Optimization of ultrasonic-assisted extraction of eugenol-rich fraction from basil leaves: Characterization of extract for phenols, flavonoids and antioxidant activity

Abstract

In this study, optimization of ultrasonic assisted extraction (UAE) of eugenol-rich fraction from O. basilicum was performed. Box-Behnken design of response surface methodology was applied with three independent variables viz. solvent concentration (25–75%), amplitude (70–90%) and sonication time (7–12 min). The effects of these three independent variables were studied on extract yield, total phenolic content, total flavonoid content, anti-oxidant activity and eugenol content present in O. basilicum. Significant (p≤0.05) effects of all the independent variables were recorded in all the product responses. Extract yield and total phenolic content ranged from 74.36–55.48% and 23.45–10.25 mgGAE/g, respectively while as total flavonoid content and anti-oxidant activity was 0.082–0.009 mg/g and 71.21–25.33% respectively and eugenol content of 0.846–0.207 mg/g was recorded for all the treatments. The optimum processing conditions obtained by numerical optimization for solvent concentration (A), amplitude (B) and sonication time (C) were 52.48%, 90% and 7.75 min, respectively. Eugenol content of 41.44% was further validated through GC-MS/MS in extract developed after following the optimal condition. Conclusively, RSM was found to be successful for optimization of UAE process of eugenol rich fraction from basil leaves. The results confirmed the success of using ethanol as a safe solvent for UAE of eugenol from basil leaves.