Design, synthesis, and apoptotic antiproliferative action of new 1,2,3-triazole/1,2,4-oxadiazole hybrids as dual EGFR/VEGFR-2 inhibitors

Figures & data

Figure 1. Structure of anticancer 1,2,4-oxadiazoles I–III.

Figure 2. Structures of previously reported compounds 6a–o and newly synthesised 7a–o.

Scheme 1. Synthetic pathway of compounds 7a–o

Table 1. Antiproliferative activity of compounds 7a–o and Erlotinib.

Comp.	Cell viability% (50 µM)	R	Antiproliferative activity IC50 ± SEM (nM)
			A-549	MCF-7	Panc-1	HT-29	Average (GI50)
7a	90	H	94 ± 9	98 ± 9	96 ± 9	96 ± 9	96
7b	91	4-F	102 ± 10	106 ± 10	104 ± 10	104 ± 10	104
7c	89	4-Cl	87 ± 8	94 ± 9	90 ± 9	92 ± 9	90
7d	88	4-Br	80 ± 8	84 ± 8	80 ± 8	82 ± 8	82
7e	91	4-CH3	98 ± 9	102 ± 9	100 ± 10	102 ± 10	101
7f	90	4-OMe	48 ± 4	51 ± 5	48 ± 4	46 ± 4	48
7g	87	4-CF3	66 ± 6	68 ± 6	68 ± 6	66 ± 6	67
7h	90	3-Cl	40 ± 4	44 ± 4	40 ± 4	42 ± 4	42
7i	89	3-Br	36 ± 3	39 ± 3	37 ± 3	37 ± 3	37
7j	91	2,4-Di-Cl	33 ± 3	36 ± 3	34 ± 3	36 ± 3	35
7k	89	3,4-Di-OMe	30 ± 3	35 ± 3	32 ± 3	32 ± 3	32
7l	88	3,4,5-Tri-OMe	26 ± 2	30 ± 3	28 ± 2	28 ± 2	28
7m	87	2,3-C4H4	42 ± 4	48 ± 4	46 ± 4	44 ± 4	45
7n	89	3,4-C4H4	68 ± 6	74 ± 7	70 ± 7	72 ± 7	71
7o	91	1,3-Dioxole	74 ± 7	80 ± 8	78 ± 7	76 ± 7	77
Erlotinib	–	–	30 ± 3	40 ± 3	30 ± 3	30 ± 3	33

Figure 3. GI₅₀ of compounds 7f, 7k, and 7l compared to Erlotinib.

Figure 4. GI₅₀ of compounds 7b, 7c, 7d, 7h, 7i, 7j and Erlotinib.

Table 2. IC₅₀ values of compounds 7h, 7i, 7j, 7k, 7l, Erlotinib and Sorafenib against EGFR and VEGFR-2.

Compd. no.	EGFR inhibition IC50 ± SEM (nM)	VEGFR-2 inhibition IC50 ± SEM (nM)
7h	105 ± 10	6.90 ± 0.07
7i	97 ± 09	5.50 ± 0.05
7j	89 ± 08	4.70 ± 0.04
7k	82 ± 07	3.80 ± 0.03
7 l	76 ± 06	2.40 ± 0.02
Erlotinib	80 ± 05	–
Sorafenib	–	0.17 ± 0.01

–, not determined.

Table 3. Caspase-3, caspase-8, Bax, and Bcl-2 levels of compounds 7j, 7k, and 7l.

Compd. no.	Caspase-3		Caspase-8		Bax		Bcl-2
	Conc (Pg/mL)	Fold change	Conc (ng/mL)	Fold change	Conc (Pg/mL)	Fold change	Conc (ng/mL)	Fold reduction
7j	460 ± 4	7.0	2.00	22	291	32	0.95	5
7k	530 ± 5	8.0	2.30	25	310	34	0.80	6
7l	587 ± 5	9.0	2.55	28	362	40	0.60	8
Staurosporine	465 ± 4	7.0	1.85	21	288	32	1.00	5
Control	65	1.0	0.09	1	9	1	5.00	1

Table 4. Ligand–protein complex interactions of the tested compounds 7h, 7i, 7j, 7k, and 7l within the active site of EGFR.

