In this study, the effect of extraction parameters (ethanol concentration, sonication time, and solvent-to-sample ratio) on Ficus deltoidea leaves was investigated using ultrasound-assisted extraction by response surface methodology (RSM). Total phenolic content (TPC) of F. deltoidea extracts was identified using Folin-Ciocalteu method and expressed in gallic acid equivalent (GAE) per g. Box-Behnken statistical design (BBD) was the tool used to find the optimal conditions for maximum TPC. Besides, the extraction yield was measured and stated in percentage. The optimized TPC attained was 455.78 mg GAE/g at 64% ethanol concentration, 10 minutes sonication time, and 20 mL/g solvent-to-sample ratio whereas the greatest extraction yield was 33% with ethanol concentration of 70%, sonication time of 40 minutes, and solvent-to-material ratio at 40 mL/g. The determination coefficient, R2, for TPC indicates that 99.5% capriciousness in the response could be clarified by the ANOVA model and the value of 0.9681 of predicted R2 is in equitable agreement with 0.9890 of adjusted R2. The present study shows that ethanol-water as solvent, a short time of 10 minutes, and adequate solvent-to-sample ratio (20 mL/g) are the best conditions for extraction.
