Lucigenin chemiluminescence

Legg and Hercules have shown that the reaction of superoxide with lucigenin results in chemiluminescence. A similar conclusion was reached by Fridovich and coworkers, who observed chemiluminescence upon the addition of lucigenin to the xanthine-xanthine oxidase system, which is known to produce 02 . In order to emit chemiluminescence, lucigenin must first be reduced by one electron to produce the radical cation 43 (Scheme 30). This species reacts with superoxide ion, producing the intermediate 1,2-dioxetane, whose decomposition is responsible for luminescence. ... 

A number of chemiluminescent reactions may proceed through unstable dioxetane intermediates (12,43). For example, the classical chemiluminescent reactions of lophine [484-47-9] (18), lucigenin [2315-97-7] (20), and transannular peroxide decomposition. Classical chemiluminescence from lophine (18), where R = CgH, is derived from its reaction with oxygen in aqueous alkaline dimethyl sulfoxide or by reaction with hydrogen peroxide and a cooxidant such as sodium hypochlorite or potassium ferricyanide (44). The hydroperoxide (19) has been isolated and independentiy emits light in basic ethanol (45). 

Classical chemiluminescence from lucigenin (20) is obtained from its reaction with hydrogen peroxide in water at a pH of about 10 Qc is reported to be about 0.5% based on lucigenin, but 1.6% based on the product A/-methylacridone which is formed in low yield (46). Lucigenin dioxetane (17) has been prepared by singlet oxygen addition to an electron-rich olefin (16) at low temperature (47). Thermal decomposition of (17) gives of 1.6% (47). 

Rost, M., Karge, E., and Klinger, W. (1998). What do we measure with luminol-, lucigenin- and penicillin-amplified chemiluminescence 1. Investigations with hydrogen peroxide and sodium hypochlorite. J. Biolumin. Chemilumin. 13 355-363. 

Storch, J., and Ferber, E. (1988). Detergent-amplified chemiluminescence of lucigenin for determination of superoxide anion production by NADPH oxidase and xanthine oxidase. Anal. Biochem. 169 262-267. 

The 02, radical can act as an oxidant as well as a reductant and chemical estimates of its production can also be based on its ability to oxidize epinephrine to adren-ochrome [62], These chemical methods have the additional advantage of not requiring highly specialized equipments. Also based on its redox property, the 02 radical can be determined by chemiluminescence methods through the measurement of the intensity of the fluorescence radiation emitted after chemical oxidation of 02 by, e.g., lucigenin [63-67], These methods, however, are limited by the poor selectivity and lack of capability for in-vivo performance. 

Me Capra in particular proposed n> that the chemiluminescence reactions of a large number of organic compounds had this concerted dioxetane decomposition step as key reaction in the production of electronically excited products, namely acridinium salts 25,26,27) indolylperoxides 28>, activated oxalic esters 29>, diphenyl carbene 30>, tetrakis-dimethylamino-ethylene 31 32>, lucigenin 33>, and substituted imidazoles 23>. 

Lucigenin 71 chemiluminescence is more complicated than that of luminol and related compounds due to the presence in the reaction mixture of several species capable of emission 135>. N-Methylacridone 72, however, has been established as the primary excited product (for references see 0 p. 90) from which energy transfer occurs to the other species 3>. 

Because of the close relations between lucigenin, N-alkylacridones, and other 9-substituted acridines, it appears appropriate to consider the chemiluminescence reactions of all these compounds simultaneously. 

In view of the increasing interest in the radical ion chemiluminescence 71 has also been investigated to see whether radical ions play an essential role here, especially by E. G. Janzen et al. 136,137,138) The reaction pathway to N-methylacridone 72 was thought to proceed perhaps via a homolytic cleavage of the lucigenin carbinol base 74, yielding N-methylacridone radical anion 75. 

The dioxetane derivative 79 may be formed as intermediate in the brilliant chemiluminescence reaction between 10,10 -dimethyl-9,9 -bi-acridylidene and excited-singlet oxygen 125>. Chemiluminescence also occurs when potassium cyanide is added to lucigenin solutions in the... 

Quenching in lucigenin fluorescence (and similar effects should operate in lucigenin and acridine chemiluminescence in general) has recently been investigated by Hercules 143>. 

Chemiluminescence from lucigenin is observed even without the catalytic transition metal ions but it is more intense when these ions are used. In aqueous or predominately aqueous solutions the CL yield is 0.01-0.02, which makes it a slightly better emitter than luminol [35], The emission of lucigenin is also catalyzed by Pb(II), Bi(III), Tl(III), and Hg(I) ions, which do not catalyze the CL of luminol [36],... 

Figure 5 Chemiluminescent reaction of lucigenin proceeding via a dioxetane intermediate.

