Antioxidant activity of some Nigerian medicinal plants used in malaria treatment

Abstract

Free radicals are reactive molecules associated with many diseases including malaria; causing complications. Thus, the need to explore compounds with free radical scavenging properties. Methanol extracts of the leaves of three medicinal plants (A. barteri, O. basilicum and H. indicum) used in Nigerian folkloric medicine for the treatment of malaria were evaluated for their antioxidant activty, total phenol and flavonoid contents. The antioxidant activity evaluation included various radicals or oxidation systems - ferric-reducing antioxidant power (FRAP), 2, 2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) radical (ABTS), and oxygen radical absorbance capacity (ORAC) assays. Total phenol and flavonoid contents were also evaluated. The leaves of A. barteri showed the highest levels of total phenol (222.30 ± 5.48 mg gallic acid equivalent/g), flavanol (22.90 ± 0.15 mg catechin equivalent/g) and flavonol contents ( 93.32 ± 2.80 mg quercetin equivalent/g) compared to O. basilicum and H. indicum. The antioxidant activity of these plants increased with increase in their total phenol and flavonoid contents. The order of the antioxidant activity of the plants was A. barteri > O. basilicum > H. indicum. These results suggest that the leaves of these plants contain polyphenols and could serve as potential sources of antioxidants which could be explored as therapeutic agents in the attenuation of free radical in malaria infection.