Inhibition Of Chemiluminescence Research Articles

Easy-to-Use Chemiluminescent-Based Assay for a Rapid and Low-Cost Evaluation of the Antioxidant Activity of Cosmetic Products

New cosmetic formulations are continuously requested by the market and the ingredients are constantly evolving. Recently the use of antioxidants has gained success and, in this context, analytical methods able to quickly and easily assess the antioxidant activity of cosmetics would make it possible to carry out analyses on new formulations even within the manufacturing process without the need for specialized laboratories and personnel, thus evaluating directly on-site the effectiveness and the shelf life of products. In this work, a chemiluminescent inhibition assay was developed for determining the total antioxidant activity in cosmetic products. The method was based on the luminol/enhancers/hydrogen peroxide/horseradish peroxidase chemiluminescent system, which generates light signals measurable through simple and compact instrumentation. The formation of the chemiluminescent signal is inhibited by the presence of antioxidant substances while it is restored once all the antioxidant molecules have been oxidized. The time of appearance of the light signal is related to the total antioxidant activity. The assay was carried out exploiting an integrated device comprising a microwell plate coupled with an array of amorphous silicon hydrogenated photosensors enclosed in a mini-dark box. The method was optimized in terms of concentrations and volumes of the required reagents and sample pre-treatment. A calibration curve was generated taking as a reference the antioxidant activity of ascorbic acid obtaining a detection limit of 10 µM. The developed method was applied to cosmetic products currently on the market as well as on spiked samples in order to evaluate the performance of the methods in terms of sensitivity, accuracy, and reproducibility.

Combining Experimental and Computational Methods to Produce Conjugates of Anticholinesterase and Antioxidant Pharmacophores with Linker Chemistries Affecting Biological Activities Related to Treatment of Alzheimer's Disease.

Effective therapeutics for Alzheimer's disease (AD) are in great demand worldwide. In our previous work, we responded to this need by synthesizing novel drug candidates consisting of 4-amino-2,3-polymethylenequinolines conjugated with butylated hydroxytoluene via fixed-length alkylimine or alkylamine linkers (spacers) and studying their bioactivities pertaining to AD treatment. Here, we report significant extensions of these studies, including the use of variable-length spacers and more detailed biological characterizations. Conjugates were potent inhibitors of acetylcholinesterase (AChE, the most active was 17d IC50 15.1 ± 0.2 nM) and butyrylcholinesterase (BChE, the most active was 18d: IC50 5.96 ± 0.58 nM), with weak inhibition of off-target carboxylesterase. Conjugates with alkylamine spacers were more effective cholinesterase inhibitors than alkylimine analogs. Optimal inhibition for AChE was exhibited by cyclohexaquinoline and for BChE by cycloheptaquinoline. Increasing spacer length elevated the potency against both cholinesterases. Structure-activity relationships agreed with docking results. Mixed-type reversible AChE inhibition, dual docking to catalytic and peripheral anionic sites, and propidium iodide displacement suggested the potential of hybrids to block AChE-induced β-amyloid (Aβ) aggregation. Hybrids also exhibited the inhibition of Aβ self-aggregation in the thioflavin test; those with a hexaquinoline ring and C8 spacer were the most active. Conjugates demonstrated high antioxidant activity in ABTS and FRAP assays as well as the inhibition of luminol chemiluminescence and lipid peroxidation in mouse brain homogenates. Quantum-chemical calculations explained antioxidant results. Computed ADMET profiles indicated favorable blood-brain barrier permeability, suggesting the CNS activity potential. Thus, the conjugates could be considered promising multifunctional agents for the potential treatment of AD.

Design and Investigation of New Water-Soluble Forms of α-Tocopherol with Antioxidant and Antiglycation Activity Using Amphiphilic Copolymers of N-Vinylpyrrolidone.

