Chiang Mai Journal of Science

 The ripe fruits of Antidesma puncticulatum are used as commercial sources for phenolic compounds and anthocyanins for functional foods. The aim of this study was to optimize the process parameters for extraction of phenolic and anthocyanin compounds with good antioxidant activity from the fruits using ultrasonic assisted extraction (UAE). A four-factor, five-level, six-center point central composite design was performed. Effects of solvent-to-solid ratio (X₁: 7.5-37.5 mL/g), acidified ethanol solution (X₂: 0-80%), extraction temperature (X₃: 20-100°C), and extraction time (X₄: 0-20 min) on the recovery of total phenolic and total anthocyanin contents with good antioxidant activity were investigated. The second order polynomial models of the response variables were obtained with an R² of 0.9455, 0.9308 and 0.8998, respectively. The optimal extraction conditions to obtain maximum yields of targeted compounds were 30 mL/g X₁, 45% (v/v) X₂, 80°C X₃ and 12 min X₂. The experimental values were in good agreement with the predicted values under the optimized conditions. The major constituents in the optimized extract were organic acids whereas phenolic compounds were minor components. Delphinidin-3-sambubioside-5-rhamnoside and delphinidin were identified by HPLC-ESI/MS as major anthocyanins in the extract. The plant extract showed moderate inhibitory activity on mushroom tyrosinase with a non-competitive inhibitory mechanism. The UAE can be considered as an effective method for extracting the biologically active compounds from fruits of A. puncticulatum.