Abstract

Phytochemical screening and determination of antioxidant activities of methanolic extracts of leaf of Stellaria media, Cajanus cajan and root of Tetracera potatoria were conducted. Phytoconstituents screened for included alkaloid, saponins, tannins, phlobatannins, flavonoids, anthraquinones and cardiac glycosides. Free radicals scavenging capacity of the extract of the three plants were assessed in vitro by 1,1 diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays, while inhibition of free radicals generation was assessed by ability of the extracts to inhibit lipid peroxides formation. The antioxidant activities of the extracts were dose dependent. The highest percentage inhibition of DPPH by T. potatoria, S. media and C. cajan was 82, 76 and 57%, respectively, as against 76% for ascorbic acid. Percentage ferric ions reduction in FRAP assay was 104, 79 and 26% for T. potatoria, S. media and C. cajan as against 100% for Gallic acid, the standard compound. The standard drugs however appeared more potent than the crude extracts because the bioactive compounds have not been isolated or purified. Lipid peroxidation assay showed that T. potatoria inhibited lipid peroxides formation by 54%. It was concluded that the abundance of flavonoids, tannins and phlobatannins in the three plants account for their high antioxidant activities which probably explains their ethnomedical applications against inflammatory conditions. It is believed that isolation of the specific bioactive principles will serve to improve the free radicals scavenging potency of the compounds.

Key words: Free radicals, phytoconstituents, Stellaria media, Cajanus cajan, Tetracera potatoria, extracts.