Synthesis and in vivo anti-ulcer evaluation of some novel piperidine linked dihydropyrimidinone derivatives

Figures & data

Scheme 1. Synthetic route of compounds (1–18).

Figure 1. Single crystal X-ray structure of enaminone (III).

Figure 2. Single crystal X-ray structure of compound 13.

Table 1. The effect of compounds on gastric lesions induced by 80% ethanol (mean ± SE).

				Compounds
	80% EtOH	Ranitidine 50 (mg/kg)		12.5 (mg/kg)		25 (mg/kg)		50 (mg/kg)
Compounds	Mean ± SE	Mean ± SE	% Change	Mean ± SE	% Change	Mean ± SE	% Change	Mean ± SE	% Change
1	7.5 ± 0.28	1.75 ± 0.47***	76.66	7.25 ± 0.47	–	6.75 ± 0.25	–	6.25 ± 0.47*	–
2	7.00 ± 0.40	2.00 ± 0.40***	71.42	6.00 ± 0.16	14.2	5.50 ± 0.28*	21.4	5.00 ± 0.16**	28.5
3	7.50 ± 0.28	2.00 ± 0.40	73.3	5.0 ± 0.40***	33.33	3.5 ± 0.2***	53.3	3.00 ± 0.4***	60.0
4	6.75 ± 0.25	2.25 ± 0.47***	66.6	6.75 ± 0.25	–	5.50 ± 0.08	–	6.25 ± 0.25	7.40
5	7.0 ± 0.40	2.0 ± 0.4***	71.4	7.0 ± 0.4	–	6.5 ± 0.28	7.1	6.25 ± 0.47	10.7
6	7.0 ± 0.40	2.5 ± 0.28***	64.2	7.25 ± 0.25	–	6.5 ± 0.2	7.1	6.25 ± 0.25	10.7
7	7.5 ± 0.28	2.75 ± 0.25***	63.3	6.75 ± 0.25	10	5.5 ± 0.2***	26.6	5.0 ± 0.4***	33.3
8	7.5 ± 0.28	2.2 ± 0.4***	70	5.0 ± 0.4***	33.3	3.7 ± 0.4***	50	3.5 ± 0.2***	53.3
9	7.0 ± 0.4	2.2 ± 0.6***	67.8	7.2 ± 0.25	–	6.5 ±	2	6.0 ± 0.4	–
10	7.0 ± 0.4	2.0 ± 0.5***	71.4	6.0 ± 0.4	14	5.75 ± 0.2*	17.8	5.5 ± 0.2*	21.4
11	7.7 ± 0.25	1.7 ± 0.4***	77.4	6.0 ± 0.4**	22.5	4.0 ± 0.1***	48.3	3.0 ± 0.4***	61.2
12	7.0 ± 0.4	2.7 ± 0.2***	60.7	7.0 ± 0.4	–	6.5 ± 0.2	7.1	6.25 ± 0.4	10.7
13	7.0 ± 0.40	1.7 ± 0.4***	75	7.0 ± 0.4	–	6.5 ± 0.2	7.1	6.0 ± 0.4	14.2
14	7.2 ± 0.25	1.70.4***	75.8	6.5 ± 0.2	10.3	5.25 ± 0.4**	27.5	4.5 ± 0.2***	37.9
15	7.7 ± 0.2	2.5 ± 0.2***	67.7	5.0 ± 0.4***	35.4	3.5 ± 0.2***	54.8	2.5 ± 0.2***	67.7
16	7.0 ± 0.4	2.0 ± 0.4***	71.4	6.5 ± 0.2	7.1	5.75 ± 0.4	17.8	5.5 ± 0.2*	21.4
17	7.2 ± 0.2	2.75 ± 0.2***	62	7.00 ± 0.4	–	5.2 ± 0.4**	27.5	4.5 ± 0.4**	37.9
18	7.7 ± 0.2	2.0 ± 0.4***	74.1	7.2 ± 0.2	6.4	6.5 ± 0.2*	16.1	6.0 ± 0.4**	22.5

Six rats were used in each group.

