Extra-weak chemiluminescence of drugs. VIII. Extra-weak chemiluminescence arising from the amino-carbonyl reaction

Extra-weak chemiluminescence (CL) from amino-carbonyl reactions of L-lysine with various sugars and aldehydes in aqueous solution was examined. Amongst the aldehydes and sugars tested, glycolaldehyde and D -arabinose produced the highest CL intensity. The CL of the amino-carbonyl reaction reached a maximum after about 60 minutes. The CL was pH dependent, and a linear relation between CL intensity and hydroge-ion concentration was demonstrated. Low oxygen levels inhibited CL and no CL was produced in nitrogen purged solutions. Addition of cupric or ferrous ion, decreased the CL. The involvement of free radical intermediates was demonstrated by ESR. Our findings suggest that the CL of the amino-carbonyl reaction arises from free radicals derived from melanoidines or their intermediates. CL should prove useful for evaluating the stability of crude drugs extracted from natural resources that contain various amino acid derivatives protein and sugar components.     

Extra-weak chemiluminescence of drugs XI. Quenching effects of purine and pyrimidine derivatives on the extra-weak chemiluminescence derived from the maillard reaction

Quenching effects of purine and pyrimidine derivatives on the extra-weak chemiluminescence (CL) derived from the Maillard reaction of L-lysine with D-arabinose were investigated The pyrimidine derivatives 2′-deoxy cytidine, uridine, and uracil quenched the CL. Cytidine did not quench the CL. Purine derivatives, e.g. uric acid and 1-methyl adenosine were particularly effective in quenching the CL. 5-Methyl adenine and xanthine also quenched the CL, but adenosine had no effect. A comparison of the CL-quenching abilities of compounds that have common basic structure was made; those with ribose at the 5-position were the strongest quenchers. A linear relationship between CL-quenching activity and the HOMO energy of the pi orbital for the various compounds was shown.     

Immunochemical approach to characterize advanced glycation end products of the Maillard reaction. Evidence for the presence of a common structure

Reaction of protein amino groups with glucose (the Maillard reaction) leads from early stage products such as Schiff base and Amadori products to advanced glycation end products (AGE), structures implicated in diabetic complications and the aging process. We have prepared the polyclonal anti-AGE antibody and the monoclonal anti-AGE antibody against AGE-bovine serum albumin and made an immunochemical approach to characterize AGE structures. Both polyclonal and monoclonal antibodies reacted with AGE-proteins such as AGE-bovine serum albumin, AGE-human serum albumin, and AGE-hemoglobin but not with unmodified counterparts. Treatments of these AGE-proteins with borohydride had no effect on the immunoreactivity. Moreover, fructosyl-epsilon-caproic acid, a synthetic Amadori compound, did not serve as an antigen, indicating that these antibodies were specific for AGE products but not for early stage products of the Maillard reaction. In addition, these antibodies were also able to recognize AGE products prepared either from alpha-tosyl-1-lysine, alpha-tosyl-1-lysine methyl ester, monoaminocarboxylic acid such as epsilon-aminocaproic acid, gamma-amino-n-butyric acid, and beta-alanine. Thus, these results strongly suggest the presence of a common structure in AGE preparations, regardless of whether AGE products are generated from proteins, amino acids, or monoaminocarboxylic acids.     

Extra-weak chemiluminescence of drugs XV. Method for determining stability of Toki-shakuyaku-san extract granules

The purpose of the study was to evaluate the quality of Toki-shakuyaku-san extract granules (TJ-23) using chemiluminescence (CL). A linear relationship was obtained between the log value of the CL of TJ-23 and the reaction temperature. An excellent correlation (r= 0.999) was found between the slope of this curve (ΔA) and the colour intensity due to the browning reaction occurring at the early stage of the Maillard reaction.     

A luminol chemiluminescence method for sensing histidine and lysine using enzyme reactions

The analysis of free amino acids in urine and plasma is useful for estimating disease status in clinical diagnoses. Changes in the concentration of free amino acids in foods are also useful markers of freshness, nutrition, and taste. In this study, the specific interaction between aminoacyl–tRNA synthetase (aaRS) and its corresponding amino acid was used to measure amino acid concentrations. Pyrophosphate released by the amino acid–aaRS binding reaction was detected by luminol chemiluminescence; the method provided selective quantitation of 1.0–30 μM histidine and 1.0–60 μM lysine.     