Compd.	MOE score (kcal/mol)	Hydrogen bond interactions	Hydrophobic interactions	Pi–H interactions
Erlotinib	−10.70	Met769	Leu694, Leu820, Val702, Gly722, Thr766, Thr830	Leu694
7h	−8.18	–	Lys721, Asp831, Val702, Leu820, Leu694, Phe699, Gly772	Gly772, Cys773
7i	−8.45	Leu764	Lys721, Asp831, Leu820, Leu694, Phe699, Gly772	Leu820
7j	−8.77	–	Gly772 Lys721, Asp831, Val702, Leu820, Leu694, Phe699	Gly772, Leu820
7k	−9.52	–	Phe699, Gly772 Lys721, Asp831, Val702, Leu820, Leu694	Gly772
7l	−9.57	Lys721	Leu694, Phe699, Gly772 Lys721, Asp831, Val702, Leu820	Leu694

Figure 5. Docking representation models of compound 7k, 7l, and Erlotinib within the binding site of EGFR (H-bond: blue dashed lines, Pi–H; green dashed lines). (A) 3D-docked model of compound 7k (cyan) showing the protein surface (grey); (B) 2D-docked model of compound 7k; (C) 3D-docked model of compound 7l (cyan) showing the protein surface (grey); (D) 2D-docked model of compound 7l; (E) 3D-docked model of compound Erlotinib (pink) showing the protein surface (grey); (F) 2D-docked model of compound Erlotinib.

Figure 6. Docking representation model of compound 7h (cyan) aligned with compound 7i (pink) showing the protein surface (grey) of the site of EGFR (H-bond or halogen bond: blue dashed lines, Pi–H; green dashed lines).

Figure 7. Docking representation model of compounds 7k and 7l within the binding site of VEGFR-2 (H-bond: blue dashed lines, Pi–H; green dashed lines). (A) 3D-docked model of compound 7k (yellow) aligned with compound 7l (cyan) showing the lipophilicity surface of active site (purple; hydrophilic, white; neutral; green; lipophilic); (B) 2D-docked model of compound 7k; (C) 2D-docked model of compound 7l.

Table 5. Ligand–protein complex interactions of the tested compounds 7h, 7i, 7j, 7k, and 7l within the active site of VEGFR-2.

Compd.	MOE score (kcal/mol)	Hydrogen bond interactions	Hydrophobic interactions	Pi–H interactions
Sorafenib	−10.73	Cys919, Glu885	Val916, Leu889, Leu840, Asp1046, Cys1045 and Phe1047	Phe1047
7h	−8.24	Asp1046	Leu889, Leu840, Asp1046, Cys1045 and Phe1047	Lys868
7i	−8.11	Asp1046	Val916, Leu889, Leu840, Asp1046, Cys1045 and Phe1047	Leu840 Leu889, Lys868, Asp1046
7j	−7.92	Asp1046	Val916, Leu889, Leu840, Asp1046, Cys1045	…………………
7k	−8.71	Asp1046	Val916, Leu889, Leu840, Asp1046, Cys1045	Lys868, Leu840
7l	−9.10	Asp1046	Phe1047, Val916, Leu889, Leu840, Asp1046, Cys1045	Lys868, Leu840

Figure 8. (A) Binding mode of compound 7l (cyan) to active site of EGFR showing DFG motif in purple. (B) Binding mode of compound 7l (cyan) to active site of VEGFR-2 showing DFG motif in purple.

Table 6. Physicochemical and pharmacokinetic properties (Lipinski parameters) of compounds 7h, 7i, 7j, 7k, and 7l.

Compd.	MW	^nROTB	HBA	HBD	Violations	MR	TPSA	log P
7h	338	4	5	0	0	89.5	70	3.33
7i	382	4	5	0	0	92.2	70	3.43
7j	372	4	5	0	0	94.5	70	3.85
7k	363	6	7	0	0	97.5	88	2.77
7l	393	7	8	0	0	103.9	97	2.76

Table 7. ADME properties of compounds 7h, 7i, 7j, 7k, and 7l.

Compd.	GI abs.	BBB	P-gp substrate	CYP1A2 inhibitor	CYP2C19 inhibitor	CYP2C9 inhibitor	CYP2D6 inhibitor	CYP3A4 inhibitor
7h	High	Yes	No	Yes	Yes	Yes	No	No
7i	High	Yes	No	Yes	Yes	Yes	No	No
7j	High	Yes	No	Yes	Yes	Yes	No	No
7k	High	No	No	Yes	Yes	Yes	No	Yes
7l	High	No	No	Yes	Yes	Yes	No	Yes