The Optimal Wavelength of Spectrophotometric Broth Microdilution Antifungal Susceptibility Test for Flucytosine and Three Azoles / 대한진단검사의학회지

BACKGROUND: There is no guideline for the appropriate wavelength at which to measure the optical density (OD) value in broth microdilution antifungal susceptibility testing, although a spectrophotometric reading method is commonly used. The present study aimed to analyze the difference in the OD values over the range of visible light and to ascertain the optimal wavelength for the spectrophotometric method of microdilution testing. METHODS: We measured the OD of background blank controls of broth medium, antifungal agents, and inocula of five type strains using a Synergy HT multi-detection microplate reader at 5-nm intervals from 380 nm to 760 nm. We also estimated the OD differences between the 50% of growth control and blank control. RESULTS: The OD of the blank control showed a parabola shape with two peaks and steadily decreased at longer wavelengths. The curves of the antifungal agent were similar to those of blank controls, and the influence of each antifungal agent on the OD was minimal. For the difference in OD between 50% of growth control and the blank control, the curve was the opposite of the blank control, and the OD increased steadily at the wavelengths above 600 nm. CONCLUSIONS: The range between 600 nm and 700 nm was the optimal wavelength for broth microdilution antifungal susceptibility testing, although any wavelength within the visible light spectrum can be used.

Studies on heterocyclic nitrogen compounds, new azoles from benzo- [G]-1, 2, 3, 4-tetra-hydroquinoline-4, 5, 10-trione derivatives

Pyrazoline, isoxazoline. pyrimidine and pyrimidinethione derivatives have been reported as highly potent agent against fungi and bacteria[1-6] As a result of our interest to prepare a new and microbial active azoles [7-10], we report here the synthesis of new azoles and pyrimidinone derivatives starting from benzo- [G] -4-chloro-l,2-dihydroquinolinoquinone-3-carboxaldehyde [2]. Formylation of benzo-[G] 1,2,3,4-tetrahydroquinoline 4,5, 10-trione [l][11] via Vilsmeier reagent [POC13/DMF] afforded benzo-[G]-4-ch1oro-l, 2-, dihydroquinolinoquinone-3-carboxaldehyde [2]. The 1HNMR spectra of [2] have shown a singlet signal at sigma 10.0 pmm due to proton of the formyl group and its mass spectra showed clear isotopic effect. Condensation of the formylated compound [2] and 4-substituted acetophenone in alkaline ethanol produced the corresponding alpha, beta unsaturated compounds [3 a-c].[1]H NMR. Spectra of the compourds [3a-c] showed the disappearance of the formyl proton at sigma10.0 ppm, meanwhile two doublets are observed around sigma 5 .8-6.2 ppm, for protons at conjugated double bond. Cycloaddition reaction of [3a-c] and hydrazine hydrate in presence of acetic acid, phenylhydrazine in catalytic amounts of piperidine, hydroxylamine hydro chloride in alkaline ethanol, urea and/or thiourea in presence of 5NHC1 afforded the corresponding pyrazolines [4a,b; 4d, e and 4g, h], isoxazolines [4c; 4f and 4i] pyrimidinone [5a; 5c and 5e] and/or pyrimidinethione [5b; 5c and 5f], respectively. The chemical structure of these new compounds were established based on IR, [1] H-NMR and mass spectra, as well as their elemental analysis [c.f. tables 1,2]