Resveratrol is one of the most widely studied bioactive plant polyphenols which possesses anticancer properties. Previously we have reported synthesis, characterization and identification of a novel resveratrol analog, SS28. In the present study, we show that SS28 induced cytotoxicity in several cancer cell lines ex vivo with an IC₅₀ value of 3–5 μM. Mechanistic evaluation of effect of SS28 in non-small cell lung cancer cell line (A549) and T-cell leukemic cell line (CEM) showed that it inhibited Tubulin polymerization during cell division to cause cell cycle arrest at G2/M phase of the cell cycle at 12–18 h time period. Immunofluorescence studies confirmed the mitotic arrest upon treatment with SS28. Besides, we show that SS28 binds to Tubulin with a dissociation constant of 0.414 ± 0.11 μM. Further, SS28 treatment resulted in loss of mitochondrial membrane potential, activation of Caspase 9 and Caspase 3, leading to PARP-1 cleavage and finally cell death via intrinsic pathway of apoptosis. Importantly, treatment with SS28 resulted in regression of tumor in mice. Hence, our study reveals the antiproliferative activity of SS28 by disrupting microtubule dynamics by binding to its cellular target Tubulin and its potential to be developed as an anticancer molecule.

Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4′-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole). ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo. We have determined the IC₅₀ value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC₅₀ 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models. Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.

Background: Curcumin is known for its multitude of medicinal properties, including anti-cancer and migrastatic activity. Efforts to overcome poor bioavailability, stability, and side effects associated with the higher dose of curcumin has led to the development of newer derivatives of curcumin. Thus, the focus of this study is to screen novel curcumin derivatives, namely ST03 and ST08, which have not been reported before, for their cytotoxicity and migrastatic property on cancer cells. Methods: Anti-cancer activity of ST03 and ST08 was carried out using standard cytotoxicity assays viz., LDH, MTT, and Trypan blue on both solid and liquid cancer types. Flow cytometric assays and western blotting was used to investigate the cell death mechanisms. Transwell migration assay was carried out to check for migrastatic properties of the compounds. Results: Both the compounds, ST03 and ST08, showed ~ 100 fold higher potency on liquid and solid tumour cell lines compared to its parent compound curcumin. They induced cytotoxicity by activating the intrinsic pathway of apoptosis in the breast (MDA-MB-231) and ovarian cancer cell lines (PA-1) bearing metastatic and stem cell properties, respectively. Moreover, ST08 also showed inhibition on breast cancer cell migration by inhibiting MMP1 (matrix metalloproteinase 1). Conclusion: Both ST03 and ST08 exhibit anti-cancer activity at nanomolar concentration. They induce cell death by activating the intrinsic pathway of apoptosis. Also, they inhibit migration of the cancer cells by inhibiting MMP1 in breast cancer cells.