The Relationship of Free Radical Scavenging and Total Phenolic and Flavonoid Contents of Garcinia lasoar PAM

The radical scavenging assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic (ABTS) acid for various extracts and fractions of Garcinia lasoar Pam stem bark had been examined. The methanol extract showed high total phenolic (272.98 mg GAE (gallic acid equivalent)/100 g) and total flavonoid (223.16 mg QE (quercetin equivalent)/100 g) contents with potential antioxidant activity (DPPH: 0.72 μg/mL; ABTS: 0.24 μg/mL). The ethyl acetate fraction of methanol extract has higher activity than the dichloromethane fraction with IC₅₀ values of 1.90 and 0.90 μg/mL in DPPH and ABTS assays, respectively. The Pearson correlation coefficients were calculated in order to identify the relationship between antioxidant activity and the total phenolic and total flavonoid contents. The antioxidant activity showed high positive relationship in both assays (r = 0.762, p < 0.05). The highest positive correlation between total flavonoid content and ABTS radical scavenging activity for methanol extract and then ethyl acetate had correlation between total flavonoid content. These results suggest that G. lasoar stem bark extracts can be used as a natural source of antioxidants.