Evaluation of the Antioxidant Activities of Ya-hom Intajak, a Thai Herbal Formulation, and its Component Plants

Purpose: To evaluate the antioxidant effect of 80 % ethanol extract and its n-hexane and dichloromethane fractions of Ya-hom Intajak, and its 47 medicinal plants components.Methods: The 80 % ethanol extract and its n-hexane and dichloromethane fractions were investigated on human low-density lipoprotein (LDL) peroxidation by thiobarbituric acid reactive substances (TBARS) assay. Antioxidant effect was also determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and ferric reducing antioxidant power (FRAP) assays.Results: The extract of Ya-hom Intajak exhibited moderate DPPH scavenging activity with an IC50 value of 99.08 µg/ml and a FRAP value of 1.12 mmol FeSO4/g. Among the individual plants, Terminalia chebula Retz., Caesalpinia sappan L., Cinnamomum bejolghota (Buch.-Ham.) and Ci. verum J. Presl, showed strong antioxidant activities. T. chebula was the most potent plant in the DPPH assay while Ca. sappan had the highest FRAP value. Among the extracts, the dichloromethane fraction showed the highest inhibitory effect on LDL peroxidation with a half maximal inhibitory concentration (IC50) value comparable to that of probucol (0.82 µg/ml). Pearson correlation analysis revealed that total phenolic content (TPC) showed high positive correlations with FRAP (r = 0.908, p < 0.01) and DPPH activities (r= 0.648, p < 0.01).Conclusion: Ya-hom Intajak is a valuable source of natural antioxidants and has a potential application as a cardiovascular protective formulation.Keywords: Ya-hom Intajak, Antioxidant activity, Terminalia chebula Retz., Caesalpinia sappan L., Cinnamomum bejolghota (Buch.-Ham.), Ci. verum J. Presl , Phenolic conten