Design and synthesis of new potent 5-HT7 receptor ligands as a candidate for the treatment of central nervous system diseases

Neuroprotective and Neurite Outgrowth Stimulating Effects of New Low-Basicity 5-HT7 Receptor Agonists: In Vitro Study in Human Neuroblastoma SH-SY5Y Cells

There is some evidence that the serotonin receptor subtype 7 (5-HT7) could be new therapeutic target for neuroprotection. The aim of this study was to compare the neuroprotective and neurite outgrowth potential of new 5-HT7 receptor agonists (AH-494, AGH-238, AGH-194) with 5-CT (5-carboxyamidotryptamine) in human neuroblastoma SH-SY5Y cells. The results revealed that 5-HT7 mRNA expression was significantly higher in retinoic acid (RA)-differentiated cells when compared to undifferentiated ones and it was higher in cell cultured in neuroblastoma experimental medium (DMEM) compared to those placed in neuronal (NB) medium. Furthermore, the safety profile of compounds was favorable for all tested compounds at concentration used for neuroprotection evaluation (up to 1 μM), whereas at higher concentrations (above 10 μM) the one of the tested compounds, AGH-194 appeared to be cytotoxic. While we observed relatively modest protective effects of 5-CT and AH-494 in UN-SH-SY5Y cells cultured in DMEM, in UN-SH-SY5Y cells cultured in NB medium we found a significant reduction of H2O2-evoked cell damage by all tested 5-HT7 agonists. However, 5-HT7-mediated neuroprotection was not associated with inhibition of caspase-3 activity and was not observed in RA-SH-SY5Y cells exposed to H2O2. Furthermore, none of the tested 5-HT7 agonists altered the damage induced by 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium ion (MPP +) and doxorubicin (Dox) in UN- and RA-SH-SY5Y cells cultured in NB. Finally we showed a stimulating effect of AH-494 and AGH-194 on neurite outgrowth. The obtained results provide insight into neuroprotective and neurite outgrowth potential of new 5-HT7 agonists.

Eco-friendly methods of synthesis and preliminary biological evaluation of sulfonamide derivatives of cyclic arylguanidines

The chemotype of arylsulfonamide derivatives of cyclic arylguanidines is a source of molecules with valuable biological activities, including antimicrobial and antitumor properties. The methods of the synthesis presented in the literature are characterized with low selectivity and high environmental nuisance. In this publication, we present a developed alternative and earlier undescribed pathway C, for the synthesis of arylsulfonamide derivatives of cyclic arylguanidines (N-(1H-arylimidazol-2-yl)arylsulfonamides and N-(1,4-dihydroquinazolin-2-yl)arylsulfonamides), including reaction between 2-(methylsulfanyl)-benzimidazole or 2-(methylsulfanyl)-3,4-dihydroquinazoline with arylsulfonamides. We also optimized previously reported methods; A (reaction of 2-aminobenzimidazole or 2-amino-3,4-dihydroquinazoline with arylsulfonyl chlorides) and B (reaction of dimethyl-(arylsulfonyl)carbonodithioimidate with aryldiamines). The conducted research allowed achieving two independent ecological and quick methods of obtaining the desired products. We used ecological methods of ultrasound-assisted or microwave synthesis, solvent-free reactions and a"green" reaction environment. In both pathways, it has proven advantageous to use H₂O as the solvent and K₂CO₃ (1 or 3 equivalent) as the basic agent. In the sonochemical variant, the efficiency reached B: 37-89 %, C: 90 % in 60 min (P = 80 W and f = 40 kHz), while in the microwave synthesis it was B: 38-74 %, C: 63-85 % in 0.5-4 min (P = 50 W). Path A led to a complementary substitution product (i.e. 1-(arylsulfonyl)-1H-benzimidazol-2-amine or 1-(arylsulfonyl)-1,4-dihydroquinazolin-2-amine). We obtained a small group of compounds that were tested for cytotoxicity. The 10f (N-(1,4-dihydroquinazolin-2-yl)naphthalene-1-sulfonamide) showed cytotoxic activity towards human astrocytoma cell line 1321 N1. The calculated IC₅₀ value was 8.22 µM at 24 h timepoint (doxorubicin suppressed 1321 N1 cell viability with IC₅₀ of 1.1 µM). The viability of the cells exposed to 10f for 24 h dropped to 48.0 % compared to vehicle control, while the cells treated with doxorubicin experienced decline to 47.5 %. We assessed its potential usefulness in pharmacotherapy in the ADMET study, confirming its ability to cross the blood-brain barrier (Pe = 5.0 ± 1.5 × 10^-6 cm/s) and the safety of its potential use in terms of DDI and hepatotoxicity.

