Abstract
A series of N-alkyl-3-(alkylamino)pyrazine-2-carboxamides and their N-alkyl-3-chloropyrazine-2-carboxamide precursors were prepared. All compounds were characterized by analytical methods and tested for antimicrobial and antiviral activity. The antimycobacterial MIC values against Mycobacterium tuberculosis H37Rv of the most effective compounds, 3-(hexylamino)-, 3-(heptylamino)- and 3-(octylamino)-N-methyl-pyrazine-2-carboxamides 14‒16, was 25 μg/mL. The compounds inhibited photosystem 2 photosynthetic electron transport (PET) in spinach chloroplasts. This activity was strongly connected with the lipophilicity of the compounds. For effective PET inhibition longer alkyl chains in the 3-(alkylamino) substituent in the N-alkyl-3-(alkylamino)pyrazine-2-carboxamide molecule were more favourable than two shorter alkyl chains.
Highlights
Pyrazines are symmetrical heterocyclic aromatic organic compounds
We prepared a series of pyrazinamide alkylamino derivatives according to the general procedures shown in Scheme 1. 3-Chloro-N-methylpyrazine-2-carboxamide (1) was previously prepared by
Allen et al [21], 3-chloro-N-propylpyrazine-2-carboxamide (3) by Zhu et al [22] and N-methyl-3(methylamino)pyrazine-2-carboxamide (9) by Albert et al [23], but they were not tested for any biological activity
Summary
Pyrazines are symmetrical heterocyclic aromatic organic compounds. Pyrazine is a weaker base than pyridine, pyridazine and pyrimidine. 6-(alkylamino)pyrazine-2-carboxamides prepared previously by Servusová et al [11], showed an interesting in vitro whole cell antimycobacterial activity. Based on these results we decided to prepare a series of 3-(alkylamino)pyrazine-2-carboxamides, to evaluate the importance of positional isomerism in these derivatives. Situated in D1 and D2 proteins on the donor side of PS2 interacted with some organic compounds, e.g., substituted benzanilides [18] or substituted 2,6-disubstituted pyridine-4-thiocarboxamides [19] or anilides of pyrazine-2-carboxylic acids [14,20] and due to this interaction interruption of the photosynthetic electron transport occurred. This study is focused on preparation of alkyl substituted derivatives of PZA It deals with the length of the alkylamino chain in position 3 and its influence on biological effects in comparison with previously evaluated 5- and 6-alkylamino isomers. The structure-activity relationships between the chemical structure and in vitro biological activities of evaluated compounds are discussed
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