Zübeyir Huyut

Rosmarinic acid inhibits some metabolic enzymes including glutathione S-transferase, lactoperoxidase, acetylcholinesterase, butyrylcholinesterase and carbonic anhydrase isoenzymes

Abstract Rosmarinic acid (RA) is a natural polyphenol contained in many aromatic plants with promising biological activities. Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread and intensively studied metalloenzymes present in higher vertebrates. Acetylcholinesterase (AChE, E.C. 3.1.1.7) is intimately associated with the normal neurotransmission by catalysing the hydrolysis of acetylcholine to acetate and choline and acts in combination with butyrylcholinesterase (BChE) to remove acetylcholine from the synaptic cleft. Lactoperoxidase (LPO) is an enzyme involved in fighting pathogenic microorganisms, whereas glutathione S-transferases (GSTs) are dimeric proteins present both in prokaryotic and in eukaryotic organisms and involved in cellular detoxification mechanisms. In the present study, the inhibition effects of rosmarinic acid on tumour-associated carbonic anhydrase IX and XII isoenzymes, AChE, BChE, LPO and GST enzymes were evaluated. Rosmarinic acid inhibited these enzymes with Kis in the range between micromolar to picomolar. The best inhibitory effect of rosmarinic acid was observed against both AChE and BChE.

Synthesis of new cyclic thioureas and evaluation of their metal-chelating activity, acetylcholinesterase, butyrylcholinesterase, and carbonic anhydrase inhibition profiles.

In the presence of trifluoracetic acid (TFAA), an efficient method for the synthesis of tetra(hexa)hydropyrimidinethione‐carboxylates has been used on the basis of three‐component condensation of thiourea with its different aldehydes and β‐diketones. Some novel cyclic thioureas were synthesized, and their hCA I, hCA II, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitors and metal‐chelating properties were evaluated. Ki values of novel synthesized compounds for AChE and BChE are in the range of 51.84–135.96 and 143.96–274.55 nM, respectively. Also, HCA I and II were effectively inhibited by these novel compounds, with Ki values in the range of 404.16–745.13 nM for hCA I and of 434.20–689.57 nM for hCA II, respectively. Additionally, acetazolamide (AZA), clinically used as a CA inhibitor, with a Ki value of 883.68 ± 121.27 nM in hCA I and 1008.66 ± 144.70 nM in hCA II. Also, tacrine inhibited AChE and BChE showed Ki values of 314.63 ± 31.66 and 373.57 ± 75.07 nM, respectively.

Synthesis and biological evaluation of aminomethyl and alkoxymethyl derivatives as carbonic anhydrase, acetylcholinesterase and butyrylcholinesterase inhibitors

Abstract Compounds containing nitrogen and sulfur atoms can be widely used in various fields such as industry, medicine, biotechnology and chemical technology. Therefore, the reactions of aminomethylation and alkoxymethylation of mercaptobenzothiazole, mercaptobenzoxazole and 2-aminothiazole were developed. Additionally, the alkoxymethyl derivatives of mercaptobenzoxazole and 2-aminothiazole were synthesized by a reaction with hemiformals, which are prepared by the reaction of alcohols and formaldehyde. In this study, the inhibitory effects of these molecules were investigated against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) enzymes and carbonic anhydrase I, and II isoenzymes (hCA I and II). Both hCA isoenzymes were significantly inhibited by the recently synthesized molecules, with Ki values in the range of 58–157 nM for hCA I, and 81–215 nM for hCA II. Additionally, the Ki parameters of these molecules for BChE and AChE were calculated in the ranges 23–88 and 18–78 nM, respectively.

Inhibitory effects of some phenolic compounds on the activities of carbonic anhydrase: from in vivo to ex vivo

Abstract Carbonic anhydrase (CA) inhibitors have been used for more than 60 years for therapeutic purposes in many diseases table such as in medications against antiglaucoma and as diuretics. Phenolic compounds are a new class of CA inhibitor. In our study, we tested the effects of arachidonoyl dopamine, 2,4,6-trihydroxybenzaldehyde and 3,4-dihydroxy-5-methoxybenzoic acid on esterase and the CO2-hydratase activities of CA I and II isozymes purified from in vivo to ex vivo. The Ki values of arachidonoyl dopamine, 2,4,6-trihydroxybenzaldehyde and 3,4-dihydroxy-5-methoxybenzoic acid were 203.80, 1170.00 and 910.00 μM, respectively for hCA I and 75.25, 354.00 and 1510.00 μM, respectively for hCA II. Additionally, IC50 values from in vivo studies were found to be in the range of 173.25–1360.0 μM for CA I and II, respectively, using CO2-hydratase activity methods. These results demonstrated that phenolic compounds used in in vivo studies could be used in different biomedical applications to inhibit approximately 30% of the CO2-hydratase activity of the total CA enzyme of rat erythrocytes.

