Evaluation of antioxidant activities of some Nigerian medicinal plants

Objective:The methanol extracts of the leaves of Kolancheo(K.) pinnata,Aspilia(A.) africana,Mucuna (M.) pruriens,Emilia(E.) coccinea,Triumfetta(T.) rhomboidea,Laportea(L.) ovalifolis,Celosia(C.) trigynea,Cucurbita(C.)moschata and Asystesia(A.)gangestica were evaluated for antioxidant activities,the reducing potentials of these plants were also determined and phytochemical screening of some of these plants were carried out.Methods:The antioxidant activities of these plants were evaluated by the use of 2,2-diphenyl -1 -picrylhydrazyl(DPPH) free radical assay and spectrophotomer.The reducing potentials of these plants were determined using Ferric chloride,Potassium Ferricyanide and Trichloroacetic acid proceedures. The phytochemical screenings of the medicinal plants were equally done using standard procedures.Results: The percentage of antioxidant activities values for the plants were:(31.00±1.80)%,(58.40±1.26) %,(59.10±1.60)%,(60.00±1.05)%,(60.80±1.28)%,(62.40±1.26)%,(64.80±2. 10)%,(75.70±2.60)%and(82.70±2.80)%for A.gangestica,C.moschata,C.trigynea,L. ovalifolia,E.coccinea,M.pruriens,A.africana,K.pinnata and T.rhomboidea.respectively.These values were dose-dependent and statistically significant at P < 0.05(ANOVA).The results showed that T.rhomboidea had the highest antioxidant activity value(82.70±2.80%) while A.gangestica had the least value (31.00±1.80%).The percentage of antioxidant activities of these plants were comparable to the standard used,Tocopherol which was found to be(97.20±1.06)%.The reducing potentials of the plants were found to be positively correlated to the antioxidant activities of the plants.Phytochemical screenings revealed the presence of alkaloids,flavonoids,terpenoids,saponins and tannins in the medicinal plants.Conclusion:The findings from this study have revealed the potentials of these plants as antioxidants.This could be exploited in drug development in search of powerful antioxidants which are urgently needed to challenge free radicals in biological systems.It will consequently help to prevent the body from free radicals originated ailments.However, further study needs to be done to isolate and characterize the active principles in these plants.