Optimization of a Novel Antioxidant Formulation Containing Phytosome of Standardized Flos Styphnolobii japonici immaturus Extract and Standardized Extracts of Rhizoma Zingiberis, Herba Centellae asiaticae, Polyscias fruticosa Using the D-Optimal Mixture D

Abstract

Oxidative stress, resulting from an imbalance between the production and elimination of free radicals, contributes to the pathogenesis of numerous chronic diseases. This study aimed to optimize the mixing ratio of a quercetin – rich Flos Styphnolobii japonici immaturus phytosome, standardized ginger extract, standardized Herba Centellae asiaticae extract, and standardized Polyscias fruticosa extract to develop a herbal formulation with strong antioxidant activity. A total of 15 formulations were constructed and evaluated using D-optimal mixture design implemented in Design-Expert software. The quadratic model was the best fit for predicting in vitro DPPH free radical scavenging activity, whereas the linear model was most appropriate for total antioxidant capacity (TAC). The optimized formulation consisted of 50% quercetin – rich Flos Styphnolobii japonici immaturus phytosome, 17.66% standardized ginger extract, 22.34% standardized Herba Centellae asiaticae extract, and 10% standardized Polyscias fruticosa extract. Experimental validation showed strong antioxidant activity, with an IC₅₀ value of 6.38 µg/ml in the DPPH assay and a TAC of 41.05 µmol AAE/g.

Keywords: Antioxidant activity; herbal formulation; D-optimal mixture design; DPPH; total antioxidant capacity.