Design, synthesis, and biological evaluation of biotinylated colchicine derivatives as potential antitumor agents

Figures & data

Figure 1. Chemical structures of biotin and biotin conjugates.

Figure 2. Chemical structures of colchicine and its derivatives.

Figure 3. Reduction-sensitive drug release mechanism of Deac-SS-Biotin triggered by DTT (Glutathione mimetic).

Scheme 1. Reagents and conditions: (a) 4-nitrophenyl carbonochloridate, Et₃N, THF, rt., 6 h; (b) THF, rt., 4 h; (c) 1, DCC, DMAP, rt., 20 h; (d) HATU, Et₃N, rt., 8 h; (e) anhydrides, NMM, DMSO, rt., 45 min; (f) (i) SOCl₂, MeOH, rt., overnight; (ii) NH₂NH₂, rt., 17 h; (g) EDCI, HOBt, DMAP, Et₃N, rt., 10 h.

Figure 4. Stabilities of Deac-SS-Biotin (9, 5 µM) in water, and PBS cell culture fluid were investigated by HPLC analysis. (A) HPLC analysis of Deac-SS-Biotin (9) in water after incubation for and 72 h; (B) HPLC analysis of Deac-SS-Biotin (9) in PBS after incubation for and 72 h; (C) HPLC analysis of Deac-SS-Biotin (9) in cell culture fluid after incubation for and 72 h.

Figure 5. In vitro release of Deac from prodrugs. (A) Release profiles of Deac from Deac-SS-Biotin (9, 5 μM) with 0 μM, 5 μM, 10 μM and 20 μM DTT in PBS (pH 7.2–7.4) (n = 3). (B) Release profiles of Deac from Deac-Biotin (10, 5 μM) with 0 μM, 5 μM, 10 μM and 20 μM DTT in PBS (pH 7.2–7.4) (n = 3). (C) HPLC spectra of Deac-SS-Biotin (9, 5 μM) with 10 μM DTT at 0 and 24 h.

Table 1. Antiproliferative activity of all compounds.

Compounds	IC50^a (μM) ± SD
	SGC-7901	A549	Hela	L929	Selectivity (L929/A549)
9	0.124 ± 0.011	0.085 ± 0.008	0.108 ± 0.010	4.22 ± 0.102	49
10	4.90 ± 0.18	4.85 ± 0.13	6.35 ± 0.11	15.8 ± 0.31	3
11a	7.52 ± 0.12	6.52 ± 0.19	3.50 ± 0.15	>20	–
11 b	2.29 ± 0.09	2.23 ± 0.12	6.94 ± 0.16	13.4 ± 0.18	6
11c	1.95 ± 0.071	1.31 ± 0.092	2.17 ± 0.10	10.7 ± 0.20	8
13	0.069 ± 0.005	0.063 ± 0.004	0.078 ± 0.005	0.131 ± 0.010	2
4^b	0.066 ± 0.004	0.076 ± 0.006	0.054 ± 0.007	0.164 ± 0.013	2

^aIC₅₀: the half maximal inhibitory concentration.

^bUsed as positive control.

Figure 6. In vitro cytotoxicity of biotin, Deac (13), and Deac-SS-Biotin (9) in A549 cells. Cytotoxicity of biotin, Deac + biotin, and Deac-SS-Biotin + biotin in A549 cells (n = 3).

Figure 7. The effect of Deac-SS-Biotin (9) on tubulin polymerisation. The tubulin had been pre-incubated for 1 min with Deac (13) at 5 µM, Deac-SS-Biotin (9) at 5 µM, Deac-SS-Biotin (9) at 5 µM and DTT at 10 µM, Deac (13) at 5 µM, Colchicine at 5 µM, Paclitaxel 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.