Medicinal plants contain bioactive compounds capable of preventing and fighting oxidative related
diseases. These compounds must be screened and assayed before effective drugs are developed. Thus,
phytochemical constituents and antioxidant activities of aqueous and methanol stem extracts of Costus
afer Ker-Gawl were evaluated. C. afer contained flavonoids, phenols, anthraquinones, cardiac
glycosides, terpenoids, alkaloids and tannins. Preliminary screening of free radical scavenging activity
of extracts with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) using thin layer chromatography tested positive.
The aqueous extract had a higher free radical scavenging activity with IC50 (concentration of samples
required for 50% inhibition of DPPH radical activity) value of 64.42 g/ml than methanol extract (92.33
g/ml). Furthermore, total phenolic content in aqueous extract (0.66 ± 0.02 mg gallic acid equivalent/g)
was significantly higher (p < 0> addition, inhibition of lipid peroxidation by aqueous extract (80.60 ± 0.28%) was significantly higher (p <
0.05) than methanol extract (77.00 ± 0.84%). Nevertheless, methanol and aqueous extracts of C. afer
possess anti-oxidative properties as well as bioactive metabolites. Thus, stem extracts of C. afer could
serve as sources of antioxidants and bioactive compounds for nutrition and therapeutic purposes.