Fatty acid synthase (FAS) is a promising antifungal target due to its marked structural differences between fungal and mammalian cells. The aim of this study was to evaluate the antifungal activity ...of flavonoids described in the scientific literature as FAS inhibitors (quercetin, trans-chalcone, ellagic acid, luteolin, galangin, and genistein) against the dermatophyte Trichophyton rubrum and their effects on fatty acid and ergosterol synthesis.
The antifungal activity of the natural products was tested by the microdilution assay for determination of the minimum inhibitory concentration (MIC). The effect of the compounds on the cell membrane was evaluated using a protoplast regeneration assay. Ergosterol content was quantified by spectrophotometry. Inhibition of FAS by flavonoids was evaluated by an enzymatic assay to determine IC50 values. Quantitative RT-PCR was used to measure transcription levels of the FAS1 and ERG6 genes involved in fatty acid and ergosterol biosynthesis, respectively, during exposure of T. rubrum to the flavonoids tested.
The flavonoids quercetin and trans-chalcone were effective against T. rubrum, with MICs of 125 and 7.5 μg/mL for the wild-type strain (MYA3108) and of 63 and 1.9 μg/mL for the ABC transporter mutant strain (ΔTruMDR2), respectively. The MICs of the fluconazole and cerulenin controls were 63 and 125 μg/mL for the wild-type strain and 30 and 15 μg/mL for the mutant strain, respectively. Quercetin and trans-chalcone also reduced ergosterol content in the two strains, indicating that interference with fatty acid and ergosterol synthesis caused cell membrane disruption. The MIC of quercetin reduced the number of regenerated protoplasts by 30.26% (wild-type strain) and by 91.66% (mutant strain). Half the MIC (0.5 MIC) of quercetin did not reduce the number of regenerated wild-type fungal colonies, but caused a 36.19% reduction in the number of mutant strain protoplasts. In contrast, the MIC and 0.5 MIC of trans-chalcone and cerulenin drastically reduced protoplast regeneration in the two strains. The FAS1 gene was repressed in the presence of MICs of quercetin, trans-chalcone, fluconazole and cerulenin. The ERG6 gene was induced in the presence of MICs of fluconazole and cerulenin and was repressed in the presence of MICs of trans-chalcone and quercetin. Trans-chalcone and quercetin inhibited the enzymatic activity of FAS, with IC50 values of 68.23 and 17.1 μg/mL, respectively.
Trans-chalcone and quercetin showed antifungal activity against T. rubrum, reducing ergosterol levels and modulating the expression of FAS1 and ERG6.
A new specimen preparation method for transmission electron microscope (TEM) observation of polymeric powder samples is proposed. Powders were placed into a glass-fiber basket, and stained with RuO4 ...at 60°C. Resultant stained powders were embedded in epoxy resin and ultramicrotomed. This sample preparation for TEM observation was applied to single crystals of LLDPE and two HDPE's which have different molecular weight distributions. Obtained electron micrographs contained edge-on single crystalline lamellae, which have never been observed in flat-on analysis by the common method. From these electron microscopic results, it was found that the single crystals of LLDPE and HDPE with a broad molecular weight distribution stacked with a number of lamellae. On the other hand, HDPE with a narrower molecular weight distribution gives single lamellae without stacking. This method has advantages that a specimen for observation can be prepared easily and gives better contrast on TEM micrographs. Compared with the results of the common shadowing method, it is clear that the stacked morphology of single crystal lamellae can be investigated more quantitatively by this preparation/staining method.
New μ-opioid receptor (MOR) agonists containing 4-hydroxypiperidine, piperidine and piperazine moieties were synthesized and evaluated to find a peripheral opioid analgesic. Among the synthesized ...compounds, 2-1-3-(N,N-dimethylcarbamoyl)-3,3-diphenylpropyl-4-hydroxypiperidin-4-ylphenoxyacetic acid (8: SS620) having phenoxyacetic acid and 4-hydroxypiperidine moieties showed the highest agonist potency on the MOR in an isolated guinea-pig ileum preparation, and it also had selectivity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells compared with the same types of δ- and κ-opioid receptors (DOR and KOR). In addition, compound 8 showed a 10 times more potent MOR agonist activity than loperamide. Furthermore, compound 8 showed a peripheral analgesic activity in vivo screening on rat.
Proposed fusion reactor blanket designs bring into focus a large number of problems dealing with the interaction of 14-MeV neutrons with different materials. Carbon, oxygen, aluminum, titanium, and ...iron are among the materials used in the blanket. To have confidence in fusion reactor blanket calculations, a necessary prerequisite is that the transport code correctly describes the interaction of 14-MeV neutrons with the materials of the blanket. Spherical assemblies of the above materials ranging from 1 to 5 mean-free-paths in thickness have been bombarded with a centered nominal 14-MeV neutron source. The emitted neutron energy spectra were measured using time-of-flight techniques (3-nsec full-width-at-half-maximum system resolution) in a geometry where the flight path (7 to 10 m) is long compared to the dimensions of the spherical targets. The spectra have been calculated with the Monte Carlo neutron transport code TART using the ENDF/B-III and -IV neutron libraries and compared with measurements.
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