IN VITRO ANTIOXIDANTS AND TOTAL PHENOLIC CONTENTS OF THREE MEDICINAL PLANTS COMMONLY USED IN NORTH – EAST NIGERIA

Aliyu Daja¹, Korawinwich Boonpisuttinant², Zainab Kassim M.¹, and Abubakar Gidado¹

¹Department of Biochemistry, Faculty of Science University of Maiduguri Nigeria.

²Thai Traditional Medicine College, Rajamangala University of Technology Thanyaburi, Thailand

E-mail: aliyudaja@yahoo.com

Abstract: Crude aqueous and ethanolic extracts of three plants Parkia bigbolosa, Kaya senegalensis, and Leptadenia hastata were analysed for their antioxidant activities and total phenolic content. The antioxidant activities were measured as radical scavenging activity by 2, 2-Diphenyl-2-picrylhydrazyl DPPH, inhibition of lipid peroxidation by Ferric-thiocyanate method and metal chelating activity by ferrous ion chelating method and Folin-ciocalteau method was used to measure the total phenolic content expressed as mg/g GAE. The highest concentration of polyphenols was observed in extracts of Kaya senegalensis followed by Parkia bigbolosa and then Leptadenia hastata. For the radical scavenging assay by DPPH, both Kaya senegalensis and Parkia bigbolosa demonstrated very good ability of scavenging with SC₅₀ value ranging between 0.025-0.027mg/ml when compared with 0.017mg/ml of ascorbic acid with no statistically significant difference (p>0.05) in terms of activity, but Leptadenia hastata showed a significantly weak scavenging activity with SC₅₀ of 1.959mg/ml and 0.524mg/ml compared to the reference standard. Kaya senegalensis aqueous extract appeared to have better ability to inhibit lipid peroxidation having LP₅₀ values of 0.257mg/ml with over five fold potency than that of the standard (p<0.05), leptadenia hastata aqueous and kaya senegalensis ethanolic extracts exhibited very poor inhibition activity (p>0.05) when compared with the reference standard Vitamin E which has LP₅₀ of 1.440mg/ml. However, all of the extracts revealed a weak ability to chelating ferrous ion with MC₅₀ values range of (3.837 to 13.838mg/ml) when compared with the standard EDTA that has MC₅₀ of 0.450mg/ml. This indicates that these plants are good source of antioxidant for free radical scavenging and some having the ability to inhibit lipid peroxidation and thus, can be used in preventing, treating or managing oxidative stress related diseases.