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PubMed1990

A novel method for studying ergosterol biosynthesis by a cell-free preparation of Aspergillus fumigatus and its inhibition by azole antifungal agents.

A novel procedure has been developed for measuring ergosterol biosynthesis from [14C]mevalonate in a cell-free extract prepared from Aspergillus fumigatus. Ergosterol accounted for approximately 60% of the 4, 14-desmethylated sterol fraction which in turn totalled 13.2% of the non-saponifiable lipid produced. The other major sterol fractions were 4, 4-dimethylated sterols and 4-monomethylated sterols which accounted for 30.8% and 20.1% respectively of non-saponifiable lipid. The cell-free system had a narrow pH optimum of 7.2-7.4 for desmethylated sterol biosynthesis. Activity decreased by 94% at pH 6.5. Fluconazole (10(-4) M), ketoconazole (10(-6) M) and itraconazole (10(-6) M) inhibited formation of desmethylated sterols by greater than 85%, while 4-monomethylated sterols and 4, 4-dimethylated sterols were increased. The IC50s for inhibition of desmethylated sterol biosynthesis were 1.4 x 10(-6) M for fluconazole, 4.0 x 10(-8) M for ketoconazole, and 3.3 x 10(-8) M for itraconazole. The difference in intrinsic potency between fluconazole and ketoconazole is particularly interesting in view of the fact that fluconazole is a more effective agent than ketoconazole in an animal infection model of systemic aspergillosis.

Antifungal Agents↗
PubMed1989

[Azoles. 27. Nitroimidazole derivatives, their antibacterial and fungicidal activity and electron affinity].

Nitroimidazole derivatives 3a-3g, 4a-4g and 5-8 were synthesized by treating 4,5-dinitro- and 2-methyl-4,5-dinitroimidazole (1,2) with phenacyl bromide, its p-substituted derivatives or epichlorohydrin. 1-(3-Chloro-2-hydroxypropyl)-4,5-dinitroimidazole (5) and its 2-methyl derivative 6 have been converted to imidazo-oxazoles 7 and 8 or amino imidazole derivatives 9-14 by the action of potassium carbonate or cyclic amines (pyrrolidine, piperidine, morpholine and N-methylpiperazine). Some of the newly synthesized nitroimidazole derivatives show antibacterial and fungicidal activity. The electron affinity of the nitroimidazole derivatives 1-24 is discussed on the basis of their half-wave potentials and in the connection with their eventual radiosensitizing properties.

Anti-Bacterial Agents↗
PubMed1988

[Azoles. 18. Sulfonylindazole derivatives].

The nucleophilic substitution of hydrogen to synthesize the sulphonyl indazole derivatives 9-16 is described. The structures of the substitution products are discussed using H-NMR spectra. Chemical structural proof was given by steric hindrance observed in the process of chorination of 9-16. The compounds 3, 4, 7, 8, 14, and 16 are studied to find an inhibition on phospholipase-A2 and lipoxygenase-I.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

Inhibition and interaction of cytochrome P450 of Candida krusei with azole antifungal drugs.

Candida krusei has become an increasingly important invasive pathogen, particularly in AIDS patients and is highly resistant to fluconazole. In vitro growth inhibition studies revealed that fluconazole and ketoconazole were approximately 800- and 19-fold less inhibitory than itraconazole. The inhibition and interaction of itraconazole, fluconazole and ketoconazole with the sterol 14 alpha-demethylase of C. krusei was studied using in vitro ergosterol biosynthesis and difference spectroscopy, respectively. Both itraconazole and ketoconazole inhibited in vitro ergosterol biosynthesis at lower concentrations than fluconazole. All three drugs interacted with microsomal P450 and interfered in the binding of carbon monoxide to P450 in direct proportion to their inhibitory effect on ergosterol biosynthesis in cell-free extracts. The slightly lower affinity of sterol 14 alpha-demethylase for fluconazole compared with itraconazole and ketoconazole is only partially responsible for poor activity of fluconazole on C. krusei.

Antifungal Agents↗
PubMed1994

Fungicides and photochemistry: photodegradation of the azole fungicide penconazole.

In order to examine the photostability of the fungicide penconazole (1-(2,4-dichloro-beta-propylphenethyl)-1H-1,2,4-triazole, 1) in the field, model experiments with organic solvents were performed. Photodegradation (lambda > 280 nm) of penconazole was found to be more efficient in isopropanol and cyclohexane solution than in the presence of cyclohexene. Photolysis in isopropanol and cyclohexane resulted in considerable formation of 1-(4-chloro-beta-propylphenethyl)-1H-1,2,4-triazole (2) and 5H,6H-(1,2,4-triazolo)-[5,1-a]-9-chloro-6-propyl-isoquinoline (3). Furthermore, photodehalogenation of 3 yielded traces of 5H,6H-(1,2,4-triazolo)-[5,1-a]-6-propyl-isoquinoline (4) and, in the presence of isopropanol 5H,6H-(1,2,4-triazolo)-[5,1-a]-9-(2-hydroxy-2-methylethyl)-6-propyl- isoquioline (5). Additionally, a lot of polar products were found in high yields which could not be isolated and characterized individually. In the presence of cyclohexene, on the other hand, photodecomposition and photodehalogenation to photoproduct 2 were found to be the main degradation pathways and photoproduct 3 was only detected as a trace component.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Antifungal activity of ketoconazole and other azoles against Malassezia furfur in vitro and in vivo.

The in vitro activity of several antifungal agents (ketoconazole, miconazole, econazole, fenticonazole, itraconazole, fluconazole) in routine clinical use against Malassezia furfur infections has been studied with freshly isolated strains of M. furfur from pityriasis versicolor lesions. The results indicate that the drugs tested exert a good activity, and both ketoconazole and itraconazole appear very active (0.8 mg/l respectively). Hair samples from the beards of volunteer patients affected by pityriasis versicolor but otherwise healthy were examined to determine ketoconazole levels during oral therapy (one or two 200 mg tablets daily). It was shown that the drug progressively accumulates in the beard, reaching levels proportional to the dose administered, although blood levels did not increase in parallel. The study of drug concentration profile has evidenced a long ketoconazole persistence in the beard at therapeutic levels. In conclusion, the possibility of reaching high and lasting ketoconazole levels in the keratin layer of the epidermis indicates that systemic ketoconazole therapy could be useful for eradication of M. furfur in patients affected by pityriasis versicolor.

Adult↗