One-step purification of lactoperoxidase from bovine milk by affinity chromatography

Design and synthesis of novel dihydropyridine- and benzylideneimine-based tyrosinase inhibitors

Tyrosinase (TYR) inhibitors are very significant as they inhibit enzyme tyrosinase activity, and its inhibition is vital for skin care, anticancer medication, and antibrowning of fruits and vegetables. This work presents a novel and economical route for the preparation of new synthetic tyrosinase inhibitors using amlodipine (4). The novel conjugates 6 (a-o) were designed, synthesized, and characterized by spectroscopic analyses, including Fourier transform infrared and low- and high-resolution mass spectroscopy. The purified compound 4 was refluxed with various aldehydes and ketones 5 (a-o) for 5-8 h in methanol at 60°C-90°C. This research modified the drug in a step-by-step manner to develop therapeutic properties as a tyrosinase inhibitor. The structures of synthesized ligands 6 (a-o) were established based on spectral and analytical data. The synthesized compounds 6 (a-o) were screened against tyrosinase enzyme. Kojic acid was taken as standard. All the prepared compounds 6 (a-o) have good inhibition potential against the enzyme tyrosinase. Compounds 6o, 6b, 6f, and 6k depicted excellent antityrosinase activity. Compound 6k, with an IC50 value of 5.34 ± 0.58 µM, is as potent as the standard kojic acid (IC50 6.04 ± 0.11 µM), standing out among all synthesized compounds 6 (a-o). The in silico studies of the conjugates 6 (a-o) were evaluated via PatchDock. Compound 6k showed a binding affinity score of 8,999 and an atomic contact energy (ACE) value of -219.66 kcal/mol. The structure-activity relationship illustrated that the presence of dihydropyridine nuclei and some activating groups at the ortho and para positions of the benzylideneimine moiety is the main factor for good tyrosinase activity. The compound 6k could be used as a lead compound for drug modification as a tyrosinase inhibitor for skin care, anticancer medication, and antibrowning for fruits and vegetables.

Screening of in Vitro Inhibition of Lactoperoxidase Enzyme by Methyl Benzoate Derivatives with Molecular Docking Studies

Lactoperoxidase enzyme (LPO) is secreted from salivary, mammary, and other mucosal glands including the bronchi, lungs, and nose, which had functions as a natural and the first line of defense towards viruses and bacteria. In this study, methyl benzoates were examined in LPO enzyme activity. Methyl benzoates are used as precursors in the synthesis of aminobenzohydrazides used as LPO inhibitors. For this purpose, LPO was purified in a single step using sepharose-4B-l-tyrosine-sulfanilamide affinity gel chromatography with a yield of 9.91 % from cow milk. Also, some inhibition parameters including the half maximal inhibitory concentration (IC50 ) value and an inhibition constant (Ki ) values of methyl benzoates were determined. These compounds inhibited LPO with Ki values ranging from 0.033±0.004 to 1540.011±460.020 μM. Compound 1 a (methyl 2-amino-3-bromobenzoate) showed the best inhibition (Ki =0.033±0.004 μM). The most potent inhibitor (1 a) showed with a docking score of -3.36 kcal/mol and an MM-GBSA value of -25.05 kcal/mol, of these methyl benzoate derivatives (1 a-16 a) series are established H-bond within the binding cavity with residues Asp108 (distance of 1.79 Å), Ala114 (distance of 2.64 Å), and His351 (distance of 2.12 Å).

Improvement of analytical method for three azo dyes in processed milk and cheese using HPLC-PDA

This study aims to develop and validate a method for simultaneously measuring three azo dyes (azorubine, brilliant black BN, lithol rubine BK) not designated in Korea. The HPLC-PDA analysis method was validated based on the ICH guidelines, and the color stability was evaluated. The milk and cheese samples were spiked with azo dyes, the correlation coefficient of calibration curve ranged from 0.999 to 1.000 and the recovery rates of azo dyes were 98.81 ∼ 115.94%, with RSD of 0.08 ∼ 3.71%. The LOD and the LOQ in milk and cheese ranged from 1.14 to 1.73 μg/mL and 3.46 to 5.25 μg/mL, respectively. In addition, the expanded uncertainties of the measurements ranged from 3.3421 to 3.8146%. The azo dyes appeared to be color stable for more than 14 days. The results indicate that this analytical method is suitable for extracting and analyzing azo dyes in milk and cheese samples, which are not permitted in Korea.

