molecules Article Fentanyl Family at the Mu-Opioid Receptor: Uniform Assessment of Binding and Computational Analysis Piotr F. J. Lipi ´nski 1,* , Piotr Kosson 2, Joanna Matali ´nska 1, Piotr Roszkowski 3, Zbigniew Czarnocki 3, Małgorzata Jaro ´nczyk 4 , Aleksandra Misicka 1,3 , Jan Cz. Dobrowolski 4 and Joanna Sadlej 4,5,* 1 Department of Neuropeptides, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland;
[email protected] (J.M.);
[email protected] (A.M.) 2 Toxicology Research Laboratory, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland;
[email protected] 3 Faculty of Chemistry, University of Warsaw, 02-093 Warsaw, Poland;
[email protected] (P.R.);
[email protected] (Z.C.);
[email protected] (A.M.) 4 National Medicines Institute, 00-725 Warsaw, Poland;
[email protected] (M.J.);
[email protected] (J.Cz.D.) 5 Faculty of Mathematics and Natural Sciences, University of Cardinal Stefan Wyszy´nski,1/3 Wóycickiego-Str., 01-938 Warsaw, Poland * Correspondence:
[email protected] (P.F.J.L.);
[email protected] (J.S.) Received: 30 January 2019; Accepted: 15 February 2019; Published: 19 February 2019 Abstract: Interactions of 21 fentanyl derivatives with µ-opioid receptor (µOR) were studied using experimental and theoretical methods. Their binding to µOR was assessed with radioligand competitive binding assay. A uniform set of binding affinity data contains values for two novel and one previously uncharacterized derivative. The data confirms trends known so far and thanks to their uniformity, they facilitate further comparisons.