METHODS: Plant extracts from hot water infusion were tested for the total phenolic content, total flavonoid content and enzyme inhibition through Folin-ciocalteu assay, aluminium chloride method and xanthine oxidase inhibition assay, respectively. Simplex-centroid mixture design was applied in this study and 13 polyherbal formulations were generated by Design Expert Software.
RESULTS: Linear, special cubic and quadratic models were selected to describe the interaction effect between polyherbal formulations and their responses. Low IC50 value (13.90 μg/mL) of xanthine oxidase activity was found in the binary combination of O. stamineus and S. rebaudiana and this probably related to its high phenolic and flavonoid contents as xanthine oxidase inhibition and phytochemicals were correlated.
CONCLUSIONS: The suggested optimal formulation was comprised of 44.26 % O. stamineus and 55.74 % S. rebaudiana and it could be developed as an alternative treatment for gout.