* p < .05,

** p < .01,

*** p < .001 vs. control group, Student’s t-test.

Table 2. The effect of compounds on gastric lesions induced by necrotising agents (mean ± SE).

		Ulcer index
Treatment	Dose (mg/kg, i.p.)	80% EtOH	0.2 mol/l NaOH	25% NaCl
Control	1 ml	7.66 ± 0.21	7.33 ± 0.21	6.83 ± 0.30
Ranitidine (standard)	50	1.50 ± 0.22***	1.00 ± 0.36***	1.16 ± 0.30***
3	12.5	6.83 ± 0.30*	4.50 ± 0.22***	5.16 ± 0.47*
3	25	4.16 ± 0.30***	2.66 ± 0.33***	2.83 ± 0.30***
3	50	3.00 ± 0.36***	1.83 ± 0.40***	1.66 ± 0.33***
8	12.5	7.00 ± 0.36	6.66 ± 0.33	6.00 ± 0.25
8	25	6.50 ± 0.42*	5.33 ± 0.71*	5.00 ± 0.44**
8	50	5.83 ± 0.30***	3.83 ± 0.30***	3.33 ± 0.30***
11	12.5	7.16 ± 0.30	6.33 ± 0.42	6.00 ± 0.36
11	25	6.16 ± 0.30**	3.66 ± 0.21***	4.83 ± 0.40**
11	50	4.83 ± 0.30***	3.66 ± 0.33***	3.83 ± 0.30***
15	12.5	4.66 ± 0.33***	3.50 ± 0.22***	3.66 ± 0.33***
15	25	2.66 ± 0.33***	2.16 ± 0.30***	2.66 ± 0.33***
15	50	2.16 ± 0.30***	1.33 ± 0.42***	1.66 ± 0.33***

Six rats were used in each group.

* p < .05,

** p < .01,

*** p < .001 vs. control group, Student’s t-test.

Table 3. The effect of compounds on indomethacin-induced gastric mucosal lesions (mean ± SE).

Treatment	Dose (mg/kg, i.p.)	Ulcer index
Control (indomethacin)	30	35.66 ± 1.05
Ranitidine (standard)	50	8.50 ± 0.56***
3	12.5	29.83 ± 1.66*
3	25	20.50 ± 1.52***
3	50	12.66 ± 1.28***
8	12.5	33.00 ± 1.52
8	25	29.50 ± 1.58*
8	50	28.66 ± 1.45**
11	12.5	33.00 ± 1.03
11	25	30.66 ± 1.28*
11	50	28.33 ± 1.78**
15	12.5	26.33 ± 1.30***
15	25	21.50 ± 1.33***
15	50	14.50 ± 1.64***

Six rats were used in each group.

* p < .05,

** p < .01,

*** p < .001 vs. control (indomethacin only) group, Student’s t-test.

Table 4. The effect of compounds on hypothermic restraint stress-induced intraluminal bleeding and gastric lesion in rats (mean ± SE).

Treatments (n = 6)	Dose (mg/kg, i.p.)	Intraluminal bleeding score	Gastric lesion ulcer index
Control		4.16 ± 0.30	33.00 ± 1.26
Ranitidine (standard)	50	0.83 ± 0.30***	9.66 ± 0.95***
3	12.5	2.83 ± 0.30*	24.16 ± 1.70**
3	25	1.50 ± 0.22***	17.66 ± 0.76***
3	50	1.16 ± 0.30***	13.83 ± 0.60***
8	12.5	3.50 ± 0.42	29.83 ± 1.50
8	25	3.33 ± 0.21*	27.66 ± 1.60*
8	50	2.50 ± 0.42*	18.66 ± 0.55***
11	12.5	3.66 ± 0.33	29.83 ± 1.51
11	25	2.66 ± 0.33**	29.00 ± 1.21*
11	50	2.00 ± 0.36***	21.00 ± 0.51***
15	12.5	2.16 ± 0.30***	25.66 ± 1.08**
15	25	1.66 ± 0.21***	16.66 ± 0.33***
15	50	1.33 ± 0.33***	12.33 ± 0.84***

Six rats were used in each group.

