N’-Alkylaminosulfonyl Analogues of 6- Fluorobenzylideneindolinones with Desirable Physicochemical Profiles and Potent Growth Inhibitory Activities on Hepatocellular Carcinoma Xiao Chen, [a] Tianming Yang, [a] Amudha Deivasigamani, [b] Muthu K. Shanmugam, [c] Kam- Man Hui, [b] Gautam Sethi, [c] and Mei-Lin Go* [a] Introduction The substituted arylideneindolin- 2-one scaffold is strongly associ- ated with anticancer activity. It has multiple targets, several of which are directly linked to on- cogenesis. [1–4] Preference for a specific target is largely deter- mined by functionalization of the scaffold, as illustrated by the pyrrolylmethyleneindolin-2-one core, which is widely linked to the inhibition of receptor tyro- sine kinases (RTKs) (Fig- ure 1 A). [5–7] Both sunitinib and toceranib have emerged from this class and are in clinical use for targeted anticancer therapies. Kinase inhibition is attributed to the ability of the indolin-2-one ring to occupy a site (hinge region) that normally accommodates the adenine moiety of ATP, while selectivity and potency for a specific RTK are attrib- uted to interactions established by substituents on the scaffold with residues found in the vicinity of the hinge region. Inhibi- tion is stereospecifically biased toward the Z isomer, and pre- dominance of this isomer is effectively achieved in pyrrolylme- thyleneindolinones by intramolecular hydrogen bonding be- tween the pyrrole NH group and the indolinone carbonyl oxygen atom. [5] In contrast to their pyrrolylmethylene counter- Figure 1. Structures of A) selected pyrrolylmethyleneindolinones with RTK inhibitory activities, B) benzylideneindo- linones investigated for sirtuin inhibitory activity, and C) lead compound 4. The benzylideneindolinone 6-chloro-3-(3’-trifluoromethylbenzy- lidene)-1,3-dihydroindol-2-one (4) was reported to exhibit potent and selective growth inhibitory effects on hepatocellu- lar carcinoma (HCC). Corroborative evidence supported multi- receptor tyrosine kinase (RTK) inhibition as a possible mode of action. However, the poor physicochemical properties of 4 lim- ited its furtherance as a lead compound. In this study, the modification of 4 was investigated with the aim of improving its potency and physicochemical profile. The 6-fluorobenzylide- neindolinone 3-12 bearing a3’-N-propylaminosulfonyl sub- stituent was found to be a promising substitute. Compound 3- 12 [6-fluoro-3-(3’-N-propylaminosulfonylbenzylidene)-1,3-dihy- droindol-2-one] was found to be tenfold more soluble than 4 and to have sub-micromolar growth inhibitory activities on HCC cells. It is apoptogenic and inhibits the phosphorylation of several RTKs in HuH7, of which the inhibition of FGFR4 and HER3 are prominent. Compound 3-12 decreased the tumor load in a physiologically relevant orthotopic HCC xenograft murine model. Structure–activity relationships support pivotal roles for the fluoro and N’-propylaminosulfonyl moieties in en- hancing cell-based activity and moderating the physicochemi- cal profile (solubility, permeability) of 3-12. [a] Dr. X. Chen, Dr. T. Yang, Prof. M.-L. Go Department of Pharmacy, National University of Singapore 18 Science Drive 4, Singapore 117543 (Republic of Singapore) E-mail : phagoml@nus.edu.sg [b] A. Deivasigamani, Prof. K.-M. Hui National Cancer Centre 11 Hospital Drive, Singapore 169610 (Republic of Singapore) [c] Dr. M. K. Shanmugam, Prof. G. Sethi Yong Loo Lin School of Medicine, National University of Singapore 10 Medical Drive, Singapore 117597 (Republic of Singapore) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cmdc.201500235. ChemMedChem 2015, 10, 1548 – 1558 # 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1548 Full Papers DOI: 10.1002/cmdc.201500235