Immobilization of lipase in chitosan-mesoporous silica material and pore size adjustment

Mesoporous silica MCM-41 was modified by carboxyl groups and assembled with chitosan to produce a novel nanocarrier for the immobilization of lipase. The prepared composite was grafted with silane coupling agent KH560 to decrease the pore size of the mesoporous material and prevent the loss of shed lipase molecules. According to the characterization of the material before and after modification and determination of related parameters, the residual activity of the lipase fixed in the CTS-MCM-41 carrier was 85 % after seven repeated use cycles. The grafting rate of MCM-41 and shrinkage effect were maximized when the concentration of KH560 was 5.0 %, and the modification was performed at 4 h at 70 °C. Using glutaraldehyde as the crosslinking agent, the optimal conditions for enzyme immobilization involved a mass ratio of the carrier to enzyme of 4:1, glutaraldehyde solution volume of 3 %, reaction time of 3 h, and reaction temperature of 45 °C. Overall, the proposed innovative carrier for the fixation of lipase is stable and can physically control the free enzyme in the pore. Moreover, the efficient miniature lipase reactor can promote large-scale industrial production.

Separation Technologies for Whey Protein Fractionation

Whey is a by-product of cheese, casein, and yogurt manufacture. It contains a mixture of proteins that need to be isolated and purified to fully exploit their nutritional and functional characteristics. Protein-enriched fractions and highly purified proteins derived from whey have led to the production of valuable ingredients for many important food and pharmaceutical applications. This article provides a review on the separation principles behind both the commercial and emerging techniques used for whey protein fractionation, as well as the efficacy and limitations of these techniques in isolating and purifying individual whey proteins. The fractionation of whey proteins has mainly been achieved at commercial scale using membrane filtration, resin-based chromatography, and the integration of multiple technologies (e.g., precipitation, membrane filtration, and chromatography). Electromembrane separation and membrane chromatography are two main emerging techniques that have been developed substantially in recent years. Other new techniques such as aqueous two-phase separation and magnetic fishing are also discussed, but only a limited number of studies have reported their application in whey protein fractionation. This review offers useful insights into research directions and technology screening for academic researchers and dairy processors for the production of whey protein fractions with desired nutritional and functional properties.

Vinyl functionalized 5,6-dimethylbenzimidazolium salts: Synthesis and biological activities

A series of vinyl functionalized 5,6-dimethylbenzimidazolium salts are synthesized. All compounds were fully characterized by elemental analyses, MS, ¹ H-NMR, ¹³ C-NMR, and IR spectroscopy techniques. Enzyme inhibition is a very active area of research in drug design and development. In this study, the synthesized novel benzimidazolium salts were evaluated toward the human erythrocyte carbonic anhydrase I (hCA I), and II (hCA II) isoenzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. They demonstrated highly potent inhibition ability against hCA I with K_i values of 484.8 ± 62.6-1389.7 ± 243.2 nM, hCA II with K_i values of 298.9 ± 55.7-926.1 ± 330.0 nM, α-glycosidase with K_i values of 170.3 ± 27-760.1 ± 269 μM, AChE with K_i values of 27.1 ± 3-77.6 ± 1.7 nM, and BChE with K_i values of 21.0 ± 5-61.3 ± 15 nM. As a result, novel vinyl functionalized 5,6-dimethylbenzimidazolium salts (1a-g) exhibited effective inhibition profiles toward studied metabolic enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly to treat some global disorders including glaucoma, Alzheimer's disease, and diabetes.

Synthesis and characterization of supermacroporous cryogel with immobilized p-aminobenzenesulfonamide as affinity ligand for the purification of lactoperoxidase from whey

This study proposed the development of a monolithic supermacroporous affinity column for direct capture of lactoperoxidase, a glycoprotein present in milk, whey, and colostrum, with several applications due to its wide antimicrobial activity. A poly(acrylamide)-based cryogel was produced by radical co-polymerization of monomers in frozen aqueous solution and activated with p-aminobenzenesulfonamide as a ligand for specific interaction with the lactoperoxidase. The axial liquid dispersion coefficients at different liquid flow rates were determined by measuring residence time distributions using the tracer pulse-response method. The axial dispersion coefficient was low and the height equivalent to theoretical plate was not dependent on the flow velocity. The adsorptive capacity of affinity cryogel was studied as a function of flow velocity and the best condition was 0.9 cm/min. The response surface methodology was applied to optimize the capture of the enzyme, as a function of pH and salt concentration. Higher purification factor value was found at a salt concentration of 80 mmol/L and pH of 8.0 (p < 0.05). There was no influence of the variables under study on the yield (p > 0.05). The results indicated that affinity cryogel is a promising chromatography support for the use in high-throughput one-step purification of lactoperoxidase from whey.

