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61.
The cytochalasin class of fungal metabolites was analyzed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) with the aim of developing a methodology for their rapid identification in microbial extracts. ESI-MS analyses of reference cytochalasins were performed and several product ions were produced in MS/MS experiments on parent ions that are structurally characteristic. A precursor ion search was performed to detect cytochalasins in an ethyl acetate extract of fungal strain RK97-F21. Three cytochalasins were detected and one of the components was identified as epoxycytochalasin H by comparing the tandem mass spectra of the product ions with those of reference compounds. This finding was further validated by LC/MS and LC/MS/MS experiments. 相似文献
62.
A series of 5-(arylthio)-2,4-diaminoquinazolines are known as selective inhibitors of dihydrofolate reductase (DHFR) from Candida albicans. We have performed docking and molecular dynamics simulations of these inhibitors with C. albicans and human DHFR to understand the basis for selectivity of these agents. Study was performed on a selected set of 10 compounds with variation in structure and activity. Molecular dynamics simulations were performed at 300 K for 45 ps with equilibration for 10 ps. Trajectory data was analyzed on the basis of hydrogen bond interactions, energy of binding and conformational energy difference. The results indicate that hydrogen bonds formed between the compound and the active site residues are responsible for inhibition and higher potency. The selectivity index, i.e the ratio of I50 against human DHFR to I50 against fungal DHFR, is mainly determined by the conformation adapted by the compounds within the active site of two enzymes. Since the human DHFR active site is rigid, the compound is trapped in a higher energy conformation. This energy difference between the two conformations E mainly governs the selectivity against fungal DHFR. The information generated from this analysis of potency and selectivity should be useful for further work in the area of antifungal research. 相似文献
63.
Total Synthesis of Cryptocaryol A by Enantioselective Iridium‐Catalyzed Alcohol C−H Allylation
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Dr. Felix Perez Andrew R. Waldeck Prof. Michael J. Krische 《Angewandte Chemie (International ed. in English)》2016,55(16):5049-5052
The polyketide natural product cryptocaryol A is prepared in 8 steps via iridium catalyzed enantioselective diol double C?H allylation, which directly generates an acetate‐based triketide stereodiad. In 4 previously reported total syntheses, 17–28 steps were required. 相似文献
64.
The growth and the enzymatic production of two microbial fungal associations were studied: Aspergillus niger and Fusarium moniliforme and Trametes versicolor and Aspergillus niger. The synergistic interrelations between the species of the first mixed culture increased the biosynthesis of α-amylase and
pectinase. T. versicolor and A. niger proved to be compatible partners in the overproduction of the enzyme laccase, whose synthesis surpassed 8.4 times the enzymatic
level in the monoculture, with both of the mixed microbial populations cocultivation facilitating the amplified synthesis
of enzymes rather than their growth acceleration. A further proof of the presence of synergism established by the cultures
was the enzyme volumetric productivities in both of the mixed microbial cultures, which increased parallel to the rise in
the combined biomass synthesis. The competent selection of compatible partners can adjust the desired enzymatic levels and
compositions in mixed fungal systems aimed at a number of specified designations. Thus, a very high level of laccase production
(97,600 IU/g dry weight) was achieved. The chosen fungal strains produce a variety of different enzymes, but first microbial
association produces mainly amylase and pectinase, necessary for their growth, and second association produces mainly laccase
and pectinase. 相似文献
65.
A new diketopiperazine dimer designated as SF5280-415 (1) was isolated from an EtOAc extract of the marine-derived fungus Aspergillus sp. SF-5280 by various chromatographic methods. The structure of 1 was mainly determined by analysis of the NMR spectroscopic data and MS data, along with Marfey’s method. This compound is a new diastereoisomer of known bispyrrolidinoindoline diketopiperazine alkaloid WIN 64745, which possesses unique architecture biosynthetically derived from an indole oxidation reaction of tryptophan. 相似文献
66.
The isolation of three new secondary metabolites from the fruiting body of Xylaria polymorpha is described. The new compounds are of mixed biosynthetic origin consisting of a polyketide starter, extended with a methyl orsellinate unit and terminated hydrolytically or with an amine-containing terminal unit. 相似文献
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