Abstract:

Purpose: To establish a method for the determination of total flavonoids and to evaluate the antioxidant activity
of the ethanol extract of Leucaena leucocephala (Lam.) de Wait fruit peel. Methods: The content of total flavonoids was
measured by NaNO2-Al(NO3)3 assay. The antioxidant property was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH)
free radical scavenging and reducing power assays. Results: The linear range of rutin was 0.01–0.05 mg/mL (r = 0.999 1).
The average recovery rate was 99.35% with relative standard deviation (RSD) of 1.37%. The content of total flavonoids was
1.76 mg/g. In DPPH radical scavenging assay, the sample exhibited antioxidant activity in a dose-dependent manner with
IC50 of 0.32 mg/mL. The IC50 for reducing power was 70.12 μg/mL. Conclusions: The developed method is rapid, accurate,
simple, reproducible and suitable for determination of total flavonoids in the fruit peel of L. leucocephala. Moreover, the
fruit peel of L. leucocephala is rich in flavonoids and possesses high antioxidant activity.

Key words: Leucaena leucocephala (Lam.) de Wait peel, flavonoids, antioxidant activity