Optimization of extraction, separation and purification of baicalin in Scutellaria baicalensis using response surface methodology

Abstract

Optimizing extraction, separation, and purification processes of bioactive ingredients improves resource utilization and reduces environmental pollution in pharmaceutical industry. Here, we report findings of a study focusing on enhancing baicalin production from Scutellaria baicalensis, an important medicinal crop with increasing market demand. Using response surface methodology, we optimized ultrasonic-assisted extract method (ethanol concentration, ultrasonic temperature, ultrasonic time) for dried powder and decocting method (liquid-solid ratio, decocting time, decocting times) for fresh slices, respectively. Baicalin was separated, purified, and refined through the processing of macroporous resin, alkali-solution, acid precipitating and methanol reflux, respectively, and was quantified via high performance liquid chromatography. The main findings were as follows: (1) Optimal extraction of dried-powder: particle size 80 mesh, liquid-solid ratio 20:1, extraction solvent ethanol 57%, ultrasonic temperature 68°C, ultrasonic time 66 min. (2) Optimal extraction of fresh slices: adding the fresh slices into boiling water, liquid-solid ratio 43:1, decocting for 93 min. (3) Optimal separation: AB-8 macroporous resin, diameter to height ratio 1:15, loading liquid baicalin concentration 25.6 mg/mL, flow rate 1 BV/h, loading volume 8 BV, and elution volume 11 BV. (4) Optimal purification: adjusting the extraction solution pH to 1.0, static placing at 80°C for 12 h, washing the precipitate twice, dissolving the crude baicalin extract with alkali NaOH, and re-precipitating with stronger acid HCl. (5) Optimal refinement: reflux extracting the above baicalin extraction with 75% methanol for 30 min at liquid-solid ratio 15:1. Collectively, these findings provide valuable references for optimizing processing conditions of important medicinal crops in pharmaceutical industry.