Abstract

Poverty, drug resistance and other factors including increasing difficulty in the control of mosquitoes (the vector of the causative organism of malaria), have led to a growing interest in phytochemical research. The antioxidant activity ofNewbouldia laevis stem bark was investigated. Air dried stem bark of N. laeviswas powdered and extracted with 95% v/v methanol by maceration, and the extract concentrated at 40^oC using rotary evaporator. The total phenolic composition of methanolic extract of air dried stem bark was estimated using spectrophotometric method. Antioxidant activity of the extract was evaluated on the basis of its ability to prevent the oxidation of β-carotene and the strength of its ferric reducing capacity also determined. Phenolic composition was calculated to be approximately 35%. Plant extract showed concentration - dependent antioxidant activity and ferric reducing power. Plant extract achieved a maximum antioxidant activity of 4% within 40 min. The total phenolic content, antioxidant activity and reducing power of the extract had direct relationship.

Key words: Newbouldia laevis, β-carotene, phenolic composition, antioxidant activity, reducing power.