Design, synthesis and biological evaluation of novel diarylpyridine derivatives as tubulin polymerisation inhibitors

Figures & data

Figure 1. Chemical structures of CA-4, CA-4P, and some pyridine derivatives.

Figure 2. The rational design of target compounds.

Scheme 1. Reagents and conditions (a) iPrMgCl^.LiCl, iodine, piperidine, THF, –10 to 5 °C, 10 min; (b) 3,4,5-trimethoxybenzeneboronic acid, Pd(PPh₃)₄, K₂CO₃, 1,4-dioxane/H₂O = 3/1, N₂ atmosphere, 126 °C, M.W., 25 min; (c) substituted phenylboronic acid, Pd(PPh₃)₄, K₂CO₃, 1,4-dioxane/H₂O = 3/1, N₂ atmosphere, 126 °C, M.W., 25 min.

Table 1. Antiproliferative activity of all compounds.

Compounds	(IC50 ± SD, μM)^a
	HeLa	SGC-7901	MCF-7
10a	20.21 ± 2.1	30.57 ± 2.5	39.83 ± 4.7
10b	50.62 ± 4.7	55.31 ± 5.6	>60
10c	3.28 ± 0.27	5.24 ± 0.69	8.49 ± 0.86
10d	15.22 ± 1.2	16.58 ± 2.2	13.94 ± 1.9
10e	>60	>60	>60
10f	37.83 ± 3.6	>60	25.80 ± 2.7
10g	17.78 ± 1.0	18.91 ± 0.97	>60
10h	4.20 ± 0.8	9.73 ± 1.7	8.54 ± 0.86
10i	13.74 ± 1.2	14.32 ± 1.1	19.58 ± 2.2
10j	>60	>60	>60
10k	39.63 ± 4.1	>60	>60
10l	18.81 ± 1.9	16.88 ± 1.7	29.61 ± 2.8
10m	>60	>60	>60
10n	30.83 ± 4.1	>60	>60
10o	>60	>60	>60
10p	>60	40.10 ± 5.2	>60
10q	>60	>60	>60
10r	55.21 ± 6.6	49.81 ± 5.1	>60
10s	>60	>60	>60
10t	0.19 ± 0.013	0.30 ± 0.030	0.33 ± 0.028
10u	>60	>60	>60
CA-4^b	0.05 ± 0.004	0.08 ± 0.006	0.04 ± 0.002

Bold represents the IC₅₀ value of the target compound with the best activity.

^aIC₅₀: the half maximal inhibitory concentration.

^bUsed as positive controls.

Figure 3. Effect of 10t on tubulin polymerisation. Tubulin had been pre-incubated for 1 min with 10t at 10 and 15 μM, CA-4 at 5 μM, taxol at 5 μM or vehicle DMSO at room temperature before GTP was added to start the tubulin polymerisation reactions. The reaction was monitored at 37 °C.

Figure 4. Effects of 2-fold IC₅₀ CA-4 and 2-fold IC₅₀ 10t on the cellular microtubule networks of Hela cells by immunofluorescence assay. Microtubules and unassembled microtubule proteins stained with α-tubulin primary antibody and FITC secondary antibody, shown in green, and nuclei stained with DAPI, shown in the blue colour.

Figure 5. Cell cycle distribution of Hela cells after 24 h treatment with 1-fold IC₅₀, 2-fold IC₅₀ and 3-fold IC₅₀ of 10t. (A) Control, (B) 1-fold IC₅₀, (C) 2-fold IC₅₀ and (D) 3-fold IC₅₀.

Figure 6. Proportion of apoptotic cells in Hela cells after 48 h treatment with 1-fold IC₅₀, 2-fold IC₅₀ and 3-fold IC₅₀ of 10t. (A) Control, (B) 1-fold IC₅₀, (C) 2-fold IC₅₀ and (D) 3-fold IC₅₀.

Figure 7. (A) The binding mode of compound 10t in the colchicine binding site of tubulin; (B) overlay of 10t in the binding site.