HPLC-UV Analysis of Chrysophanol in Senna occidentalis Extract Obtained by Using the RSM-Optimized Ultrasonic Extraction Process

In this experiment, chrysophanol analysis in Senna occidentalis (aerial parts) extract obtained by optimizing ultrasound-assisted extraction (UAE) variables (temperature, time, and liquid-to-solid ratio) using response surface methodology (RSM) was performed by employing the HPLC-UV method. For UAE process optimization, a highly significant quadratic model (p < 0.001) was projected to attain maximum chrysophanol yield. The extraction temperature, time, and liquid-to-solid ratio for the best UAE method were determined to be 49.3 °C, 57.7 min, and 18.7 mL/g, respectively. The optimized extract was subjected to a chrysophanol analysis utilizing HPLC-UV (fitted with a Pinnacle C18 column), and a gradient mobile phase composed of 0.5% formic acid (solvent A), acetonitrile (solvent B), methanol (solvent C), at a flow rate of 1.0 mL/min, and an optimum wavelength of 279 nm, respectively. It furnished a compact and intense peak of chrysophanol at Rt = 23.809 min. The experimental value (20.47 mg/g) of chrysophanol obtained was close to the predicted value (19.32 mg/g), indicating that they agreed under the optimized extraction condition. UAE also displayed remarkable improvement in chrysophanol extraction compared with the conventional solvent extraction (CSE) method. Hence, our improved ultrasonic extraction process showed a potential use for effective chrysophanol extraction from commercial herbal supplements comprising the Senna species.