Chemical composition and antimicrobial activity of bergamot-mint (Mentha citrata Ehrh.) essential oils isolated from the herbage and aqueous distillate using different methods

In this study, chemical composition and antibacterial activity of the primary essential oil (PEO) and secondary essential oil (SEO) derived from steam distillation (SD) and hydro distillation (HD) of Mentha citrata Ehrh. were investigated using gas chromatography-flame ionization detector (GC-FID), GC⿿mass spectrometry (GC⿿MS), disc diffusion assay and micro dilution broth assay. The oils isolated from herb and aqueous distillate using different methods showed substantial variations in their composition and antibacterial activity profile. Major constituents of the oils were linalool (33.9⿿77.1%), linalyl acetate (2.2⿿45.4%), α-terpineol (2.3⿿24.9%), β-caryophyllene (0.0⿿3.2%) and nerol (0.5⿿3.1%). The SEOs showed activity against all eight tested bacterial strains (MIC: 250⿿1000 μg/mL), while PEOs were active against seven strains (MIC: 250⿿ >1000 μg/mL).