Antimicrobial Activity of Films and Coatings Containing Lactoperoxidase System: A Review

The production of safe and healthy foodstuffs is considered as one of the most important challenges in the food industry, and achieving this important goal is impossible without using various processes and preservatives. However, recently, there has been a growing concern about the use of chemical preservatives and attention has been focused on minimal process and/or free of chemical preservatives in food products. Therefore, researchers and food manufacturers have been induced to utilize natural-based preservatives such as antimicrobial enzymes in their production. Lactoperoxidase, as an example of antimicrobial enzymes, is the second most abundant natural enzyme in the milk and due to its wide range of antibacterial activities, it could be potentially applied as a natural preservative in various food products. On the other hand, due to the diffusion of lactoperoxidase into the whole food matrix and its interaction and/or neutralization with food components, the direct use of lactoperoxidase in food can sometimes be restricted. In this regard, lactoperoxidase can be used as a part of packaging material, especially edible and coating, to keep its antimicrobial properties to extend food shelf-life and food safety maintenance. Therefore, this study aims to review various antimicrobial enzymes and introduce lactoperoxidase as a natural antimicrobial enzyme, its antimicrobial properties, and its functionality in combination with an edible film to extend the shelf-life of food products.

One-Step and Colorimetric Detection of Fish Freshness Indicator Hypoxanthine Based on the Peroxidase Activity of Xanthine Oxidase Grade I Ammonium Sulfate Suspension

The global food waste problem, especially aquatic product spoilage, stimulates the accurate freshness analysis of food products. However, it still remains a great challenge to realize in-field determination of fish freshness at the time of use. In the present study, a colorimetric enzyme biosensor was developed for one-step detection of hypoxanthine (Hx), which is an important intermediate of adenosine triphosphate decomposition during fish storage. We demonstrate that xanthine oxidase grade I ammonium sulfate suspension (XOD-ASS) possesses peroxidase activity. It can oxidize different peroxidase substrates, including 3,3′,5,5′-tetramethylbenzidine, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, and o-phenylenediamine in the presence of H₂O₂, producing visible color reactions. Further experiments indicate that XOD-ASS displayed effective peroxidase activity and could be used for H₂O₂ detection. Based on this, a one-step Hx detection method was established using only XOD-ASS as the catalyst. The method displays a good linear relationship in the range from 20 to 100 μM with a detection limit of 6.93 μM. Additionally, we successfully applied this method in testing Hx accumulation in sea bass fish samples of different storage times. The recovery values range from 97.44 to 102.56%. It is exciting to note that, compared with other methods, our proposed method provides a robust advantage on the economic reaction system, ease of preparation, short time consumption, and moderate reaction temperature. We believe that this method shows good application prospects for on-site fish freshness determination.

Quantitative analysis of differentially expressed milk fat globule membrane proteins between donkey and bovine colostrum based on high-performance liquid chromatography with tandem mass spectrometry proteomics

This study was designed to provide novel insights into milk fat globule membrane (MFGM) proteins in donkey colostrum (DC) and bovine colostrum (BC) using quantitative proteomics. In total, 179 (DC) and 195 (BC) MFGM proteins were characterized, including 71 shared, 108 DC-specific, and 124 BC-specific proteins. Fifty-one shared proteins were selected as differentially expressed MFGM proteins, including 21 upregulated and 30 downregulated proteins in DC. Gene ontology analysis showed that these proteins were mainly enriched in cellular components, including the extracellular exosome, extracellular space, and plasma membrane. Additionally, they were further involved in metabolic pathways, including cholesterol metabolism, the peroxisome proliferator-activated receptor signaling pathway, and purine metabolism. Furthermore, several key protein factors with high connectivity were identified via protein-protein interaction analysis. These results provide more comprehensive knowledge of differences in the biological properties of MFGM proteins in DC and BC as well as pave the way for future studies of the nutritional and functional requirements of these important ingredients toward the development of dairy products based on multiple milk sources.

