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An Investigation into the Cytotoxicity and Mode of Action of Some Novel N-Alkyl-Substituted Isatins

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journal contribution
posted on 18.10.2007, 00:00 by Kara L. Vine, Julie M. Locke, Marie Ranson, Stephen G. Pyne, John B. Bremner
A range of substituted N-alkylisatins were synthesized and their cytotoxicity evaluated against several cancer cell lines in vitro. SAR studies indicated that the introduction of an aromatic ring with a one or three carbon atom linker at N1 enhanced the activity from that of the allyl, 2‘-methoxyethyl, and 3‘-methylbutyl N-substituted isatins. Furthermore, electron-withdrawing groups substituted at the meta or para position of the ring were favored over the ortho orientation. Of the 24 compounds screened, nine displayed sub-micromolar IC50 values and in general demonstrated greater selectivity toward leukemia and lymphoma cell lines over any of the carcinoma cell lines tested. 5,7-Dibromo-N-(p-methylbenzyl)isatin (6) was the most active compound, inhibiting the metabolic activity of both U937 and Jurkat cancer cell lines at 0.49 μM. Various N-alkylisatins were also found to dramatically alter lymphocyte morphology, destabilize microtubules, inhibit tubulin polymerization, induce G2/M cell cycle arrest, and activate the effector caspase-3 and -7.