Optimization, extraction, and purification of three bioactive compounds from Entada phaseoloides by high‐speed countercurrent chromatography

The objective of this paper was to develop a preparative method for the separation and purification of phaseoloidin, entadamide A, and entadamide A‐β‐D‐glucopyranoside from the crude extract of Entada phaseoloides by high‐speed countercurrent chromatography (HSCCC) for the first time. Optimized by orthogonal experiments, the extraction conditions were extraction temperature of 65°C, solid‐to‐liquid ratio of 1:15 (g/mL), ethanol concentration of 40%, and extraction time of 2.5 h. Using n‐butanol‐acetic acid‐water (4:1:5, v/v/v) as the two‐phase solvent system, 38.79 mg phaseoloidin (the purity was 99.3% with a recovery of 98.1%), 34.85 mg entadamide A (the purity was 96.4% with a recovery of 98.5%), and 33.97 mg entadamide A‐β‐D‐glucopyranoside (the purity was 98.6% with a recovery of 97.7%) were obtained from 500 mg crude extract by HSCCC in head‐to‐tail elution mode. The retention ratio of stationary phase was 51.0%. According to the antioxidant activity assays, phaseoloidin, entadamide A, and entadamide A‐β‐D‐glucopyranoside had certain scavenging abilities on 1,1‐diphenyl‐2‐picrylhydrazyl free radicals and hydroxyl free radicals.