Synthesis and in vitro anticancer activity of certain novel 1-(2-methyl-6-arylpyridin-3-yl)-3-phenylureas as apoptosis-inducing agents

Abstract

In connection with our research program on the development of novel anticancer candidates, herein we report the design and synthesis of novel series of 1-(2-methyl-6-arylpyridin-3-yl)-3-phenylureas 5a-l. The target pyridins were evaluated for their in vitro anticancer activity against two cancer cell lines: non-small cell lung cancer A549 cell line and colon cancer HCT-116 cell line. Compound 5l emerged as the most active congener towards both A549 and HCT-116 cell lines with IC₅₀ values equal to 3.22 ± 0.2 and 2.71 ± 0.16 µM, respectively, which are comparable to those of Doxorubicin; 2.93 ± 0.28 and 3.10 ± 0.22, respectively. Furthermore, compound 5l stood out as the most potent pyridine derivative (mean % GI = 40), at US-NCI Developmental Therapeutic Program anticancer assay, with broad-spectrum antitumor activity against the most tested cancer cell lines from all subpanels. Compound 5l was able to provoke apoptosis in HCT-116 cells as evidenced by the decreased expression of the anti-apoptotic Bcl-2 protein, and the enhanced expression of the pro-apoptotic proteins levels; Bax, cytochrome C, p53, caspase-3 and caspase-9. Moreover, 5l disrupted the HCT-116 cell cycle via alteration of the Sub-G₁ phase and arresting the G₂-M stage. Also, 5l showed a significant increase in the percent of annexinV-FITC positive apoptotic cells from 1.99 to 15.76%.

Keywords: Anticancer agents; apoptosis; cell cycle; pyridine-urea; synthesis.

Figure 1

Structures of certain pyridine-based approved anticancer drugs, and the target pyridines 5a–l.

Scheme 1

Synthesis of target derivatives 5a–l; (i) Ethyl alcohol, NH₂NH₂·H₂O, reflux 3 h.; (ii) NaNO₂, HCl, stirring 2 h.; (iii) Xylene, reflux 1 h.; (iv) Xylene, reflux 4 h.

Figure 2

The most susceptible cancer cell lines towards the impact of target pyridines 5a and 5l according to the GI%.

Figure 3

Effect of compound 5l on the phases of cell cycle of HCT-116 cells. *Significantly different from control at p < 0.05. (Two-way ANOVA test).

Figure 4

Effect of sulfonamide 5l on the percentage of annexin V-FITC-positive staining in HCT-116 cells. The experiments were done in triplicates. The four quadrants identified as: LL: viable; LR: early apoptotic; UR: late apoptotic; UL: necrotic.