New Isatin–Indole Conjugates: Synthesis, Characterization, and a Plausible Mechanism of Their in vitro Antiproliferative Activity

Abstract

Background

Cancer remains the leading cause of human morbidity universally. Hence, we sought to assess the in vitro antiproliferative activity of new isatin-based conjugates (5a–s) against three human cancer cell lines.

Methods

The antiproliferative activities of compounds 5a–s were evaluated in vitro and their ADME (absorption, distribution, metabolism and excretion) was carried out using standard protocols. Subsequently, Western blot analysis was conducted to elucidate the potential antiproliferative mechanism of compounds 5a–s.

Results

The in vitro antiproliferative activities of compounds 5a–s against the tested cancer cell lines ranged from 20.3 to 95.9%. Compound 5m had an IC₅₀ value of 1.17 µM; thus, its antiproliferative potency was approximately seven-fold greater than that of sunitinib (IC₅₀ = 8.11 µM). In-depth pharmacological testing was conducted with compound 5m to gain insight into the potential antiproliferative mechanism of this class of compounds. Compound 5m caused an increase in the number of cells in the G1 phase, with a concomitant reduction of those in the G2/M and S phases. Additionally, compound 5m significantly and dose-dependently reduced the amount of phosphorylated retinoblastoma protein detected. Compound 5m enhanced expression of B cell translocation gene 1, cell cycle-associated proteins (cyclin B1, cyclin D1, and phosphorylated cyclin-dependent kinase 1), and a pro-apoptotic protein (Bcl-2-associated X protein gene), and activated caspase-3. ADME predictions exposed the oral liability of compounds 5a-s.

Conclusion

Herein, we revealed the antiproliferative activity and ADME predictions of the newly-synthesized compounds 5a–s and provided a detailed insight into the pharmacological profile of compound 5m. Thus, compounds 5a–s can potentially be exploited as new antiproliferative lead compounds for cancer chemotherapeutic.

Keywords:

• synthesis
• isatin
• indole
• antiproliferative
• cancer cell line

Acknowledgment

The authors would like to extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for funding this research through Research Group Project Number RG-1440-140.

Supporting Materials

Detailed protocols for the pharmacological evaluation of the title compounds 5a–s, Western blot results for compound 5m (Figures S1–S3), and ADME Table (Table S1) are provided as Supporting materials.

Disclosure

Dr Adam B Keeton reports support of this project through the Deanship of Scientific Research at King Saud University through Research Group Project Number RG-1440-140. The authors declare no other conflicts of interest.