Table 2. IC₅₀ (μM) of Cephalosporin Conjugates Reported as Mean ± SD^a.

compound	IMP-1	IMP-28	NDM-1	VIM-2
6	3.3 ± 0.2	14 ± 1	77 ± 12	76 ± 11
8	0.47 ± 0.08	0.46 ± 0.04	>100	10 ± 0.5
9	4.7 ± 0.4	1.1 ± 0.2	94 ± 0.2	16 ± 1
10	48 ± 0.7	30 ± 9	51 ± 1	19 ± 1
11	43 ± 3	45 ± 5	>100	73 ± 0.1
12	2.2 ± 0.4	4.3 ± 0.8	>100	49 ± 3
13	>100	>100	72 ± 2	53 ± 12
15	>100	>100	>100	57 ± 9
DPA	29 ± 0.5	29 ± 5	10 ± 0.1	10 ± 0.8

^aAssay used nitrocefin used as the chromogenic substrate. A detailed description of the assay can be found in the Experimental Section.