RESUMEN
The present study describes the antimicrobial activity of five pimarane-type diterpenes obtained by fungal biotransformation against several nosocomial multidrug-resistant bacteria. Among the investigated metabolites, ent-8(14),15-pimaradien-3ß-ol was the most active compound, with very promising minimal inhibitory concentration values (between 8.0 and 25.0 µg mL(-1)). Time-kill assays using this metabolite against Staphylococcus aureus (HCRP180) revealed that this compound exerted its bactericidal effect within 24 h at all the evaluated concentrations (8.0, 16.0, and 24.0 µg mL(-1)). When this metabolite was associated with vancomycin at their minimal bactericidal concentration values, the resulting combination was able to drastically reduce the number of viable strains of S. aureus within the first 6 h, compared with these chemicals alone. The checkerboard assays conducted against this microorganism did not evidence any synergistic effects when this same combination was employed. In conclusion, our results point out that ent-8(14),15-pimaradien-3ß-ol is an important metabolite in the search for new effective antimicrobial agents.
Asunto(s)
Abietanos/farmacología , Antibacterianos/farmacología , Staphylococcus aureus/efectos de los fármacos , Abietanos/química , Abietanos/aislamiento & purificación , Antibacterianos/química , Antibacterianos/aislamiento & purificación , Aspergillus ochraceus/metabolismo , Asteraceae/química , Biotransformación , Farmacorresistencia Bacteriana Múltiple , Pruebas de Sensibilidad Microbiana , Raíces de Plantas/química , Vancomicina/farmacologíaRESUMEN
The schistosomicidal effects of pimaradienoic acid (PA) and two derivatives, obtained by fungal transformation in the presence of Aspergillus ochraceus, were investigated. PA was the only compound with antischistosomal activity among the three diterpenes studied, with the ability to significantly reduce the viability of the parasites at concentrations ranging from 25 to 100 µM. PA also promoted morphological alterations of the tegument of Schistosoma mansoni, separated all the worm couples, and affected the production and development of eggs. Moreover, this compound was devoid of toxicity toward human fibroblasts. In a preliminary in vivo experiment, PA at a dose of 100 mg/kg significantly diminished the number of parasites in infected Balb/c mice. Taken together, these results show that PA may be potentially employed in the discovery of novel schistosomicidal agents, and that diterpenes are an important class of natural compounds for the investigation of agents capable of fighting the parasite responsible for human schistosomiasis.
Asunto(s)
Aspergillus ochraceus/metabolismo , Diterpenos/metabolismo , Diterpenos/uso terapéutico , Schistosoma mansoni/efectos de los fármacos , Esquistosomiasis mansoni/tratamiento farmacológico , Esquistosomicidas/metabolismo , Esquistosomicidas/uso terapéutico , Animales , Asteraceae/química , Biotransformación , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Diterpenos/química , Diterpenos/farmacología , Fibroblastos/efectos de los fármacos , Humanos , Ratones , Ratones Endogámicos BALB C , Extractos Vegetales/química , Extractos Vegetales/metabolismo , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Schistosoma mansoni/crecimiento & desarrollo , Esquistosomiasis mansoni/parasitología , Esquistosomicidas/química , Esquistosomicidas/farmacologíaRESUMEN
Aspergillus westerdijkiae is a new species of fungus that was recently dismembered from Aspergillus ochraceus taxon. Most isolates of A. westerdijkiae are able to produce large amounts of a mycotoxin called ochratoxin A (OA). OA has been found in food and beverages, such as coffee. A. westerdijkiae is very similar to A. ochraceus, and several isolates previously identified as A. ochraceus are now identified as A. westerdijkiae. By using sequences of the beta-tubulin gene, we analyzed several isolates from Brazilian coffee bean samples, previously identified as A. ochraceus, to compare with those of A. westerdijkiae. In fact, most (84%) were identified as A. westerdijkiae. Since this species consistently produces large amounts of OA, we developed a specific primer-pair for detecting and quantifying it in coffee beans by using real-time PCR. The primers Bt2Aw-F 5'TGATACCTTGGCGCTTGTGACG and Bt2Aw-R 5'CGGAAGCCTAAAAAATGAAGAG provided an amplicon of 347 bp in all A. westerdijkiae isolates, and no cross-reaction was observed using DNA from A. ochraceus. The sensitivity of real-time PCR was more than 100 times higher than the cfu technique.
