Abstract
Background: Cancer can be considered as a disease in which normal cells start behaving badly, multiplying uncontrollably, ignoring signals to stop and accumulating to form a mass that is generally termed as a tumor. Apoptosis or programmed cell death is a physiological process that enables organisms to control their cell numbers in many developmental and physiological settings and to eliminate unwanted cells and it plays essential role in chemotherapy-induced tumor-cell killing. The correct balance between apoptosis and inhibition of apoptosis is important in animal development as well as in tissue homeostasis. The aim of this paper is to introduce the readers about the design strategy and synthesis of effective cytotoxic and apoptotic inducing agents based on benzo[d]imidazo[2,1-b]thiazole scaffold.
Methods: Benzo[d]imidazo[2,1-b]thiazole-propenone conjugates were synthesized by the condensation of 7- methoxy-2-(aryl)benzo[d]imidazo[2,1-b]thiazol-3-yl)prop-2-yn-1-ones with aryl/hetero aryl amines in ethanol at room temperature. These in turn were obtained from 7-methoxy-2-(aryl)benzo[d]imidazo[2,1-b]thiazole-3- carbaldehydes on treatment with ethynylmagnesium bromide followed by oxidation.
Results: 3-Arylaminopropenone linked 2-arylbenzo[d]imidazo[2,1-b]thiazole conjugates prepared in this investigation exhibited significant cytotoxic activity and arrested HeLa cancer cells in G1 phase. The treatment of the conjugate led to 40% of loss of mitochondrial membrane potential (DΨm) in HeLa cells and 4 fold increase in the levels of reactive oxygen species (ROS). In addition, it induces apoptosis in HeLa cells, this was examined by the wound healing assay, Actin filaments and Hoechst staining assay.
Conclusion: The encouraging biological profile exhibited by these 3-arylaminopropenone 2-aryl linked benzo[d]imidazo[2,1-b]thiazole conjugates demonstrate that they have the potential to be developed as a lead by further structural modifications to obtain potential chemotherapeutic agents that are likely to target the HeLa cancer cells.
Keywords: Benzo[d]imidazo[2, 1-b]thiazole, cytotoxicity, apoptosis, mitochondrial membrane depolarization, ROS.
Graphical Abstract
(b) Khanna, I.K.; Yu, Y.; Huff, R.M.; Weier, R.M.; Xu, X.; Koszyk, F.J.; Collins, P.W.; Cogburn, J.N.; Isakson, P.C.; Koboldt, C.M.; Masferrer, J.L.; Perkins, W.E.; Seibert, K.; Veenhuizen, A.W.; Yuan, J.; Yang, D.C.; Zhang, Y.Y. Selective cyclooxygenase-2 Inhibitors: Heteroaryl modified 1,2-Diarylimidazoles are potent, orally activeanti-inflammatory agents. J. Med. Chem., 2000, 43, 3168.
(b) Li, W.T.; Hwang, D.R.; Song, J.S.; Chen, C.P.; Chuu, J.J.; Hu, C.B.; Lin, H.L.; Huang, C.L.; Huang, C.Y.; Tseng, H.Y.; Lin, C.C.; Chen, T.W.; Lin, C.H.; Wang, H.S.; Shen, C.C.; Chang, C.M.; Chao, Y.S.; Chen, C.T. Synthesis and biological activities of 2-amino-1-arylidenamino imidazoles as orally active anticancer agents. J. Med. Chem., 2010, 53, 2409.
(b) Hulten, J.; Bonham, N.M.; Nillroth, U.; Hansson, T.; Zuccarello, G.; Bouzide, A.; Aaqvist, J.; Classon, B.; Danielson, H. Cyclic HIV-1 protease inhibitors derived from mannitol: synthesis, inhibitory potencies, and computational predictions of binding affinities. J. Med. Chem., 1997, 40, 885.
(c) Dauben, P.; Dodd, R.H. Synthesis of Cyclic sulfonamides via intramolecular copper-catalyzed reaction of unsaturated iminoiodinanes. Org. Lett., 2000, 2, 2327.
