Design, Synthesis, in silico and in vitro Evaluation of New Combretastatin A-4 Analogs as Antimitotic Antitumor Agents

Title:Design, Synthesis, in silico and in vitro Evaluation of New Combretastatin A-4 Analogs as Antimitotic Antitumor Agents

Volume: 19 Issue: 10

Author(s): Shaker A. Abdul Hussein, Ammar Kubba, Asim A. Balakit, Lubna H. Tahtamouni*Ali H. Abbas

Affiliation:

• Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa, Jordan
• Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins, Colorado, CO 80523, USA

Abstract:

Background: Combretastatin A-4 (CA-4) binds β-tubulin at the colchicine-binding site preventing tubulin from polymerizing into microtubules. CA-4 and cis combretastatin analogs isomerize to the trans form resulting in decreased cytotoxicity and anti-tubulin activity. However, the excellent anti-cancer potential and relatively simple molecular structure of CA-4 provide an encouraging starting point for the development of new, more stable and more potent anti-tubulin compounds.

Objective: This study aimed to synthesize a new series of compounds derived from 4-(3,4,5- trimethoxyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione derivatives (compounds 10-12) with substituted phenyl group at C5 of the triazole ring (B-ring) as analogs of CA-4, with different alkyl and aryl side chain substituents at the triazole moiety, resulting in the permanent cis configuration of the two phenyl rings. Moreover, the anti-cancer activities of the new compounds were assessed.

Methods: Chemical synthesis was carried out by conventional organic methods. The newly synthesized CA-4 analogs were characterized by FT-IR, ¹HNMR, ¹³CNMR, and HR-MS(ESI) techniques. Molecular docking studies, including docking score (ΔG), ADMET, DFT, and molecular similarities, were performed. The anti-proliferative activity of the new compounds against three human cancer cell lines (A549, Hep G2, and HCT-116) and the normal cell line WI-38 was evaluated using the MTT assay, and their ability to inhibit tubulin polymerization, and consequently, their effects on cell cycle progression and induction of apoptosis were assessed.

Results: Molecular docking studies showed that compounds 11b and 11d exhibited the highest docking scores (-13.30 and -14.01 Kcal/mol, respectively) into the colchicine-binding site, scores very close to the reference drug colchicine (-13.50 Kcal/mol), and that hydrogen bonding and hydrophobic interaction are essential for binding. The most active cytotoxic compound, 11b, had potent IC₅₀ values against the three human cancer cell lines (3.83, 10.20, and 10.67 μM against Hep G2, HCT- 116, and A549, respectively) while exhibiting low cytotoxicity against non-cancer-human WI-38, suggesting that compound 11b targets rapidly growing cancer cells. Moreover, compound 11b exhibited potent anti-tubulin activity which was comparable to CA-4. Targeting microtubules caused cell cycle arrest at the G2/M phase resulting in the induction of apoptosis.

Conclusion: These findings indicate that compound 11b is a promising β-tubulin-binding compound with antimitotic action that has the potential to treat cancer.

Cite this article as:

Hussein A. Abdul Shaker, Kubba Ammar, Balakit A. Asim, Tahtamouni H. Lubna*, Abbas H. Ali, Design, Synthesis, in silico and in vitro Evaluation of New Combretastatin A-4 Analogs as Antimitotic Antitumor Agents, Medicinal Chemistry 2023; 19 (10) . https://dx.doi.org/10.2174/1573406419666230530155741