Synthesis and investigation of the conversion reactions of pyrimidine-thiones with nucleophilic reagent and evaluation of their acetylcholinesterase, carbonic anhydrase inhibition, and antioxidant activities

The conversion reactions of pyrimidine‐thiones with nucleophilic reagent were studied during this scientific research. For this purpose, new compounds were synthesized by the interaction between 1,2‐epoxy propane, 1,2‐epoxy butane, and 4‐chlor‐1‐butanol and pyrimidine‐thiones. These pyrimidine‐thiones derivatives (A–K) showed good inhibitory action against acetylcholinesterase (AChE), and human carbonic anhydrase (hCA) isoforms I and II. AChE inhibition was in the range of 93.1 ± 33.7–467.5 ± 126.9 nM. The hCA I and II were effectively inhibited by these compounds, with Ki values in the range of 4.3 ± 1.1–9.1 ± 2.7 nM for hCA I and 4.2 ± 1.1–14.1 ± 4.4 nM for hCA II. On the other hand, acetazolamide clinically used as CA inhibitor showed Ki value of 13.9 ± 5.1 nM against hCA I and 18.1 ± 8.5 nM against hCA II. The antioxidant activity of the pyrimidine‐thiones derivatives (A–K) was investigated by using different in vitro antioxidant assays, including Cu2+ and Fe3+ reducing, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH•) radical scavenging, and Fe2+ chelating activities.

Inhibition properties of some flavonoids on carbonic anhydrase I and II isoenzymes purified from human erythrocytes

Carbonic anhydrases (CAs, E.C.4.2.1.1) play a critical role in many important physiological events and treatment of some diseases. Flavonoids or phenolic compounds have been discovered as novel CAs inhibitors instead of the traditional sulfonamides, with different binding to CAs, pro‐drug activities, and new inhibition mechanisms. Here, we investigated the inhibition effects of some flavonoids including malvin, callistephin, oenin, pelargonin, silychristin, and 1‐(4‐methoxyphenyl)‐2‐methyl‐3‐nitro‐1‐H‐indol‐6‐ol (ID‐8) against hCA I and II, which purified from human erythrocytes by affinity column chromatography. Both hCA isoenzymes were inhibited by flavonoids, with IC50 and Ki values in the range of 2.34 nM to 346.5 μM and 51.01–99.55 μM for hCA I and 86.60–750.00 μM for hCA II, respectively. These results showed that flavonoids especially malvin and oenin effectively inhibited hCA I and II isoenzymes. Hence, they may be used as an effective CA inhibitor in medical applications for treatment of certain diseases such as glaucoma, in the future.

The in vivo effects of cefazolin, cefuroxime, and cefoperazon on the carbonic anhydrase in different rat tissues

In this paper, the in vivo effects of some antibiotics including cefazolin, cefuroxime, and cefoperazon, on the activity of the carbonic anhydrase enzyme (CA) in heart, brain, eye, liver, and kidney tissues of rats were evaluated. For this purpose, 16 different groups, which each containing six rats (n = 6), were formed (control group, cefazolin groups, cefuroxime groups, and cefoperazon groups). The rats were necropsied 60 min after the intraperitoneal injection of the chemicals into the rats. The CA activities were measured for each tissue using esterase activity methods. The activity values for each tissue obtained were statistically calculated. The CA activities in the liver tissue were assessed, and the activities of the cefoperazon groups were decreased compared to the sham groups from the third hour (p < 0.05). In the cefuroxime and cefoperazon groups, the CA activities in the eye tissue were decreased during the first 3 h and then increased (p < 0.05).

