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Aim: Elucidation of the antiproliferative efficacy and mechanism of action of a design‐optimized noscapine analog, N‐4‐CN. Methods: Cell viability was studied using an MTT assay. The drug‐tubulin interactions were investigated using spectrofluorometry. The architectural defects, hyper stabilization, and recovery competence of cellular microtubules were studied using immunofluorescence microscopy. DCF‐DH and rhodamine 123 were used as probes to to examine the levels of reactive oxygen species and the loss of mitochondrial membrane potential, respectively. Flow cytometry revealed the cell cycle progression pattern of the drug‐treated cells. Key findings: Among the cell lines tested, N‐4‐CN showed the strongest inhibition of the viability of the triple‐negative breast cancer (TNBC) cell line MDA‐MB‐231(IC50, 2.7 ± 0.1 µmol/L) and weakest inhibition of the noncancerous epithelial cell line, VERO (IC50, 60.2 ± 3 µmol/L). It perturbed tertiary structure of tubulin and stabilized colchicine binding to the protein. In cells, N‐4‐CN hyperstabilized the microtubules, and prevented the recovery of cold‐depolymerized microtubules. Its multitude of effects on tubulin and microtubules facilitated cell cycle arrest and subsequent cell death that were complemented by elevated levels of reactive oxygen species (ROS). Significance: Owing to its ability to perturb a well‐defined cancer drug target, tubulin, and to promote ROS‐facilitated apoptosis, N‐4‐CN could be investigated further as a potential therapeutic against many neoplasms, including TNBC. [ABSTRACT FROM AUTHOR]

Objectives: To examine the antiproliferative effect of a rationally designed, novel noscapine analogue, 9‐((perfluorophenyl)methylene) aminonoscapine, '9‐PAN') on MDA‐MB‐231 breast cancer cell line, and to elucidate the underlying mechanism of action. Methods: The rationally designed Schiff base‐containing compound, 9‐PAN, was characterized using IR, NMR and mass spectra analysis. The effect of the compound on cell viability was studied using an MTT assay. Cell cycle and cell death analyses were performed using flow cytometry. Binding interactions of 9‐PAN with tubulin were studied using spectrofluorometry. Reactive oxygen species (ROS) generation and mitochondrial membrane potential (MMP) were investigated using the probes, DCFDA and rhodamine‐123, respectively. Immunofluorescence imaging was used to visualize cellular microtubules. Key findings: 9‐PAN inhibited cell proliferation (IC50 of 20 ± 0.3 µm) and colony formation (IC50, 6.2 ± 0.3 µm) by arresting the cells at G2/M phase of the cell cycle. It bound to tubulin in a concentration‐dependent manner without considerably altering the tertiary conformation of the protein or the polymer mass of the microtubules in vitro. The noscapinoid substantially damaged cellular microtubule network and induced cell death, facilitated by elevated levels of ROS. Conclusions: 9‐PAN exerts its antiproliferative effect by targeting tubulin and elevating ROS level in the cells. [ABSTRACT FROM AUTHOR]