In vitro antifungal effects of the essential oil of Mentha piperita L. and its comparison with synthetic menthol on Aspergillus niger

The antifungal activity of Mentha piperita L. essential oil and its comparison with synthetic menthol on Aspergillus niger growth have been determined in vitro. The chemical compositions of essential oil of M. piperita provided from the aerial parts of plants grown in a village in Kerman Province in June 2012 were determined. The sample was cleaned and then dried in the shade. Essential oil was made by hydro-distillation method andanalyzed by capillary gas chromatography (GC) using flame ionization (FID) and capillary gas chromatography coupled mass spectrometry (GC/MS). The main oil content from the plants of M. piperita was 3.26% (v/w). Twenty three (23) compounds were identified in the essential oil of M. piperita, making 96.25% of the total oil. The major components were menthol (38.33%), menthone (21.45%) and menthyl acetate (12.49%). For study of antifungal activity, the essential oil was tested against A. niger (strain PTCC = 5223) by disc diffusion method via average inhibition zone. The results showed that essential oil from M. piperita at 1 and 1/2 oil dilutions exhibited a strong antifungal activity than gentamycin (8 mg/ml) antibiotic on A. niger and exhibited a strong synthetic menthol at 10% dilution. The relative high amount of menthol and menthone in the M. piperitaessential oil showed that they could display antifungal activity.   Key words: Mentha piperita L., Aspergillus niger, menthol, antifungal activity.