1 CSC 4-(3-acetoxymethyl-2-carboxy-8-oxo-5-thia-1-aza-bicyclo[4.2.0]oct-2-en-7-ylcarbamoyl)-1-carboxy-butyl-ammonium 1.000 2 P1C Deacetoxycephalosporin-C 0.857 3 CEN 7beta-(4carboxybutanamido) cephalosporanic acid 0.800 4 APV 6-(5-amino-5-carboxy-pentanoylamino)-3-hydroxymethyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid 0.733 5 IP1 Isopenicillin N 0.733