The anticancer potential of CITme, a quinoline derivative

Abstract

3-[3-(7-chloro-quinolin-4-yl amino) phenyl]-1-(4-methoxy-phenyl) prop-2-enone citrate “CITme” is a substituted quinoline derivative, synthesized as a potential antitumour agent. The aim of this study was to investigate CITme with regard to antitumour activity, toxicity and pharmacokinetics. In vitro screening for neoplastic cytotoxic effects using standard cell culture techniques revealed cytotoxic activity against HeLa, DU-145, MCF-7, Jurkat and CoLo 320 human derived cancer cell lines at low concentrations. Toxicity was significantly less in either normal resting and stimulated lymphocytes or primary chicken fibroblast cells. CITme showed highest cytotoxic specificity for DU-145 with an IC50 of 11 μM compared to 38.2 ìM for lymphocytes after a three-day incubation period and 2.5 μM, after a seven-day incubation period. CITme exhibited poor solubility in aqueous solutions and this had to be addressed prior to in vivo acute toxicity studies being performed. CITme was found to be insoluble in many biocompatible and acceptable formulating solvents. 2-methyl pyrrolidone and Cremophor EL showed promise as potential solvents but the solubility proved to be too low to enable therapeutic CITme dosing while avoiding solvent/carrier toxicity. An oral microcrystalline cellulose suspension, two combinations of 2-methyl pyrrolidone with plasma protein complexation and a propheroid formulation were also tested. These were tested in pilot acute toxicity studies using BALB/c mice or Sprague Dawley rats. No plasma concentrations were observed with the cellulose suspension and both the 2-methyl pyrrolidone formulations elicited toxic responses in vehicle control and experimental groups despite working well below the published LD50 of 2-methyl pyrrolidone. A unique formulation developed by the Department of Pharmacy of NWU referred to as propheroid drug delivery system, provided sufficient solubility for acute and chronic toxicity studies of CITme. In vivo acute and chronic toxicity study of the propheroid delivery system formulation alone and the CITme propheroid at 30 mg/kg/day and 60 mg/kg body weight (acute toxicity study), and 10mg/kg/day (chronic toxicity study) demonstrated safety after seven and forty-five (six weeks) days administration by oral gavage. The potential anti-tumour activity of CITme could not be determined in a nude mouse tumour model, using the most susceptible in vitro cell line, DU-145 due to the low success rate of tumour induction and the long lag period required for the development of subcutaneous prostate tumours after transplantation of either a DU-145 cell suspension or DU-145 tumour tissue blocks. An LC-MS/MS method was developed to separate and quantify CITme from plasma and organ homogenates. The LC-MS/MS method was used to determine the pharmacokinetic parameters of I.V. administered CITme. A pharmacokinetic study of CITme in mice indicated that CITme is absorbed after an oral administration and exhibits a very rapid distribution (metabolism) and/or elimination after IV administration. CITme could be found at relatively high concentrations 24 hours after oral dosing and to a smaller extent 10 minutes after I.V. administration in both the liver and kidney tissues. Despite the fact that the efficacy and oral pharmacokinetics properties of CITme could not be determined, this study has proved that CITme is a selective and potent anti-tumour agent in vitro with low toxicity both in vitro and in vivo and therefore this compound warrants further scientific evaluation.