Isoxazole Derivatives against Carbonic Anhydrase: Synthesis, Molecular Docking, MD Simulations, and Free Energy Calculations Coupled with In Vitro Studies

Abstract

Heterocyclic compounds with a five-membered ring as a core, particularly those containing more than one heteroatom, have a wide spectrum of biological functions, especially in enzyme inhibition. In this study, we present the synthesis of five-membered heterocyclic isoxazole derivatives via sonication of ethyl butyrylacetate with aromatic aldehyde in the presence of a SnII-Mont K10 catalyst. The synthesized compounds were characterized using sophisticated spectroscopic methods. In vitro testing of the compounds reveals three derivatives with significant inhibitory action against carbonic anhydrase (CA) enzyme. The compound AC2 revealed the most promising inhibitory activity against CA among the entire series, with an IC 50 = 112.3 ± 1.6 μM (% inh = 79.5) followed by AC3 with an IC 50 = 228.4 ± 2.3 μM (% inh = 68.7) compared to the standard with 18.6 ± 0.5 μM (% inh = 87.0). Molecular docking (MD) study coupled with extensive MD simulations (400 ns) and MMPBSA study fully supported the in vitro enzyme inhibition results, evident from the computed Δ G bind (AC2 = −13.53 and AC3 = −12.49 kcal/mol). The in vitro and in silico studies are also augmented by a fluorescence-based enzymatic assay in which compounds AC2 and AC3 showed significant fluorescence enhancement. Therefore, on the basis of the present study, it is inferred that AC2 and AC3 may serve as a new framework for designing effective CA inhibitors.

Chemistry of heterocycles as carbonic anhydrase inhibitors: A pathway to novel research in medicinal chemistry review

“…20d (R = 2-Ffuorophenyl) showed excellent inhibition against hCA IX with K i values of 22 nM whereas 24e showed better inhibition against hCA XII with K i values of 8.7 nM [23] (Scheme 3). Newly synthesized compounds were also subjected to in silico studies by using Gaussian 09 with the B3LYP/6-31G basis set to optimize geometry and it was observed that compounds 28b and 28c with high binding energy of −15.07 and −13.95 kcal/mol proved to be potent inhibitors against CA IX [24] (Scheme 4). Newly synthesized compounds were evaluated for their inhibitory activity against cytosolic hCA II by taking zonisamide as a standard drug and it was observed that 34h, X = COOCH 3 34i (R 1 = R 2 = H, R 3 = OH, X = CN), 34j (R 1 = R 2 = H, R 3 = OH, X = COOC 2 H 5 ) with IC 50 values of 4.55 ± 0.22, 4.91 ± 1.13, and 7.78 ± 0.08 µM, respectively, due to the presence of electron-donating OH group.…”

“…Newly synthesized compounds were also subjected to in silico studies by using Gaussian 09 with the B3LYP/6‐31G basis set to optimize geometry and it was observed that compounds 28b and 28c with high binding energy of −15.07 and −13.95 kcal/mol proved to be potent inhibitors against CA IX [ 24 ] (Scheme 4).…”

“…Alafeefy et al developed a procedure to synthesize novel sulfonamides containing aroyl hydrazone-,[1,24]triazolo[3,4]thiadiazinyl or 2-(cyanophenylmethylene)-1,3,4-thiadiazol-3(2H)-yl, moieties 1807(a-d), 1808(a-d), 1810(a-b), and 1813(a-d) by taking 2-oxo-N′-S C H E M E 270 Synthesis of 1774(a-k). S C H E M E 271 Synthesis of 1781(a-k).…”

Antiviral effect of fucoxanthin obtained from Sargassum siliquastrum (Fucales, Phaeophyceae) against severe acute respiratory syndrome coronavirus 2

“…Molecular dynamics is a computer simulation method for evaluating the stability of a small molecule binding to a protein target (Guterres and Im 2020). Several previous studies have reported on ligand-protein complex formations by validating their results using molecular docking and MD simulations, to support their in vitro results (Elkaeed et al 2022, Saleem et al 2022, Deswal et al 2023, Nassar et al 2023.…”

Benzofuran-Isoxazole Hybrids: Synthesis, Antimicrobial Activity and Dual Target Docking Studies

“…Their structural features make them essential building blocks in organic synthesis, contributing to the creation of bioactive compounds. Isoxazoles are also recognized for their antimicrobial [13,14], anticancer [15,16], anticholinesterase [17] and diuretic properties [18].…”