Composição e atividade antifúngica de extratos de Chenopodium ambrosioides L.

• Autor(a) principal: Jardim, Carolina Marangon
• Data de Publicação: 2006
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2059
• topic: Essências e óleos essenciais; Erva-de-santa-maria; Composição; Fungicidas; Análise cromatográfica; Chenopodium ambrosioides; Essential oil; Composition; Fungicides; Chromatographic analysis; Chenopodium ambrosioides; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA

Essential oil obtained by hydrodistillation (yield 0.3%), and hexanic extract, obtained by maceration (yield 1.1%), of the aerial parts of Chenopodium ambrosioides L., evaluated by the poison food methodology (0.3; 0.1; 0.05 and 0.3; 0.2; 0.1%; respectively), presented antifungal activity against the phytopathogens Aspergillus flavus, A. glaucus, A. niger, A. ochraceous, Colletotrichum gloesporioides, C. musae, Fusarium oxysporum and F. semitectum. Excellent antifungal activity, ranging from 70 to 100%, was observed up to a concentration of 0.2 and 0.1%, for the hexanic extract and essential oil, respectively, depending on the fungus evaluated. Using gas chromatography with flame ionization (GC/FID) and gas chromatography coupled to mass spectrometry (GC/MS), combined to calculation of the Kováts index of retention (KI), the hexanic extract and essential oil compositions were established. In the essential oil, 13 compounds were identified, corresponding to 90.22% of its constitution, the major ones being: (Z)-ascaridole (61.43%), (E)-ascaridole (18.62%), carvacrol (3.87%), p-cymene (2.05%) and [alfa]-terpinene (0.85%). The hexanic extract compounds are: [alfa]-terpinene (11.24%), p-cymene (6.05%), benzyl alcohol (0.38%), (Z)-ascaridole (53.98%), carvacrol (2.27%), (E)-ascaridole (17.25%) corresponding to 91.17% of its constitution. Following fractioning by thin layer chromatography (TLC) (elution with dichloromethane: ethyl acetate, 9:1 v/v), a bioassay using TLC Bioautography technique revealed the antifungal fraction of the hexanic extract and essential oil. One single active fraction was obtained for both the samples, presenting retention coefficient (Rf) equivalent to 0.89 and longitudinal width (Wb) of 5.0 cm, with the compounds being identified by analysis in GC/FID, GC/MS and KI calculation. The active fraction of the hexanic extract is composed of (Z)-ascaridole (53.98%), (E)-ascaridole (17.25%), [alfa]-terpinene (11.24%) and p-cymene (6.05%) and that of the essential oil is constituted by p-cymene (25.40%), (Z)-ascaridole (44.35%)and (E)-ascaridole (30.25%). Analysis by GC/FID of hexanic extract and essential oil stability after 90-day storage at 4 and 25 oC, showed decomposition of the compounds [alfa]-terpinene, p-cymene, (Z)-ascaridole and (E)-ascaridole in the samples. Decompositions were greater for the samples stored at 25 oC. Quantification of ergosterol, main sterol constituent of the fungic cellular membrane, by GC/MS, utilizing SIM mode (Selective Ion Monitoring), in stored swine ration treated with hexanic extract (0.2%) and essential oil (0.1%) pointed to activity of the species C. ambrosioides in fungal growth control. The results obtained indicate the antifungal potential of the essential oil and hexanic extract of C. ambrosioides, with emphasis on the compounds ascaridole (Z and E), [alfa]-terpinene and p-cymene, which, after further systematic studies, are commercially viable as storage fungi control agents.