Mirna Helena Regali Seleghim

A multi-screening approach for marine-derived fungal metabolites and the isolation of cyclodepsipeptides from Beauveria felina

Extracts obtained from 57 marine-derived fungal strains were analyzed by HPLC-PDA, TLC and 1H NMR. The analyses showed that the growth conditions affected the chemical profile of crude extracts. Furthermore, the majority of fungal strains which produced either bioactive of chemically distinctive crude extracts have been isolated from sediments or marine algae. The chemical investigation of the antimycobacterial and cytotoxic crude extract obtained from two strains of the fungus Beauveria felina have yielded cyclodepsipeptides related to destruxins. The present approach constitutes a valuable tool for the selection of fungal strains that produce chemically interesting or biologically active secondary metabolites.

Biodegradation of methyl parathion by whole cells of marine-derived fungi Aspergillus sydowii and Penicillium decaturense.

Seven marine fungi strains (Aspergillus sydowii CBMAI 934, A. sydowii CBMAI 935, A. sydowii CBMAI 1241, Penicillium decaturense CBMAI 1234, Penicillium raistrickii CBMAI 931, P. raistrickii CBMAI 1235, and Trichoderma sp. CBMAI 932) were screened by their growth in the presence of methyl parathion (MP) in a solid culture medium. The strains with best growth were A. sydowii CBMAI 935 and P. decaturense CBMAI 1234. Biodegradation reactions were performed in 10, 20 and 30d in a malt extract liquid medium containing commercial MP and whole cells of A. sydowii CBMAI 935 and P. decaturense CBMAI 1234. In 20d, A. sydowii CBMAI 935 was able to degrade all pesticide, whereas P. decaturense CBMAI 1234 promoted a complete degradation in 30d. A. sydowii CBMAI 935 and P. decaturense CBMAI 1234 could degrade the product of the MP enzymatic hydrolysis, p-nitrophenol, on average of 51 and 40% respectively. Both strains used MP as a sole source of carbon and provided satisfactory results. Metabolites detected in the medium showed that the presumable reaction pathway occurred through the activation of MP to its more toxic form, methyl paraoxon, which was further degraded to p-nitrophenol.

Evaluating methods for the isolation of marine-derived fungal strains and production of bioactive secondary metabolites

In the present investigation we evaluate methods for the isolation and growth of marine-derived fungal strains in artificial media for the production of secondary metabolites. Inoculation of marine macroorganisms fragments in Petri dishes proved to be the most convenient procedure for the isolation of the largest number of strains. Among the growth media used, 3% malt extract showed the best result for strains isolation and growth, and yielded the largest number of strains from marine macroorganisms. The percentage of strains isolated using each of the growth media which yielded cytotoxic and/or antibiotic extracts was in the range of 23-35%, regardless of the growth media used. Further investigation of extracts obtained from different marine-derived fungal strains yielded several bioactive secondary metabolites, among which (E)-4-methoxy-5-(3-methoxybut-1-enyl)-6-methyl-2H-pyran-2-one is a new metabolite isolated from the Penicillium paxilli strain Ma(G)K.

Marine Fungi Aspergillus sydowii and Trichoderma sp. Catalyze the Hydrolysis of Benzyl Glycidyl Ether

Whole cells of the marine fungi Aspergillus sydowii Gc12, Penicillium raistrickii Ce16, P. miczynskii Gc5, and Trichoderma sp. Gc1, isolated from marine sponges of the South Atlantic Ocean (Brazil), have been screened for the enzymatic resolution of (±)-2-(benzyloxymethyl)oxirane (benzyl glycidyl ether; 1). Whole cells of A. sydowii Gc12 catalyzed the enzymatic hydrolysis of (R,S)-1 to yield (R)-1 with an enantiomeric excess (ee) of 24–46% and 3-(benzyloxy)propane-1,2-diol (2) with ee values <10%. In contrast, whole cells of Trichoderma sp. Gc1 afforded (S)-1 with ee values up to 60% and yields up to 39%, together with (R)-2 in 25% yield and an ee of 32%. This is the first published example of the hydrolysis of 1 by whole cells of marine fungi isolated from the South Atlantic Ocean. The hydrolases from the two studied fungi exhibited complementary regioselectivity in opening the epoxide ring of racemic 1, with those of A. sydowii Gc12 showing an (S) preference and those of Trichoderma sp. Gc1 presenting an (R) preference for the substrate.

