Petr Jílek

Synthesis and antimycobacterial properties of N-substituted 6-amino-5-cyanopyrazine-2-carboxamides

A series of fifteen new compounds related to pyrazinamide (PZA) were synthesized, characterized with analytical data and screened for antimycobacterial, antifungal and antibacterial activity. The series consists of 6-chloro-5-cyanopyrazine-2-carboxamide and N-substituted 6-amino-5-cyanopyrazine-2-carboxamides, derived from the previous by nucleophilic substitution with various non-aromatic amines (alkylamines, cycloalkylamines, heterocyclic amines). Some of the compounds exerted antimycobacterial activity against Mycobacterium tuberculosis equal to pyrazinamide (12.5-25 μg/mL). More importantly, 6-chloro-5-cyanopyrazine-2-carboxamide and 5-cyano-6-(heptylamino)pyrazine-2-carboxamide were active against Mycobacterium kansasii and Mycobacterium avium, which are unsusceptible to PZA. Basic structure-activity relationships are presented. Only weak antifungal and no antibacterial activity was detected.

The serum levels of calcium, magnesium, iron and zinc in patients with recurrent vulvovaginal candidosis during attack, remission and in healthy controls.

The real cause of recurrent vulvovaginal candidosis (RVVC) is concealed and the etiopathogenesis of this disease remains to be determined. In a cohort study, concentrations of metals in 44 patients with RVVC and 30 healthy age‐matched women were measured and compared. The concentrations of serum calcium (Ca), magnesium (Mg) and iron (Fe) were measured photometrically, the zinc (Zn) levels were determined using flame atomic absorption spectrometry. For statistical analysis were used the Students t‐tests (paired analysis for attack vs. remission; non‐paired analysis for patient vs. control). Although all measured metals were within normal ranges the patients with RVVC had in contrast to the healthy controls significantly lower levels of serum Ca, Mg and Zn and insignificantly higher levels of Fe. These relative changes may contribute to the development of attacks in patients with RVVC.

Synthesis and Antimicrobial Evaluation of 6-Alkylamino-N-phenylpyrazine-2-carboxamides.

This work presents synthesis and antimicrobial evaluation of nineteen 6‐alkylamino‐N–phenylpyrazine‐2‐carboxamides. Antimycobacterial activity was determined against Mycobacterium tuberculosis H37Rv, M. kansasii and two strains of M. avium. Generally, the antimycobacterial activity increased with prolongation of simple alkyl chain and culminated in compounds with heptylamino substitution (3e, 4e) with MIC = 5–10 μm against M. tuberculosis H37Rv. On the contrary, derivatives with modified alkyl chain (containing e.g. terminal methoxy or hydroxy group) as well as phenylalkylamino derivatives were mainly inactive. The most active compounds (with hexyl to octylamino substitution) were evaluated for their in vitro activity against drug‐resistant strains of M. tuberculosis and possessed activity comparable to that of the reference drug isoniazid. None of the tested compounds were active against M. avium. Some derivatives exhibited activity against Gram‐positive bacteria including methicillin‐resistant Staphylococcus aureus (best MIC = 7.8 μm), while Gram‐negative strains as well as tested fungal strains were completely unsusceptible. Active compounds were tested for in vitro toxicity on various cell lines and in most cases were non‐toxic up to 100 μm.

Antibacterial Activity of N-Benzylsalicylthioamides

The in-vitro biological activity of N-benzylsalicylthioamides against 8 bacterial strains was determined by broth microdilution method; results were compared with those obtained with neomycin, penicillin G, ciprofloxacin and penicillin V. The compounds showed moderate to high activity against G+ bacteria; especially compounds 4, 6, 13, 16–21 and 24 exhibited comparable or higher activity than reference drugs. The antibacterial activity was analyzed by quantitative structure-activity relationship (QSAR). The antibacterial activity increased with lipophilicity, with the presence of halogens and with increasing value of Hammet substituent constant σ.

N-Benzylsalicylthioamides as novel compounds with promising antimycotic activity.

The in vitro biological activity of N-benzylsalicylthioamides was evaluated against eight fungal strains by the broth microdilution method and the results were compared with those obtained with fluconazole. The compounds exhibited an in vitro antifungal activity against the fluconazole-susceptible as well as the fluconazole-resistant fungal strains. The biological activity was analyzed by quantitative structure-activity relationship (QSAR).

Stereospecific reduction of the original anticancer drug oracin in rat extrahepatic tissues

The liver is the major site of drug metabolism in the body. However, many drugs undergo metabolism in extrahepatic sites and in the gut wall and lumen. In this study, the distribution and activity of reductases in rat that reduced potential cytostatic oracin to its principal metabolite 11‐dihydrooracin (DHO) were investigated. The extension and stereospecificity of oracin reduction to DHO were tested in microsomal and cytosolic fractions from the liver, kidney, heart, lung and wall of small intestine, caecum and large intestine. Intestinal bacterial reduction of oracin was studied as well. The amount of DHO enantiomers was measured by HPLC with Chiralcel OD‐R as chiral column. Reductive biotransformation of oracin was mostly stereospecific for (+)‐DHO, but the enantiomeric ratio differed significantly among individual tissues and subcellular fractions (from 56% (+)‐DHO in heart microsomes to 92% (+)‐DHO in liver cytosol). Stereospecificity for (‐)‐DHO (60%) was observed in bacterial oracin reduction in the lumen of small intestine, caecum and large intestine. Shift of the (+)‐DHO/(‐)‐DHO enantiomeric ratio from 90:10 (in liver subcellular fractions) to 60:40 (in‐vivo) clearly demonstrated the importance of the contribution of extrahepatic metabolism to the total biotransformation of oracin to DHO.

Comparison of two long-term gestagen regimens in the management of recurrent vulvovaginal candidiasis: A pilot study

Vulvovaginal candidiasis (VVC) is a hormonal‐dependent infection but in contrast to sporadic VVC, therapy of recurrent vulvovaginal candidiasis (RVVC) is still unsolved. Long‐term administration of medroxyprogesterone acetate was evaluated for the management of RVVC. Overall, 20 patients were treated with Depo‐Provera; 14 patients were treated with Provera. Gestagen therapy was evaluated based on visual analogue scale (VAS), the frequency of attacks, the side effects of gestagens and the consumption of antifungals. There was a reduced symptomatology in both of the groups and substantial reduction in antifungal drug consumption during the second year of gestagen use. Twenty‐four patients (70.6%) evaluated their condition regarding the vulvovaginal area as improvement (VAS decrease of 3‐5 points). Five patients (14.7%) mentioned minimal or no improvement. Further, a number of antifungal drug‐treated episodes dropped dramatically during the study period. Both regimes provided similar results, but five patients from the Depo‐Provera group had to withdraw from gestagen therapy. Gestagen supplementation ameliorated the quality of life for the majority of patients with RVVC and suggested a potential role in the management of this syndrome, even if beneficial effect was evident after longer application, and some patients met with side effects that led to an interruption of therapy.