Novel hydrazide-hydrazone and amide substituted coumarin derivatives: Synthesis, cytotoxicity screening, microarray, radiolabeling and in vivo pharmacokinetic studies

Synthesis and Biological Evaluation of Novel Heterocyclic Imines Linked Coumarin- Thiazole Hybrids as Anticancer Agents

Background:

Human Galectin-1, a protein of lectin family showing affinity towards β-galactosides has emerged as a critical regulator of tumor progression and metastasis, by modulating diverse biological events including homotypic cell aggregation, migration, apoptosis, angiogenesis and immune escape. Therefore, galectin-1 inhibitors might represent novel therapeutic agents for cancer.

Methods:

A new series of heterocyclic imines linked coumarin-thiazole hybrids (6a-6r) was synthesized and evaluated for its cytotoxic potential against a panel of six human cancer cell lines namely, lung (A549), prostate (DU-145), breast (MCF-7 & MDA-MB-231), colon (HCT-15 & HT-29) using MTT assay. Characteristic apoptotic assays like DAPI staining, cell cycle, annexin V and Mitochondrial membrane potential studies were performed for the most active compound. Furthermore, Gal-1 inhibition was confirmed by ELISA and fluorescence spectroscopy.

Results:

Among all, compound 6g 3-(2-(2-(pyridin-2-ylmethylene) hydrazineyl) thiazol-4-yl)-2H-chromen-2- one exhibited promising growth inhibition against HCT-15 colorectal cancer cells with an IC50 value of 1.28 ± 0.14 µM. The characteristic apoptotic morphological features like chromatin condensation, membrane blebbing and apoptotic body formation were clearly observed with compound 6g on HCT-15 cells using DAPI staining studies. Further, annexin V-FITC/PI assay confirmed effective early apoptosis induction by treatment with compound 6g. Loss of mitochondrial membrane potential and enhanced ROS generation were confirmed with JC-1 and DCFDA staining method, respectively by treatment with compound 6g, suggesting a possible mechanism for inducing apoptosis. Moreover, flow cytometric analysis revealed that compound 6g blocked G0/G1 phase of the cell cycle in a dose-dependent manner. Compound 6g effectively reduced the levels of Gal-1 protein in a dose-dependent manner. The binding constant (Ka) of 6g with Gal-1 was calculated from the intercept value which was observed as 1.9 x 107 M-1 by Fluorescence spectroscopy. Molecular docking studies showed strong interactions of compound 6g with Gal-1 protein.

Conclusion:

Our studies demonstrate the anticancer potential and Gal-1 inhibition of heterocyclic imines linked coumarin-thiazole hybrids.

Excellent antitumor and antimetastatic activities based on novel coumarin/pyrazole oxime hybrids

A series of hybrids 10a-v based on coumarin/pyrazole oxime have been synthesized, and exhibit good to excellent antitumor activities. Compound 10n has shown remarkable anticancer effect on SMMC-7721 cells (IC₅₀ = 2.08 μM), which is considerably lower than 5-FU (IC₅₀ = 37.8 μM) and similar to ADM (IC₅₀ = 2.67 μM), with little effect on normal hepatic cells LO2. Notably, the suppression experiments of metastatic activities reveal that 10n also displays significant anti-metastasis effects through inhibiting cell migration and invasion in highly metastatic SMMC-7721 cell line, and dose-dependently reverses TGF-β1-induced epithelial-mesenchymal transition (EMT) procedure better than ADM. Finally, 10n also possesses low acute toxicity and potent tumor growth inhibitory property against SMMC-7721 cell lines in vivo. Our findings suggest that novel coumarin/pyrazole oxime hybrids are promising therapeutic agent candidates for further research.