Dopamine is an important neurotransmitter in the human brain and its altered concentrations can lead to various neurological diseases. We studied the binding of novel compounds at the dopamine D 2 (D 2 R) and D 3 (D 3 R) receptor subtypes, which belong to the D 2 -like receptor family. The synthesis, in silico, and in vitro characterization of 10 dopamine receptor ligands were performed. Novel ligands were docked into the D 2 R and D 3 R crystal structures to examine the precise binding mode. A quantum mechanics/molecular mechanics study was performed to gain insights into the nature of the intermolecular interactions between the newly introduced pentafluorosulfanyl (SF 5 ) moiety and D 2 R and D 3 R. A radioligand displacement assay determined that all of the ligands showed moderate-to-low nanomolar affinities at D 2 R and D 3 R, with a slight preference for D 3 R, which was confirmed in the in silico studies. N-{4-[4-(2-Methoxyphenyl)piperazin-1-yl]butyl}-4-(pentafluoro-λ6-sulfanyl)benzamide (7i) showed the highest D 3 R affinity and selectivity (pK i values of 7.14 [D 2 R] and 8.42 [D 3 R]).

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The aim of this study was to develop a novel reversed-phase high-performance liquid chromatography (RP-HPLC) method for efficient separation of ivabradine and its 11 impurities. Similar polarity of impurities in the sample mixture made method optimization challenging and accomplishable only when different chemometric tools, such as principal component analysis (PCA), Box–Behnken design (BBD), and desirability function as a multicriteria approach, were employed. The presence of 3 positional isomers (impurities III, V, and VI), keto–enol tautomerism of impurity VII, and diastereoisomers of impurity X made separation of this complex mixture even more challenging. Chromatographic retention parameters obtained with the mobile phase consisting of 30 mM phosphate buffer and acetonitrile (80:20, v/v) on four different RP-HPLC columns at varying pH values (3.0, 4.0, and 5.0) were subjected to the PCA analysis to select the column with the most appropriate selectivity. Then the column temperature, pH of the aqueous component of mobile phase, phosphate buffer molarity and the organic solvent content in the mobile phase were estimated employing BBD. Valid and reliable mathematical models towards resolution of twelve critical peak pairs were obtained. After determination of the desirability making criteria for all responses, desirability functions were established and used in optimization. The proposed optimal chromatographic conditions included the Zorbax Eclipse Plus C18 chromatographic column (100 × 4.6 mm, 3.5 μm), the column temperature of 34 °C, the mobile phase flow rate of 1.6 mL min−1 and the UV detection at 220 nm. The mobile phase consisted of the 28 mM phosphate buffer at pH 6.0 and acetonitrile (85:15, v/v). Separation of one pair of positional isomers was not achieved, so methanol was added to the organic part of mobile phase in small increments with the optimal ratio of methanol to acetonitrile 59:41, v/v. The overall organic component of the mobile phase also increased to 18%, accelerating the chromatographic analysis.

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The 46th EuroCongress on Drug Synthesis and Analysis (ECDSA-2017) was arranged within the celebration of the 65th Anniversary of the Faculty of Pharmacy at Comenius University in Bratislava, Slovakia from 5–8 September 2017 to get together specialists in medicinal chemistry, organic synthesis, pharmaceutical analysis, screening of bioactive compounds, pharmacology and drug formulations; promote the exchange of scientific results, methods and ideas; and encourage cooperation between researchers from all over the world. The topic of the conference, “Drug Synthesis and Analysis,” meant that the symposium welcomed all pharmacists and/or researchers (chemists, analysts, biologists) and students interested in scientific work dealing with investigations of biologically active compounds as potential drugs. The authors of this manuscript were plenary speakers and other participants of the symposium and members of their research teams. The following summary highlights the major points/topics of the meeting.

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The human serum albumin (HSA) is well known for its extraordinary binding capacity for both endogenous and exogenous compounds, including a wide range of drugs. The goal of our investigation was to evaluate the distribution process for 15 CNS active compounds. The drug-plasma protein interaction was evaluated under simulative physiological conditions on the HSA-based stationary phase by using the mixture of Sørensen phosphate buffer (pH 7.40) and acetonitrile modifier as a mobile phase (84:16 v/v). The retention parameters (k) were used to approximate the % of protein-binding by calculating the P(%) values. The results obtained through this study demonstrated that the constitutional properties (e.g. number of total bonds, atoms, carbon atoms) and lipophilicity have a strong positive impact on the HSA-binding affinity. The coefficient of diffusion has a negative impact, while the atoms and sites available for the CYP450 oxidation showed the most significant correlation (r = 0.92). This study provides a basis for further in vitro chromatographical investigations of drug-HSA interaction for CNS active compounds. The correlation between obtained retention data and the availability to enzymes oxidation indicates the application of the tested system in the assessment of the metabolic degradation profile of CNS related drugs.