Inhibition Profiles of Some Symmetric Sulfamides Derived from Phenethylamines on Human Carbonic Anhydrase I, and II Isoenzymes

In this work, the inhibitory effect of some symmetric sulfamides derived from phenethylamines were determined against human carbonic anhydrase (hCA) I, and II isoenzymes, and compared with standard compound acetazolamide. IC₅₀ values were obtained from the Enzyme activity (%)-[Symmetric sulfamides] graphs. Also, K_i values were calculated from the Lineweaver-Burk graphs. Some symmetric sulfamides compounds (11-18) demonstrated excellent inhibition effects against hCA I, and II isoenzymes. These compounds demonstrated effective inhibitory profiles with IC₅₀ values in ranging from 21.66-28.88 nM against hCA I, 14.44-30.13 nM against hCA II. Among these compounds, the best K_i value for hCA I (K_i : 8.34±1.60 nM) and hCA II (K_i : 16.40±1.00 nM) is compound number 11. Besides, the IC₅₀ value of acetazolamide used as a standard was determined as hCA I, hCA II 57.75 nM, 49.50 nM, respectively. Moreover, in silico ADME-Tox study showed that all synthesized compounds (11-18) had good oral bioavailability in light of Jorgensen's rule of three, and of Lipinski's rule of five.

Synthesis of novel tris-chalcones and determination of their inhibition profiles against some metabolic enzymes

In this study, we report the synthesis of novel tris-chalcones and testing of human carbonic anhydrase I, and II isoenzymes (hCA I, and hCA II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase (α-Gly) inhibitors for the development of novel chalcone structures towards for treatment of some diseases. The compounds demonstrated K_i values between 13.6 ± 1.1 and 50.0 ± 17.1 nM on hCA I, 9.9 ± 0.8 and 39.5 ± 15.1 nM on hCA II, 3.1 ± 0.2 and 20.1 ± 1.9 nM on AChE, 4.9 ± 0.4 and 14.7 ± 5.2 nM on BChE and 3.9 ± 0.2 and 22.4 ± 10.7 nM on α-Gly enzymes. The results revealed that novel tris-chalcones can have promising drug potential for glaucoma, leukaemia, epilepsy; Alzheimer's disease that was associated with the high enzymatic activity of hCA I, hCA II, AChE, and BChE enzymes.

A sensitive, high-throughput fluorescent method for the determination of lactoperoxidase activities in milk and comparison in human, bovine, goat and camel milk

Lactoperoxidase (LPO) is one of the major antibacterial ingredients in milk and an extensively employed indicator for milk heat treatment. The traditional method for LPO activity measurement using ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonate) cannot achieve high sensitivity and is affected by indigenous milk thiocyanate. A more sensitive microplate fluorescent assay was developed by monitoring generation of red-fluorescent resorufin from LPO catalysed oxidation of Amplex® Red (1-(3,7-dihydroxyphenoxazin-10-yl)ethanone) in this study. The assay is particularly suitable for milk LPO activity measurement as it eliminates the influences of indigenous milk hydrogen peroxide and thiocyanate. The method limit of detection was 7.1x10^-6 U/mL of LPO in milk and good intra-run and inter-run precision was obtained. The LPO activities ranked as bovine > goat > camel > human in the four types of milk analysed. The high sensitivity and low cost of this assay makes it suitable for LPO activity analyses in both laboratory and commercial scales.

Molecular docking and inhibition profiles of some antibiotics on lactoperoxidase enzyme purified from bovine milk

Antibiotics are generally used for human and veterinary applications to preserve and to control microbial diseases. Milk has a biologically significant enzyme known as lactoperoxidase (LPO) that is a member of peroxidase family. In metabolism, LPO has ability to catalyze the transformation of thiocyanate (SCN^-) to hypothiocyanite (OSCN^-) that is an antibacterial agent and the reaction occurs with hydrogen peroxide. In this work, LPO inhibition effects of some antibiotics including cefazolin, oxytetracycline, flunixin meglumine, cefuroxime, tylosin, vancomycin, chloramphenicol and lincomycin were tested. Among the antibiotics cefazolin was indicated the strongest inhibitory efficacy. The half maximal inhibitory concentration (IC₅₀) and the inhibition constant (K_i) values of cefazolin were found as 8.19 and 34.66 µM, respectively. It was shown competitive inhibition. 5-Methyl-1,3,4-thiadiazol-2-yl moiety activity plays a key role in the inhibition mechanism of cefazolin.Communicated by Ramaswamy H. Sarma.