(d) Katritzky, A.R.; Wu, J.; Rachwal, S.; Rachwal, B.; Macomber, D.W.; Smith, T.P. Preparation of 6-, 7- and 8-membered sultams by friedel-crafts cyclization of ω-phenylalkanesulfamoyl chlorides. Org Prep Proced, 1992, 24, 463.
(e) Greig, I.R.; Tozer, M.J.; Wright, P.T. Synthesis of cyclic sulfonamides through intramolecular diels−alder reactions. Org. Lett., 2001, 3, 369.
(f) Matthew, D.M.; Joseph, M.D.; Paul, R.H. Synthesis of phosphorus and sulfur heterocycles via ring-closing olefin metathesis. Chem. Rev., 2004, 104, 2239-2258.
(g) Dawson, P.E.; Muir, T.W.; Lewis, C.I.; Kent, S.B.H. Synthesis of proteins by native chemical ligation. Science, 1994, 266, 776.
(b) Al-Tel, T.H.; Al-Qawasmeh, R.A.; Zaarour, R. Design, synthesis and in vitro antimicrobial evaluation of novel Imidazo[1,2-a]pyridine and imidazo[2,1-b][1,3]benzothiazole motifs. Eur. J. Med. Chem., 2011, 46, 1874-1881.
(b) Andreani, A.; Burnelli, S.; Granaiola, M.; Leoni, A. New Antitumor Imidazo[2,1-b]thiazole Guanylhydrazones and Analogues. J. Med. Chem., 2008, 51, 809.
(c) Andreani, A.; Granaiola, M.; Locatelli, A.; Morigi, R. Substituted 3-(5-Imidazo[2,1-b]thiazolylmethylene)-2-indolinones and Analogues: Synthesis, Cytotoxic Activity, and Study of the Mechanism of Action. J. Med. Chem., 2012, 55, 2078.
(d) Andreani, A.; Burnelli, S.; Granaiola, M.; Leoni, A. Antitumor Activity of New Substituted 3-(5-Imidazo[2,1-b]thiazolylmethylene)-2-indolinones and 3-(5-Imidazo[2,1-b]thiadiazolylmethylene)-2-indolinones: Selectivity against Colon Tumor Cells and Effect on Cell Cycle-Related Events. J. Med. Chem., 2008, 51, 7508.
(e) Trapani, G.; Franco, M.; Latrofa, A.; Reho, A.; Liso, G. Synthesis, in vitro and in vivo cytotoxicity, and prediction of the intestinal absorption of substituted 2-ethoxycarbonyl-imidazo[2,1-b]benzothiazoles. Eur. J. Pharm. Sci., 2001, 14, 209.
(b) Shaik, S.P.; Vishnuvardhan, M.V.P.S.; Sultana, F.; Rao, A.V.S.; Bagul, C.; Bhattacharjee, D.; Kapure, J.S.; Jain, N.; Kamal, A. Design and synthesis of 1,2,3-triazolo linked benzo[d]imidazo[2,1-b]thiazole conjugates as tubulin polymerization inhibitors. Bioorg. Med. Chem., 2017, 25, 3285.
(c) Sultana, F.; Reddy, S.B.; Reddy, G.V.; Naik, V.L.; Ravikumar, A.; Rani, S.R.; Alarafi, A.M.; Kumar, S.H.; Kamal, A. Synthesis of benzo[d]imidazo[2,1-b]thiazole-chalcone conjugates as microtubule targeting and apoptosis inducing agents. Bioorg. Chem., 2018, 76, 1-12.
(b) Zhu, C.; Zuo, Y.; Wang, R.; Liang, B.; Yue, X.; Wen, G.; Shang, N.; Huang, L.; Chen, Y.; Du, J.; Bu, X. Discovery of potent cytotoxic ortho-aryl chalcones as new scaffold targeting tubulin and mitosis with affinity-based fluorescence. J. Med. Chem., 2014, 57, 6364.