摘要Objective: To determine the free radical scavenging potentials pytochemical constituents of ethanol leaves extracts of Allamanda cathartica (A. cathartica) and Bixa orellana (B. orellana) and thus their effects in antimalarial activities. Methods: Both ethanol extracted plant samples were administered at 50 mg/mL, 100 mg/mL and 200 mg/mL to Albino rats and then administered with CCl4 at 1 mL/kg body weight, in liquid paraffin (1:1, v/v) for 2 days (negative control) and compared with 5% Tween 80 (placebo) and vitamin E (positive control) pretreatments. Thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and catalase (CAT) activities in blood and liver tissues were assessed. Results: In CCl4 treated rats, TBARS levels significantly increased, while decreased GSH and CAT levels were recorded for both plant extracts. Generally, higher TBARS and GSH values were recorded for blood than for liver homogenates; with reverse trend observed for CAT level. Increased concentrations of A. cathartica extract recorded significant antioxidant levels similar to tocopherol (vitamin E). Reducing sugars, saponins, flavonoids were recorded for both species; alkaloids in A. cathartica and terpenoids in B. orellana. Conclusions: A.cathartica, possess phytochemicals that recorded significant antioxidative defense activities for blood and liver tissues with increasing concentration. However B. orellana did not record similar results.