Synthesis of nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds - Determination of their carbonic anhydrase, acetylcholinesterase, butyrylcholinesterase and α-glycosidase inhibition properties

Sulfur-containing pyrroles (1-3), tris(2-pyridyl)phosphine(selenide) sulfide (4-5) and 4-benzyl-6-(thiophen-2-yl)pyrimidin-2-amine (6) were synthesized and characterized by elemental analysis, IR and NMR spectra. In this study, the synthesized compounds of nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds (1-6) were evaluated against the human erythrocyte carbonic anhydrase I, and II isoenzymes, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase enzymes. The synthesized heterocyclic compounds showed IC₅₀ values in range of 33.32-60.79 nM against hCA I, and 37.05-66.64 nM against hCA II closely associated with various physiological and pathological processes. On the other hand, IC₅₀ values were found in range of 13.13-22.21 nM against AChE, 0.54-31.22 nM against BChE, and 13.51-26.55 nM against α-glycosidase as a hydrolytic enzyme. As a result, nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds (1-6) demonstrated potent inhibition profiles against indicated metabolic enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly in the treatment of some global disorders including glaucoma, Alzheimer's disease and diabetes.

Experimental and computational interaction studies of terbium (III) and lanthanide (III) complexes containing 2,2'-bipyridine with bovine serum albumin and their in vitro anticancer and antimicrobial activities

To investigate the chemotherapeutic and pharmacokinetic aspects of two lanthanide complexes (Tb(III) and La(III) containing 2,2'-bipyridine ligand), in vitro binding studies were carried out with BSA by employing multiple biophysical methods and molecular modeling study. There are different techniques containing fluorescence, absorption spectroscopy and competitive experiments to determine the interaction mode between BSA and these complexes. These complexes efficiently quenched the BSA emission through a static procedure. The results showed that the terbium and lanthanum complexes exhibited a high propensity for BSA interaction via van der Waals force. Further, competitive examination and docking study showed that the interaction site of these complexes on BSA is site III. The results of docking calculations were in good agreement with experimental examinations. Also, the energy transfer from BSA to these complexes has happened with high possibility. Moreover, antimicrobial studies of different bacterial and fungi indicated its promising antibacterial activity. In vitro cytotoxicity of the Tb complex and La complex was carried out in MCF-7 and A-549 cell lines, which revealed significantly good activity.Communicated by Ramaswamy H. Sarma.

Evaluation of in vitro inhibitory effects of some natural compounds on tyrosinase activity and molecular docking study: Antimelanogenesis potential

Tyrosinase enzyme is a functional oxidase that is extensively divided in nature. It is the main enzyme in melanin synthesis and is also involved in designating the color of mammalian hair and skin. Additionally, it is accountable for the unfavorable enzymatic browning that happens in plant-derived foods, limiting the shelf-life of new-cut crops with the resultant economic harm. Recently, there has been a remarkable concern to study the inhibitory activity of the tyrosinase enzyme and some inhibitory molecules isolated from natural sources. For tyrosinase enzyme, afzelin, narcissoside, justiciresinol, thalassiolin B, carpachromene, neobavaisoflavone, and kojic acid (as standard) as natural phenols have IC₅₀ values in the range of 2.37-7.90 µM. Theoretical methods, such as gaussian software program and molecular modeling, were used to compare the biological and chemical activity values of molecules. To compare the biochemical and chemical activity values of molecules, chemical activities with quantum chemical parameters, and biological activities against tyrosinase with the ID of 5M8L molecules were investigated.

The inhibition of lactoperoxidase catalytic activity through mesna (2-mercaptoethane sodium sulfonate)

Here, we show that mesna (sodium-2-mercaptoethane sulfonate), primarily used to prevent nephrotoxicity and urinary tract toxicity caused by chemotherapeutic agents such as cyclophosphamide and ifosfamide, modulates the catalytic activity of lactoperoxidase (LPO) by binding tightly to the enzyme, functioning either as a one electron substrate for LPO Compounds I and II, destabilizing Compound III. Lactoperoxidase is a hemoprotein that utilizes hydrogen peroxide (H₂O₂) and thiocyanate (SCN^-) to produce hypothiocyanous acid (HOSCN), an antimicrobial agent also thought to be associated with carcinogenesis. Our results revealed that mesna binds stably to LPO within the SCN^- binding site, dependent of the heme iron moiety, and its combination with LPO-Fe(III) is associated with a disturbance in the water molecule network in the heme cavity. At low concentrations, mesna accelerated the formation and decay of LPO compound II via its ability to serve as a one electron substrate for LPO compounds I and II. At higher concentrations, mesna also accelerated the formation of Compound II but it decays to LPO-Fe(III) directly or through the formation of an intermediate, Compound I*, that displays characteristic spectrum similar to that of LPO Compound I. Mesna inhibits LPO's halogenation activity (IC₅₀ value of 9.08 μM) by switching the reaction from a 2e^- to a 1e^- pathway, allowing the enzyme to function with significant peroxidase activity (conversion of H₂O₂ to H₂O without generation of HOSCN). Collectively, mesna interaction with LPO may serve as a potential mechanism for modulating its steady-state catalysis, impacting the regulation of local inflammatory and infectious events.

