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Studies on pyrazine derivatives. Part VIII. Synthesis and tuberculostatic activity of some 6-alkylthio- and 6-phenylthiopyrazine-2-carboxylic acids.

2-Cyano-6-alkylthio- and 6-phenylthiopyrazines were prepared from 2-cyano-6-chloropyrazine (CCP) in the reaction with mercaptans. By the transformation of the -CN group the corresponding amides, thioamides, amidoximes, acids, esters and hydroxamic acids and hydrazides were obtained. The oxidation of sulfur in the above mentioned compounds led to sulfoxy- and sulfonyl derivatives. In the screening for antituberculous activity compounds 30 and 42 showed the greatest activity (MIC = 31.2 microgram/cm3) against H37Rv strain and compund 8 so did against saprophytic ATCC 607 strain. The compounds with 6-benzylthio grouping were more active against ethionamide, isoniazide and capreomycine resistant strains.

Antitubercular Agents↗

[Substances with central nervous system activity. Derivatives of octahydro-1,4-dihydroxypyrrolo(1,2-a)pyrazine-6-carboxylic acids].

Compounds with potential activity on the Central Nervous System were prepared starting either from 2,5-diethoxycarbonylpyrrolidine or from N-benzyloxycarbonyl-2,5-pyrrolidinedicarboxylic acid anhydride. By the Arndt-Eistert reaction it was possible to obtain chain lengthening at position 6. The carboxy group was also successfully reduced to a hydroxymethyl group. The synthetic work was completed with the synthesis of some derivatives having a phenyl ring condensed at position 7 and 8. Some pharmacological data on the Central Nervous System depressant activity of the prepared compounds are also reported.

Aggression↗

Studies on pyrazine derivatives. Part X. Synthesis and tuberculostatic activity of some 6-cyclamino-, 6-imidazolyl--and triazolylpyrazine-2-carboxylic acids derivatives.

The 6(2'-methylpiperidine-, 2',6'-dimethylmorpholino-, imidazolyl- and triazolyl)-2-cyanopyrazines were prepared from 2-cyano-6-chloropyrazine. The -CN group was then transformed into COOH, CONH2, CSNH2, CONHNH2, CONHOH and C(NOH)NH2 functions. All compounds obtained were of weak tuberculostatic activity. Comp. 13 was active against isoniazide, capreomycin and ethionamide resistent strains at the concentration range of 31.2--62.5 microgram/cm3.

Antitubercular Agents↗

Studies on pyrazine derivatives. XXX. Synthesis of pyrazinylamino-1,3-diazacycloalkanes of potential circulatory activity.

A series of pyrazinylamino-1,3-diazacycloalkanes was obtained by reaction of the corresponding substituted aminopyrazines with aliphatic amines. Selected compounds were studied with respect to their potential circulatory activity. The effect on the blood pressure, isolated rat tail artery and heart atria, and an influence on the human blood platelet aggregation were investigated.

Amines↗

Stability, blood partition, and protein binding of a chemoprotective agent, 2-(allylthio)pyrazine.

The stability of 2-AP, a chemoprotective agent, in various pH solutions and human gastric juice, the blood partition of 2-AP between plasma and blood cells, and the factors influencing the binding of 2-AP to 4% human serum albumin (HSA) were evaluated. 2-AP was stable in human gastric juice and pH solutions ranging from 1 to 12, however, 2-AP was unstable in pH 13 solution; the disappearance rate constant was 0.00759/h. 2-AP reached equilibrium rapidly between plasma and blood cells of rabbit blood. The equilibrium plasma/blood cells partition ratios were independent of initial rabbit blood concentrations of 2-AP, 1, 5, and 10 micrograms/ml; the values were in the range of 5.99-11.8. Binding of 2-AP to 4% HSA was dependent on HSA concentration, incubation temperature, 'the buffer' pH, and addition of acetylsalicylic acid. The binding of 2-AP was independent of buffers containing various concentrations of chloride ion, heparin, and alpha-1-acid glycoprotein.

Animals↗