title: Effect of side-chain substitution of a CH2 group by sulfur on the antimicrobial activity of natural penicillins and cephalosporins.
abstract: The S-carboxymethyl-D-cysteine side-chain analogs of cephalosporin C and deacetoxycephalosporin C were found to have markedly increased in vitro activity against Gram-positive and Gram-negative bacteria compared to the natural antibiotics. The S-carboxymethyl-L-cysteine analogs were less active than the S-carboxymethyl-D-cysteine analogs but against most organisms tested, still more active than the natural compounds. The effect of replacement of CH2 with S was less dramatic in the case of penicillin N and isopenicillin N. The S-carboxymethyl-D-cysteine analog of deacetoxycephalosporin C was found to be orally available in rats.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001419:Bacteria / Q000187:drug effects*; D001682:Biological Availability; D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D010406:Penicillins / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship
chemical_list: D002511:Cephalosporins; D010406:Penicillins