Optimization of Ultrasonic-assisted Extraction of Flavonoid from Portulaca oleracea L. by Response Surface Methodology and Chemical Composition Analysis

Optimization of ultrasonic extraction of Portulaca oleracea L. flavonoids (POE) was investigated using single-factor experimentation combined with response surface methodology. The optimal conditions for the highest yield (16.25 mg RE/g DW) of POF was 39.01% ethanol, 55.25 degrees C extraction temperature, 15 min extraction time, and 23.92 (v/m) liquid-to-solid ratio. The crude extract of POF was purified on the polyamide resin. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole assays of the flavonoids were evaluated, which suggested the concentrations of the flavonoids (0-1 mg/mL) and quercetin (0-1 mg/mL). Quercetin was identified in the extract by comparing relative retention time of the reference standard.