The relationship between mother and infant plasma trace element and heavy metal levels and the risk of neural tube defect in infants

Abstract Objective: To determine levels of trace elements [copper (Cu), zinc (Zn), selenium (Se), and cobalt (Co)] and heavy metals [arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd)] in the plasma of mothers and infants and investigate the relationship between those levels and neural tube defects (NTD). Methods: A total of 100 neonates diagnosed with NTD and placed in the Neonatal Intensive Care Unit of Yuzuncu Yil University, Turkey between May 2013 and December 2016 comprised the study group. The control group consisted of 70 healthy neonates not diagnosed with NTD or any other congenital anomalies. For both the groups, mother and infant plasma levels of Cu, Zn, Co, Cd, Se, Hg, As, and Pb were measured and compared. Plasma levels of Cu, Zn, Co, Cd, Se, Hg, As, and Pb were measured and compared between two groups of mothers and infants. Findings: Mother and infant plasma levels of trace elements Zn and Se were determined to be significantly lower in the study group compared with the control group, while Cu levels were significant elevated in the study group (all p values < .05). Plasma levels of heavy metals As, Pb, and Cd were found to be significantly higher in the NTD control group (p < .05 for all). There was no association between maternal infection, maternal smoking status, history of miscarriage, or history of NTD with the development of NTD (p > .05). Differences in maternal age, birth weight, length of gestation, and infant gender for the two groups were also determined not to be statistically significant. Results: High plasma levels of heavy metals As, Pb, and Cd and trace element Cu were identified as risk factors for the development of NTD. At the same time, low plasma levels of trace elements Zn and Se were also found to be risk factors for NTD. However, no association between Hg and Co plasma levels and increased risk for the development of NTD was observed. This study, while being the most comprehensive case study to date investigating the relationship between heavy metals and trace element levels and increased risk of NTD, nonetheless highlights the need for further research in order to make definite statements regarding this relationship.

Antioxidant and Antiradical Properties of Selected Flavonoids and Phenolic Compounds

Phenolic compounds and flavonoids are known by their antioxidant properties and one of the most important sources for humans is the diet. Due to the harmful effects of synthetic antioxidants such as BHA and BHT, natural novel antioxidants have become the focus of attention for protecting foods and beverages and reducing oxidative stress in vivo. In the current study, we investigated the total antioxidant, metal chelating, Fe3+ and Cu2+ reduction, and free radical scavenging activities of some phenolic and flavonoid compounds including malvin, oenin, ID-8, silychristin, callistephin, pelargonin, 3,4-dihydroxy-5-methoxybenzoic acid, 2,4,6-trihydroxybenzaldehyde, and arachidonoyl dopamine. The antioxidant properties of these compounds at different concentrations (10–30 μg/mL) were compared with those of reference antioxidants such as BHA, BHT, α-tocopherol, and trolox. Each substance showed dose-dependent antioxidant activity. Furthermore, oenin, malvin, arachidonoyl dopamine, callistephin, silychristin, and 3,4-dihydroxy-5-methoxybenzoic acid exhibited more effective antioxidant activity than that observed for the reference antioxidants. These results suggest that these novel compounds may function to protect foods and medicines and to reduce oxidative stress in vivo.

The Relationship of Oxidation Sensitivity of Red Blood Cells and Carbonic Anhydrase Activity in Stored Human Blood: Effect of Certain Phenolic Compounds

It has been reported that many modifications occur with the increase of oxidative stress during storage in erythrocytes. In order to delay these negative changes, we evaluated whether the addition of substances likely to protect antioxidant capacity in stored blood would be useful. Therefore, we investigated the effects of resveratrol, tannic acid, and caffeic acid in lipid peroxidation and antioxidant capacity of erythrocytes in stored blood. Donated blood was taken into four CPD containing blood bags. One bag was used as the control, and the others were supplemented with caffeic acid (30 μg/mL), resveratrol (30 μg/mL), and tannic acid (15 μg/mL), respectively. Erythrocyte lipid peroxidation, sensitivity to oxidation, glutathione levels and carbonic anhydrase, glutathione peroxidase, and catalase activities were measured on days 0, 7, 14, 21, and 28. In the control group, erythrocyte malondialdehyde levels and sensitivity to oxidation were increased whereas glutathione, glutathione peroxidase, and catalase levels were decreased (p < 0.05). Resveratrol and caffeic acid prevented malondialdehyde accumulation and preserved glutathione, glutathione peroxidase, and catalase activities in erythrocytes. We demonstrated that resveratrol, caffeic acid, and tannic acid in stored blood could decrease the sensitivity to oxidation of erythrocytes in vitro but did not exhibit such effects on CA activity.