Enzyme pretreatment combined with ultrasonic-microwave-assisted surfactant for simultaneous extraction of essential oil and flavonoids from Baeckea frutescens

This work was designed to develop an integrated method of ultrasonic-microwave assisted extraction with enzyme pre-treatment and surfactant aqueous (ES-UME) for the simultaneous extraction of essential oil and flavonoids from Baeckea frutescens. The optimal parameters confirmed by single factor optimization combined with Box-Behnken Design were as follows: Cellulase and Hemicellulase concentration 10% (w/v), Triton X-114 concentration 2% (w/v), extraction time 1.5 h, ultrasonic power 478 W, microwave power 535 W, and liquid/solid ratio 16 mL/g. Under the optimal parameters, the extraction yields of essential oil and main five representative flavonoids epicatechin, rutin, isoquercitrin, myricetin, and quercetin reached 6.38, 0.53, 18.58, 10.72, 1.68, and 2.11 mg/g, respectively. Compositional analysis revealed α-Pinene (16.13%), Linalool (15.00%), 4-Carvomenthenol (10.98%), β-Caryophyllene (6.52%), and α-Terpineol (5.43%) were the most prominent components of essential oil. Furthermore, the essential oil exhibited broad-spectrum antimicrobial activity against 7 tested strains and excellent antioxidant activity through DPPH (2, 2-diphenyl-1-picrylhydrazyl), ABTS (2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), and antibacterial assays. Moreover, flavonoids extracts were preconcentrated by 9.70-fold compared with the original extracts using the cloud-point property of surfactants. Overall, the developed method was a potential and desirable alternative that can simultaneously extract volatile and non-volatile bioactive constituents from plant materials in food, healthy, and pharmaceutical industries.