Acute and chronic toxicity of diuron and carbofuran to the neotropical cladoceran Ceriodaphnia silvestrii

In order to contribute to the increase of the body of knowledge on the sensitivity of tropical indigenous species to pesticides, acute and chronic toxicity tests were conducted with the neotropical cladoceran Ceriodaphnia silvestrii. Tests were carried out with the active ingredients diuron and carbofuran and one of their commercial formulations, the Diuron Nortox® 500 SC and the Furadan® 350 SC, respectively. For carbofuran, the active ingredient was more toxic than the commercial product, whereas for diuron, the commercial product appeared more toxic. In addition, hormetic effects on fertility were recorded for intermediate diuron concentrations. Acute and chronic toxicity data indicated that C. silvestrii was among the most sensitive invertebrate species for both test compounds. Based on concentrations measured in Brazilian water bodies, these compounds represent ecological risks for causing direct and indirect toxic effects on C. silvestrii and other aquatic organisms. Our results support previous claims on the advantages of using native species to better tune ecological risk assessment of chemicals in tropical ecosystems.

Bioconversion of Iodoacetophenones by Marine Fungi

Nine marine fungi (Aspergillus sclerotiorum CBMAI 849, Aspergillus sydowii Ce19, Beauveria felina CBMAI 738, Mucor racemosus CBMAI 847, Penicillium citrinum CBMAI 1186, Penicillium miczynskii Ce16, P. miczynskii Gc5, Penicillium oxalicum CBMAI 1185, and Trichoderma sp. Gc1) catalyzed the asymmetric bioconversion of iodoacetophenones 1–3 to corresponding iodophenylethanols 6–8. All the marine fungi produced exclusively (S)-ortho-iodophenylethanol 6 and (S)-meta-iodophenylethanol 7 in accordance to the Prelog rule. B. felina CBMAI 738, P. miczynskii Gc5, P. oxalicum CBMAI 1185, and Trichoderma sp. Gc1 produced (R)-para-iodophenylethanol 8 as product anti-Prelog. The bioconversion of para-iodoacetophenone 3 with whole cells of P. oxalicum CBMAI 1185 showed competitive reduction–oxidation reactions.

Biodegradation of the Organophosphate Pesticide Profenofos by Marine Fungi

Pesticides play an important role in modern agriculture. Synthetic pesticides are recognized as a cost-effective method of controlling pests, improving productivity and food quality. However, while pesticides may have a beneficial effect on agricultural productivity, their indiscriminate use causes many serious problems to the environment and human health, since these compounds are toxic to non-target species (Diez, 2010; Coutinho et al., 2005).

