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.