Evaluation of the antioxidant properties of the leaf extracts of Philippine medicinal plants Casuarina equisetifolia Linn, Cyperus brevifolius (Rottb) Hassk, Drymoglossum piloselloides Linn, Ixora chinensis Lam, and Piper abbreviatum Opiz

In our continuing search for natural antioxidants, the decoction, ethanol, and 50:50 ethanol:water extracts of the medicinal plants Casuarina equisetifolia Linn, Cyperus brevifolius (Rottb) Hassk, Drymoglossum piloselloides Linn, Ixora chinensis Lam, and Piper abbreviatum Opiz found in different areas in Mindanao are evaluated for their antioxidant potentials. The decoction and 50:50 ethanol:water extracts of C. equisetifolia and I. chinensis showed considerable 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical-scavenging activity ranging from 80.06 to 91.79% when compared to the commercial antioxidant butylated hydroxytoluene (BHT). The total phenolics content of the leaf extracts ranges from 34.67 to 285.62 gallic acid equivalence with the ethanol extract of D. piloselloides exhibiting the highest phenolics content at 285.62 mg g-1 sample. The ethanol extract of D. piloselloides also demonstrated the highest total antioxidant capacity, 87.54 ascorbic acid equivalents and 149.43 butylated hydroxytoluene equivalents. The results indicate that C. equisetifolia, I. chinensis, and D. piloselloides can be important sources of antioxidants that may offer protection from the harmful effects of oxidative stress.