A Method for Dextruxin Analysis by HPLC-PDA-ELSD-MS

Destruxinas (Dtx) sao ciclodepsipetideos produzidos por fungos entomopatogenicos, que sao utilizados como controle biologico em insetos pragas em diferentes agriculturas. A presente investigacao reporta uma nova abordagem para analises de destruxinas produzidas por uma linhagem do fungo Beauveria felina, utilizando-se de LC-PDA-ELSD-MS. Em comparacao com os metodos anteriores, a nova abordagem utiliza-se de uma limpeza previa da amostra em cartuchos C 18 que removem efetivamente os constituintes do meio de cultura. Alem disso, o uso dos solventes MeCN/MeOH 50:50, (v/v) como eluentes mais fortes no sistema de gradiente em 0,1% de H 2 O demonstrou fornecer a melhor resolucao dos picos cromatograficos. Deteccoes simultâneas usando arranjo de fotodiodos (PDA), detector de espalhamento de luz evaporativa (ELSD) e espectrometria de massas (MS) indicaram praticamente uma resposta identica de todos os detectores na analise das destruxinas. Cinco amostras obtidas da cultura de B. felina foram analisadas, e indicaram a presenca de 20 destruxinas conhecidas e de 6 ciclodepsipetideos ainda nao reportados. Considerando a reducao do uso do MeCN, e a eficacia do ELSD como detector para destruxina, o metodo prova que pode ser de grande valia e de baixo custo operacional para controle de qualidade nas analises de destruxinas produzidas por linhagens de fungos. Destruxins (Dtx) are cyclodepsipeptides produced by enthomopathogenic fungi, which are used in biological control of different agricultural insect plagues. The present investigation reports a new approach for analysis of destruxins produced by the fungal strain Beauveria felina, using LC-PDA-ELSD-MS. Compared to previous methods, the new approach uses a clean-up on C 18 cartridges, which effectively removes growth media constituents. Moreover, the use of 50:50 (v/v) MeCN/MeOH as the strongest eluting solvent in a gradient system over 0.1% H 2 O proved to give a better resolution of chromatographic peaks. Simultaneous detection using photodiode array (PDA), evaporative light scattering detector (ELSD) and mass spectrometry (MS) indicated a practically identical response of all detectors for destruxins analysis. Five samples obtained from the culture media of B. felina were analysed, and indicated the presence of twenty known destruxins and six yet unreported cyclodepsipeptides. Considering the reduced use of MeCN, and the effectiveness of ELSD as a detector for destruxins, the method proved to be valuable and cost-effective for quality control analysis of destruxin-producing fungal strains.

Growth Assessment of Marine-Derived Fungi in the Presence ofEsfenvalerate and its Main Metabolites

The growth and biodegradation potential of marine-derived fungi were evaluated by measuring the radial growth of colonies. It was observed that Penicillium raistrickii CBMAI 931, Aspergillus sydowii CBMAI 935, Cladosporium sp. CBMAI 1237, Microsphaeropsis sp. Dr(A)6, Acremonium sp. Dr(F)1, Westerdykella sp. Dr(M2)4 and Cladosporium sp. Dr(M2)2 were able to grow and develop in the presence of the pyrethroid insecticide esfenvalerate (S,Sfenvalerate) and its main metabolites (3-phenoxybenzaldehyde, 3-phenoxybenzoic acid, 3-phenoxybenzyl alcohol and 2-(4-chlorophenyl)-3-methylbutyric acid), showing the possibility of esfenvalerate biodegradation by these strains. The presence of technical grade esfenvalerate and its metabolites caused growth inhibition, while fungal development was not affected by the presence of the commercial insecticide SUMIDAN 150 SC in the culture medium. This fact might show that the biodegradation of the esfenvalerate in the commercial insecticide is slower than that of the technical grade active ingredient, since slower biodegradation of esfenvalerate would reduce the concentration of phenolic compounds and thus the growth inhibition. Future studies will focus on the quantitative biodegradation analysis of technical grade esfenvalerate and active ingredient in the commercial insecticide.

Dynamics of fipronil in Óleo Lagoon in Jataí Ecological Station, São Paulo-Brazil

Fipronil is a phenylpyrazole pesticide widely used to protect sugar-cane crops from insect pests. After reaching the environment, this insecticide may have several fates. This research aimed to propose a kinetic model to describe the fate of commercial fipronil Regent 800WG in the sediment-water interface of the Oleo Lagoon in the Mogi-Guaçu river floodplain, situated within the Jataí Ecological Station, by means of a microcosm scale experiment. Results showed that a small fraction of the pesticide is quickly dragged to the sediment while most of it remains in the water column. Biodegradation proves to be an important fipronil degradation route, especially when microorganisms capable of using fipronil as sole carbon source increase their population, as a function of exposure time. Biodegradation rates were higher in the sediment than in the water column.