In vitro antioxidant activity of n-butanol extract of Curcuma longa and its potential to protect erythrocytes membrane against osmotic-induced haemolysis

Antioxidant activity of Curcuma longa rhizomes (Turmeric) has been widely investigated in Asia. This work evaluated the antioxidant potential of Nigerian variety of Curcuma longa with the main hypothesis that variation in plant phytochemicals in type and/or amount is a function of geographical location/soil type. The experimental models used for the antioxidant studies include: iron (III) reducing capacity, total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay and in vitro inhibition of osmotic-induced haemolysis. The extract was found to reduce osmotic pressure-induced haemolysis of mammalian erythrocytes in a dose-dependent manner and also gave high total antioxidant capacity. At 1000 μg/mL concentration, its DPPH radical scavenging ability compared favourably well with those of the standard compounds - ascorbic and garlic acids. The implications of these findings in the usage of Curcuma longa as food additives and ethnomedicinal practice in Nigeria are discussed.