2-Phenethylamines in Medicinal Chemistry: A Review

A concise review covering updated presence and role of 2-phenethylamines in medicinal chemistry is presented. Open-chain, flexible alicyclic amine derivatives of this motif are enumerated in key therapeutic targets, listing medicinal chemistry hits and appealing screening compounds. Latest reports in discovering new bioactive 2-phenethylamines by research groups are covered too.

Cardioprotective Activity of Some 2-Arylimino-1,3-Thiazole Derivatives

The article presents the synthesis of 2-arylimino-4-methyl-2,3-dihydro-1,3-thiazoles via Hantzsch reaction of thioureas and 3-chloropentane-2,4-dione or ethyl 2-chloro-3-oxobutanoate. The structure of synthesized compounds was confirmed by LCMS, 1H, and 13C NMR spectra. Cardioprotective activity of synthesized thiazole derivatives were studied in vitro on the isolated rings of the thoracic aorta of laboratory rats. Based on pharmacological studies, the tested compounds possessed a moderate to high cardioprotective effect. A prospective 1-[2-(4-methoxyphenylimino)-4-methyl-3-(4-methylpiperazine-1-yl)-2,3-dihydro-1,3-thiazole-5-yl] ethan-1-one hydrochloride 4c was identified. The mentioned compound has delayed the development of constrictor responses of isolated rings of the thoracic rat aorta and exceeds the activity of L-carnitine by 18.2% and meldonium by 12.9%. The compound 4c may be proposed as a potential cardioprotective agent for in-depth pharmacological studies.

Synthesis, spectroscopic investigation, and DFT study of N,N'-disubstituted ferrocene-based thiourea complexes as potent anticancer agents

In the present work, the synthesis, characterization (FT-IR, multinuclear (¹H and ¹³C) NMR, AAS, Raman, and elemental analyses), DNA binding (cyclic voltammetry, UV-Vis spectroscopy), and in vitro biological screening of nine new ferrocene-incorporated thioureas (A1-A9) are reported. Furthermore, the single-crystal X-ray structure of compound A8 was also determined. The ferrocene-based N,N'-disubstituted thioureas were derived by allowing the ferrocenyl anilines to react with freshly prepared isothiocyanates under a N₂ atmosphere in dry acetone. The DNA binding studies performed by cyclic voltammetry and UV-Vis spectroscopy produced results that are in close agreement with one another for the binding constants (K) and an electrostatic mode of interaction was observed. The DFT/B3LYP method was used to determine the charge distribution and HOMO/LUMO energies of the optimized structure. The DFT calculated HOMO and LUMO energies correlate well with the experimentally determined redox potential values. The synthesized ferrocenyl thioureas exhibited good scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). These complexes were also scanned for their in vitro cytotoxic activity against MCF-7 carcinoma cells, and also towards the non-cancerous cell line MCF-10A. The results showed modest cytotoxicity against the subjected cancer cell line compared with a standard chemotherapeutic drug (cisplatin). However, these ferrocenyl derivatives have fewer toxic effects in normal cells.

Design, synthesis, molecular docking studies and in vitro screening of ethyl 4-(3-benzoylthioureido) benzoates as urease inhibitors

Thioureas are exceptionally versatile building blocks towards the synthesis of wide variety of heterocyclic systems, which also possess extensive range of pharmacological activities. The substituted benzoic acids were converted into corresponding acid chlorides, these acid chlorides were then treated with potassium thiocyanate in acetone and then the reaction mixture was refluxed for 1-2h afford ethyl 4-(3-benzoylthioureido)benzoates thioureas in good yields. All the newly synthesized compounds were evaluated for their urease inhibitory activities and were found to be potent inhibitors of urease enzyme. Compounds 1f and 1g were identified as the most potent urease inhibitors (IC50 0.21 and 0.13 μM, respectively), and was 100-fold more potent than the standard inhibitors. Further molecular docking studies were carried out using the crystal structure of urease to find out the binding mode of the inhibitors with the enzyme.

Conformational Preferences and Internal Rotation in Alkyl- and Phenyl-Substituted Thiourea Derivatives

Potential energy surfaces (PES) for rotation about the N-C(sp(3)) or N-C(aryl) bond and energies of stationary points on PES for rotation about the C(sp(2))-N bond are reported for methylthiourea, ethylthiourea, isopropylthiourea, tert-butylthiourea, and phenylurea, using the MP2/aug-cc-pVDZ method. Analysis of alkylthioureas shows that conformations, with alkyl groups cis to the sulfur atom, are more stable (by 0.4-1.5 kcal/mol) than the trans forms. All minima adopt anti configurations with respect to nitrogen pyramidalization, whereas syn configurations are not stationary points on the MP2 potential surface. In contrast, analysis of phenylthiourea reveals that a trans isomer in a syn geometry is the global minimum, whereas a cis isomer in an anti geometry is a local minimum with a relative energy of 2.7 kcal/mol. Rotation about the C(sp(2))-N bond in alkyl and phenyl thioureas is slightly more hindered (9.1-10.2 kcal/mol) than the analogous motion in the unsubstituted molecule (8.6 kcal/mol). The maximum barriers to rotation for the methyl, ethyl, isopropyl, tert-butyl, and phenyl substituents are predicted to be 1.2, 8.9, 8.6, 5.3, and 0.9 kcal/mol, respectively. Corresponding PESs are consistent with the experimental dihedral angle distribution observed in crystal structures. The results of the electronic structure calculations are used to benchmark the performance of the MMFF94 force field. Systematic discrepancies between MMFF94 and MP2 results were improved by modification of selected torsion parameters and one of the van der Waals parameters for sulfur.