Design, Synthesis and Molecular Docking Study of Novel 3-Phenyl-β-Alanine-Based Oxadiazole Analogues as Potent Carbonic Anhydrase II Inhibitors.

Kashif Rafiq,Ahmed Al-Harrasi,Ajmal Khan,Majid Khan,Sobia Ahsan Halim,Najeeb Ur Rehman

doi:10.3390/molecules27030816

Abstract

Carbonic anhydrase-II (CA-II) is strongly related with gastric, glaucoma, tumors, malignant brain, renal and pancreatic carcinomas and is mainly involved in the regulation of the bicarbonate concentration in the eyes. With an aim to develop novel heterocyclic hybrids as potent enzyme inhibitors, we synthesized a series of twelve novel 3-phenyl-β-alanine 1,3,4-oxadiazole hybrids (4a–l), characterized by 1H- and 13C-NMR with the support of HRESIMS, and evaluated for their inhibitory activity against CA-II. The CA-II inhibition results clearly indicated that the 3-phenyl-β-alanine 1,3,4-oxadiazole derivatives 4a–l exhibited selective inhibition against CA-II. All the compounds (except 4d) exhibited good to moderate CA-II inhibitory activities with IC50 value in range of 12.1 to 53.6 µM. Among all the compounds, 4a (12.1 ± 0.86 µM), 4c (13.8 ± 0.64 µM), 4b (19.1 ± 0.88 µM) and 4h (20.7 ± 1.13 µM) are the most active hybrids against carbonic CA-II. Moreover, molecular docking was performed to understand the putative binding mode of the active compounds. The docking results indicates that these compounds block the biological activity of CA-II by nicely fitting at the entrance of the active site of CA-II. These compounds specifically mediating hydrogen bonding with Thr199, Thr200, Gln92 of CA-II.

Highlights

Carbonic anhydrases (CAs, EC 4.2.1.1) are a class of well-studied metalloenzymes widely distributed in living organisms [1]
The Carbonic anhydrase-II (CA-II) is expressed in malignant brain tumors [15,16,17], renal cancer cell lines, and gastric and pancreatic carcinomas [15,17]
A total reaction volume of 200 μL containing 20 μL of the synthetic compounds 4a–l prepared in DMSO, followed by the addition of 140 μL of the HEPES-tris buffer, 20 μL of purified bovine erythrocyte CA-II (0.15 mg/mL) prepared in buffer, and 20 μL of a solution of 4-nitrophenyl acetate [36,44]. 20 μL of tested compounds were incubated with the enzyme carbonic anhydrase II (EC 4.2.1.1) for 15 min in 96-well flat bottom plate

Summary

Introduction

Carbonic anhydrases (CAs, EC 4.2.1.1) are a class of well-studied metalloenzymes widely distributed in living organisms [1] These are strongly involved in regulating cell homeostasis, intracellular pH, fluid secretion, ion transport and biosynthetic reactions by catalyzing the reversible hydration of carbon dioxide (CO2) to bicarbonate ion (HCO3−) and proton (H+) [2,3,4,5,6,7]. The binding mode of compounds 4e and 4j demonstrated that the carbamate nitrogen of 4e interacted with a water molecule in the vicinity of active site, while the substituted R group mediated π-π interaction with the phenyl ring of Phe131, whereas the carbonyl oxygen of 4j accepted H-bond with the amino group of Thr199.

General Instrumentation

Carbonic Anhydrase II Inhibition Assay

Conclusions