Water-soluble forms of α-tocopherol (TP) as an effective antioxidant were obtained by encapsulating it into nanoparticles (NPs) of amphiphilic copolymers of N-vinylpyrrolidone with triethylene glycol dimethacrylate (CPL1-TP) and N-vinylpyrrolidone with hexyl methacrylate and triethylene glycol dimethacrylate (CPL2-TP) synthesized by radical copolymerization in toluene. The hydrodynamic radii of NPs loaded with TP (3.7 wt% per copolymers) were typically ca. 50 or 80 nm depending on copolymer composition, media, and temperature. Characterization of NPs was accomplished by transmission electron microscopy (TEM), IR-, and 1H NMR spectroscopy. Quantum chemical modeling showed that TP molecules are capable to form hydrogen bonds with donor groups of the copolymer units. High antioxidant activity of both obtained forms of TP has been found by the thiobarbituric acid reactive species and chemiluminescence assays. CPL1-TP and CPL2-TP effectively inhibited the process of spontaneous lipid peroxidation as well as α-tocopherol itself. The IC50 values of luminol chemiluminescence inhibition were determined. Antiglycation activity against vesperlysine and pentosidine-like AGEs of TP water-soluble forms was shown. The developed NPs of TP are promising as materials with antioxidant and antiglycation activity and can be used in various biomedical applications.

The quantitative determination of glutathione by the effect of the chemiluminescence inhibition in the catalytic oxidation reaction of luminol with hydrogen peroxide in the presence of hemoglobin

Aim. To develop a method for the quantitative determination of reduced glutathione in a lyophilized powder for the preparation of “Hepaval®” solution for intravenous and intramuscular administration by the effect of inhibiting chemiluminescence in the luminol (H2L)–Н2О2–hemoglobin (Hb) system.Materials and methods. The study object was the reduced glutathione substance and lyophilized powder for the preparation of “Hepaval®” solution for injection, ampoules of 4 mL No. 10 manufactured by “Valartin pharma” (Italy). The glutathione content in powder was determined using the chemiluminescence method by the effect of inhibiting the luminol oxidation reaction with hydrogen peroxide in the presence of Hb as a catalyst. The analysis was performed by the standard addition method.Results and discussion. As a result of the studies, it has been found that under optimal conditions glutathione shows a noticeable inhibitory effect on chemiluminescence in the H2L–H2O2–Hb system. This phenomenon was used to develop a new procedure for the quantitative determination of glutathione in the substance and lyophilized powder for the preparation of “Hepaval®” aqueous solution for injection. The linear dependence of the integral chemiluminescence intencity (S) on the molar concentration of glutathione was maintained in the concentration range of (2 – 20) × 10–7 mol L-1. The graph equation was S = (–1.6 ± 0.2) × 107 × c + (198.9 ± 2.0), (r = 0.999). The relative standard deviation (RSD) was ±1.82 % (n = 7, P = 0.95). Conclusions. The method has been developed, and the possibility of the quantitative determination of glutathione in powder for the preparation of “Hepaval®” solution for injection by the method of the chemiluminescence inhibition of the H2L–Н2О2–Нb system has been shown. The content of glutathione in powder calculated with reference to dried substance was 91.49 % (against 90.8 % by the certificate). The accuracy was +0.76 %.

New Multifunctional Agents Based on Conjugates of 4-Amino-2,3-polymethylenequinoline and Butylated Hydroxytoluene for Alzheimer’s Disease Treatment

New hybrids of 4-amino-2,3-polymethylenequinoline with different sizes of the aliphatic ring linked to butylated hydroxytoluene (BHT) by enaminoalkyl (7) or aminoalkyl (8) spacers were synthesized as potential multifunctional agents for Alzheimer’s disease (AD) treatment. All compounds were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. Lead compound 8c, 2,6-di-tert-butyl-4-{[2-(7,8,9,10- tetrahydro-6H-cyclohepta[b]quinolin-11-ylamino)-ethylimino]-methyl}-phenol exhibited an IC50(AChE) = 1.90 ± 0.16 µM, IC50(BChE) = 0.084 ± 0.008 µM, and 13.6 ± 1.2% propidium displacement at 20 μM. Compounds possessed low activity against carboxylesterase, indicating likely absence of clinically unwanted drug-drug interactions. Kinetics were consistent with mixed-type reversible inhibition of both cholinesterases. Docking indicated binding to catalytic and peripheral AChE sites; peripheral site binding along with propidium displacement suggest the potential of the hybrids to block AChE-induced β-amyloid aggregation, a disease-modifying effect. Compounds demonstrated high antioxidant activity in ABTS and FRAP assays as well as inhibition of luminol chemiluminescence and lipid peroxidation in mouse brain homogenates. Conjugates 8 with amine-containing spacers were better antioxidants than those with enamine spacers 7. Computational ADMET profiles for all compounds predicted good blood-brain barrier distribution (permeability), good intestinal absorption, and medium cardiac toxicity risk. Overall, based on their favorable pharmacological and ADMET profiles, conjugates 8 appear promising as candidates for AD therapeutics.

