Optimization of Supercritical Carbon Dioxide Extraction of Xanthones from Mangosteen Pericarp by Response Surface Methodology

Mangosteen fruit pericarp is one of the important sources of bioactive compound xanthone. Supercritical carbon dioxide (SC-CO₂) extraction was employed to extract xanthones from mangosteen fruit pericarp at three different levels of pressure (200–300 bar), temperature (40–60 °C) and solvent to material ratio (100–300 kg/kg). The optimal conditions for the total xanthone yield and the influence of parameters were determined by response surface methodology (RSM) using Box–Behnken design. In our study, the increase in total xanthone yield in SC-CO₂ fluid extraction depends more on the solute’s vapor effect. From response surface plots, pressure, temperature and solvent to material ratio exhibited independent and interactive effects on the extraction of xanthones. A regression equation for predicting the total xanthone yield was derived by statistical analysis, and a model with predictive ability of 0.99 was obtained. Maximum xanthone yield of 8.01% was predicted by RSM at 60 °C, 300 bar and a solvent to material ratio of 300 kg/kg while experimentally a yield of 7.56% was achieved. HPLC analysis was carried out for the optimum conditions for the identification and quantification of the xanthones. The antioxidant activities of the extracts were investigated by ferric reducing antioxidant power (FRAP) and the results showed that the extracts were enriched with antioxidant compound.