Composição e atividade antifúngica do óleo essencial de hortelã-pimenta (Mentha piperita L.) / Composition and antifungal activity of pepper mint (Mentha piperita L.) essential oil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Pepper mint (Mentha piperita L.) essential oil (EO), obtained by hydro distillation of dry leaves, was evaluated in vitro through a poison food assay (0.1; 0.2 and 0.3%) presented antifungal activity against Aspergillus flavus, A. ochraceous, A. niger, A. glaucus, Fusarium oxysporum, F. semitectum, Colletotrichum musae and C. gloeosporioides. The EO was fractioned by preparative silica gel thin layer chromatography (TLC), using hexane dichloromethane (2:1, v/v) as solvent, presenting 7 fractions (five being visible under ultraviolet light and two when revealed with vanillin-sulfuric acid). Its antifungal fraction (AF) was identified by TLC bioautography. AF activity, with Rf value of 0.47 and band width (Wb) of 8.0 cm, was fractioned into active three sub-fractions, evaluated through poison food assay at 0.1% and 0.2%. The components of the crude OE and of the active sub-fractions were identified by gas chromatography using the Kováts index (KI), along with gas chromatography-mass spectrometry (GC-MS), with a total of 57 compounds being identified. Active sub-fraction 1, whose main compound was menthol, was found to be more efficient for most of the fungi evaluated, followed by active subfraction 3, whose main compound was carvone. In view of the antifungal activity obtained by the EO in vitro, its antifungal potential, in vivo was evaluated in corn-based swine ration. Rations were treated with essential oil at 0.2% under three humidity conditions (13, 15 and 18%) and stored for 30, 60 and 90 days. The level of fungal contamination was evaluated through ergosterol quantified by GC-MS and selective ion monitoring (SIM). The concentrations of ergosterol in the samples quantified ranged from 0.01 to 11.44 μg/g of ration. The best fungal control (95.8%, at 13% humidity) was obtained in the first month of storage followed by 91.0%, at 15% humidity in the second month. EO stability was assessed through gas chromatography, stored at 4C and 25C, by comparing the ratios of the peak areas of its main components (1.8-cineole, menthone, neomenthol, menthol, carvone, menthyl acetate, trans-caryophyllene, and viridiflorol) and internal standard (nonane). At room temperature, trans-caryophyllene showed the highest variation between its initial amount and after storage. Menthone and 1,8-cineole degraded the most when stored at 4oC. As expected, the main components of the essential oil, as a whole, were more stable at lower temperatures (4oC).

ASSUNTO(S)

quimica organica essências e óleos essenciais hortelã-pimenta composição composition mentha piperita essential oil chromatographic analysis mentha piperita fungicides análise cromatográfica pepper mint fungicidas

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