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

⿢Essential oil of bergamot-mint was isolated using steam- and hydro distillation methods.⿢Primary essential oils and aqueous distillate volatiles (hydrophilic fractions) were isolated.⿢Comparative chemical compositions and antibacterial activity were assessed.⿢Chemical composition (linalool: 33.9⿿77.1%; linalyl acetate: 2.2⿿45.4%) varied substantially.⿢Antibacterial activity profile (ZOI: 0.0⿿27 mm; MIC: 125⿿>1000 μg/mL) varied substantially.

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).

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