Novel Regioselective Synthesis of 1,3,4,5-Tetrasubstituted Pyrazoles and Biochemical Valuation on F₁F_O-ATPase and Mitochondrial Permeability Transition Pore Formation

• Main Authors: Vincenzo Algieri (Author), Cristina Algieri (Author), Paola Costanzo (Author), Giulia Fiorani (Author), Antonio Jiritano (Author), Fabrizio Olivito (Author), Matteo Antonio Tallarida (Author), Fabiana Trombetti (Author), Loredana Maiuolo (Author), Antonio De Nino (Author), Salvatore Nesci (Author)
• Format: Book
• Published: MDPI AG, 2023-02-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

An efficient, eco-compatible, and very cheap method for the construction of fully substituted pyrazoles (Pzs) via eliminative nitrilimine-alkene 1,3-dipolar cycloaddition (ENAC) reaction was developed in excellent yield and high regioselectivity. Enaminones and nitrilimines generated in situ were selected as dipolarophiles and dipoles, respectively. A deep screening of the employed base, solvent, and temperature was carried out to optimize reaction conditions. Recycling tests of ionic liquid were performed, furnishing efficient performance until six cycles. Finally, a plausible mechanism of cycloaddition was proposed. Then, the effect of three different structures of Pzs was evaluated on the F₁F_O-ATPase activity and mitochondrial permeability transition pore (mPTP) opening. The Pz derivatives' titration curves of <b>6a</b>, <b>6h</b>, and <b>6o</b> on the F₁F_O-ATPase showed a reduced activity of 86%, 35%, and 31%, respectively. Enzyme inhibition analysis depicted an uncompetitive mechanism with the typical formation of the tertiary complex enzyme-substrate-inhibitor (<i>ESI</i>). The dissociation constant of the <i>ESI</i> complex (<i>K</i>_i') in the presence of the <b>6a</b> had a lower order of magnitude than other Pzs. The pyrazole core might set the specific mechanism of inhibition with the F₁F_O-ATPase, whereas specific functional groups of Pzs might modulate the binding affinity. The mPTP opening decreased in Pz-treated mitochondria and the Pzs' inhibitory effect on the mPTP was concentration-dependent with <b>6a</b> and <b>6o</b>. Indeed, the mPTP was more efficiently blocked with 0.1 mM <b>6a</b> than with 1 mM <b>6a</b>. On the contrary, 1 mM <b>6o</b> had stronger desensitization of mPTP formation than 0.1 mM <b>6o</b>. The F₁F_O-ATPase is a target of Pzs blocking mPTP formation.

Item Description

10.3390/pharmaceutics15020498
1999-4923