Table 2. CXCR1/2 Antagonistic Activity for Compounds B1–B10.

	R1	CXCR1 IC50 (μM)a	CXCR2 IC50 (μM)a	ratiob
2	Ph	4.7	0.006	778
B1	H	>100	29.7	3
B2	4-Cl-Ph	38.1	0.915	42
B3	3-Cl-Ph	47.8	0.305	157
B4	2-Cl-Ph	21.7	0.054	402
B5	4-F-Ph	∼100	2.19	∼46
B6	methyl	>100	0.269	>372
B7	ethyl	∼100	0.140	∼714
B8	propyl	14.7	0.068	216
B9	n-butyl	54.6	0.043	1270
B10	isobutyl	41.8	0.305	137
SCH527123		0.16	0.01	16

^aThe IC₅₀ values are an average of triplicate determinations.

^bRatio = CXCR1 IC₅₀/CXCR2 IC₅₀.