Comparative study of chemistry compositions and antimicrobial potentials of essential oils and oleoresins from dried and fresh Mentha longifolia L.

Objective:To investigate the chemical compositions and antimicrobial potentials of the essential oils and oleoresins obtained from fresh and dried Mentha longifolia L.Methods:Gas chromatography and gas chromatography-mass spectrometer techniques were used to determine the profiling of the essential oils and oleoresins.In order to determine the antimicrobial efficacy of the volatile oil and oleoresins,the pathogenic fungus Aspergillus niger(1884),Aspergillus flavus(2479),Fusarium monoliforme(1893),Fusarium graminearum(2088)and Penicillium viridicatum(2007)were undertaken whereas four pathogenic bacteria Bacillus subtilis(1790),Staphylococcus aureus(3103)(Gram-positive),Escherichia coli(1672),Pseudomonas aeruginosa(1942)(Gram-negative)were selected for the present study.Food poisoned,inverted Petri plate,agar well diffusion and disk diffusion methods were employed for investigating antimicrobial potentials.Results:Piperitenone oxide,an oxygenated monoterpene,dominated the chemical compositions of essential oils and oleoresins whose compositions varied from 23.5%-87.8%.Both essential oils showed good antifungal activities against Aspergillus and Fusarium species.The antibacterial investigations revealed that Gram-positive bacteria were more sensitive to the essential oils.Conclusions:Drying the fresh herbal materials influences the chemical contents and the biological activities of the essential oils and oleoresins.Such results indicate that essential oils of Mentha longifolia L.can be possible candidates for further investigations to isolate and characterize their active principles as possible new natural preservatives.