In-vitro and In-vivo Antioxidant Activity of Ethanol Leaf Extract of Justicia carnea

This study investigated the in-vitro antioxidant activity of ethanol leaf extract of Justicia carnea and its effect on antioxidant status of alloxan-induced diabetic albino rats. The in-vitro antioxidant activity was assayed by determining the total phenol, flavonoids, ascorbic acid, β-carotene and lycopene contents and by using 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical, reducing antioxidant power and inhibition of lipid peroxidation antioxidant systems. Oxidative stress was produced in rats by single intraperitoneal injection of 150 mg/kg alloxan and serum concentration of malonaldehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) were determined. Five experimental groups of rats (n=6) were used for the study. Two groups of diabetic rats received oral daily doses of 100 and 200 mg/kg Justicia carnea leaf extract respectively while gilbenclamide (5 mg/ml); a standard diabetic drug was also given to a specific group for 14 days. From the result, the leaf extract contained a higher concentration of flavonoids followed byphenols, ascorbic acid, lycopene and β-carotene. The extract displayed more potent reducing power ability with EC50 of 40 µg/ml compared to BHA (EC50 of 400µg/ml). The percentage DPPH radical scavenging activity of the extract was also higher with EC50 of 200µg/ml and increased with increase in concentration while BHA had EC50of 320µg/ml. The inhibition of lipid peroxidation also increased with increase in concentration with EC50 of 58µg/ml and comparable with BHA (EC50=60µg/ml). The effect of the plant extract on antioxidant enzyme activities was concentration-dependent. Administration of 100mg/kg of the plant extract resulted in a significant decrease (p<0.05) in serum MDA concentration, while 200 mg/kg of the extract caused a significant (p˂0.05) increase in superoxide dismutase (SOD) and catalase activities with a non-significant increase (p>0.05) in the serum level of MDA when compared with the diabetic untreated group. These findings suggest that ethanol leaf extract of Justicia carnea have antioxidant properties and could handle diabetes-induced oxidative stress.