Computer-aided selection of new antiepileptic candidates for the treatment of ABC pumpsassociated refractory epilepsy.

MANUEL COUYOUPETROU; MARÍA E. RUIZ; MAURICIO E. 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 (SolBio); 2013

Sociedad Iberoamericana de Bioinformática

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-nonsubstrates anticonvulsant agents [3] OnE of the selected candidates was Acesulfame potassium (ACF), an artificial sweetener with wellknown 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 apicalto- 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.