[Structure-activity relationship in cephalosporin antibiotics. I. Impact of nitrogen functions on biological activity of cephalosporins--7-aminocephalosporanic acid derivatives].

The impact of the nitrogen containing functional groups of the radical at position 7 in the cefem nucleus on antimicrobial activity of cephalosporins against gram-positive and gram-negative organisms was studied. 235 compounds were tested. It was shown that the presence or absence of the above mentioned functional groups could not be used as the only factor for estimating the pharmacological properties of the antibiotics under investigation. There were different and, occasionally, diametrically opposite effects of the spatial arrangement of the nitrogen-containing descriptors on gram positive and gram negative organisms. It was concluded that prediction of the biological activity of cephalosporins by the pattern recognition according to the presence and spatial arrangement of the functional groups was possible. A way for designing novel compounds with the required biological activity is proposed.