Угнетение хлорофиллином хемилюминесценции, сопровождающей катализируемую комплексом цитохрома c с кардиолипином квазилипоксигеназную реакцию

Lipid peroxidation is a key factor in programmed cell death of various etiologies. This process also occurs when ionizing radiation acts on biological systems. It is the essence of the theory of lipid radiotoxins, which is part of the structural and metabolic theory of the biological action of ionizing radiation. Non-enzymatic lipid peroxidation eventually leads to death by the mechanism of ferroptosis, while enzymatic lipid peroxidation, catalyzed by the cytochrome c-cardiolipin complex, triggers apoptosis along the mitochondrial pathway. According to the results of research conducted over the past 10 years, it has been established that drugs based on chlorophyll are effective as radioprotectors. The only mechanism of their action may be the inhibition of radical reactions involving lipids. Therefore, drugs based on chlorophyll can be used as the antioxidants in the prevention and treatment of various pathologies caused by free radical lipid oxidation. In the present study, using the method of activated coumarin-334 (quinolysidine[5,6,7-gh]3-acetylcoumarin) chemiluminescence, we have established the suppression of the reaction of radical lipid oxidation caused by the quasilipoxygenase activity of the cytochrome c-cardiolipin complex. This conclusion was arrived at on the basis of reliable suppression of chemiluminescence by sodium chlorophyllin at concentrations of 1.56 μm and higher. The obtained result shows the relevance of further multi-faceted research of the possibility of effective use of various chlorophyll derivatives in the treatment and prevention of pathological conditions caused by oxidative stress.

Determination of L-Cystine in Tablets Using the Chemiluminescence Method

Aim. To develop the method for the quantitative determination of L-cystine in sublingual tablets Elthacin ® using the method of chemiluminescence inhibition in the H 2 L (luminol) – Н 2 О 2 – Нb (hemoglobin) system. Materials and methods. The study objects were the pure substance of L-cystine of pharmaceutical grade and sublingual tablets Elthacin ® produced by the Medical Scientific-Production Complex “Biotics Ltd” (Russia) containing 70 mg of glycine, L-glutaminic acid and L-cystine in their composition. The intensity of chemiluminescence was measured on the device with a FEU-84-A photoelectric multiplier using an IMT-0.5 measuring instrument of low currents and a quick-acting automatic potentiometer. Results and discussion. The method of the L-cystine quantitative determination in tablets based on the inhibition of chemiluminescence in the H 2 L – H 2 O 2 – Hb system has been developed. The calibration graph was linear over the concentration range from 7 to 70 μg · mL –1 . No interferences were observed in the presence of common components of the tablets, such as glycine and L-glutaminic acid. RSD = ± 2.35 %, (δ = + 1.13 %), LOD (3S) = 4 μg · mL –1 , LOQ (10S) = 13 μg · mL –1 for the sublingual tablets Elthacin ® . Conclusions. The method proposed is promising for further research on the subject of its application for the determination of L-cystine in drugs.

Employment of teicoplanin-coated magnetic particles for quantifying gram-positive bacteria via catalase-catalyzed hydrolysis reaction of H2O2

