Optimization of recrystallization purification process of betulin in birch bark

Abstract

Objective: This study aimed to promote the high-value utilization of birch bark in Changbai Mountain area. Methods: Taking birch bark as the research object, betulin was extracted by ethanol, then purified by recrystallization, and its antioxidant activity in vitro was investigated. Results: The optimal extraction process conditions of betulin were as follows: ethanol volume fraction 80%, solid-liquid ratio (m birch bark∶V ethanol) 1∶30 (g/mL), extraction at 95 ℃ for 1.5 h. under the control of these conditions, the alcohol extraction rate was 66.21%. Using absolute ethanol as solvent for recrystallization, V absolute ethanol∶m solid=30∶1 (mL/g), recrystallization at -20 ℃, and the recrystallization yieldreached 80.00%, with highest purityof 99.81%. When the concentration of betulin solution was 1.0 mg/mL, the scavenging rates of DPPH and hydroxyl free radical were 89.94% and 27.79% respectively. Conclusion: Betulin has good antioxidant capacity.

Keywords

• birch bark
• betulin
• soxhlet extraction
• antioxidant activity