Abstract:

Rhus punjabensis var. sinica Rehd. fruit was superfinely crushed at 0-10℃ and degreased with petroleum ether (60-90℃), and then the dihydrofisetin was extracted from fruit powder by supercritical CO₂ extraction. The suitable entrainer was chosen, and the extraction conditions were optimized by orthogonal experiment. The total antioxidant capacity of the obtained dihydrofisetin and its scavenging effects on DPPH·, superoxide anion radicals (O₂^-·) and hydroxyl radicals (·OH) were investigated. The results showed that the particle size of R. punjabensis var. sinica fruit powder could be up to 0.1-1 μm after ultrafine-pulverization and cell-wall breaking ratio was over 95%; the suitable entrainer was ethanol with volume fraction of 70%, the optimal conditions for the extraction were solid-liquid ratio 5:3(g:mL), extraction pressure 30 MPa, extraction temperature 55℃, extraction time 2 h, separating axeⅠtemperature 55℃ and pressure 10 MPa, separating axeⅡtemperature 40℃ and pressure 5 MPa. Under these conditions, the yield of dihydrofisetin was 0.46%, the purity was 80.26%. The dihydrofisetin had strong antioxidant activity, and the half-clearance concentration(IC₅₀) of DPPH·, O₂^-· and ·OH were 6.93, 59.63 and 9.05 mg/L, respectively. The radical scavenging abilities on DPPH· and O₂^-· were close to those of V_C. The scavenging capacity of ·OH and total antioxidant capacity were better than those of V_C.

Key words: Rhus punjabensis var. sinica Rehd. fruit, dihydrofisetin, ultrafine-pulverization, supercritical extraction, HPLC