Comparative Evaluation of the Anti-oxidant Potential of Selected Plants Used for Diabetes in Sri Lanka

Introduction: Plants are good sources of antioxidants, which have been used to treat diseases such as diabetes, arthritis, and cancer. Herbals used for diabetes have anti-oxidant potential, which could reduce complications and improve patients' health conditions. This study focused on comparing anti-oxidant activity in leaves of Gymnema sylvestre and Costus pictus, seeds of Nigella sativa and Trigonella foenum graceum, and fruit of Momordica charantia. Methods: The plant samples were collected from the Jaffna District and authenticated in the University of Jaffna. The extract of each plant was prepared by maceration. DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical scavenging assay was used to evaluate the in vitro anti-oxidant activity of methanolic extracts of these plant extracts using ascorbic acid as standard. The folin-ciocalteu method was used to quantify the total phenolic content present in the plant extracts. One-way ANOVA was used to compare the anti-oxidant activity of extracts with standard. Pearson correlation was used to assess the correlation between anti-oxidant activity and the total phenolic content of the extracts. Results: The IC50 values for DPPH assay were 1246.66±10.91, 1917.89±13.86, 813.82±2.08, 767.87±2.39, and 729.81±3.28 μg/ml, and the total phenolic content were 13.23±0.23, 14.70±0.54, 18.04±0.24, 20.92±0.31, and 35.72±0.59 mg GAE/g for T. foenum graceum, M. charantia, G. sylvestre, N. sativa, C. pictus respectively. C.pictus showed the highest anti-oxidant activity, and M. charantia showed the least antioxidant activity among the tested plant extracts. C. pictus leaf extract had high total phenolic content. T. foenum graceum seed extract had low total phenolic content among the tested plant extracts. Anti-oxidant activity of tested plant extracts was significantly low compared to ascorbic acid (p<0.001). Also, anti-oxidant activities of tested plant extracts showed significant differences between them (p<0.001). Conclusion: N. sativa and C. pictus exhibited potential anti-oxidant activities and could be beneficial in preventing and controlling complications in patients with diabetes.