Synthesis of N(4)-(substituted phenyl)-N(4)-alkyl/desalkyl-9H-pyrimido[4,5-b]indole-2,4-diamines and identification of new microtubule disrupting compounds that are effective against multidrug resistant cells.

Aleem Gangjee, Nilesh Zaware, Ravi Kumar Vyas Devambatla, Sudhir Raghavan, Cara D Westbrook, Nicholas F Dybdal-Hargreaves, Ernest Hamel, Susan L Mooberry

Index: Bioorg. Med. Chem. 21(4) , 891-902, (2013)

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Abstract

A series of fourteen N(4)-(substituted phenyl)-N(4)-alkyl/desalkyl-9H-pyrimido[4,5-b]indole-2,4-diamines was synthesized as potential microtubule targeting agents. The synthesis involved a Fisher indole cyclization of 2-amino-6-hydrazinylpyrimidin-4(3H)-one with cyclohexanone, followed by oxidation, chlorination and displacement with appropriate anilines. Compounds 6, 14 and 15 had low nanomolar potency against MDA-MB-435 tumor cells and depolymerized microtubules. Compound 6 additionally had nanomolar GI(50) values against 57 of the NCI 60-tumor panel cell lines. Mechanistic studies showed that 6 inhibited tubulin polymerization and [(3)H]colchicine binding to tubulin. The most potent compounds were all effective in cells expressing P-glycoprotein or the βIII isotype of tubulin, which have been associated with clinical drug resistance. Modeling studies provided the potential interactions of 6, 14 and 15 within the colchicine site.Copyright © 2012 Elsevier Ltd. All rights reserved.