Computer-aided selection of new antiepileptic candidates for the treatment of ABC pumps- associated refractory epilepsy

MANUEL COUYOUPETROU; MARÍA ESPERANZA RUIZ; MAURICIO DI IANNI; ALAN TALEVI; GUIDO PESCE; LUIS BRUNO-BLANCH

Rosario

Congreso; 4to. Congreso Argentino de Bioinformática y Biología Computacional (4CAB2C) y 4ta. Conferencia Internacional de la Sociedad Iberoamericana de Bioinformática (SoIBio); 2013

Facultad de Ciencias Agrarias - Universidad Nacional de Rosario

Background Limited bioavailability of antiepileptic drugs at the brain and epileptic focus due to overexpression of ATP-binding cassette (ABC) pumps is one of the main hypothesis to explain that around one third of the epileptic patients present multi-drug resistance phenomena (refractory or intractable epilepsy). Development of new drug candidates which are not recognized by the most expressed ABC transporters (among them P-glycoprotein, Pgp) is one of the proposed strategies to circumvent efflux transporters and solve the multi-drug resistance issue [1]. Material and Methods We have developed an ensemble of machine learning algorithms to discriminate Pgp-substrates from non-substrates in virtual screening and drug design campaigns [2]. We have previously applied such algotihms jointly with docking studies as computational filters to select novel Pgp-non-substrates anticonvulsant agents [3] On of the selected candidates was Acesulfame potassium (ACF), an artificial sweetener with well-known toxicological profile. To confirm such prediction, the drug has been submitted to murine models of seizure and in vitro permeability tests in MDCK II-MDRI culture cell model, which expresses Pgp at their apical membrane. The same in vitro test was also performed with a P-gp substrate (trimethoprim, TMP) with and without and inhibitor (amiodarone, AMD) in the media, as positive control. Bi-directional permeability studies employing MDCK II-MDR I cells were conducted at 37 ºC with moderate shaking, with and without AMD, to determine the membrane permeability and P-gp transport liability of the test compounds (ACF and TMP). Results and conclusions Acesulfame anticonvulsant activity was confirmed in the Maximal Electroshock Seizure test [4]. The apparent permeability coefficient (Papp) of the test compounds was determined in the apical-to-basolateral (A?B) and basolateral-to-apical (B?A) directions, and the PappBA/ PappAB ratio was calculated with and without the P-gp inhibitor. The results obtained (with / without AMD, respectively) were 1.04 / 2.26 for TMP (p0.5). Therefore, the null hypothesis of equal ratios could not be rejected for ACF, suggesting that the drug is not a P-gp substrate. Though further studies should be performed including more candidates, these are encouraging results that validate the developed virtual screenign approach to select novel antiepileptic drugs capable of treating Pgp-mediated refractory epilepsy