Table 2. Inhibition of p38α and PBMC Cytokine Release by 5-(2,6-Dichlorophenyl)-2-(arylthio)-6H-pyrimido[1,6-b]pyridazin-6-ones.

compd	R5	R6	R7	p38α IC50 (μM)	PBMC IL-1β IC50 (μM)	PBMC TNFα IC50 (μM)
21	H	H	H	0.25	0.40	0.45
22	H	H	Me	1.4	0.37	0.87
23	H	H	F	0.123	0.099	0.293
24	H	F	H	0.45	0.44	0.72
25	H	Cl	H	0.28	0.35	0.90
26	H	Me	H	1.4	0.21	0.28
27	Et	H	H	0.75	0.98	2.8
28	Me	H	H	0.20	0.33	3.7
29	OH	H	H	0.36	0.14	0.49
30	H	Cl	Cl	0.8	0.97	1.2
31	H	Me	Me	1.9	2.4	3.5
32	H	Cl	F	0.5	0.18	0.48
33	NH2	H	F	0.22	0.28	1.2
34	Cl	H	F	0.036	0.053	0.275
3	F	H	F	0.009	0.045	0.051
35	Me	H	Cl	0.18	0.18	0.16
36	Me	H	Me	0.26	0.69	0.32