The antioxidant activity of Caesalpinia sappan heartwood extracted with different ethanol concentrations

The effect of different ethanol concentrations, used for the extraction of C. sappan wood, on the antioxidant capacity was investigated. The heartwood of C. sappan was extracted with 95%, 75%, and 50% ethanol and subsequently partitioned using deionized water, dichloromethane, and ethyl acetate. The fractions were subjected to different antioxidant assays based on free radical scavenging activity (DPPH, ABTS^•+ and in-vitro lipid peroxidation). Additionally, the content of total phenols and flavonoids was determined. The present study provides evidence that the total phenolic content and antioxidant capacity of C. sappan heartwood extracts were significantly dependent on the ethanol concentration used for extraction. However, the subsequent ethyl acetate fraction showed the overall strongest anti-oxidative activity in the assays. The crude extract prepared by using 75% ethanol contains a considerable amount of total phenols (741.8 mg GAE/g C. sappan heartwood), with low IC₅₀ values (2.4 μg/mL in DPPH assay, 2.98 μg/mL in ABTS assay, and 14.2 μg/mL in lipid peroxidation assay). Interestingly, the ethyl acetate fraction obtained from the 75% ethanol crude extract showed the highest scavenging activity (2.24 μg/mL for DPPH radical assay, 2.38 μg/mL for ABTS assay). Accordingly, total phenolic content and antioxidant capacity were closely correlated (R² <0.83 and p-value <.0.01).