In order to improve the antibacterial activity of cefozopran (CZOP) against methicillin-resistant Staphylococcus aureus (MRSA), we initiated chemical modification to introduce a 2-(5-amino-1, 2, 4-thiadiazol-3-yl)-2(Z)-hydroxyimino acetyl group at the C-7 position and a 3- or 6-substituted imidazo[1, 2-b]pyridazinium or 5-substituted imidazo[1, 2-a]pyridmium group at the C-3' position. Although this approach successfully enhanced the anti-MRSA activity of CZOP two to eight times, a slight decrease in the activity against Gram-negative bacteria including Pseudomonas aeruginosa was involved. Among the novel derivatives, 3-(6-aminoimidazo[1, 2-b]pyridazinium-1-yl)methyl-7β-[2-(5-amino-1, 2, 4-thiadiazol-3-yl)-2(Z)-hydroxyiminoacetamido]-3-cephem-4-carboxylate (44a) showed an excellent balance of activity against MRSA and Gram-negative bacteria.
为了提高cefozopran (
CZOP) 对耐
甲氧西林金黄色葡萄球菌 (MRSA) 的抗菌活性,我们开始了
化学修饰,引入一个2-(5-
氨基-1, 2, 4-
噻二唑-3-基)-2(Z)-羟亚
氨基乙酰基团在C-7位,以及一个3位或6位取代的
咪唑[1, 2-b]
吡啶鎓或5位取代的
咪唑[1, 2-a]
吡啶鎓基团在C-3'位。尽管这种方法成功地将
CZOP对MRSA的抗性提高了两到八倍,但对包括
铜绿假单胞菌在内的革兰氏阴性菌的活性略有下降。在这些新衍
生物中,3-(6-
氨基
咪唑[1, 2-b]
吡啶鎓-1-基)甲基-7β-[2-(5-
氨基-1, 2, 4-
噻二唑-3-基)-2(Z)-羟亚
氨基乙酰
氨基]-3-头孢烯-4-
羧酸酯(44a)表现出了对MRSA和革兰氏阴性菌的活性之间的优良平衡。