Effect of ascorbic acid on the chemiluminescence of polyphenols

The chemiluminescence of gallic acid by hydrogen peroxide had completely inhibited by the presence of ascorbate. After ascorbate had disappeared by oxidation, chemiluminescence returned. The concentration of gallic acid was virtually unchanged by presence of ascorbate, but started to decrease after the disappearance of ascorbate. This might be attributable to the rapid reduction of quinone, which was the first product of the chemiluminescence reactions, to gallic acid by ascorbate or the donation of proton to the phenoxy radical from ascorbate to stop the chemiluminescence reaction at the first stage. The effects of ascorbate on the chemiluminescence of other polyphenols depended on their oxidation rate.     

Determination of bisphenol A using a flow injection inhibitory chemiluminescence method.

A new flow injection chemiluminescence (CL) method has been developed for the determination of bisphenol A (BPA), based on the inhibitory effect of BPA on the chemiluminescence reaction between luminol and potassium hexacyanoferrate. Under optimum conditions, the decrease in CL emission intensity was linear with BPA concentration in the range 8.0 x 10(-7)-1.2 x 10(-5) mol/L, and the detection limit was 3.1 x 10(-7) mol/L. The relative standard deviation (RSD) of 11 replicate measurements was 2.6% for 2.0 x 10(-6) mol/L BPA (n = 11). The sampling frequency was calculated to be ca. 120/h. This method has been successfully used to determine the content of BPA in aqueous solution of polycarbonate materials. A brief discussion on the possible chemiluminescence reaction mechanism is presented.     

Luminol chemiluminescence catalysed by colloidal platinum nanoparticles.

Platinum colloids prepared by the reduction of hexachloroplatinic acid with citrate in the presence of different stabilizers were found to enhance the chemiluminescence (CL) of the luminol-H(2)O(2) system, and the most intensive CL signals were obtained with citrate-protected Pt colloids synthesized with citrate as both a reductant and a stabilizer. Light emission was intense and reproducible. Transmission electron microscopy and X-ray photoelectron spectroscopy studies were conducted before and after the CL reaction to investigate the possible CL enhancement mechanism. It is suggested that this CL enhancement is attributed to the catalysis of platinum nanoparticles, which could accelerate the electron-transfer process and facilitate the CL radical generation in aqueous solution. The effects of Pt colloids prepared by the hydroborate reduction were also investigated. The application of the luminol-H(2)O(2)-Pt colloids system was exploited for the determination of compounds such as uric acid, ascorbic acid, phenols and amino acids.     

苦瓜干制前后氨基酸组分的变化

经酸水解,利用氨基酸自动分析仪测定干制加工前后的苦瓜中总氨基酸和游离氨基酸含量。结果表明干制前后的苦瓜在氨基酸质量分数上有明显差别,总氨基酸质量分数分别为11.99%和10.87%,游离氨基酸分别为2.36%和0.70%。结论:干制前后的苦瓜中氨基酸质量分数差别明显,其中碱性氨基酸质量分数的变化尤其显著,总氨基酸中精氨酸质量分数下降50%,在游离氨基酸中下降78%;同时还原糖质量分数也由干制前的4.86%下降为干制后的1.86%,说明苦瓜干制过程中发生了美拉德反应,造成了氨基酸和还原糖含量的下降。     

Dissolved oxygen determination by electrocatalysed chemiluminescence with in-line solid phase media

Dissolved elemental oxygen is determined in a flowing aqueous stream using glucose oxidase to catalyse the reaction between D -glucose and O₂ to produce hydrogen peroxide. The levels of the resulting H₂O₂ are detected and quantified by luminol chemiluminescence using in-line solid phase media for pH adjustment of the reagent stream and for controlled release of the luminophore. The reaction is initiated by electrochemical catalysis. By the use of excess D -glucose in the reagent flow stream, the intensity of chemiluminescence is rendered proportional only to fluctuations in the dissolved O₂ concentration. The methodology provides a means for the detection of aqueous O₂ in the range 0–10 mg/L. © 1998 John Wiley & Sons, Ltd.     

Estimation of tyrosine by the attenuation of 4-iodophenol enhanced chemiluminescence

Tyrosine markedly attenuates the chemiluminescence output intensity from the 4-iodophenol enhanced chemiluminescence assay system in a manner consistent with competition between the amino acid and luminol for the 4-iodophenoxy radical. This effect provides the basis for a sensitive assay of tyrosine. Interference by the other amino acids has been assessed; major interference by cysteine can be removed by incubation with iodoacetic acid.     