The behaviour of some antihypertension drugs on human serum paraoxonase-1: an important protector enzyme against atherosclerosis

Objectives

Paraoxonase-1 (PON1) enzyme is related to high-density lipoprotein (HDL), which is calcium dependent. It has essential roles such as protecting LDL against oxidation and detoxification of highly toxic substances. It is a significant risk to reduce the levels of this enzyme in patients with diabetes mellitus, cardiovascular diseases, hyperthyroidism and chronic renal failure.

Methods

Here, it was reported that the purification of human serum PON1 using straightforward methods and determination of the interactions between some antihypertension drugs and the enzyme.

Key finding

It was found that these drugs exhibit potential inhibitor properties for human serum PON1 with IC50 values in the range of 131.40–369.40 μm and Ki values in the range of 56.24 ± 6.75–286.74 ± 28.28 μm. These drugs showed different inhibition mechanisms. It was determined that midodrine and nadolol were exhibited competitive inhibition, but atenolol and pindolol were exhibited non-competitive inhibition.

Conclusion

Usage of these drugs would be hazardous in some cases.

The green synthesis and molecular docking of novel N-substituted rhodanines as effective inhibitors for carbonic anhydrase and acetylcholinesterase enzymes

Recently, inhibition effects of enzymes such as acetylcholinesterase (AChE) and carbonic anhydrase (CA) has appeared as a promising approach for pharmacological intervention in a variety of disorders such as epilepsy, Alzheimer's disease and obesity. For this purpose, novel N-substituted rhodanine derivatives (RhAs) were synthesized by a green synthetic approach over one-pot reaction. Following synthesis the novel compounds, RhAs derivatives were tested against AChE and cytosolic carbonic anhydrase I, and II (hCAs I, and II) isoforms. As a result of this study, inhibition constant (Ki) were found in the range of 66.35 ± 8.35 to 141.92 ± 12.63 nM for AChE, 43.55 ± 14.20 to 89.44 ± 24.77 nM for hCA I, and 16.97 ± 1.42 to 64.57 ± 13.27 nM for hCA II, respectively. Binding energies were calculated with docking studies as -5.969, -5.981, and -9.121 kcal/mol for hCA I, hCA II, and AChE, respectively.

Synthesis and biological evaluation of bromophenol derivatives with cyclopropyl moiety: Ring opening of cyclopropane with monoester

Trans-(1R*,2R*,3R*)-Ethyl 2-(3,4-dimethoxyphenyl)-3-methylcyclopropane-1-carboxylate (6) and its cis isomer 7 were obtained from the reaction of the methyl isoeugenol (5) with ethyl diazoacetate. The reduction and bromination reactions of the ester 6 and 7 together with the hydrolysis of all esters were carried out. Opening ring of cyclopropane was observed in the reaction of 7 with bromine. The opening of cyclopropane ring with COOR and synthesis of esters, alcohols and acids (6-26) are new. These obtained bromophenol derivatives (6-26) were effective inhibitors of the cytosolic carbonic anhydrase I and II isoforms (hCA I and II) and acetylcholinesterase (AChE) enzymes with Ki values in the range of 7.8 ± 0.9-58.3 ± 10.3 nM for hCA I, 43.1 ± 16.7-150.2 ± 24.1 nM for hCA II, and 159.6 ± 21.9-924.2 ± 104.8 nM for AChE, respectively. Acetylcholinesterase inhibitors are the most popular drugs applied in the treatment of diseases such as Alzheimer's disease, Parkinson's disease, senile dementia, and ataxia, among others.

