New potentially active pyrazinamide derivatives synthesised under microwave conditions

Abstract

A series of 18 N-alkyl substituted 3-aminopyrazine-2-carboxamides was prepared in the work for this contribution. All these substances were prepared according to previously experimentally set and proven conditions using the methodology of microwave assisted synthesis. This approach for the aminodehalogenation reaction was chosen due to higher yields and shorter reaction times. Compounds were put to the evaluation of their antibacterial, antifungal and herbicidal properties.Only a small number of substances showed activity against fungi which was the same or higher than standards. They were namely the compounds with alicyclic side chain. The biological efficacy of the compounds was increasing with rising lipophilicity. The same relationship can be found for the herbicidal activities. These compounds also inhibited photosynthetic electron transport in spinach chloroplasts and the IC50 values of the most active compounds varied in the range from 14.3 to 1590 mol/L. The inhibitory activity was connected not only with the lipophilicity but also with the presence of secondary amine fragment bounded to the pyrazine ring. Structure-activity relationships are discussed as well.