Background and Purpose: The root extracts of Dennettia tripetala G. Baker and Milicia excelsa (Welw.) C. Berg was investigated for their in-vitro antioxidant activities.
Materials and Methods:  The pulverized roots of Dennettia tripetala and Milicia excelsa were extracted separately by cold maceration using ethyl acetate, methanol, n-butanol and water respectively as the extracting solvents. In-vitro antioxidant, the activity of root extracts was then investigated using DPPH model. The results obtained was analyzed using One-way Analysis of Variance (ANOVA) involving GraphPad Prism 5 Software.
Results: The antioxidant assay of various extracts, using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging model, revealed that the ethanol and n-butanol extracts of D. tripetala had better radical scavenging activity with IC₅₀ values of 2.02 and 0.631 µg/mL for ethanol and n-butanol extracts, respectively.  The methanol and ethanol extracts of M. excelsa showed higher radical scavenging capacity with IC₅₀ of 0.194 and 8.84 µg/mL compared to that of the ascorbic acid which had IC₅₀ value of 4.60 µg/mL.
Conclusion: The radical scavenging ability of the extracts could be attributed to the presence of flavonoids and phenolics.