Arginase Inhibitory and Antioxidant Activities of Caesalpinia coriaria (Jacq.) Willd. Bark Extract

Objective: The aim of this study was to investigate the arginase inhibitory and the antioxidant activities of the bark extract of Caesalpinia coriaria (Jacq.) Willd. (Dewi tree). Methods: The bark of Dewi tree was extracted successively under reflux condition with n-hexane, ethyl acetate, and methanol. Each extract was tested for its activity in inhibiting arginase activity by measuring the quantity of urea produced in the reaction mixture using a microplate reader. The active extracts were determined for their total flavonoid content followed by antioxidant activity by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method using ultraviolet-visible spectrophotometry with ascorbic acid as standard. Phytochemical screening was conducted to determine the presence of alkaloids, saponins, flavonoids, tannins, and steroids. Results: Arginase inhibitory activity test showed that the ethyl acetate and methanol extracts have average inhibition values of 14.43 and 33.59%, respectively, at concentration of 100 μg/mL. The total flavonoid content of the methanol and ethyl acetate extract were 7.75 and 6.30 mgQE/g sample, respectively. The methanol and ethyl acetate extracts showed antioxidant activity with an IC₅₀ values of 4.720 and 3.647 μg/mL, respectively. The ethyl acetate extract contained flavonoid, tannin, saponin, and steroid, while the methanol extract contained flavonoid, tannin, and saponin. Conclusion: In conclusion, C. coriaria bark extracts possessed low arginase inhibitory activity. The methanol and ethyl acetate extracts have good antioxidant activity.