The lotus plant (Nelumbo nucifera Gaertn.) is not known in Western countries for food consumption. However, for more than 3000 years, lotus has been cultivated as a crop in Far East Asia, for food and medicine. This plant also plays a significant role in religious and cultural activities. The aim of the present study was to examine the antioxidant and DNA protection activities in the extracts from the leaves of the lotus plant.
The extract from the lotus leaf was used in this study. Antioxidant activities were measured by both 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging and 2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•+) decolourisation methods. To further evaluate the effect of lotus extracts on UV induced DNA damages, the DNA protection assay was employed. Lotus leaf extracts had effective DPPH bleaching activity and ABTS•+ radical scavenging activity in a concentration dependent manner.
Furthermore, the lotus leaf extracts to inhibit the oxidative DNA damages were assessed by measuring the conversion of supercoiled pUC119 plasmid DNA to the linear forms. UV irradiation of DNA with hydrogen peroxide resulted in the formation of linear forms of DNA, indicating double-strand DNA breaks.
Addition of lotus plant extracts to DNA resulted in a partial inhibition of the conversion of supercoiled DNA to linear forms, indicating that
the lotus plant extract was able to protect plasmid DNA against hydroxyl radical induced oxidative damage. The inhibition of hydroxyl radical induced DNA strand breaks by lotus plant extracts exhibited a concentration dependent relationship. Similar protective results were also obtained in the l phage DNA (Hind III digested) experiment