Studies on Anti-MRSA Parenteral Cephalosporins. III. Synthesis and Antibacterial Activity of 7.BETA.-[2-(5-Amino-1,2,4-thiadiazol-3-yl)-2(Z)-alkoxyiminoacetamido]-3-[(E)-2-(1-alkylimidazo[1,2-b]pyridazinium-6-yl)thiovinyl]-3-cephem-4-carboxylates and Related Compounds.
作者:TOMOYASU ISHIKAWA、KEIJI KAMIYAMA、YUTAKA NAKAYAMA、YUJI IIZAWA、KENJI OKONOGI、AKIO MIYAKE
DOI:10.7164/antibiotics.54.257
日期:——
In the course of our exploration for a novel cephalosporin derivative having excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), we modified the C-3 linked spacers of cephem derivatives bearing a l-methylimidazo[l, 2-b]pyridazinium-6-yl group at the C-3' position and 2-(5-amino-l, 2, 4-thiadiazol-3-yl)-2(Z)-cyclopentyloxyiminoacetyl group at the C-7 position. The optimal spacers were the (E)-2-vinyl and (E)-2-thiovinyl groups seen in 19a and 29aa, respectively. Their anti-MRSA activity was 16 to 32 times as potent as that of cefozopran (CZOP). Focusing on the (E)-2-vinyl and (E)-2-thiovinyl spacers, we further modified the alkoxyimino groups in the C-7 acyl moiety and the 1-alkylimidazo[l, 2-b]pyridazinium moieties at the C-3' position and investigated the structureactivity relationships (SAR) of the derivatives. Consequently, we selected 7β-[2-(5-aminol, 2, 4-thiadiazol-3-yl)-2(Z)-fluoromethoxyiminoacetamido]-3-[(E)-2-(l-methylimidazo[l, 2-b]pyridazinium-6-yl)thiovinyl]-3-cephem-4-carboxylate (29ca) as a new anti-MRSA parenteral cephalosporin candidate for further biological evaluation. The selected 29ca showed anti-MRSA activity comparable to that of vancomycin (VCM) both in vitro and in vivo, high affinity (IC50=2.7 μg/ml) for penicillin binding protein 2' (PBP2') of MRSA and potent activity against Gram-negative bacteria as well.
在我们探索具有优异抗甲氧西林耐药金黄色葡萄球菌(MRSA)抗菌活性的新的头孢菌素衍生物的过程中,我们对具有l-甲基咪唑[1, 2-b]吡咯噻啉-6-基团的C-3链接间隔物进行了修改,其位于C-3'位置,以及具有2-(5-氨基-1, 2, 4-噻二唑-3-基)-2(Z)-环戊基氧基亚胺乙酰基团的C-7位置。最优间隔物是19a和29aa中的(E)-2-乙烯基和(E)-2-硫乙烯基,分别其抗MRSA活性是头孢佐芬(CZOP)活性的16到32倍。我们针对(E)-2-乙烯基和(E)-2-硫乙烯基间隔物,进一步修改了C-7酰基部分的烷氧亚胺基团和C-3'位置的1-烷基咪唑[1, 2-b]吡咯噻啉基团,并研究了这些衍生物的构效关系(SAR)。因此,我们选择了7β-[2-(5-氨基-1, 2, 4-噻二唑-3-基)-2(Z)-氟甲氧基亚胺乙酰氨基]-3-[(E)-2-(l-甲基咪唑[1, 2-b]吡咯噻啉-6-基)硫乙烯基]-3-头孢菌素-4-羧酸酯(29ca)作为新的抗MRSA注射用头孢菌素候选物进行进一步的生物评价。所选择的29ca在体外和体内的抗MRSA活性与万古霉素(VCM)相当,对MRSA的青霉素结合蛋白2'(PBP2')具有高亲和力(IC50=2.7 μg/ml),并对革兰阴性细菌同样表现出强大的活性。