Ultrasound-assisted supramolecular solvent extraction with enzymatic pretreatment of Celastrus orbiculatus roots: Process optimization, enrichment, and antibacterial activity

Ultrasound offers a greener and more efficient alternative to conventional extraction methods, requiring less solvent and shorter processing times. This study developed an ultrasound - assisted enzyme - supramolecular solvents (SUPRAS) extraction (UAESE) method to synergistically extract two key triterpenoids from Celastrus orbiculatus roots. In this study, ultrasound-assisted extraction was performed in a 30 L ultrasonic cleaning bath operating at a frequency of 40 kHz. Based on single-factor experiments, Plackett-Burman design (PBD) and Box-Behnken design (BBD) were employed to optimize the extraction parameters. The optimal integrated process involves: ultrasound-assisted enzymatic pretreatment with 6% enzyme at pH 5 and 41℃ for 50 min; formulation of a SUPRAS containing 5% octanoic acid, 30% ethanol, and 60% aqueous phase at pH 4; and final ultrasonic extraction at 40℃ for 70 min with 640 W power and a liquid-solid ratio of 12 mL/g. The optimized UAESE method achieved a significantly higher extraction yield compared to other extracts. Then scanning electron microscopy (SEM) was employed to explore the extraction mechanism of UAESE. Subsequent enrichment of the UAESE crude extract with an AB-8 resin yielded a purified product containing 13.545 ± 0.542% pristimerin (PRI). Furthermore, the enriched extract showed significant activity against methicillin-resistant Staphylococcus aureus (MRSA), primarily attributed to celastrol (CEL)and PRI. In conclusion, the proposed method offers an innovative, efficient, and environmentally sustainable approach to extracting diverse triterpenoids from plant materials.