province

Abstract

Abstract Free radicals are formed in the human body to prevent virus and bacteria infections. However, they can react with macromolecules including protein, lipid, DNA (deoxyribonucleic acid) inducing serious diseases such as aging, heart disease, stroke, cancer, genetic mutations, weakened immune system and more. Therefore, antioxidant substances are required for the protection against oxidizing agents. Many synthetic antioxidant compounds have shown toxic and/or mutagenic effects which stimulated the interest of researchers to find out for natural antioxidants. Several analytical methods have been developed to determine the antioxidant capacity of natural substances. The most famous antioxidant assay is the DPPH free radical scavenging because it is simple, rapid, and convenient. 23 methanolic extracts from 16 medicinal plants, collected at the Ma Da forest in Dong Nai province, were investigated for their antioxidant activity by the DPPH method. The results indicated that all the studied extracts showed an inhibition of over 50% at the concentration of 100 µg mL-1, 22 illustrated greater than 50% inhibition at 50 µg mL-1, and 18 demonstrated over 50% inhibition at 25 µg mL-1. Ten MeOH extracts exhibited strong inhibitory activity with more than 50% inhibition at 10 µg mL-1 and three showed 50% inhibition at 5 µg mL-1. Among them, the bark wood of Anisoptera costata and Dipterocarpus costatus, belonging to Dipterocarpaceae family, displayed the highest DPPH free radical scavenging activity, with the IC50 values of approximately 3.15 µg mL-1. These values are similar with the positive control, trolox (IC50 = 2.73 µg mL-1). To the best of our knowledge, this is the first time that these extracts possessing the DPPH free radical scavenging activity were reported.