Miloš Macháček

New groups of antimycobacterial agents: 6-chloro-3-phenyl-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones and 6-chloro-3-phenyl-2H-1,3-benzoxazine-2,4(3H)-dithiones.

A series of 6-chloro-3-phenyl-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones 3 and a series of 6-chloro-3-phenyl-2H-1,3-benzoxazine-2, 4(3H)-dithiones 4 were synthesized by melting 6-chloro-3-phenyl-2H-1, 3-benzoxazine-2,4(3H)-dione and its derivatives substituted on the phenyl ring 2 with tetraphosphorus decasulfide. Compounds 2c-e, 3 and 4 exhibited in vitro activity against Mycobacterium tuberculosis, M. kansasii (two strains) and M. avium better than or comparable to that of isoniazid. Replacement of the oxo group by a thioxo group at position 4 led to improvement in activity against M. tuberculosis and M. kansasii. The Free-Wilson method and procedure developed by the authors were used to analyse the structure-activity and structure-antimycobacterial profile relationships, respectively.

N-Benzylsalicylthioamides: Highly Active Potential Antituberculotics

A gseries of 29 new derivatives of N‐benzylsalicylthioamides was synthesized and the compounds were tested for in‐vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium kansasii, and Mycobacterium avium. The activity was analyzed by quantitative structure‐activity relationship (QSAR). Activity increased with increasing lipophilicity and electron donating effect of the substituents in the acyl moiety and decreased with the electrophilic superdelocalizability of the molecules. The most active compounds are more active than isoniazid (INH) and are active against INH‐resistant potential pathogenic strains of mycobacterium.

Synthesis and Biological Evaluation of Quinazoline-4-thiones

Several 2,2-dimethyl-3-phenyl-1,2-dihydroquinazoline-4(3H)-thiones and 2-methyl-3-phenylquinazoline-4(3H)-thiones were synthesized and tested for their antimycobacterial, photosynthesis-inhibiting, and antialgal activity. Antimycobacterially active compounds were found among the 6-chloro substituted compounds. 6-Chloro-3-(4-isopropylphenyl)-2-methylquinazoline-4(3H)-thione exhibited higher activity than the isoniazid standard against Mycobacterium avium and M. kansasii. Most of the compounds possessed photosynthesis-inhibiting activity. 6-Chloro-2,2-dimethyl-3-phenyl-1,2-dihydro-quinazoline-4(3H)-thione and its 3´-chloro- and 3´,4´-dichloro analogs were most effective in the inhibition of oxygen evolution rate in spinach chloroplasts. Of compounds selected for toxicological screening, 6-chloro-3-(4-isopropylphenyl)-2-methyl-quinazoline-4(3H)-thione was the only one active in the brine shrimp bioassay.

INVESTIGATION OF THE COLOUR REACTION OF PHENOLS WITH MBTH. II, PROPERTIES OF THE ISOLATED PRODUCTS OF THE REACTION WITH PHENOL, 2,6-DIMETHYLPHENOL AND 4-METHYLPHENOL

The following model compounds for the study of the oxidative coupling reactions of 2-hydrazono-3-methylbenzothiazoline (MBTH) with phenolic compounds were prepared: thep-coupling products of the reagent with phenol and 2,6-xylenol and theo-coupling product withp-cresol. The proposed structure of the dyes was confirmed. In strongly polar and ionic media the azobetaine form of the products predominates, and in non-polar media the azine structure. The principal physico-chemical properties of the products were determined and the results contributed to formulation of the course of the coupling reaction, and to optimization of the conditions for determination of small amounts of phenolic substances. The violeto-coupling product is less stable than the redp-coupling products, and intramolecularly hydrogen-bonded six-membered ring is assumed to exist in the structure. In acid medium the dyes are mainly monoprotonated, and partly diprotonated in concentrated sulphuric acid medium. The products are stable up to about pH 11. These properties make extraction into low-polarity solvents possible. The dye derived from 2,6-xylenol andp-cresol has not hitherto been prepared. The principal spectral characteristics, γmax(ɛ), of the products in ethanol medium are: 499 nm (4.7 × 104 1·mole−1 cm−1) for the phenol derivative, 486 nm (5.0 × 104) for the 2,6-xylenol product, and γmax 540 nm for thep-cresol product.

Synthesis of Some 2, 6-Disubstituted 4-Amidopyridines and -Thioamidopyridines, and Their Antimycobacterial and Photosynthesis-Inhibiting Activity

Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic*Author to whom correspondence should be addressed.Received: 8 March 1999 / Revised and Accepted: 28 February 2000 / Published: 3 March 2000Abstract: A group of 26 new 2-halogeno-6-alkylsulfanyl- and 2,6-bis-alkylsulfanyl-4-amidopyridines and corresponding thioamidopyridines was synthesised. Some of the ami-dopyridines and all thioamidopyridines were tested for their antimycobacterial activityagainst atypical mycobacterial strains. Promising photosynthesis-inhibiting activity was alsofound for some of the amidopyridines.Keywords: Thioamidopyridines, antimycobacterial activity, photosynthesis-inhibiting ac-tivity.IntroductionSome events during the past decade have dramatically changed the nature and magnitude of theproblem of tuberculosis. The HIV epidemic and increasing resistance to antituberculous drugs dictatethe need of development of new antituberculotics [1-3].

Antileukotrienic phenethylamido derivatives of arylalkanoic acids in the treatment of ulcerative colitis

A series of arylalkanoic acid derivatives bearing methyl(phenethyl)amino groups were prepared and their inhibition of LTB(4) biosynthesis was evaluated. Regression analysis showed the slightly different parabolic dependences of this activity on lipophilicity of alpha-methyl and alpha-unsubstituted alkanoic acid derivatives. The relationship derived for alpha-unsubstituted alkanoic acids was extended by previously prepared group of similar derivatives of arylacetic acids without any change of regression coefficients and statistical criteria. It was concluded that the most active compounds belong to 2-arylpropanoic acid derivatives with lipophilicity close to logP(opt) (=6.97). But generally, the structural changes in the acidic part of compounds under study did not yield the substantial improvement of LTB(4) biosynthesis inhibition in comparison with the previously prepared series of derivatives IV. The anti-inflammatory effect of the compounds under study was evaluated in three animal models of inflammation and their possible utilization in the treatment of ulcerative colitis (UC) was followed. From 12 evaluated compounds, 4 compounds are more active in UC inhibition than the standard sulfasalazine but it can be stated that the change of connecting chain between aromatic ring and carboxyl did not bring about the important improvement of this activity in comparison with previous derivatives of arylacetic acids. Possible relation between LTB(4) biosynthesis inhibition and ulcerative colitis is seriously broken by the compound 8a with carbonyl as the additional functional group on the connecting chain between carboxyl and aromatic ring.

Some Anilides of 2-Alkylthio- and 2-Chloro-6-Alkylthio-4- Pyridinecarboxylic Acids: Synthesis and Photosynthesis- Inhibiting Activity

Many compounds containing a -CONH- group display photosynthesis inhibiting activity. Based on this structural feature, a group of anilides of 2-alkylthio-(1b-4f) or 2-chloro-6-alkylthio-4-pyridinecarboxylic acids (5a-6c) was synthesised. The prepared compounds were tested for their inhibition of the oxygen evolution rate (OER) in spinach chloroplasts. A quasi-parabolic dependence between photosynthesis-inhibiting activity and the lipophilicity of the compounds was determined for 1b-4f as well as for 5a-6c. The inhibitory activity of compounds 1b-4f was higher than that of 5a-6c for comparable lipophilicity values.