Potent mammalian topoisomerase II inhibitors: 1-cyclopropyl-6,8-difluoro-1,4-dihydro-7-(2,6-dimethyl-4-pyridinyl)-4-substituted-quinolines

Improvement of Aqueous Solubility of Lapatinib-Derived Analogues: Identification of a Quinolinimine Lead for Human African Trypanosomiasis Drug Development

Lapatinib, an approved epidermal growth factor receptor inhibitor, was explored as a starting point for the synthesis of new hits against Trypanosoma brucei, the causative agent of human African trypanosomiasis (HAT). Previous work culminated in 1 (NEU-1953), which was part of a series typically associated with poor aqueous solubility. In this report, we present various medicinal chemistry strategies that were used to increase the aqueous solubility and improve the physicochemical profile without sacrificing antitrypanosomal potency. To rank trypanocidal hits, a new assay (summarized in a cytocidal effective concentration (CEC50)) was established, as part of the lead selection process. Increasing the sp3 carbon content of 1 resulted in 10e (0.19 μM EC50 against T. brucei and 990 μM aqueous solubility). Further chemical exploration of 10e yielded 22a, a trypanocidal quinolinimine (EC50: 0.013 μM; aqueous solubility: 880 μM; and CEC50: 0.18 μM). Compound 22a reduced parasitemia 109 fold in trypanosome-infected mice; it is an advanced lead for HAT drug development.

QSAR analysis of 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridines with anticancer activity

In the present study a quantitative structure activity relationship (QSAR) analysis was applied to a series of 100 of 7- and 3-substituted 1,4-dihydro-4-oxo-1-(2-thiazolyl)-1,8-naphthyridine derivatives. The Chem-X (version 2000) software was used to develop 3D QSAR models. The steric and electrostatic interactions between a probe atom (H(+)) and a set of aligned molecules were assessed using the comparative molecular field analysis method. Statistically relevant models were derived for both electrostatic and steric fields. A 2D model over a restricted series of close structural analogs was derived as well. A number of conclusions on the relationship between the type and size of different substituents and the antitumor activity of the compounds were derived.

Synthesis and biological relationships of 3′,6-substituted 2-phenyl-4-quinolone-3-carboxylic acid derivatives as antimitotic agents

As part of a continuing search for potential anticancer drug candidates in the 2-phenyl-4-quinolone series, 3',6-substituted 2-phenyl-4-quinolone-3-carboxylic acid derivatives and their salts were synthesized and evaluated. Preliminary screening showed that carboxylic acid analogs containing a m-fluoro substituted 2-phenyl group displayed the highest in vitro anticancer activity. Activity decreased significantly if a chlorine or methoxy group replaced the fluorine atom. 3'-Fluoro-6-methoxy-2-phenyl-4-quinolone-3-carboxylic acid (68) had the highest in vitro cytotoxic activity among all tested carboxylic acid derivatives and their salts. The mechanism of action may be similar, but not identical, to that of tubulin binding drugs, such as navelbine and taxol. Compound 68 merits further investigation as a novel hydrophilic antimitotic agent.