Design, green synthesis and pharmacological evaluation of novel 5,6-diaryl-1,2,4-triazines bearing 3-morpholinoethylamine moiety as potential antithrombotic agents^*

Figures & data

Figure 1. Currently used oral antiplatelet drugs.

Figure 2. Designing hypothesis for the new compounds by fusing three pharmacophores in a single molecule for antiplatelet and vasodilatory action without ulcerogenesis.

Scheme 1. Green synthesis of 5,6-diaryl-N-morpholinoethyl-1,2,4-triazin-3-amines (3a–3q). Reagents and conditions: (a) thiosemicarbazide, methyl iodide, ionic liquid [Bbim⁺Br⁻]: DMSO (1:10), 70 °C, 10–110 min; (b) 4-(2-aminoethyl)morpholine (4 eq.), neat, 100–110 °C, 2–4 h.

Table 1. Structures and in vitro antiplatelet aggregation activity data of the synthesized 3-substituted 5,6-diaryl-1,2,4-triazines (3a–3q)..

Compd. no.	X	Y	Mol. Form.	% Inhibition of platelet aggregation (in vitro, 10 µg/ml)
3a	H	H	C21H23N5O	63.95
3b	4-Cl	4-Cl	C21H21Cl2N5O	34.79
3c	4-CH3	4-CH3	C23H27N5O	71.25
3d	4-CH3	4-Cl	C22H24ClN5O	75.00
3e	4-Cl	4-CH3	C22H24ClN5O	48.02
3f	H	4-F	C21H22FN5O	68.88
3g	4-F	H	C21H22FN5O	66.93
3h	4-Cl	4-Br	C21H21BrClN5O	39.51
3i	4-Br	4-Cl	C21H21BrClN5O	41.93
3j	4-Cl	4-F	C21H21ClFN5O	68.72
3k	4-F	4-Cl	C21H21ClFN5O	70.16
3l	H	4-Cl	C21H22ClN5O	58.79
3m	4-Cl	H	C21H22ClN5O	36.29
3n	4-CH3	4-NO2	C22H24N6O3	49.68
3o	4-NO2	4-CH3	C22H24N6O3	46.77
3p	4-CH3	3-Cl	C22H24ClN5O	58.87
3q	3-Cl	4-CH3	C22H24ClN5O	62.50
Aspirin	–	–	–	34.00

The bold values suggest the noteworthy/comparable activity of respective compounds.

Table 2. Antithrombotic activity (ex vivo and in vivo) data of the synthesized 3-substituted 5,6-diaryl-1,2,4-triazines (3a–3q) at a dose of 10 mg/kg bw p.o.

Comp. no.	% Inhibition of platelet aggregation (ex vivo)	Thrombus wt. (mg)	% Inhibition of thrombosis	Time to occlusion (min)	Bleeding time (min)
Control	–	6.60	–	15.0	18.0
3a	37.65	4.80	27.27	12.5	17.0
3b	32.53	4.20	36.36	18.0	16.0
3c	19.87	4.00	39.39	21.0	19.5
3d	53.19	4.00	39.39	>30	25.0
3e	44.47	5.00	24.24	12.0	17.5
3f	22.37	4.90	25.75	12.5	24.0
3g	19.11	4.30	34.84	27.0	25.5
3h	23.82	4.90	25.75	20.5	18.0
3i	36.47	4.85	26.51	21.5	20.5
3j	19.94	4.20	36.36	29.0	24.5
3k	17.64	4.25	35.60	29.5	25.0
3l	45.29	4.75	28.03	19.0	20.5
3m	26.17	4.50	31.81	23.5	19.5
3n	36.42	4.25	35.60	21.0	16.5
3o	35.58	4.25	35.60	21.5	16.5
3p	17.64	4.00	39.39	27.0	>30
3q	18.58	4.10	37.87	27.5	>30
Clopidogrel*	84.03	3.00	54.54	>30	>30
Aspirin†	47.80	3.00	54.54	>30	>30

The bold values suggest the noteworthy/comparable activity of respective compounds.

*Clopidogrel used at a dose of 25 mg/kg body weight.

†Aspirin used at a dose of 50 mg/kg body weight.

Figure 3. Effect of compound (3d) and aspirin on gastric mucosa. (a) Control with no gastric lesions; (b) Compound (3d) showing mild gastric lesions (10 mg/kg); (c) Compound (3d) showing moderate gastric lesions (100 mg/kg); (d) Aspirin showing severe gastric lesions (100 mg/kg).

Figure 4. Docking simulations of compound (3d) with active sites of (a) COX-1 (PDB: 2OYE) and (b) COX-2 (PDB: 6COX), respectively.