Asunto(s)
Aspergillus ochraceus/aislamiento & purificación , Aspergillus/aislamiento & purificación , Coffea/microbiología , ADN de Hongos/química , Genes Fúngicos , Tubulina (Proteína)/genética , Aspergillus/genética , Aspergillus/metabolismo , Aspergillus ochraceus/genética , Aspergillus ochraceus/metabolismo , Secuencia de Bases , Recuento de Colonia Microbiana , Reacciones Cruzadas , ADN de Hongos/genética , Contaminación de Alimentos/análisis , Amplificación de Genes , Datos de Secuencia Molecular , Ocratoxinas/biosíntesis , Reacción en Cadena de la Polimerasa/métodos , Semillas/microbiología , Sensibilidad y Especificidad , Alineación de Secuencia , Especificidad de la EspecieRESUMEN
The growth and the extracellular amylase production by Aspergillus ochraceus were studied in a stationary culture medium. Maximum growth rate of this fungus was found after 5 days of incubation at 30 degrees C, but maximum amylase production was obtained after 2 days. The highest amylase production were attained with lactose, maltose, xylose and starch as carbon sources. The extracellular amylase production and mycelial growth were influenced by the concentration of starch. Other carbohydrates supported growth but did not induce amylase synthesis and glucose repressed it, indicating catabolite repression in this microorganism. The presence of both mechanisms of induction and repression suggests that at least these multiple forms of regulation are present in A. ochraceus. Of the nitrogen sources tested, casaminoacids, ammonium nitrate and sodium nitrate stimulated the highest yield of amylase. Optimal amylase production was obtained at pH 5.0, but enzyme activity was found only in the 4.0-6.0 pH range. These results were probably due to the inhibitory effect of NH4(+)-N in the culture medium.
Asunto(s)
Amilasas/biosíntesis , Aspergillus ochraceus/metabolismo , Proteínas Fúngicas/biosíntesis , Aspergillus ochraceus/crecimiento & desarrollo , Metabolismo de los Hidratos de Carbono , Carbohidratos/farmacología , Carbono/metabolismo , Caseínas/farmacología , Medios de Cultivo/farmacología , Inducción Enzimática/efectos de los fármacos , Glucosa/farmacología , Nitratos/farmacología , Nitritos/farmacología , Nitrógeno/metabolismo , Almidón/metabolismo , Almidón/farmacología , TemperaturaRESUMEN
Inhibitory effects of essential oils of oregano (Origanum vulgare), mint (Menta arvensis), basil (Ocimum basilicum), sage (Salvia officinalis) and coriander (Coriandrum sativum), on the mycelial growth and ochratoxin A production by Aspergillus ochraceus NRRL 3174 were studied. Cultures were incubated on yeast extract-sucrose (YES) broth, at concentrations of 0, 500, 750 and 1000 p.p.m. of essential oils during 7, 14 and 21 d at 25 degrees C. At 1000 p.p.m., oregano and mint completely inhibited the fungal growth and ochratoxin A production up to 21 d, while basil was only effective up to 7 d. At 750 p.p.m., oregano was completely effective up to 14 d, whereas mint allowed fungal growth but no ocratoxin A production up to 14 d. At 500 p.p.m., no evident inhibition could be in observed with any of the essential oils under analysis. Sage and coriander showed no important effect at any of the concentrations studied. These inhibitory effects are interesting in connection with the prevention of mycotoxin contamination in many foods and they could be used instead of synthetic antifungal products.
Asunto(s)
Aspergillus ochraceus/efectos de los fármacos , Micotoxinas/biosíntesis , Ocratoxinas/biosíntesis , Aceites Volátiles/farmacología , Especias , Aspergillus ochraceus/crecimiento & desarrollo , Aspergillus ochraceus/metabolismo , Contaminación de Alimentos/prevención & control , Microbiología de AlimentosRESUMEN
A produçäo de ocratoxina A foi estudada usando-se sementes selecionadas como substrato nutritivo estéril para Aspergillus ochraceus. A produçäo foi maior no girassol do que nas demais sementes examinadas. Dentre os três cultívares de sorgo testados, dois foram altamente resistentes ao ataque do fungo