Table 2.

Inhibitory activities of conjugates 1–6: COX inhibition as determined for COX-1 and COX-2; cytotoxicity as determined in proliferation assays for tumor cell lines HCT 116 and MDA-MB-231 for an incubation time of 72 h.

Compd	IC50 [µm]
	oCOX-1[a]	mCOX-2[b]	HCT 116[c]	MDA-MB-231[d]
cisplatin	–	–	12.0[e]	20.0[e]
1	1.033	0.563	53.0	39.8
1[f]	–	–	56.0	47.4
2	>25	>25	66.4	45.5
3	4.1[e]	0.045[e]	1.1[e]	1.65[e]
4	>25[e]	>25[e]	0.065[e]	0.05[e]
5	0.745	>25	1.3	0.55
6	>25	>25	0.31	0.33

^[a]Ovine COX-1.

^[b]Murine COX-2.

^[c]Colorectal carcinoma (no COX-2 expression).

^[d]Breast adenocarcinoma (COX-2 expression).

^[e]As determined previously.^[9]

^[f]Pre-incubation of stock in DMSO for 24 h before dilution with medium. For the proliferation assays, all compounds except cisplatin were dissolved in DMSO before dilution with culture medium. Cisplatin was directly dissolved in culture medium.^[9]

Values are the mean of duplicates (COX assay) or six replicates (proliferation assay), with standard deviation <10% (and <5% for 95% of the values).