RESUMO
The aim of the current study was to investigate the entomopathogenic capacity of the mold Fusarium verticillioides and the effect of its mycotoxins fumonisins, on the grain beetle Sitophilus zeamais. We evaluated the capacity of this fungus to infect live insects, the antifungal activity of constituents of the insect's epicuticle, and the effect of a fumonisin extract on the fitness of the insects. We found that F. verticillioides could not penetrate the cuticle of S. zeamais and that the fumonisin extract had no negative effects on the fitness of the insects. However, the progeny of the insects increased, and the fumonisin extract had repellent effects. This is the first report about the effects of fumonisins on the relationship between F. verticillioides and S. zeamais, which may provide useful information about interactions between pathogenic microorganisms and insects, especially on stored product pests.
Assuntos
Antifúngicos/metabolismo , Fumonisinas/metabolismo , Fusarium/fisiologia , Extratos Vegetais/metabolismo , Gorgulhos/fisiologia , Animais , Antifúngicos/análise , Comportamento Animal/efeitos dos fármacos , Desenvolvimento de Medicamentos , Comportamento Alimentar/efeitos dos fármacos , Fumonisinas/análise , Insetos/efeitos dos fármacos , Extratos Vegetais/análise , Relação Estrutura-Atividade , Zea mays/microbiologiaRESUMO
AIMS: To evaluate the antifungal activity and to analyse the structure-activity relationship of eleven natural phenolic compounds against four Candida species which are resistant to fluconazole. METHODS AND RESULTS: Four different species of Candida isolates were used: Candida albicans, Candida krusei, Candida tropicalis and Candida dubliniensis. The phenolic compound carvacrol showed the highest anti-Candida bioactivity, followed by thymol and isoeugenol. The obtained minimum inhibitory concentration (MIC) values obtained were used in a quantitative structure-activity relationship (QSAR) analysis where the electronic, steric, thermodynamic and topological descriptors served as dependent variables. According to the descriptors obtained in this QSAR study, the antifungal activity of phenols has a first action specific character which is based on their interaction with plasma or mitochondrial membranes. The second action is based on a steric descriptor-the maximal and minimal projection of the area-which could explain the inability of some phenolic compounds to be biotransformed to quinones methylene by Candida species. CONCLUSIONS: According to the descriptors obtained in this QSAR study, the anti-Candida activity of ortho-substituted phenols is due to more than one action mechanism. The anti-Candida activity of phenolic compounds can be predicted by their molecular properties and structural characteristics. SIGNIFICANCE AND IMPACT OF THE STUDY: These results could be employed to predict the anti-Candida activity of new phenolic compounds in the search for new alternatives or complementary therapies to combat against candidiasis.
Assuntos
Antifúngicos/farmacologia , Candida/efeitos dos fármacos , Fluconazol/farmacologia , Fenóis/farmacologia , Antifúngicos/química , Candida/isolamento & purificação , Cimenos , Farmacorresistência Fúngica , Eugenol/análogos & derivados , Eugenol/farmacologia , Humanos , Monoterpenos/farmacologia , Fenóis/química , Relação Quantitativa Estrutura-Atividade , Timol/farmacologiaRESUMO
1. A study was conducted to evaluate whether feed supplementation with thymol or isoeugenol can alter Japanese quail growth rate and final body weight, the female onset of puberty, hen-day egg production and the physical and chemical characteristics of the egg, as well as its potential to alter hatchability. 2. From 4 to 16 weeks of age, birds from each cage (1 male: 3 females) were assigned to 1 of 3 treatments that differed in the supplement added to the feed: control, thymol or isoeugenol (400 mg/kg). The average ages (d) at first egg lay (FIRST), at 25% egg production (A25% EP), at 50% egg production (A50% EP) and weekly and cumulative hen-day egg production (HDEP) were calculated. In addition, physical and chemical characteristics of the eggs, their fertility and hatchability were also evaluated for each group. 3. Feed supplementation did not significantly affect growth rate, final body weight, egg production parameters, fertility and physical characteristics of egg or most of the fatty acid components of the yolk. 4. The group treated with isoeugenol showed an increase in the percentage of palmitoleic fatty acid compared to the control, with thymol group showing intermediates values. 5. Both thymol and isoeugenol supplemented groups showed increased hatchabilities, by 18.8% and 11.8%, respectively, compared to their control counterparts. 6. The improvement in the hatching success of the eggs from the thymol and isoeugenol supplemented groups without a negative impact on their performance may have important economic implications for future breeding programmes, particularly if these effects generalise from quail to other more commercially important poultry species, such as chickens or turkeys.
Assuntos
Ração Animal/análise , Coturnix/fisiologia , Eugenol/análogos & derivados , Timol/administração & dosagem , Animais , Peso Corporal , Coturnix/crescimento & desenvolvimento , Suplementos Nutricionais/análise , Eugenol/administração & dosagem , Ácidos Graxos/metabolismo , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Masculino , Oviparidade , Óvulo/fisiologia , Distribuição Aleatória , Fatores Sexuais , Maturidade SexualRESUMO
Some evidence suggests that fumonisin B(1) (FB(1)), a worldwide toxic contaminant of grains produced by Fusarium verticillioides, exhibits an oxidative stress mediated genotoxicity. We studied the DNA damage (by the alkaline comet and the micronucleus tests) and biomarkers of cellular oxidative stress (malondialdehyde, MDA; catalase, CAT; and superoxide dismutase, SOD) in spleen mononuclear cells of male Wistar rats subchronically (90 days) fed on a control experimental diet (CED) or poisoned with experimental diets contaminated with a culture material containing 100 ppm of FB(1) (FED), with 40 ppb of aflatoxin B(1) (a common toxic co-contaminant in cereals, AFB(1)ED), and with a mixture of both toxins (MED). The DNA damage was found in 13.7%, 81.7%, 98.0% and 99.3% (comet assay) and in 2.8%, 7.0%, 10.8% and 8.8% (micronucleus technique) in groups CED, FED, AFB(1)ED and MED, respectively. The MDA levels as well as the CAT and SOD activities were increased in all the poisoned animals. A similar behavior was observed in cells exposed in vitro to the toxins. These data support the hypothesis of an oxidative stress mediated genotoxicity induced by FB(1). Furthermore, the extent of DNA damage assessed by the comet assay suggests a possible protective effect of the fumonisins-AFB(1) mixtures in vitro against the genotoxicity induced individually by the toxins.
Assuntos
Aflatoxina B1/toxicidade , Biomarcadores/metabolismo , Fumonisinas/toxicidade , Mutagênicos/toxicidade , Micotoxinas/toxicidade , Estresse Oxidativo , Animais , Catalase/metabolismo , Malondialdeído/metabolismo , Testes de Mutagenicidade , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismoRESUMO
The minimum inhibitory concentration (MIC) of cyclic terpenes (limonene, menthol, menthone and thymol) against Fusarium verticillioides MRC 826 was assessed by using the semisolid agar antifungal susceptibility (SAAS) technique. Limonene, menthol, menthone and thymol were evaluated at final concentrations of 25, 50, 75, 150, 200, 250, 500 and 1000 microL/L of culture medium. Limonene and thymol showed the highest inhibitory effects on F. verticillioides development. Thus, the effects of monoterpenes on fumonisin B1 (FB1) biosynthesis were evaluated by using corn grain (Zea mays) as substrate. The monoterpenes were inserted on maize 1 day before inoculation with a conidial suspension of F. verticillioides to give final concentrations of 75 ppm. At this concentration, thymol was the most active inhibitor on FB1 biosynthesis.