A new FRET-based functional chemosensor for fluorometric detection of Fe3+and its validation through in silico studies

Synthesis, molecular docking and molecular dynamics simulations, drug-likeness studies, ADMET prediction and biological evaluation of novel pyrazole-carboxamides bearing sulfonamide moiety as potent carbonic anhydrase inhibitors

Pyrazoles are unique bioactive molecules with a versatile biological profile and they have gained an important place on pharmaceutical chemistry. Pyrazole compounds containing sulfonamide nuclei also attract attention as carbonic anhydrase (CA) inhibitors. In this study, a library of pyrazole-carboxamides were synthesized and the structures of the synthesized molecules were characterized using FT-IR, 1H-NMR, 13C-NMR and HRMS. Then the inhibition effects of newly synthesized molecules on human erythrocyte hCA I and hCA II isoenzymes were investigated. Ki values of the compounds were in the range of 0.063-3.368 µM for hCA I and 0.007-4.235 µM for hCA II. Molecular docking studies were performed between the most active compounds 6a, 6b and the reference inhibitor, acetazolamide (AAZ) and the hCA I and hCA II receptors to investigate the binding mechanisms between the compounds and the receptors. These compounds showed better interactions than the AAZ. ADMET analyzes were performed for the compounds and it was seen that the compounds did not show AMES toxicity. The stability of the molecular docking results over time was analysed by 50 ns molecular dynamics simulations. Molecular dynamics simulations revealed that 6a and 6b exhibited good stability after docking to the binding sites of hCA I and hCA II receptors, with minor conformational changes and fluctuations.

A naphthyl appended ninhydrin based colorimetric chemosensor for Cu2+ ion: Detection of cysteine and ATP

A ninhydrin-based colorimetric chemosensor (LH) was synthesized using 3-hydroxy-2-naphthoic hydrazide and 11H-indeno[1,2-b]quinoxalin-11-one. It was characterized by spectroscopic and single crystal X-ray diffraction techniques. In a semi-aqueous (MeOH/HEPES) system, LH displayed a characteristic chromogenic change from colorless to yellow upon adding Cu2+ ion, with the appearance of a new peak at λmax = 460 nm. A 1:1 binding stoichiometry between LH and Cu2+ ion has been found, with LOD = 2.3 μM (145 ppb) and LOQ = 8 μM (504 ppb). Based on experimental results the formula of [Cu(L)Cl(H2O)2] (1) was assigned and this in-situ generated 1 was found to exhibit a discoloration of upon gradual addition of cysteine (LOD = 60 nM) as well as ATP (LOD = 130 nM) having 1:2 and 1:1 stoichiometry respectively. The LH was useful for recognition of Cu2+ ion in real water samples and on filter paper strips. A two-input-two-output logic gate circuitry was also constructed by employing 1 and cysteine. The DFT/TDDFT calculations performed on LH and 1 were consistent with experimental findings. The binding affinity of LH towards HSA and BSA were determined with HSA having greater affinity than BSA, which was also supported by theoretical calculations.

Construction of CdTe@γ-CD@RBD nanoprobe for Fe3+-sensing based on FRET mechanism in human serum

A Fe³⁺ optical sensor (CdTe@γ-CD@RBD) has been developed by using gamma-cyclodextrin (γ-CD) as a bridge to link CdTe quantum dots (QDs) and a Rhodamine B derivative (RBD). The RBD molecule can enter the cavity of the γ-CD anchored onto the surfaces of the QDs. In the presence of Fe³⁺, the fluorescence resonance energy transfer (FRET) process from QDs to RBD will be initiated, rendering the nanoprobe to display a response to Fe³⁺. The degree of fluorescence quenching presented a satisfactory linearity between 10 and 60 μΜ with the incremental concentrations of Fe³⁺, and the calculated limit of detection was 2.51 μΜ. Through sample pretreatment procedures, the probe has been used in the determination of Fe³⁺ in human serum. The average recoveries in the spiking levels are ranged from 98.60 % to 107.20 % with a relative standard deviation of around 1.43 %-2.96 %. This finding leads to a method for fluorescent detection of Fe³⁺ with high sensitivity and exceptional selectivity. We believe that this study can give a new insight into the rational design and application of FRET-based nanoprobes.

A Carbazole-based Fluorescent Turn-off Chemosensor for Iron (II/III) Detection in a Dimethyl Sulfoxide

We designed a novel carbazole-based chemosensor from 2-(N-hexylcarbazol-3'-yl)-pyridine-5-carbaldehyde which was named probe 7b. The main purpose of this study is to investigate whether metal ions in liquid media can be detected with probe 7b. The details were presented in this paper. First, the molecular absorption and fluorescence properties of probe 7b were characterized by spectrophotometers. Then, several methods were applied to check its sensing properties. The results showed that probe 7b has a sense towards Fe3+ ion than other interfering metal ions. The selectivity and sensitivity of probe 7b towards Fe3+ were very satisfactory to use in applications. Also, it was observed that when aqueous Fe3+ ion solutions were added to probe 7b in dimethyl sulfoxide (DMSO), the fluorescence intensity of probe 7b decreased. This situation (turn-off of emission) is due to the paramagnetic effect between probe 7b and Fe3+ ions. The limit of detection (LOD) value was found as 1.38 nM for probe 7b. This value is very small to compete with its counterparts in the literature. A real sample experiment indicated that probe 7b can detect Fe3+ ions more than other ions in real media, too. As a result, it was deduced that probe 7b is a very strong candidate to use in sensor technology.

The role of Bax/Bcl-2 and Nrf2-Keap-1 signaling pathways in mediating the protective effect of boric acid on acrylamide-induced acute liver injury in rats

INTRODUCTION

This study aims to investigate whether boric acid (BA) can protect rats from acrylamide (AA)-induced acute liver injury.

MATERIALS AND METHODS

AA was used to induce acute liver injury. Thirty rats were divided into five group including Group 1 (saline), Group 2 (AA), Group 3 (20 mg/kg BA), Group 4 (10 mg/kg BA+AA) and Group 5 (20 mg/kg BA+AA). Their blood and liver were harvested to be kept for analysis. Liver function enzyme activities were performed by spectrophotometric method. Catalase (CAT), superoxide dismutase (SOD) activity, and malondialdehyde levels were determined by colorimetric method. The in-silico studies were performed using the "blind docking" method.

RESULTS

Administration AA to rats, biochemical parameters, liver histology, and expression levels of apoptotic markers were negatively affected. However, after the administration of BA, the altered biochemical parameters, liver histology, and expression levels of apoptotic markers were reversed. Moreover, the mechanisms of AA-induced deterioration in the levels of SOD, CAT, and Nrf2-Keap-1 and the mechanisms of the protective effect of BA against these deteriorations were explained by in silico studies.

CONCLUSION

Thus, the present study could explain the interactions between AA and thiol-containing amino acid residues of Keap-1, the effect of BA on these interactions, and the biochemical toxicity caused by the AA. In this sense, this work is the first of its kind in the literature. Based on the biochemical, histopathological, and in silico results, it can be suggested that BA has the potential to be used as a protective agent against AA-induced liver injury.