Diphenyl Urea Derivatives as Inhibitors of Transketolase: A Structure-Based Virtual Screening

Transketolase is an enzyme involved in a critical step of the non-oxidative branch of the pentose phosphate pathway whose inhibition could lead to new anticancer drugs. Here, we report new human transketolase inhibitors, based on the phenyl urea scaffold, found by applying structure-based virtual screening. These inhibitors are designed to cover a hot spot in the dimerization interface of the homodimer of the enzyme, providing for the first time compounds with a suggested novel binding mode not based on mimicking the thiamine pyrophosphate cofactor

Epicatechin gallate impairs colon cancer cell metabolic productivity

Green tea and grape phenolics inhibit cancer growth and modulate cellular metabolism. Targeting the tumor metabolic profile is a novel therapeutic approach to inhibit cancer cell proliferation. Therefore, we treated human colon adenocarcinoma HT29 cells with the phenolic compound epicatechin gallate (ECG), one of the main catechins in green tea and the most important catechin in grape extracts, and evaluated its antiproliferation effects. ECG reduced tumor viability and induced apoptosis, necrosis, and S phase arrest in HT29 cells. Later, biochemical determinations combined with mass isotopomer distribution analysis using [1,2-13C2]-d-glucose as a tracer were used to characterize the metabolic network of HT29 cells in response to different concentrations of ECG. Glucose consumption was importantly decreased after ECG treatment. Moreover, metabolization of [1,2-13C2]-d-glucose indicated that the de novo synthesis of fatty acids and the pentose phosphate pathway were reduced in ECG-treated cells. Interestingly, ECG inhibited the activity of transketolase and glucose-6-phosphate dehydrogenase, the key enzymes of the pentose phosphate pathway. Our data point to ECG as a promising chemotherapeutic agent for the treatment of colon cancer.Financial support was provided by grants SAF2008-00164, SAF2011-25726, AGL2006-12210-C03-02/ALI, and AGL2009-12374-C03-03/ALI from the Spanish government Ministerio de Economía y Competitividad and personal financial support (FPU program) and from the Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, Spanish Ministry of Science and Innovation & European Regional Development Fund (ERDF) “Una manera de hacer Europa” (ISCIII-RTICC grants RD06/0020/0046). We have also received financial support from the AGAUR-Generalitat de Catalunya (grant 2009SGR1308, 2009 CTP 00026, and Icrea Academia Award 2010 granted to M.C.) and the European Commission (FP7) ETHERPATHS KBBE-grant agreement no. 22263.Peer Reviewe

Structures of the reported diphenyl urea derivatives.

<p>In the upper part, compounds which showed good inhibitory activity. In the bottom part, compounds which showed poor activity. The pharmacophoric points are also shown; in red for hydrogen acceptor points, in blue for hydrogen donor points and in green for hydrophobic points.</p

Activities of the reported diphenyl urea derivatives.

<p>Activities of the reported diphenyl urea derivatives.</p

Proposed binding mode of compound T2 and its derivatives (T2A–T2F).

<p>Black dots represent hydrogen bonds.</p

Transketolase structure model.

<p>A) Homology model of human transketolase showing the antiparallel alpha helices involved in dimerization. B) Close view of the alpha helix D200-G210 showing the selected residues of the 5-point pharmacophore. HY: hydrophobic contact, HA: hydrogen acceptor, HD: hydrogen donor.</p

Chaperone treatment prevents beta-cell dysfunction under high glucose and palmitic acid treatment.

<p>hIAPP-INS1E cells were transduced with Ad-BiP, Ad-PDI or treated with TUDCA or PBA for 24 hours. After 24 hours, cells were treated with 25 mM of glucose and palmitic acid (HG+PA). Glucose-stimulated insulin secretion was performed at low (2.8 mM) and high (16 mM) glucose using INS1E cells as control as expressed by % of insulin content. Insulin levels were determined by ELISA. Results are expressed as mean ± S.E.M from three independent experiments. ^##<i>p</i><0.05 <i>vs</i> INS1E control, *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001 <i>vs</i>. hIAPP-INS1E cells treated with HG+PA. No statistical differences were found between Con and BiP, PDI, TUDCA and PBA.</p