Fluorometric Measurement of 5-Fluorocytosine in Biological Fluids

Wade, D. N.; Sudlow, Gillian

doi:10.1002/jps.2600620531

Cited by 17 publications

(6 citation statements)

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“…The fluorescence quantum yield of 5FC is ≈60 times greater than the quantum yield reported for cytosine by Daniels and Hauswirth (φ f = 8 × 10 -5 ). Although fluorescence from 5FC has not been reported previously to the best of our knowledge, fluorescence from the 5FC anion generated in alkaline solution has been used as an assay for 5FC concentrations in blood. , The increased quantum yield of 5FC indicates that the more slowly decaying signals seen in the transient absorption measurements are indeed attributable to the fluorescent excited state. This is also supported by the calculated radiative lifetime of 14 ns.…”

Section: Discussionmentioning

confidence: 99%

Singlet Excited-State Dynamics of 5-Fluorocytosine and Cytosine: An Experimental and Computational Study

et al. 2005

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The photophysics of singlet excited 5-fluorocytosine (5FC) was studied in steady-state and timeresolved experiments and theoretically by quantum chemical calculations. Femtosecond transient absorption measurements show that replacement of the C5 hydrogen of cytosine by fluorine increases the excited-state lifetime by two orders of magnitude from 720 fs to 73 ± 4 ps. Experimental evidence indicates that emission in both compounds originates from a single tautomeric form. The lifetime of 5FC is the same within experimental uncertainty in the solvents ethanol and dimethylsulfoxide. The insensitivity of the S 1 lifetime to the protic nature of the solvent suggests that proton transfer is not the principal quenching mechanism for the excited state. Excited state calculations were carried out for the amino-keto tautomer of 5FC, the dominant species in polar environments, in order to understand its longer excited-state lifetime. CASSCF and CAS-PT2 calculations of the excited states show that the minimum energy path connecting the minimum of the 1 π, π* state with the conical intersection responsible for internal conversion has essentially the same energetics for cytosine and 5FC, suggesting that both bases decay nonradiatively by the same mechanism. The dramatic difference in lifetimes may be due to subtle changes along the decay coordinate. A possible reason may be differences in the intramolecular vibrational redistribution rate from the Franck-Condon active, in-plane modes to the out-of-plane modes that must be activated to reach the conical intersection region.

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Section: Discussionmentioning

confidence: 99%

Singlet Excited-State Dynamics of 5-Fluorocytosine and Cytosine: An Experimental and Computational Study

et al. 2005

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“…Several microbiological (4,(12)(13)(14), chemical (17,20), and chromatographic (1, 7, 19) methods have been used to measure these two antifungal agents in body fluids. Amphotericin B, which is often used in combination with flucytosine, may complicate measurement of flucytosine by bioassay methods (4,13,14).…”

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confidence: 99%

Simplified bioassay method for measurement of flucytosine or ketoconazole

Bodet¹,

Jorgensen²,

Drutz³

1985

J Clin Microbiol

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A simple agar-well diffusion bioassay suitable for measurement of flucytosine or ketoconazole was developed by using Candida pseudotropicalis ATCC 46764 as the assay organism. A test medium composed of (per liter) 7 g of Trypticase peptone, 7 g of YNB (yeast-nitrogen base), 15 g of glucose, and 15 g of agar was seeded with an inoculum which had been grown to no. 2 McFarland turbidity after 4 to 6 h in YNB-glucose broth. Determinations of flucytosine or ketoconazole were performed without necessity of heating or diluting of serum samples to alleviate amphotericin B interference. A linear relationship between zone diameters and logo

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“…Building on established methods used in previous research [ 25 ], this study employed Hippocratic screening to evaluate the safety profile of C. papaya leaf extract. Specifically, two female rats were orally administered a single dose of 2000 mg/kg and observed individually in open fields at 5, 10, 15, 30, 60, 120, and 240 min after administration and 24 h a day for clinical signs and mortality, as measured by motor activity (observing animal movements using infrared (I.R.)…”

Section: Methodsmentioning

confidence: 99%

Safety of Oral Carica papaya L. Leaf 10% Ethanolic Extract for Acute and Chronic Toxicity Tests in Sprague Dawley Rats

Taychaworaditsakul,

Saenjum,

Lumjuan

et al. 2024

Toxics

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Carica papaya L. leaves, traditionally utilized in dietary supplements and pharmaceuticals, exhibit a broad spectrum of potentially therapeutic properties, including anti-inflammatory, antimalarial, and wound healing properties. This study examined the acute and chronic toxicity of 10% ethanolic-extracted C. papaya leaf in Sprague Dawley rats. The acute toxicity assessment was a single oral dose of 5000 mg/kg body weight, while the chronic toxicity assessment included daily oral doses of 100, 400, 1000, and 5000 mg/kg over 180 days. Systematic monitoring covered a range of physiological and behavioral parameters, including body and organ weights. End-point evaluations encompassed hematological and biochemical analyses, along with gross and histopathological examinations of internal organs. Findings revealed no acute toxicity in the C. papaya leaf extract group, although a significant decrease in uterine weight was observed without accompanying histopathology abnormalities. In the chronic toxicity assessment, no statistically significant differences between the control and the C. papaya leaf extract groups were detected across multiple measures, including behavioral, physiological, and hematological indices. Importantly, histopathological examination corroborated the absence of any tissue abnormalities. The study results indicate that C. papaya leaf extract exhibited no adverse effects on the rats during the 180-day oral administration period, affirming its potential safety for prolonged usage.

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Fluorometric Measurement of 5-Fluorocytosine in Biological Fluids

Cited by 17 publications

References 0 publications

Singlet Excited-State Dynamics of 5-Fluorocytosine and Cytosine: An Experimental and Computational Study

Singlet Excited-State Dynamics of 5-Fluorocytosine and Cytosine: An Experimental and Computational Study

Simplified bioassay method for measurement of flucytosine or ketoconazole

Safety of Oral Carica papaya L. Leaf 10% Ethanolic Extract for Acute and Chronic Toxicity Tests in Sprague Dawley Rats

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