Design, Synthesis and Biological Investigation of 2-Anilino Triazolopyrimidines as Tubulin Polymerization Inhibitors with Anticancer Activities

Abstract

A further investigation aiming to generate new potential antitumor agents led us to synthesize a new series of twenty-two compounds characterized by the presence of the 7-(3′,4′,5′-trimethoxyphenyl)-[1,2,4]triazolo[1,5-a]pyrimidine pharmacophore modified at its 2-position. Among the synthesized compounds, three were significantly more active than the others. These bore the substituents p-toluidino (3d), p-ethylanilino (3h) and 3′,4′-dimethylanilino (3f), and these compounds had IC50 values of 30–43, 160–240 and 67–160 nM, respectively, on HeLa, A549 and HT-29 cancer cells. The p-toluidino derivative 3d was the most potent inhibitor of tubulin polymerization (IC50: 0.45 µM) and strongly inhibited the binding of colchicine to tubulin (72% inhibition), with antiproliferative activity superior to CA-4 against A549 and HeLa cancer cell lines. In vitro investigation showed that compound 3d was able to block treated cells in the G2/M phase of the cell cycle and to induce apoptosis following the intrinsic pathway, further confirmed by mitochondrial depolarization and caspase-9 activation. In vivo experiments conducted on the zebrafish model showed good activity of 3d in reducing the mass of a HeLa cell xenograft. These effects occurred at nontoxic concentrations to the animal, indicating that 3d merits further developmental studies.

Antiproliferative and Tubulin-Destabilising Effects of 3-(Prop-1-en-2-yl)azetidin-2-Ones and Related Compounds in MCF-7 and MDA-MB-231 Breast Cancer Cells

“…Isocombretastatin 2f [ 25 ], dihydronaphthalene OXi6196 [ 26 , 27 ], phenstatin 2g [ 28 ] and chalcones 3a and 3b display comparable biological activity to CA-4 [ 29 ]; however, poor water solubility and cis/trans isomerization of combretastatins remain problematic [ 30 ]. CA-4 analogues are reported in which a heterocycle replaces the olefinic bond of CA-4 and prevents cis/trans isomerization [ 22 , 31 , 32 , 33 ]. The pyrrole 4a induces significant apoptosis [ 34 ], while the bis -indole sabizabulin 4b is effective in metastatic breast [ 35 , 36 ] and prostate cancers [ 37 ].…”

4-(Aryl)-Benzo[4,5]imidazo[1,2-a]pyrimidine-3-Carbonitrile-Based Fluorophores: Povarov Reaction-Based Synthesis, Photophysical Studies, and DFT Calculations

“…Azolopyrimidines are ubiquitous heterocyclic systems, particularly important in living organisms as a core of purine bases, and these heterocycles are widely present among biologically active compounds, including those with antiviral [1-4], anticancer [5][6][7], antibacterial [8,9], and antidiabetic activity [10,11]. In addition to a wide range of biological activities, azolopyrimidines are considered promising candidates for important fluorescence applications [12][13][14][15].…”

“…Furthermore, strongly electron-withdrawing pyrimidine derivatives have found applications for the synthesis of push-pull molecules and the construction of functionalized π-conjugated materials such as dye-sensitized solar cells [16], non-doped OLED and laser dyes [17], and nonlinear optical materials [18]. Among the methods for the structural modification of azolopyrimidines, the approaches based on the creation of polycyclic fused analogs of azolopyrimidines such as benzo [4,5]imidazo[1,2-a]pyrimidines are of growing interest and significance [19][20][21]. Since polycyclic fused systems with a conjugated planar structure exhibit relevant photophysical properties, they have found applications as phosphors in optoelectronics or as fluorescent dyes for textile and polymer materials [22].…”

“…We recently reported the synthesis of asymmetric donor-acceptor azoloazine fluorophors based on 4-heteroaryl-substituted 2-phenyl-2H-benzo [4,5]imidazo[1,2-a][1,2,3] triazolo [4,5-e]pyrimidine via the reaction of nucleophilic aromatic hydrogen substitution (S N H) and studied their microenvironmental sensitivity in the PLICT process (Scheme 1) [42].…”

Special Issue “Novel Anti-Proliferative Agents”

“…Another approach to contrast tumoral cell proliferation is acting in the mitotic stage of the cell cycle with microtubule binding agents [25] and telomerase inhibitors [26]. In this Special Issue, Viola and collaborators described 2-anilino-triazolopyrimidines as tubuluin polymerization inhibitors [27], Pérez-Pérez and collaborators reported salicylamides as affecting tubulin polymerization and/or STAT3 phosphorylation [28], Shakeel and collaborators studied pyrazole hybrid chalcones that arrested the cell cycle, induced apoptosis in a dose-dependent manner and inhibited the polymerization of tubulin [29], and El-Hamamsy and collaborators reported on selective non-nucleoside potent telomerase inhibitor BIBR1532 derivatives that were demonstrated to inhibit telomerase inside living cancer cells [30].…”