Theoretical analysis of a site-specific chemiluminescence reaction and its application to quantitation of lipid hydroperoxides

A system was designed for chemiluminescent measurement of lipid hydroperoxides by their site-specific reaction in sodium dodecylsulfate micelles. Ferrous ion-induced decomposition of lipid hydroperoxides in the sodium dodecylsulfate micelles resulted in strong chemiluminescence of the Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one (CLA). After addition of ferrous sulfate to the micelles containing lipid hydroperoxide and luciferin, the chemiluminescence intensity reached a maximum rapidly and then decreased. The sequence of this reaction was elucidated by theoretical analysis, which demonstrated that the maximum chemiluminescence intensity is proportional to the initial concentration of hydroperoxide. Good linear relationships were observed between the maximum counts of chemiluminescence and the amounts of hydroperoxides of linoleic acid, phosphatidylcholine, choresterol (5 alpha), cumene and tert-butyl and hydrogen peroxide. This chemiluminescence method was simple and sensitive enough to detect picomole levels of linoleic acid and phosphatidylcholine hydroperoxides.     

Variables in xanthine oxidase-initiated luminol chemiluminescence: Implications for chemiluminescence measurements in biological systems

We tested the effects of generally used chemiluminescence inhibitors on an example of luminol chemiluminescence elicited by xanthine oxidase/hypoxanthine system, and attempted to assess their capabilities in discovering the reaction pathways leading to chemiluminescence. Luminol itself is a xanthine oxidase inhibitor and its concentration affects the reaction mechanism. Maximal chemiluminescence response was observed at luminol concentration inhibiting urate production. Chemiluminescence was totally inhibited by superoxide dismutase, the inhibition by catalase depended on luminol concentration. Ferricytochrome c, a detector of superoxide, either stimulated or inhibited chemiluminescence in a concentration-dependent manner. Chemiluminescence was highly stimulated by peroxidases. A pronounced inhibition of chemiluminescence was caused by chelators; 1 mm desferal and 0.01 mm diethyldithiocarbamate. It is suggested that measurement of luminol chemiluminescence is not a suitable method for discrimination among individual reactive oxygen species and their quantitative determination in biological systems.     

Amino Acid Analyses of Desert Varnish from the Sonoran and Mojave Deserts

There has long been a debate as to whether desert varnish deposits are microbially mediated or are deposited by inorganic processes. Several researchers have cultured bacteria from the surface of desert varnish suggesting that bacteria are intimately associated with varnish coatings and may play a role in their formation. To test this hypothesis, we have collected scrapings of desert varnish from the Sonoran Desert in Arizona and the Mojave Desert in California and analyzed them for amino acids. Thirteen amino acids were found in desert varnish indicating a biogenic component of these varnishes. Two protein amino acids that were not detected in any of the varnishes are cysteine and tryptophan. Two nonprotein amino acids,β-alanine andγ-amino butyric acid, were found. These are known to be formed by enzymatic decarboxylation, thereby indicating possible organismal activity in varnish. Some D -enantiomers of the amino acids were also found. In addition to small amounts of the D -enantiomer of aspartic acid, which is rapidly formed by racemization and was present in most samples, D -alanine and D -glutamic acid were found. These latter two amino acids are components of the peptidoglycan cell wall material of bacteria. L -lysine was also detected, but not diaminopimelic acid. The combination of L -lysine, D -alanine, and D -glutamic acid is characteristic of the peptidoglycan from Gram-positive bacteria. Although the presence of these biomarkers does not prove that Gram-positive bacteria produce the coatings, finding them is consistent with the hypothesis that they may play a role in desert varnish formation.     

Stepwise synthesis of oligopeptides with N-carboxy α-amino acid anhydrides. II. Oligopeptides with some polar side chains

The reaction of NCA's with some amino acids having a nucleophilic functional group on the side chain was studied in a heterogeneous reaction medium (acetonitrile-water). Glutamic acid and aspartic acid, having a free carboxyl group on the side chain, were successfully used to synthesize oligopeptides without interactions of the γ- and β-carboxyl group with NCA's. Two products were obtained by the reaction of NCA with L -lysine, which contains a free amino group on the side chain. ε-Protected lysine was used to prepare α-peptides as a nucleophile in the reaction. No racemization was observed in the synthesis of peptides by the NCA method in the heterogeneous solvent system. Oligopeptides with some polar side chains were synthesized by the NCA method.     

Hydroperoxide-induced chemiluminescence of the perfused lung.

Light-emission of the perfused lung is induced by t-butyl hydroperoxide, giving chemiluminescence yields that oscillate between 800 and 1500 counts/s depending on the site and position of the lung. The response of the perfused lung to infusion with different hydroperoxides gives a pattern similar to that observed with the liver microsomal fraction; ethyl hydroperoxide shows a much higher chemiluminescence yield than the tertiary (t-butyl and cumene)hydroperoxides. Alveolar oedema affected the light-emission of the perfused lung depending on the time at which oedema developed, decreasing light emission on infusion of hydroperoxide in the oedematous lung and increasing it when oedema appeared after the maximal chemiluminescence yield was already achieved. Paraquat, administered in vivo, augmented light-emission by approximately 2-fold. The effect of paraquat was a time-dependent process. Lung chemiluminescence, compared with liver chemiluminescence, needed higher hydroperoxide concentration to induce light-emission.     