* p < .05,

** p < .01,

*** p < .001 control (distilled water) group, Student’s t-test.

Table 5. The effect of compounds on gastric secretion, acidity and gastric lesion index in pylorus-ligated shay rats (mean ± SE).

Treatment	Dose (mg/kg, i.p.)	Volume of gastric content (ml)	Titratable acidity (mEq/l)	Ulcer index
Control	–	11.23 ± 0.18	173.88 ± 5.12	3.33 ± 0.21
Ranitidine (standard)	50	4.06 ± 0.18***	58.88 ± 1.85***	0.50 ± 0.22***
3	12.5	9.03 ± 0.24***	153.88 ± 5.40*	2.33 ± 0.33*
3	25	6.31 ± 0.25***	97.77 ± 2.93***	1.83 ± 0.30**
3	50	4.63 ± 0.22***	84.84 ± 2.38***	1.16 ± 0.30***
8	12.5	10.50 ± 0.34	161.11 ± 4.36	3.16 ± 0.30
8	25	9.36 ± 1.22**	133.33 ± 3.22***	2.50 ± 0.22*
8	50	6.46 ± 0.16***	115.00 ± 5.75***	2.00 ± 0.13*
11	12.5	10.20 ± 0.29*	160.55 ± 3.48	2.83 ± 0.30
11	25	7.35 ± 0.19***	141.11 ± 6.30**	2.50 ± 0.42
11	50	6.63 ± 0.21***	116.66 ± 4.63***	2.33 ± 0.21**
15	12.5	6.68 ± 0.18***	116.11 ± 2.64***	1.83 ± 0.30**
15	25	5.50 ± 0.24***	86.11 ± 3.98***	1.50 ± 0.22***
15	50	4.76 ± 0.23***	73.33 ± 2.43***	1.00 ± 0.36***

Six rats were used in each group.

* p < .05,

** p < .01,

*** p < .001 vs. control (distilled water) group, Student’s t-test.

Figure 3. (A) Treatment with 80% ethanol only, showing mucosal ulceration. (B) Treatment with ranitidine (50 mg/kg) showing normal mucosa. (C) Treatment with compound 3 (50 mg/kg) showing intact mucosa with mild ulceration. (D) Treatment with compound 8 (50 mg/kg) showing intact normal mucosa. (E) Treatment with compound 11 (50 mg/kg) showing intact normal mucosa. (F) Treatment with compound 15 (50 mg/kg) showing intact normal mucosa.

Table 6. The effect of compounds on the change in gastric wall mucus in stomach tissue induced by 80% ethanol (mean ± SE).

Treatment	Dose (mg/kg, i.p.)	Gastric wall mucus (mean ± SE, µg/g)
Control (normal)	–	276.53 ± 10.19
80% EtOH	1 ml	201.91 ± 8.32***^,^a
Ranitidine (standard)	50	287.24 ± 10.70***^,^b
3	12.5	242.08 ± 4.03*^,^b
3	25	241.66 ± 6.91**^,^b
3	50	256.18 ± 8.39***^,^b
8	12.5	206.39 ± 7.18^b
8	25	212.00 ± 6.40^b
8	50	244.65 ± 5.36**^,^b
11	12.5	192.87 ± 12.84^b
11	25	224.88 ± 4.64*^,^b
11	50	237.36 ± 3.31**^,^b
15	12.5	231.78 ± 4.77*^,^b
15	25	248.09 ± 7.69**^,^b
15	50	275.32 ± 5.37***^,^b

Six rats were used in each groups.

* p < .05,

** p < .01,

*** p < .001 vs. control (80% ethanol only) group, Student’s t-test.

^a As compared to the control group.

^b As compared to 80% ethanol only group.

