Synergistic antioxidant and anti-inflammatory effects of combined supplementation with oral zinc and dietary Moringa oleifera leaf in streptozotocin-induced diabetic rats

Abstract

Individual interventions with zinc or M. oleifera leaf powder have shown some promise in managing diabetes-induced oxidative stress and inflammation. This study examined the synergistic effect of oral zinc and dietary M. oleifera leaf supplementation on the serum antioxidant and anti-inflammatory activities in streptozotocin-induced diabetic rats. Seven groups of 56 rats were used in the experiment: (1) normal rats + normal diet, (2) normal rats + 3% M. oleifera leaf-supplemented diet, (3) non-treated diabetic rats, (4) diabetic rats + 200 mg/kg metformin, (5) diabetic rats + 3% M. oleifera leaf-supplemented diet, (6) diabetic rats + 100 mg/kg oral zinc sulfate, and (7) diabetic rats + 3% M. oleifera leaf-supplemented diet + 100 mg/kg oral zinc sulfate. ELISA assay kits were used for antioxidant and anti-inflammatory markers respectively. The results suggest that when all treated diabetic groups were compared with non-treated diabetic control at p<0.05, only groups 4 and 7 showed a significant increase in superoxide dismutase activity. Only group 5 showed a significant increase in reduced glutathione. No significant changes were observed in catalase and the total antioxidant capacity. MDA decreased significantly in group 7 only. There was a significant reduction in interleukin-6 in groups 6 and 7. Only group 7 showed significantly reduced C-reactive protein. Tumor necrosis factor-α reduced significantly in group 6 only. Overall, the combined supplementation with zinc and M. oleifera outperformed the individual treatments with either zinc or M. oleifera in ameliorating diabetes-induced oxidative stress and inflammation, indicating a possible synergistic effect of their combination.