Based on the specific affinity behavior of teicoplanin towards Gram-positive (G+) bacteria, teicoplanin-coated magnetic particles were employed to separate G+ bacteria. Moreover, intracellular catalase released by catalase-positive bacteria led to catalyzed hydrolysis of H2O2 and inhibition of chemiluminescent signal of luminol-H2O2 system. By combining the separation capability of teicoplanin-coated magnetic particles and the inhibition of luminol chemiluminescence by catalase, a facile method was proposed for quantifying catalase-positive G+ bacteria. In this proof-of-principle work, Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus were adopted as model bacteria to evaluate its quantification performance. The three bacteria were quantified within the dynamic ranges of 5.0 × 102–5.0 × 107 CFU mL−1, 4.0 × 102–4.0 × 107 CFU mL−1 and 2.0 × 102–2.0 × 107 CFU mL−1, with detection limits of 156 CFU mL−1, 86 CFU mL−1 and 44 CFU mL−1, respectively. Gram-negative bacteria and catalase-negative G+ bacteria both displayed minor interference. The results for quantifying bacteria in milk, human urine and physiological saline samples demonstrated its reliability for real application. It provided a promising technique tool for food safety, medical diagnosis as well as drug quality control.

Comparative study of the chemiluminescence of coelenterazine, coelenterazine-e and Cypridina luciferin with an experimental and theoretical approach

Imidazopyrazinone is a typical scaffold present in marine bioluminescence, in which thermal energy is converted into excitation energy in an enzyme-catalyzed reaction. In fact, the imidazopyrazinone scaffold is a common link among organisms of eight phyla. The characterization of the light emission mechanism is essential for the development of future applications in bioimaging, bioanalysis and biomedicine. Herein, we have studied the chemiluminescent reaction of three commercially-available imidazopyrazinones (Cypridina luciferin, Coelenterazine and Coelenterazine-e) in several aprotic solvents at different pH. We have found that at acidic pH only DMF and DMSO consistently present high light emission, while chemiluminescence in other solvents is negligible. We have attributed this to the inability of most solvents to allow for the deprotonation of the imidazopyrazinone core, thereby preventing the oxygenation step. We have also observed that increasing the pH of the solution leads to the inhibition of chemiluminescence, which we attributed to the deprotonation of the dioxetanone intermediate, as the neutral species is the one associated with efficient chemiexcitation. We have also observed that the pKa of dioxetanone increases with the dielectric constant of the medium. Finally, our work indicated that the chemiexcitation yield increases with increasing polarity of the medium, due to a reduced transition dipole moment associated with S0 → S1 transition.

Teicoplanin-functionalized magnetic beads for detection of Staphylococcus aureus via inhibition of the luminol chemiluminescence by intracellular catalase.

An affinity-based protocol is described for the detection of Staphylococcus aureus (S. aureus). It is utilizing teicoplanin-functionalized magnetic beads as carriers. Teicoplanin, which binds to the walls of cells of S. aureus via five hydrogen bonds, acts as the recognition agent. Captured S. aureus is magnetically separated from the sample matrix and then specifically lysedby lysostaphin which cleaves the cross-linking pentaglycine bridges of peptidoglycan in the cell wall. Lastly, S. aureus is quantified via the inhibitory effect of released intracellular catalase on a chemiluminescent (CL) system composed of peroxidase, luminol, H2O2 and p-iodophenol because catalase decomposes H2O2. S. aureus can be detected with CL response in the 140 to 1.4 × 107CFU·mL-1 concentration range and a detection limit as low as 47CFU·mL-1 at a signal-to-noise ratio of 3. The method was evaluated by analyzing spiked samples including milk, human urine and saline injection solutions. The reliability was demonstrated by a recovery test and by comparison with a conventional plate counting method. Graphical abstract An antibiotic-affinity protocol is developed to detect Staphylococcus aureus (S. aureus) by utilizing teicoplanin-functionalized magnetic beads (Teic-MBs) as carriers. S. aureus can be quantified by measuring the inhibition of luminol chemiluminescence (CL) signal by intracellular catalase.

Flavonoids and triterpenes from Combretum fragrans with anti-inflammatory, antioxidant and antidiabetic potential.

