Diketopiperazines produced by an Aspergillus fumigatus Brazilian strain

Seven diketopiperazines, corresponding to the cyclos (L)-Pro-(L)- Phe, (L)-Pro-Gly, (L)-Pro-( L)-Pro, (L)- Pro-(L)-Val, (L)-4-OH-Pro-(L)-Leu, (L)-4-OH-Pro-(L)- Phe, and (L)-Pro-(L)-Leu, were isolated from the Aspergillus fumigatus fermentation broth. The relative and absolute stereochemistries were determined on the basis of NOESY experiments and by using a modified version of Marfey's method using HPLC, respectively.166B1448145

Liquid and vapour-phase antifungal activities of selected essential oils against candida albicans: microscopic observations and chemical characterization of cymbopogon citratus

<p>Abstract</p> <p>Background</p> <p>Use of essential oils for controlling <it>Candida albicans </it>growth has gained significance due to the resistance acquired by pathogens towards a number of widely-used drugs. The aim of this study was to test the antifungal activity of selected essential oils against <it>Candida albicans </it>in liquid and vapour phase and to determine the chemical composition and mechanism of action of most potent essential oil.</p> <p>Methods</p> <p>Minimum Inhibitory concentration (MIC) of different essential oils in liquid phase, assayed through agar plate dilution, broth dilution & 96-well micro plate dilution method and vapour phase activity evaluated through disc volatilization method. Reduction of <it>C. albicans </it>cells with vapour exposure was estimated by kill time assay. Morphological alteration in treated/untreated <it>C. albicans </it>cells was observed by the Scanning electron microscopy (SEM)/Atomic force microscopy (AFM) and chemical analysis of the strongest antifungal agent/essential oil has been done by GC, GC-MS.</p> <p>Results</p> <p>Lemon grass (<it>Cymbopogon citratus</it>) essential oil exhibited the strongest antifungal effect followed by mentha (<it>Mentha piperita</it>) and eucalyptus (<it>Eucalyptus globulus</it>) essential oil. The MIC of lemon grass essential oil in liquid phase (288 mg/l) was significantly higher than that in the vapour phase (32.7 mg/l) and a 4 h exposure was sufficient to cause 100% loss in viability of <it>C. albicans </it>cells. SEM/AFM of <it>C. albicans </it>cells treated with lemon grass essential oil at MIC level in liquid and vapour phase showed prominent shrinkage and partial degradation, respectively, confirming higher efficacy of vapour phase. GC-MS analysis revealed that lemon grass essential oil was dominated by oxygenated monoterpenes (78.2%); α-citral or geranial (36.2%) and β-citral or neral (26.5%), monoterpene hydrocarbons (7.9%) and sesquiterpene hydrocarbons (3.8%).</p> <p>Conclusion</p> <p>Lemon grass essential oil is highly effective in vapour phase against <it>C. albicans</it>, leading to deleterious morphological changes in cellular structures and cell surface alterations.</p

Biosynthesis of Oleyl Oleate Wax Ester by Non-commercial Lipase

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Oleyl oleate can be considered a synthetic analogue of jojoba oil. This one has been the main natural source of wax esters for commercial applications since the global ban on whale hunting. Lipase catalyzed production of this ester was carried out using oleic acid and oleyl alcohol in a solvent-free system. Lipase from Rhizopus sp. CBMAI 1127 was used as the biocatalyst and commercial enzyme Lipozyme TL IM (R) was used to compare results. The acid/alcohol molar ratio showed significant effects for both lipases and the amount of enzyme had a significant effect just for Lipozyme TL IM (R). The rate of the esterification reaction using lipase from Rhizopus sp. CBMAI 1127 was very similar to that obtained with commercial lipase. The present study also evaluated antimicrobial and emulsifying properties of this ester. Emulsifying capacity of the synthesized oleyl oleate was lower than Tween 80 and sodium dodecyl sulfate, and no antimicrobial activity was observed.20512031209Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Production of xylanolytic enzymes by Penicillium janczewskii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The production of extracellular xylanase, beta-xylosidase and alpha-L-arabinofuranosidase by the mesophilic fungus Penicillium janczewskii under submerged cultivation was investigated with different carbon sources. Optimization steps included studies of carbon source concentration, temperature of cultivation and initial pH of culture medium. The production of these enzymes was increased two times when cultures were supplemented with brewer's spent grain at 2% concentration, pH 6.0 and carried out at 25 degrees C. Under these optimized conditions were obtained xylanase activity of 15.19 U mL(-1) and 23.54 U mg prot(-1), beta-xylosidase activity of 0.16 U mL(-1) and 0.25 U mg prot(-1) and alpha-L-arabinofuranosidase activity of 0.67 U mL(-1) and 1.04 U mg prot(-1). Brewer's spent grain is a promising substrate for P. janczewskii growth and xylanolytic enzyme production, since it is the main by-product from the brewing industry, available in large amounts and at low-cost in many countries. (C) 2010 Elsevier Ltd. All rights reserved.1011141394143Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES