Synthesis and biological evaluation of novel salicylidene uracils: Cytotoxic activity on human cancer cell lines and inhibitory action on enzymatic activity

A series of salicylidene uracil (1-18) derived from 5-aminouracil and substituted salicylaldehydes were analyzed for cytotoxic activity and enzyme inhibitory potency. Nine out of eighteen derivatives (6-8, 10, 12-15, 18) are novel molecules synthesized for the first time in this work, and other derivatives were previously synthesized by our group. The compounds were characterized by Proton nuclear magnetic resonance, carbon nuclear magnetic resonance, fourier transform infrared spectroscopy, and elemental analysis. All compounds were tested for their in vitro cytotoxicity against PC-3 (human prostate adenocarcinoma), A549 (human alveolar adenocarcinoma), and SHSY-5Y (human neuroblastoma) cancer cell lines and the nontumorigenic HEK293 (human embryonic kidney cells) cell line. The 3,5-di-tert-butylsalicylaldehyde derived compound (8) was toxic to PC-3 human prostate adenocarcinoma cells, showing a promising IC50 value at 7.05 ± 0.76 μM. The present study also aimed to evaluate the inhibitory effects of the compounds against several key enzymes, namely carbonic anhydrase I and II (CA I and CA II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and glutathione reductase (GR), which are implicated in various global disorders, such as Alzheimer's disease, epilepsy, cancer, malaria, diabetes, and glaucoma. The inhibitory profiles of the tested compounds were assessed by determining their Ki values, which ranged from 2.96 to 9.24 nM for AChE, 3.78 to 12.57 nM for BChE, 8.42 to 25.74 nM for CA I, 7.24 to 19.74 nM for CA II, and 0.541 to 1.124 μM for GR. Molecular docking studies were also performed for all compounds. Most derivatives exhibited much more effective inhibitory action compared with clinically used standards. Thus, our findings indicate that the salicylidene derivatives presented in this study are promising drug candidates that need further evaluation.

A safe alternative synthesis of primary carbamates from alcohols; in vitro and in silico assessments as an alternative acetylcholinesterase inhibitors

Carbamates are important molecules because they are used in various biochemical processes. In this study, effective alternative method for the synthesis of primary carbamates from alcohols was developed in the presence of chlorosulfonyl isocyanate (CSI) in pyridine at room temperature in mild conditions. The primary carbamates were synthesized excellent yield. This method is easy, practical, and inexpensive without any additive, metal, or catalyst. Alzheimer's disease (AD) is a neurodegenerative disease and has been reported to affect approximately 50 million people worldwide in 2020. Drugs that reversibly inhibit the acetylcholinesterase (AChE) activity are used for the treatment of AD. For this reason, there is a growing interest in developing alternative AChE inhibitors. Concordantly, Anti-anticholinesterase activity of synthesized carbamate derivatives was investigated as an alternative AChE inhibitors. In order to determine the inhibitory effect of these molecules, IC50, and Ki values and inhibition types were determined. According to the Ki results, the most effective inhibitors were 3 b and 3e with the Ki values of 22 and 38 µM, respectively. It was found that all molecules showed competitive inhibition type. For clarify the inhibitors-enzyme interactions, molecular docking studies were performed and possible binding interactions between the synthesized molecules and AChE were determined. Additionally, the pharmacokinetic and properties of the synthesized molecules were evaluated in silico.Communicated by Ramaswamy H. Sarma.

In Vitro Inhibition Profiles and Molecular Docking Analysis of Benzohydrazide Derivatives on Red Blood Cell Carbonic Anhydrases Isozymes

Background:

Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes that contain zinc ions on the active side and convert carbon dioxide to bicarbonate in metabolism. Human CA-I and CA-II, which are the most abundant CA isozymes in erythrocytes, have been therapeutic targets in the treatment of glaucoma, hypertension, ulcer, osteoporosis, and, neurological disorders. Benzohydrazides are biologically active compounds, and their various pharmacological effects have been reported.

Aim:

In light of this, the objective of this study was to investigate the in vitro effects of benzohydrazide derivatives on the activities of hCA-I and hCA-II, determine the compounds as selective inhibitors for these isoenzymes, and estimate the inhibition mechanism through molecular docking studies.

Method:

In this work, we synthesized the 10 different derivatives of benzohydrazide containing various functional group of different positions.

Results:

As a result, all benzohydrazide derivatives inhibited both isozymes in vitro and 2-amino 3-nitro benzohydrazide (10) was found the most efficient inhibitor of both hCA isozymes with the IC50 values of 0.030 and 0.047 µM, respectively. In the molecular docking studies, 3-amino 2-methyl benzohydrazide (3) had the lowest estimated free binding energies against hCA isozymes as -6.43 and -6.13 kcal/mol.

Biological evaluation and in silico study of benzohydrazide derivatives as paraoxonase 1 inhibitors

Serum paraoxonase 1 (PON1) is found in all mammalian species and is a calcium-dependent hydrolytic enzyme. PON1 hydrolyze several substrates, including carbonates, esters, and organophosphates. In the current study, we aimed to investigate the effect of the presynthesized benzohydrazide derivatives (1-9) on PON1 activity. Benzohydrazide compounds moderate inhibited PON1 with the half-maximal inhibitory concentration values ranging from 76.04 ± 13.51 to 221.70 ± 13.59 μM and K_I values ranging from 38.75 ± 12.21 to 543.50 ± 69.76 μM. Compound 4 (2-amino-4-chlorobenzohydrazide) showed the best inhibition (K_I  = 38.75 ± 12.21 μM). Molecular docking and ADME-Tox studies of benzohydrazide derivatives were also carried out. In this context, we hope that the results obtained in this study contribute to the determination of the side effects of current and new benzohydrazide-based pharmacological compounds to be developed.

Using of group-based selected flavonoids as alternative inhibitors for potato polyphenol oxidase

One of the main problems encountered after fresh-cutting of foods is enzymatic browning causing changes in the texture, taste, and color. The variety of physical and chemical-based antibrowning methods was applied to extend the shelf life of these products. Accordingly, methods using natural compounds are of great importance for health. In this study, it was aimed to prevent enzymatic browning in potato (Solanum tuberosum L. cv. Marfona) by limiting the polyphenol oxidase (PPO) activity with selected flavonoids. First of all, we purified the potato PPO (pPPO) by single-step affinity chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE were applied on pPPO. Then, the inhibition effects of 7-hydroxyflavone, 7-hydroxy-4'-nitroisoflavone, myricetin, luteolin, 7-methoxyflavone, 6-fluoroflavone, diosmetin, rutin, and diosmin on purified PPO enzyme were investigated. Kinetic assays indicated that myricetin was a remarkable inhibitor with the K_i value of 5 µM on pPPO. PRACTICAL APPLICATIONS: Potatoes are one of the important diet in many countries. In the processing of potatoes, enzymatic oxidation catalyzed by polyphenol oxidases (PPOs) is lead to losing its taste, flavor, and color. In this current paper, group-based selected flavonoids were proposed as alternative inhibitors of potato PPO enzyme. These flavonoids allowing to limit the PPO activity are commercially available, and they can be potential candidates to be used as antibrowning agents during potato processing.

Changes in Some Quality Properties of Kefir during Storage and Inhibition Effect of Water Soluble Extracts on Angiotensin-I Converting Enzyme Purified by Human Plasma

Angiotensin converting enzyme (ACE)-inhibitory activity in water soluble extracts (WSEs) of kefir was investigated. Kefir was produced traditionally using kefir grains and stored at refrigerated temperature for 20 days. During storage period (on 1, 5, 10, 15 and 20 days) in vitro ACE-inhibitory activity in WSEs was determined. ACE was purified from human plasma to determine kinetic parameters. Purified ACE had a specific activity of 20.75 EU.mg−1, a yield of 16.6% with a factor of 22100. The inhibition effects of kefir on ACE increased at 15 storage days than other storage days. Some microbiological and physicochemical characteristics of kefir were also studied. Counts of presumptive LAB on M-17 and presumptive LAB on MRS in the kefir were about 108 CFU.ml−1 throughout the storage period. Yeast counts were lower than lactic acid bacteria counts and the average of the counts was approximately 106 log CFU.ml−1. Storage period had a significant effect (P < 0.05) on titratable acidity and pH values. On the contrary, it had no significant effect (P > 0.05) on viscosity and serum separation values of kefir.