Synthesis of oxazolidinone from enantiomerically enriched allylic alcohols and determination of their molecular docking and biologic activities

Enantioselective synthesis of functionalized cyclic allylic alcohols via kinetic resolution in transesterifcation with different lipase enzymes has been developed. The influence of the enzymes and temperature activity was studied. By determination of ideal reaction conditions, byproduct formation is minimized; this made it possible to prepare enantiomerically enriched allylic alcohols in high ee's and good yields. Enantiomerically enriched allylic alcohols were used for enantiomerically enriched oxazolidinone synthesis. Using benzoate as a leaving group means that 1 mol % of potassium osmate is necessary and can be obtained high yields 98%. Inhibitory activities of enantiomerically enriched oxazolidinones (8, 10 and 12) were tested against human carbonic anhydrase I and II isoenzymes (hCA I and hCA II), acetylcholinesterase (AChE), and α-glycosidase (α-Gly) enzymes. These enantiomerically enriched oxazolidinones derivatives had K_i values in the range of 11.6 ± 2.1-66.4 ± 22.7 nM for hCA I, 34.1 ± 6.7-45.2 ± 12.9 nM for hCA II, 16.5 ± 2.9 to 35.6 ± 13.9 for AChE, and 22.3 ± 6.0-70.9 ± 9.9 nM for α-glycosidase enzyme. Moreover, they had high binding affinity with -5.767, -6.568, -9.014, and -8.563 kcal/mol for hCA I, hCA II, AChE and α-glycosidase enzyme, respectively. These results strongly supported the promising nature of the enantiomerically enriched oxazolidinones as selective hCA, AChE, and α-glycosidase inhibitors. Overall, due to these derivatives' inhibitory potential on the tested enzymes, they are promising drug candidates for the treatment of diseases like glaucoma, leukemia, epilepsy; Alzheimer's disease; type-2 diabetes mellitus that are associated with high enzymatic activity of CA, AChE, and α-glycosidase.

Enhanced Antibacterial Activity of Lactoperoxidase-Thiocyanate-Hydrogen Peroxide System in Reduced-Lactose Milk Whey

The product of the lactoperoxidase system (LPOS) has been developed as a preservative agent to inhibit foodborne bacteria, but its action was, heretofore, limited to several original compounds in milk. This research was conducted to analyze the application of the lactoperoxidase system against Escherichia coli in fresh bovine milk and its derivative products to determine the strength of antibacterial activity. Lactoperoxidase was purified from bovine whey using the SP Sepharose Big Beads Column. The enzymatic reaction involving lactoperoxidase, thiocyanate, and hydrogen peroxide was used to generate the antibacterial agent from LPOS. This solution was then added to milk, skimmed milk, untreated whey, reduced-LPO whey, reduced-lactose whey, and high-lactose solution containing E. coli at an initial count of 6.0 log CFU/mL. LPOS showed the greatest reduction of bacteria (1.68 ± 0.1 log CFU/mL) in the reduced-lactose whey among the products tested. This result may lead to a method for enhancement of the antimicrobial activity of LPOS in milk and derived products.

Inhibition effects of selected thiophene-2-sulfonamides on lactoperoxidase

Lactoperoxidase (LPO, E.C.1.11.1.7) is a natural antibacterial agent which is secreted from salivary, mammary, and other mucosal glands. It is one of the crucial enzymes in biological systems, so protection of LPO activity is extremely important for the immune system. Within the scope of this study; in vitro effects of some thiophene-2-sulfonamide derivatives (1a-7a) on bovine milk LPO enzymatic activity were investigated. LPO was purified from the Sepharose-4B-L-tyrosine-5-amino-2-methylbenzenesulfonamide column prepared using affinity chromatography technique with a yield of 169.66 EU/mg specific activity in 452.44 times. As a result, 5-(2-thienylthio) thiophene-2-sulfonamide demonstrated the strongest inhibition impact among these compounds. This molecule has shown a competitive inhibition and it was determined that the IC₅₀ value was 3.4 nM and the Ki value was 2 ± 0.6 nM.

The Significance of Lactoperoxidase System in Oral Health: Application and Efficacy in Oral Hygiene Products

Lactoperoxidase (LPO) present in saliva are an important element of the nonspecific immune response involved in maintaining oral health. The main role of this enzyme is to oxidize salivary thiocyanate ions (SCN^-) in the presence of hydrogen peroxide (H₂O₂) to products that exhibit antimicrobial activity. LPO derived from bovine milk has found an application in food, cosmetics, and medical industries due to its structural and functional similarity to the human enzyme. Oral hygiene products enriched with the LPO system constitute an alternative to the classic fluoride caries prophylaxis. This review describes the physiological role of human salivary lactoperoxidase and compares the results of clinical trials and in vitro studies of LPO alone and complex dentifrices enriched with bovine LPO. The role of reactivators and inhibitors of LPO is discussed together with the possibility of using nanoparticles to increase the stabilization and activity of this enzyme.

