Antimicrobial activity and composition of essential oils of Mentha spicata cultivated under organic farming conditions in Turkey

Mentha spicata L. is cultivated and commonly used in Turkey [1]. The present study is focused on determination of the essential oil composition and antimicrobial activity of essential oils Mentha spicata which are cultivated in the experimental farm of Selcuk University under organic farming conditions. The aim of the study was to cultivate Mentha spicata under organic farming conditions and to conclude the results for traditional use. The antimicrobial activity of the essential oils from the upper parts of the plants was done by a semi-quantitative disc-diffusion method. The minimum inhibitory concentrations (MIC) were determined based on a micro-well dilution method against the strains of E. coli, S. enteritidis, S.cholerasuis, P. aeruginosa, S. aureus, B. cereus, S .lutea, C. albicans. Analysis of essential oils of Mentha spicata was found rich in carvone (52.35%), eucalyptol (9.25%), limonene (8.74%) and dihydrocarveol (4.76%). The antimicrobial activity results and examined micro-organisms are showed in Table 1.

Table 1. Antimicrobial activity of M. spicata essential oils against the bacteria and fungi strains tested

M. spicata	mm	14	11	17	19	22	23	16	22
	MIC mg/ml	31.25	31.25	31.25	62.50	31.25	62.50	62.50	62.50
C*	mm	29	22	23	24	28	25	29	24
	MIC mg/ml	62.50	15.62	62.50	62.50	15.62	15.62	62.50	31.25

*C: Control; In disc diffusion assays, Gentamicin (µg/disc, Oxoid) and Nystatin (100 IU/disc, Oxoid) were used as positive control for anti-bacteria and anti-fungal actitivities, respectively. In MIC experiments, controls were as follows: Ciproflaxacin for bacteria; Amphotericin B for C. albicans.

References:1. Baytop, T (1999). Türkiye'de Bitkiler ile Tedavi, Geçmişte ve Bugün, 302–305.