Effect of antioxidants on chemiluminescence produced by reactive oxygen species

Luminol chemiluminescence was used to evaluate the scavenging of superoxide, hydroxyl and alkoxy radicals by four antioxidants: dipyridamole, diethyldithiocarbamic acid, (+)catechin, and ascorbic acid. Different concentrations of these compounds were compared with well-known oxygen radical scavengers in their capacity to inhibit the chemiluminescence produced in the reaction between luminol and specific oxygen radicals. Hydroxyl radicals were generated using the Fenton reaction and these produced chemiluminescence which was inhibited by diethyldithiocarbamate. Alkoxy radicals were generated using the reaction of tert-butyl hydroperoxide and ferrous ion and produced chemiluminescence which was inhibited equally by all of the compounds tested. For the determination of superoxide scavengers we describe a new, simple, economic, and rapid chemiluminescence method consisting of the reaction between luminol and horseradish peroxidase (HRP). With this method it was found that 40 nmol/l dipyridamole, 0.18 μmol/l ascorbic acid, 0.23 μmol/l (+)catechin, and 3 μmol/l diethyldithiocarbamic acid are equivalent to 3.9 ng/ml superoxide dismutase (specific scavenger of superoxide) in causing the same degree of chemiluminescence inhibition. These results not only indicated that the antioxidative properties of these compounds showed different degrees of effectiveness against a particular radical but also that they may exert their action against more than one radical.     

Flow injection chemiluminescence determination of vitamin B12 using on-line UV-persulfate photooxidation and charge coupled device detection

A sensitive chemiluminescence method for vitamin B(12) using a charge-coupled device (CCD) photodetector combined with on-line UV-persulfate oxidation in a simple continuous flow system has been developed. The principle for the determination of vitamin B(12) is based on the enhancive effect of cobalt (II) on the chemiluminescence reaction between luminol and percarbonate in alkaline medium. In addition, percarbonate has been investigated and proposed as a powerful source of hydrogen peroxide as oxidant agent in this chemiluminescence reaction. The digestion of vitamin B(12) to release the cobalt (II) is reached by UV irradiation treatment in a persulfate medium. The CCD detector, directly connected to the flow cell, is used with the continuous flow manifold to obtain the full spectral characteristics of cobalt (II) catalyzed luminol-percarbonate reaction. The vitamin B(12) oxidation process and chemical conditions for the chemiluminescence reaction were investigated and optimized. The increment of the emission intensity was proportional to the concentration of vitamin B(12) , giving a second-order calibration graph over the cobalt (II) concentration range from 10 to 5000 μg L(-1)(r(2) = 0.9985) with a detection limit of 9.3 μg L(-1). The proposed method was applied to the determination of vitamin B(12) in different kinds of pharmaceuticals.     

奥利亚罗非鱼胶原蛋白酸解液美拉德反应产物风味成分分析

以奥利亚罗非鱼鱼皮中胶原蛋白酸解液和葡萄糖为主要基质进行美拉德反应,采用氨基酸自动分析仪和GC-MS分析了游离氨基酸组成和主要风味成分。结果表明,酸解后游离氨基酸完全符合胶原蛋白特有的氨基酸组成,且风味氨基酸占59.77%。此外鉴定出19种风味成分,其中包括乙酸乙酯(30.34%)、2,3-二羟基丙醛、柠檬烯、1,1-乙二醇二乙酸酯、己二酸二丁酯、二乙二醇丁醚醋酸酯、苯甲酸乙酯、2-乙酰基吡咯等。     

Flow‐injection chemiluminescence method for the determination of chloramphenicol based on luminol–sodium periodate order‐transform second‐chemiluminescence reaction

A new chemiluminescence (CL) reaction was observed when chloramphenicol solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate was injected into the reaction mixture of chloramphenicol and alkaline luminol. This reaction is described as an order‐transform second‐chemiluminescence (OTSCL) reaction. The OTSCL method combined with a flow‐injection technique was applied to the determination of chloramphenicol. The optimum conditions for the order‐transform second‐chemiluminescence emission were investigated. A mechanism for OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristics, the UV‐visible spectra and the chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of chloramphenicol over the range 5.0 × 10^?7–5.0 × 10^?5 mol/L with a correlation coefficient of 0.9969 and a detection limit of 6.0 × 10^?8 mol/L (3σ). The relative standard deviation (RSD) for 11 repeated determinations of 5.0 × 10^?6 mol/L chloramphenicol is 1.7%. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.