Novel Regioselective Synthesis of 1,3,4,5-Tetrasubstituted Pyrazoles and Biochemical Valuation on F1FO-ATPase and Mitochondrial Permeability Transition Pore Formation

Abstract

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 F1FO-ATPase activity and mitochondrial permeability transition pore (mPTP) opening. The Pz derivatives’ titration curves of 6a, 6h, and 6o on the F1FO-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 (ESI). The dissociation constant of the ESI complex (Ki’) in the presence of the 6a had a lower order of magnitude than other Pzs. The pyrazole core might set the specific mechanism of inhibition with the F1FO-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 6a and 6o. Indeed, the mPTP was more efficiently blocked with 0.1 mM 6a than with 1 mM 6a. On the contrary, 1 mM 6o had stronger desensitization of mPTP formation than 0.1 mM 6o. The F1FO-ATPase is a target of Pzs blocking mPTP formation.

Ionic Liquids in Pharmaceutical and Biomedical Applications: A Review

“…They are an ideal medium for reactions using transition metal catalysts with high polarity and weak bonding ability. Recently, ILs have been used as green solvents, reagents, catalysts, and enantioselectivity enhancers in the synthesis of various active pharmaceutical ingredients [ 28 , 29 ]. Marcin et al have examined the efficiency of employing ILs with various cations (ammonium-, piperidinium-, pyridinium-, and imidazolium-based), each having a distinct structure of alkyl side-chains, pairing with the [N(Tf) 2 ] anion as novel co-solvents for the reaction of acetic anhydride with curcumin under moderate conditions.…”

1,2,3-Triazole Hybrids Containing Isatins and Phenolic Moieties: Regioselective Synthesis and Molecular Docking Studies

“…Finally, to verify the goodness of the developed synthetic procedure, we reproduced the reaction on a gram-scale, obtaining similar reaction yields (Table 2, entry 11). Ultimately, the 1,3-dipolar cycloaddition was carried out in ionic liquid [mPy]OTf [40,41] (Table 2, entry 12), with the aim of recycling the solvent and catalytic system after the reaction. Unfortunately, in these conditions, only traces of product 23 were observed (Table 2, entry 12).…”

“…OH).13 C NMR (DMSO-d 6 , 125 MHz): δ (ppm)40.98, 47.92, 58.04, 109.62, 111.12, 118.29, 119.94, 124.23, 125.47, 126.61, 139.03, 143.22, 146.54, 151.15, 159.11, 166.42, 175.96, 183.89. ESI(+)-MS: m/z [M + H] + calcd for [C 20 H 17 N 4 O 7 ] + , 425.1092, found 425.1098.…”