Enzyme-assisted microwave hydro-distillation essential oil from Fructus forsythia, chemical constituents, and its antimicrobial and antioxidant activities

An efficient enzyme-assisted microwave hydro-distillation (EAMHD) essential oil from Fructus forsythiae was investigated in the present study. Under optimal process conditions, the maximum extraction yield of the essential oil reached 3.27%, which increased by 39.15% and 45.33% more than those of normal microwave hydro-distillation (MHD) and traditional hydro-distillation (HD), respectively. GC/MS analysis revealed the presence of 21 compounds in Fructus forsythiae essential oil. Higher amounts of oxygenated monoterpenes were existed in the essential oil of EAMHD (26.47%) in comparison with MHD (22.37%) and HD (16.79%). Meanwhile, the antimicrobial and antioxidant activities were also assessed in vitro, EAMHD extracted essential oil exhibited relatively good antimicrobial activity with the minimum inhibitory concentration (MIC) values for all the susceptible microorganisms ranging from 0.78 to 6.25 mg/ml, and showed considerable linoleic acid oxidation inhibition (63.56%) in the β-carotene–linoleic acid bleaching assay. Furthermore, samples scanning electron micrographs illustrated the severely structural disruption of EAMHD.