Despite the well-documented benefits of Combretum fragrans in Cameroon, only few scientific works have been done on it. In this study we isolated eight compounds from the leaves extract of C. fragrans: velutin (1), belamcanidin (2), cirsilineol (3), cirsimaritin (4), 3β-acetoxy-20,24-epoxy-11,25-hydroxy-dammarane (5), combretin A (6), combretin B (7) and a mixture of arjunolic acid (8a) and asiatic acid (8b). Compounds 6 and 7 presented potent anti-inflammatory, antioxidant and antidiabetic activities. Compounds 1, 3, 5 and the mixture of 8a and 8b were significantly active, and compounds 2 and 4 presented moderate activity for reactive oxygen species inhibitory and free-radical scavenging. All compounds were isolated using chromatographic techniques; their structures were elucidated by spectroscopic techniques and their spectroscopic data compared with those of the literature. Anti-inflammatory activity was evaluated via the oxidative burst assay using a luminol-amplified chemiluminescence technique, antioxidant activity by free-radical scavenging activity (DPPH) and antidiabetic activity via α-glucosidase inhibition. All of the isolated compounds (1-8) were reported to exhibit significant antioxidant activity. Compounds 1, 3, and 5-8 exhibited potent chemiluminescence inhibition effect, and only compounds 6 and 7 inhibited α-glucosidase. Thus, C. fragrans can be used as an effective natural source of anti-inflammatory, antioxidant and antidiabetic compounds.

Determination of propyl gallate in edible oil by high-performance liquid chromatography with chemiluminescence detection

ABSTRACTA novel and convenient method based on high-performance liquid chromatography coupled with chemiluminescence (HPLC) for the determination of propyl gallate in edible oil is reported. The detection was based on the inhibition of chemiluminescence between luminol and hydrogen peroxide in alkaline solution. The analysis was performed using a C18 column with isocratic 60:40 methanol/water. Under the optimum conditions, the concentration of propyl gallate was linear from 9 × 10−6 mol L−1 to 1 × 10−4 mol L−1 with a detection limit of 2 × 10−7 mol L−1. The method is simple, sensitive, and inexpensive and was used for the determination of propyl gallate in edible oil.

Methylglyoxal as a scavenger for superoxide anion-radical.

Methylglyoxal at a concentration of 5 mM caused a significant inhibition of superoxide anion radical (O2 (·-)) comparable to the effect of Tirone. In the process of O2 (·-) generation in the system of egg phosphatidylcholine liposome peroxidation induced by the azo-initiator AIBN, a marked inhibition of chemiluminescence in the presence of 100 mM methylglyoxal was found. At the same time, methylglyoxal did not inhibit free radical peroxidation of low-density lipoprotein particles, which indicates the absence of interaction with methylglyoxal alkoxyl and peroxyl polyenoic lipid radicals. These findings deepen information about the role of methylglyoxal in the regulation of free radical processes.

Effect of Proline-Containing Oligopeptides PGP and RGP on Proliferative and Protein-Synthesizing Activity of Cultured Pulmonary Fibroblasts under Conditions of Oxidative Stress.

We studied the effect of glyprolines Pro-Gly-Pro (PGP) and Arg-Gly-Pro (RGP) on the primary culture of pulmonary fibroblasts from newborn albino rats under normal conditions and during oxidative stress. Under physiological conditions, the peptides had no effect on parameters of cell division. Hydrogen peroxide induced intensive oxidative stress accompanied by suppression of protein-synthesizing function. When hydrogen peroxide was added to the culture containing the test peptides, correction of the oxidative status was observed accompanied by activation of DNA-synthesizing activity and inhibition of lucigenin-dependent chemiluminescence.

On the pharmacology of oxidative burst of human neutrophils.

The effect of three therapeutically used drugs and five polyphenolic compounds on the mechanism of oxidative burst was compared in whole blood and isolated neutrophils at cellular and molecular level. In 10 microM concentration, the compounds investigated decreased the oxidative burst of whole blood in the rank order of potency: N-feruloylserotonin (N-f-5HT) > curcumin (CUR) > quercetin (QUER) > arbutin (ARB) > resveratrol (RES) > dithiaden (DIT) > carvedilol (CARV) > brompheniramine (BPA). The ratio between the percentage inhibition of extracellular versus intracellular chemiluminescence (CL) followed the rank order QUER > N-f-5HT > RES > CUR > DIT and is indicative of the positive effect of the compounds tested against oxidative burst of neutrophils, demonstrating suppression of reactive oxygen species extracellularly with minimal alteration of intracellular reactive oxygen species (ROS). Activation of protein kinase C was significantly decreased by DIT, CUR, QUER and N-f-5HT. CARV, DIT, QUER and ARB reduced activated neutrophil myeloperoxidase release more significantly compared with the effect on superoxide anion generation. All compounds tested increased the activity of caspase-3 in cell-free system. It is suggested that other regulatory mechanisms than protein kinase C might participate in the inhibition of neutrophil activation with the compounds tested. Different mechanisms are concerned in controlling the assembly of NADPH oxidase and the regulatory role of calcium ions is suggested. Compounds decreasing the amount of extracellular ROS generation, yet affecting but minimally intracellular ROS generation, are promising for further investigation in vivo.