Design, Synthesis and Biological Evaluation of Novel 1,3,5-Triazines: Effect of Aromatic Ring Decoration on Affinity to 5-HT7 Receptor

Considering the key functions of the 5-HT7 receptor, especially in psychiatry, and the fact that effective and selective 5-HT7 receptor ligands are yet to be available, in this work, we designed and synthesized novel 1,3,5-triazine derivatives particularly based on the evaluation of the effect of substituents at aromatic rings on biological activity. The tested compounds showed high affinity to the 5-HT7 receptor, particularly ligands N2-(2-(5-fluoro-1H-indol-3-yl)ethyl)-N4-phenethyl-1,3,5-triazine-2,4,6-triamine 2 (Ki = 8 nM) and N2-(2-(1H-indol-3-yl)ethyl)-N4-(2-((4-fluorophenyl)amino)ethyl)-1,3,5-triazine-2,4,6-triamine 12 (Ki = 18 nM) which showed moderate metabolic stability, and affinity to the CYP3A4 isoenzyme. As for the hepatotoxicity evaluation, the tested compounds showed moderate cytotoxicity only at concentrations above 50 µM. Compound 12 exhibited less cardiotoxic effect than 2 on Danio rerio in vivo model.

New, Eco-Friendly Method for Synthesis of 3-Chlorophenyl and 1,1'-Biphenyl Piperazinylhexyl Trazodone Analogues with Dual 5-HT1A/5-HT7 Affinity and Its Antidepressant-like Activity

Serotonin 5-HT_1A and 5-HT₇ receptors play an important role in the pathogenesis and pharmacotherapy of depression. Previously identified N-hexyl trazodone derivatives, 2-(6-(4-(3-chlorophenyl)piperazin-1-yl)hexyl)-[1,2,4]triazolo[4,3-a]pyridin-3(2H)-one hydrochloride (7a·HCl), with high affinity for 5-HT_1AR and 2-(6-(4-([1,1'-biphenyl]-2-yl)piperazin-1-yl)hexyl)-[1,2,4]triazolo[4,3-a]pyridin-3(2H)-one hydrochloride (7b·HCl), a dual-acting 5-HT_1A/5-HT₇ receptor ligand, were prepared with a new microwave-assisted method. The protocol for the synthesis of 7a and 7b involved reductive alkylation under a mild reducing agent. We produced the final compounds with yield of 56-63% using ethanol or 51-56% in solvent-free conditions in 4 min. We then determined the 5-HT₇R binding mode for compounds 7a and 7b using in silico methods and assessed the preliminary ADME and safety properties (hepatotoxicity and CYP3A4 inhibition) using in vitro methods for 7a·HCl and 7b·HCl. Furthermore, we evaluated antidepressant-like activity of the dual antagonist of 5-HT_1A/5-HT₇ receptors (7b·HCl) in the forced swim test (FST) in mice. The 5-HT_1AR ligand (7a·HCl) with a much lower affinity for 5-HT₇R compared to that of 7b·HCl was tested comparatively. Both compounds showed antidepressant activity, while 5-HT_1A/5-HT₇ double antagonist 7b·HCl showed a stronger and more specific response.