Lactoperoxidase, an antimicrobial enzyme, is inhibited by some indazoles

Lactoperoxidase (LPO) has bactericidal and bacteriostatic activity on various microorganisms and it creates a natural antimicrobial defense system. So, LPO is one of the essential enzyme in biological systems and the protection of the LPO activity is extremely important for the immune system. Because of these features, the protection of the activity of the LPO has vital importance for the health of the organisms. Also, LPO is used in various sectors from cosmetics industry to agriculture industry due to its broad antimicrobial properties. Therefore, the identification of inhibitors and activators of the LPO is becoming increasingly important. In present study we aimed to investigate the inhibitory effects of some indazoles [1H-indazole (1a), 4-Bromo-1H-indazole (2a), 6-Bromo-1H-indazole (3a), 7-Bromo-1H-indazole (4a), 4-chloro-1H-indazole (5a), 6-chloro-1H-indazole (6a), 7-chloro-1H-indazole (7a), 4-fluoro-1H-indazole (8a), 6-fluoro-1H-indazole (9a), 7-fluoro-1H-indazole (10a)] on bovine milk LPO. Indazole derivatives are heterocyclic organic molecules with a wide range of biological activity. For this aim, bovine milk LPO was purified using Sepharose-4B-l-tyrosine-5-amino-2-methyl benzenesulfonamide affinity chromatography method. Then, the potential inhibitory effects of indazoles on LPO activity were investigated. K_i values were calculated for each indazole molecule. K_i values were ranging from 4.10 to 252.78 µM for 1a to10a. All of the indazole molecules we studied showed strong inhibitory effect on LPO activity. Also we determined inhibition types of the indazoles to clarify the mechanisms of inhibition.

Structural studies on inhibitory mechanisms of antibiotic, corticosteroid and catecholamine molecules on lactoperoxidase

AIM

Lactoperoxidase (LPO) is an essential protein with broad spectrum antimicrobial activity present in mammalian milk. It imparts immunity to infants against wide range of pathogenic infections. Several in vitro studies have shown inhibition of LPO activity by pharmaceutical compounds including commonly used antibiotics such as ampicillin and gentamicin, and molecules like prednisolone, norepinephrine, etc. Prescription of such drugs to lactating mothers might have adverse health effects on infants. The aim of our study was the elucidation of the structural aspects of the inhibitory mechanism of ampicillin, gentamicin, amoxicillin, prednisolone and norepinephrine on LPO.

MATERIAL AND METHODS

Three dimensional structure of camel LPO (cLPO) was developed using homology modeling and used for in silico experimental studies. The Schrödinger induced fit docking along with binding affinity estimation experiments were performed. The cLPO and Ligands were prepared using Protein Preparation Wizard and Ligprep modules available in Schrodinger suite. For estimating Binding affinity Prime Molecular Mechanics with Generalized Born and Surface Area (MMGB-SA) module was used.

KEY RESULTS

The five drug ligands formed three to five hydrogen bonding interactions with cLPO. Amino acids Arg-231, Asp-232, Ser-370, Arg-371 and Glu-374 of cLPO were crucial for these interactions. The binding affinity values for gentamicin were highest and for norepinephrine were the lowest.

SIGNIFICANCE

This study concludes that the five drug molecules show potential ability to inhibit the LPO activity. Further, a very high sequence similarity of cLPO with human LPO imparts high significance to these conclusions in relation to human health especially in new born infants.

Downstream processing of lactoperoxidase from milk whey by involving liquid emulsion membrane

The current work deals with downstream processing of lactoperoxidase using liquid emulsion membrane from the bovine milk whey, which is a by-product from dairy industry. It is an alternate separation technique that can be used for the selective extraction of lactoperoxidase. The extraction of lactoperoxidase in liquid emulsion membrane takes place due to the electrostatic interaction between the enzyme and polar head group of reverse micellar surfactant. The optimum conditions resulted in 2.86 factor purity and activity recovery of 75.21%. Downstream processing involving liquid emulsion membrane is a potential technique for the extraction of lactoperoxidase from bovine whey.