Chemiluminescent assay of phenol in wastewater using HRP-catalysed luminol oxidation with and without enhancers

Two methods for phenol determination based on the suppression of chemiluminescence (CL) produced upon HRP-catalysed oxidation of luminol were developed.

Determination of matrine in medicine and bio-fluids based on inhibition of luminol-myoglobin chemiluminescence

A green, rapid and sensitive flow injection procedure based on the inhibition of the chemiluminescence (CL) intensity from the luminol-myoglobin (Mb) system is proposed for the determination of matrine. The decrement of CL signal was linear with the logarithm of the matrine concentration over the range from 10 to 1000 ng/mL (R2 = 0.9978) offering a detection limit of 3.5 ng/mL. At a flow rate of 2.0 mL/min, one analysis cycle, including sampling and washing, could be accomplished in 0.5 min with a relative standard deviation (RSD) of less than 5.0%. The sensitive flow injection method was successfully applied to the determination of matrine in pharmaceutical injection and human serum, with recoveries from 94.1 to 113.4% and RSDs of less than 5.0%.

Determination of estradiol valerate in pharmaceutical preparations and human serum by flow injection chemiluminescence

A novel method for the detection of trace estradiol valerate (EV) in pharmaceutical preparations and human serum was developed by inhibition of luminol chemiluminescence (CL) by estradiol valerate on the zinc deuteroporphyrin (ZnDP)-enhanced luminol-K3 Fe(CN)6 chemiluminescence system. Under optimized experimental conditions, CL intensity and concentration of estradiol valerate had a good linear relationship in the ranges of 8.0 × 10(-8) to 1.0 × 10(-5) g/mL. Detection limit (3σ) was estimated to be 3.5 × 10(-8) g/mL. The proposed method was applied successfully for the determination of estradiol valerate in pharmaceutical preparations and human serum and recoveries were 97.0-105.0% and 95.5-106.0%, respectively. The possible mechanism of the CL system is discussed.

Effects of gold-chloroquine complexes on respiratory burst of polymorphonuclear leukocytes.

The effects of gold-chloroquine derivatives with the formula [Au(PR3)(CQ)]PF6 (where R = Ph (1), Et or Me) on the superoxide anion production by human neutrophils (PMNs, polymorphonuclear cells) were investigated. When these complexes (0.1-3 mumol/l) were added to PMNs prior to the activators formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate (PMA), they inhibited isoluminol-horseradish peroxidase-dependent chemiluminescence (CLisol). The inhibition was a direct result of effects on PMNs since chemiluminescence in the cell-free system (horseradish peroxidase-hydrogen peroxidase-isoluminol) was not affected. The above mentioned concentrations of the complexes did not show in vitro toxicity on the cells. On the other hand, when 1 mumol/l of complex 1 was added to cells after stimulation, the chemiluminescence of PMNs stimulated by PMA was inhibited, but not the chemiluminescence stimulated by fMLP. The gold-chloroquine binding was essential for the referred activity as chemiluminescence was not influenced by the precursors chloroquine (CAS 54-05-7) and AuCl(PPh3). Furthermore, the extent of inhibition of chemiluminescence in PMNs activated by PMA did not increase with the duration of preincubation in presence of 1 mumol/l of 1. Extensive washing of cells after preincubation with 1 mumol/l of 1 reversed the aforementioned inhibition. All these results show that the gold-chloroquine binding can lead to compounds with specific properties that could make them useful in the treatment of some inflammatory diseases.

Inhibition of Chemiluminescence by Phenol and Some of its Analogues

Inhibition of Chemiluminescence by Phenol and Some of its Analogues