Design, synthesis and biological evaluation of 4-aminoquinoline derivatives as receptor-interacting protein kinase 2 (RIPK2) inhibitors

Figures & data

Figure 1. Representative inhibitors of RIPK2.

Scheme 1. Synthesis of 4-aminoquinoline-based derivatives. Reagents and conditions: (a) 6-bromo-4-chloroquinoline, amines, tert-butanol, 80 °C, 4 h; (b) boronic acids or boronic esters, Pd(PPh₃)₄, Na₂CO₃, H₂O, 1,4-dioxane, 80 °C, 8 h; (c) 2-pyridineboronic acid, Pd(OAc)₂, DPPF, Cs₂CO₃, CuCl, DMF, 80 °C, 12 h; (d) 6-bromo-4-chloroquinoline, amines, NaH, DMF, 0–40 °C.

Figure 2. Docking study on compound 14 bound within the ATP site of RIPK2 (PDB ID: 6RNA).

Table 1. Modifications in back pocket of RIPK2.

Compd.	R	RIPK2 IC50 (nM)^a
1		243.4 ± 14.8
2		54.8 ± 3.4
3		>1000
4		92.5 ± 22.1
5		31.4 ± 6.2
6		10.7 ± 0.1
7		>1000
8		150.8 ± 30.1
9		421.2 ± 105.9
10		12.2 ± 2.5
11		82.3 ± 12.2
12		22.2 ± 5.2
13		118.2 ± 21.5

^aThe IC₅₀ values are shown as the mean ± SD from two separate experiments. Positive control Ponatinib IC₅₀ = 8.2 ± 2.9 nM.

Table 2. Optimisation on C6 position.

Compd.	R	RIPK2 IC50 (nM)^a
14		5.1 ± 1.6
15		6.0 ± 1.5
16		3.6 ± 1.4
17		1.5 ± 0.3
18		24.0 ± 11.6
19		16.4 ± 1.6
20		8.2 ± 1.6
21		4.1 ± 0.9
22		19.0 ± 6.7
23		9.5 ± 3.7
24		19.6 ± 12.0
25		11.1 ± 3.6
26		9.4 ± 1.1
27		3.7 ± 0.4
28		7.3 ± 3.5
29		17.2 ± 2.3
30		41.7 ± 19.0

^aThe IC₅₀ values are shown as the mean ± SD from two separate experiments. Positive control Ponatinib IC₅₀ = 8.2 ± 2.9 nM.

Table 3. Inhibition of compounds 31–38 on RIPK2.

Compd.	R	RIPK2 IC50 (nM)^a
31		8.1 ± 3.9
32		2.4 ± 0.2
33		12.4 ± 8.9
34		11.0 ± 1.7
35		7.1 ± 4.7
36		7.2 ± 2.6
37		14.5 ± 5.6
38		19.2 ± 0.7

^aThe IC₅₀ values are shown as the mean ± SD from two separate experiments. Positive control Ponatinib IC₅₀ = 8.2 ± 2.9 nM.

Figure 3. The effect of indicated compounds on the secretion of classic proinflammatory cytokine TNF-α in MDP-induced Raw264.7. TNF-α secretion in the supernatant of Raw264.7 cells from controls without stimulated, controls stimulated and compounds treated under stimulated conditions. The concentrations are presented as the mean ± SD. ^###p < 0.001 vs non-stimulated controls group, *p < 0.05, **p < 0.01, ***p < 0.001 vs stimulated controls group, in multivariate analysis.

Table 4. Selectivity, ClogP and LipE of compound 14, 15, 21, 32, 36.

Compd.	RIPK2 IC50 (nM)^a	RIPK1 IR@1µM (%)	ClogP	LipE^b
14	5.1 ± 1.6	<1	3.89	4.40
15	6.0 ± 1.5	<1	3.95	4.27
21	4.1 ± 0.9	<1	3.40	4.99
32	2.4 ± 0.2	19	4.32	4.30
36	7.2 ± 2.6	<1	4.47	3.67
P5	2.6 ± 1.2	–	1.88	6.70

^aThe IC₅₀ values are shown as the mean ± SD from two separate experiments. Positive control Ponatinib IC₅₀ = 8.2 ± 2.9 nM. ^bLipE = pIC₅₀ − ClogP.

Figure 4. Compound 14 selectivity is represented in a dendrogram view of the human kinome phylogenetic tree²⁵. Red: >90% inhibition (5 kinase). Orange: 50 − 90% inhibition (3 kinases). Green: <50% inhibition. RIP2 kinase (red) inhibited by 97%.

Eid S, Turk S, Volkamer A, et al. Kinmap: a web-based tool for interactive navigation through human kinome data. BMC Bioinformatics. 2017;18(1):16.

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