Figure 4. Light micrographs showing the effect of compounds 3, 8, 11 and 15 on ethanol-induced gastric lesions of rats. (A) Treatment with ethanol (PAS); (B) pre-treatment with standard drug ranitidine (50 mg/kg) (PAS); (C) pre-treatment with compound 3 (50 mg/kg) (PAS); (D) pre-treatment with compound 8 (50 mg/kg) (PAS); (E) pre-treatment with compound 11 (50 mg/kg) (PAS); (F) pre-treatment with compound 15 (50 mg/kg) (PAS).

Table 7. The effect of compounds on the levels of MDA, NP-SH and TP in stomach tissue induced by 80% ethanol (mean ± SE).

Treatment	Dose (mg/kg, i.p.)	MDA (nmol/g)	NP-SH (nmol/g)	Total protein (g/l)
Control (normal)	–	1.14 ± 0.06	5.03 ± 0.10	122.55 ± 3.23
80% EtOH	1 ml	7.42 ± 0.30***^,^a	3.22 ± 0.20***^,^a	47.50 ± 2.08***^,^a
Ranitidine (standard)	50	1.65 ± 0.02***^,^b	4.24 ± 0.15**^,^b	104.59 ± 1.59***^,^b
3	12.5	4.47 ± 0.44***^,^b	3.15 ± 0.20^b	58.68 ± 3.19*^,^b
3	25	3.07 ± 0.16***^,^b	4.23 ± 0.23**^,^b	74.65 ± 3.79***^,^b
3	50	1.95 ± 0.05***^,^b	4.56 ± 0.17***^,^b	95.80 ± 1.51***^,^b
8	12.5	6.63 ± 0.26^b	3.49 ± 0.16^b	45.90 ± 1.14^b
8	25	4.83 ± 0.24***^,^b	3.61 ± 0.12^b	55.88 ± 1.71*^,^b
8	50	3.75 ± 0.07***^b	4.61 ± 0.27**^,^b	66.26 ± 1.47***
11	12.5	5.16 ± 0.22***^,^b	2.93 ± 0.11^b	53.89 ± 1.48*^,^b
11	25	3.99 ± 0.17***^,^b	3.40 ± 0.18^b	64.27 ± 2.08***^,^b
11	50	3.36 ± 0.08***^,^b	4.35 ± 0.11***^,^b	72.25 ± 1.43***^,^b
15	12.5	3.51 ± 0.08***^,^b	3.38 ± 0.07^b	71.45 ± 1.43***^,^b
15	25	2.72 ± 0.10***^,^b	4.29 ± 0.24**^,^b	81.43 ± 3.65***^,^b
15	50	1.90 ± 0.06***^,^b	4.92 ± 0.30***^,^b	96.60 ± 1.18***^,^b

Six rats were used in each groups,

* p < .05,

** p < .01,

*** p < .001 vs. control (80% ethanol only) group, Student’s t-test.

^a As compared to the control group.

^b As compared to 80% ethanol only group.

Table 8. Determination of LD₅₀ of active compounds by Karber method.

	Group	Dose (mg/kg)	Number of animals	DD (a)	Dead	MM (b)	Pro.(a*b)
Compound 3	1	5	10		0
	2	25	10	20	0	0	0
	3	50	10	25	2	1	25
	4	100	10	50	5	3.5	175
	5	200	10	100	8	6.5	650
	6	300	10	100	10	9	900
						Total product	1750
						LD50 = 125 mg/kg
Compound 8	1	5	10		0
	2	25	10	20	2	1	20
	3	50	10	25	6	4	100
	4	100	10	50	9	7.5	375
	5	200	10	100	10	9.5	950
	6	300	10	100	10	10	1000
	–	–	–	–	–	Total product	2445
						LD50 = 55.5 mg/kg
Compound 15	1	5	10		0	0
	2	25	10	20	1	0.5	10
	3	50	10	25	3	2	50
	4	100	10	50	4	3.5	175
	5	200	10	100	9	6.5	650
	6	300	10	100	10	9.5	950
	–	–	–	–	–	Total product	1835
						LD50 = 116.5 mg/kg

DD: dose difference; MM: mean mortality; Factor = last lethal dose – (total product/number of animals).