Effect of 6-Benzoyl-benzothiazol-2-one scaffold on the pharmacological profile of α-alkoxyphenylpropionic acid derived PPAR agonists

Figures & data

Figure 1. Design of α–alkoxyphenylpropionic acid derivatives bearing various central nitrogen heterocycles.

Scheme 1. Synthesis of 5-benzoyl-3,3-difluoro-1,3-dihydro-2H-indol-2-one 11. Reagents and conditions: (a) DAST, DCM, r.t.; (b) i: i-PrMgCl, n-BuLi, dry THF, 0 °C; ii: benzaldehyde, −78 °C; (c) Dess-Martin periodinane, DCM, r.t.

Scheme 2. Synthesis of optically pure α–alkoxyphenylpropionic acids 21, 22. Reagents and conditions: (a) ethanol or trifluoroethanol [Rh(OAc)₂]₂,toluene, reflux; (b) 1,2-bromo-chloroethane, K₂CO₃, CH₃CN, reflux; (c) NaH, dry THF, 0 °C to r.t.; (d) H₂, Pd/C, ethanol, r.t.; (e) LiOH, THF/H₂O, r.t.; (f) 1-ethyl-3–(3-dimethylaminopropyl)-carbodiimide hydrochloride, triethylamine, HOBT, (S)-(-)-2-phenylglycinol, DCM, 0 °C to r.t.; (g) 5 M H₂SO₄, dioxane/H₂O, reflux.

Scheme 3. Synthesis of PPAR agonists 31–38. Reagents and conditions: (a) K₂CO₃, DMF, 120 °C; (b) LiOH, THF/H₂O, r.t.

Scheme 4. Synthesis of optically pure and oxime derived PPAR agonists 39–46. Reagents and conditions: (a) K₂CO₃, 17a or 17 b, DMF, 120 °C; (b) LiOH, THF/H₂O, r.t; (c) hydroxylamine hydrochloride or O-methylhydroxylamine hydrochloride, pyridine, reflux; (d) NaH, 21a,b or 22a,b, HMPA, r.t.

Table 1. In vitro profile of compounds 31–38 on PPARγ affinity and PPARα/γ transactivation.

Cmpd	X	n	Pos^a	Ki (nM)^b	hPPAR gene reporter
					αGal4 (%)^c	αEC50 (nM)^d	γGal4 (%)^c	γEC50 (nM)^d
31	S	0	5	8	81	256	145	61
32a	S	0	6	4	100	2400	89	15
33	S	1	6	220	19	10000	69	219
34	S	1	7	4	116	2050	97	37
35	O	1	6	3	97	10,000	119	2
36	O	1	7	1	80	10,000	113	80
37	CH2	0	5	6.5	100	10,000	60	40
38	CF2	0	5	4	89	10,000	75	5
rosi^e				8	28	10,000	100	4
mura^f				2	84	595	128	3
WY14643				/	100	10,000	N.A.	N.A.

^a Pos: position of the benzoyl substitution on the heterocycle.

^b hPPARγ binding affinity: K_i values were calculated according to the equation K_i = IC₅₀/(1 + [L]/K_d), where IC₅₀ is the concentration of test compound required to inhibit 50% of the specific binding of the radioligand, [L] is the concentration of the radioligand used, and K_d is the dissociation constant for the radioligand at the PPARγ receptor.

^c Efficiency: Emax was the maximal PPAR fold activation relative to maximum activation obtained with WY14643 (10 µM) and rosiglitazone (1 μM) corresponded to 100% in GAL4 chimeric hPPARα and hPPARγ system.

^d EC₅₀^: Concentration required to induce 50% maximum activity of tested compound.

^e Rosiglitazone.

^f Muraglitazar.

NA: not active.

Table 2. In vitro profile of compounds 32, 39–46 on PPARγ affinity and PPARα/γ transactivation.

Cmpd	X	R	Stereo	Ki (nM)^b	hPPAR gene reporter
					αGal4 (%)^c	αEC50 (nM)^d	γGal4 (%)^c	γEC50 (nM)^d
32a	O	CH3	Rac	4	100	2400	89	15
39a	NOH	CH3	Rac	2	129	10,000	91	24
39b	NOH	CF3	Rac	165	29	10,000	44	10
40a	NOCH3	CH3	Rac	4	159	129	87	2
40b	NOCH3	CF3	Rac	1.3	56	180	95	7
41a	O	CH3	S	0.5	166	522	142	8
42a	O	CH3	R	70	0	10,000	39	300
43a	NOH	CH3	S	0.5	153	10,000	123	16
44a	NOCH3	CH3	S	0.7	154	32	115	2
44b	NOCH3	CF3	S	3	59	525	150	0.9
45a	NOH	CH3	R	210	30	10,000	66	799
46a	NOCH3	CH3	R	86	124	1480	87	558
46b	NOCH3	CF3	R	33	117	1665	116	9
rosi^e				8	28	10,000	100	4
mura^f				2	84	595	128	3
WY14643				/	100	10,000	N.A.	N.A.

^a Pos: position of the benzoyl substitution on the heterocycle.

^b K_i values were calculated according to the equation K_i = IC₅₀/(1 + [L]/K_d), where IC₅₀ is the concentration of test compound required to inhibit 50% of the specific binding of the radioligand, [L] is the concentration of the radioligand used, and K_d is the dissociation constant for the radioligand at the PPARγ receptor.

^c Potency: Emax was the maximal PPAR fold activation relative to maximum activation obtained with WY14643 (10 µM) and rosiglitazone (1 μM) corresponded to 100% in GAL4 chimeric hPPARα and hPPARγ system.

^d EC₅₀^: Concentration required to induce 50% maximum activity of tested compound.

^e Rosiglitazone.

^f Muraglitazar.

NA: not active.

Figure 2. Predicted binding mode of (A) (S)-34 (pink) and (S)-36 (cyan) and (C) (S)-33 (pink) and (S)-35 (cyan) enantiomers with PPARγ LBD (PDB id 1I7I). Key amino acid side chains are shown in white stick format and are labelled and hydrogen bonds are shown in red dotted lines. Overlapping and molecular surface maps of (B) (S)-34 (pink) and (S)-36 (cyan) and (D) (S)-33 (pink) and (S)-35 (cyan) enantiomers with PPARγ LBD (PDB id 1I7I). The protein and key amino acid side chains are shown in white rounded ribbon and white stick format, respectively. The molecular surface maps are shown in grey.

Table 3. In vivo efficacy of compounds 39a,b, 40a,b, 43a, 44a,b, 45a in ob/ob mice animal models.

		Change	(%)^a
Cmpd	TG^b	Gly^c	Ins^d	ΔBW^e
39a	−69	−49	−34	−10
39b	−30	−18	10	75
40a	−83	−58	−76	188
40b	−54	−37	−55	−70
43a	−33	−55	−29	113
44a	−79	−46	−81	177
44b	−69	−36	−89	−17
45a	21	−7	51	328
rosi^f	−46	−57	−73	100
mura^g	−34	−46	−46	206

^aPercent change versus control for ob/ob mice at day 4.

^bTriglycerides.

^cGlycemia.

^dInsulin.

^eBody weight variation between day 0 and day 4 are expressed in% of rosiglitazone in the same study.

^fRosiglitazone.

^gMuraglitazar.