A Comparative Study of in vitro Antioxidant Activity and Phytochemical Constituents of Methanol Extract of Aframomum melegueta and Costus afer Leaves

Based on local claims on the efficacy of Aframomum melegueta (alligator pepper) and Costus afer (ginger lily) in the treatment of malaria, the present study compared the antioxidant activity and phytochemical constituents of extracts of A. melegueta and C. afer leaves. Methanol extracts of the plant leaves were obtained using standard procedures. The antioxidant property of the plants extracts were evaluated using DPPH (1,1-diphenyl-1-picryl-hydrazyl) radical, Total Phenol Content (TPC), Total Flavonoid Content (TFC), Proanthocyanidin Content (PC), Ferric acid Reducing Antioxidant Potential (FRAP) and ThioBarbituric Acid Reducing Substances (TBARS) assay. The phytochemical screening test revealed the presence of alkaloids, reducing sugars, flavonoids, tannins, saponins, steroids, cardiac glycosides and terpenoids in both extracts. The antioxidant study showed that the A. melegueta extract had higher DPPH radical scavenging ability (IC50 of 122.25ug/ml), FRAP (35.38μmol Fe(II)/g) and TBARS (% inhibition of 62.08%) than C. afer (IC50 of 156.48ug/ml, 12.25 μmol Fe(II)/g, and 42.5%, respectively). The C. afer extract, however, recorded higher levels of TFC, PC and a lower TPC content when compared with the A. melegueta counterpart. The results suggest that C. afer and A. melegueta extracts could serve as free radical scavengers, acting as primary antioxidants. The results support local claims of their therapeutic uses in the treatment of malaria in folklore medicine.