Several N-methyl-9-acridinecarboxylic acid derivatives (e.g., 10-methyl-9-acridinecarboxylic chloride and esters derived therefrom [39]) are chemiluminescent in alkaline aqueous solutions (but not in aprotic solvents). The emission is similar to that seen in the CL of lucigenin and the ultimate product of the reaction is N-methylacridone, leading to the conclusion that the lowest excited singlet state of N-methylacridone is the emitting species [40], In the case of the N-methyl-9-acridinecarboxylates the critical intermediate is believed to be either a linear peroxide [41, 42] or a dioxetanone [43, 44], Reduced acridines (acridanes) such as N-methyl-9-bis (alkoxy) methylacridan [45] also emit N-methylacridone-like CL when oxidized in alkaline, aqueous solutions. Presumably an early step in the oxidation process aromatizes the acridan ring. 

HTAC and HTAH have been used as surfactants in the chemiluminescence reaction of lucigenin (10,10 -dimethyl-9,9 -biacridinium dinitrate) with biological reductants (such as fructose, glucose, ascorbic and uric acid) or hydrogen peroxide [38],... 

One of the nonionic surfactants most used as an enhancer of chemiluminescent reactions is Brij-35. This surfactant increases the reaction of lucigenin with catecholamines by a factor of 2.6 compared with the CL intensity in an aqueous medium [42], This enhancement can be explained in the following way it is known that oxygen from the polyoxyethylene chains in Brij-35 can react with sodium ion to form an oxonium ion, by which means the polyoxyethylene chains act as an oxonium cation. In this way the increase in CL intensity due to Brij-35 can be attributed to the same effect described for the micelles of a cationic surfactant. 

The dismutation (disproportioning) of two free radicals is accompanied by release of a portion of reaction energy as a light quantum. As the quantum yield of such a process is extremely low, the detection of this type of chemiluminescence is technically complicated. Several compounds like lucigenin and luminol have a high quantum yield after reaction with peroxide radicals. Therefore, they are widely used for the detection of these radicals, particularly in the examination of phagocyting cells. 

The molecular species responsible for luminol and lucigenin chemiluminescence are not fully defined. Clearly, luminol chemiluminescence requires the combined activities of both the NADPH oxidase and myeloperoxidase inhibitors of either enzyme (e.g. diphenylene iodonium for the oxidase and salicylhydroxamic acid for myeloperoxidase) completely prevent luminol... 

The molecular species responsible for lucigenin chemiluminescence are not fully defined. Because this probe does not permeate the cell, only secreted oxidants are detected. Several reports have suggested that this probe measures O2 secretion or else H2O2 secretion on the other hand, some evidence indicates that this cannot be so. Certainly, the oxidant(s) detected by lucigenin is dependent on O2 formation, but the kinetics of activated 02" and H2O2 formation by neutrophils do not parallel those of lucigenin chemiluminescence. Thus, this probe is at least an indirect measure of O2 secretion. 

Dahlgren, C., Aniansson, H., Magnusson, K.-E. (1985). Pattern of formylmethionyl-leucyl-phenylalanine-induced luminol- and lucigenin-dependent chemiluminescence in human neutrophils. Infect. Immun. 47, 326-8. 

Edwards, S. W. (1987). Luminol- and lucigenin-dependent chemiluminescence of neutrophils Role of degranulation. J. Clin. Lab. Immunol. 22, 35-9. 

Lucigenin (10,10 -dimethyl-9,9 -biacridinium or bis-Af-methylacridinium (38)), in the presence of hydrogen peroxide in alkaline media, exhibits chemiluminescence with a maximum emission wavelength at 445 nm. Lucigenin chemiluminescence was first reported in 1935 by Glen and Petsch, and the 1,2-dioxetane 39 was postulated as a key intermediate. Nevertheless, the mechanism of lucigenin chemiluminescence was only elucidated by McCapra and Richardson, who also proposed the thermal decomposition... 

Scheme 28) Quantum yields of lucigenin oxidation by hydrogen peroxide in alkaline media are comparable with the values obtained in luminol oxidation (1.24 x 10 E mol ) ° . However, the use of other peroxides, such as tcrt-butyl hydroperoxide, results in a decrease of chemiluminescence quantum yields of two orders of magnitude, confuming the hypothesis that a 1,2-dioxetane is the HEI, since its formation would be impossible with alkyl peroxides . 

Hypolipemic activity. Fiber, administered orally to nine adults with ileostomies at a dose of 13 g/day, increased the excretion of cholesterol " Petroleum ether extract of the fresh fruit, administered to pigs at a concentration of 3.5 g/kg of diet, was inactive "" . Purified green barley extract, in human mononuclear culture of cells isolated from perithelial blood and synovial fluid of patients with rheumatoid arthritis, was active . Leaf essence, administered to atherosclerotic New Zealand White male rabbits at a dose of 1% of diet, produced a decrease of plasma total cholesterol, triacylglycerol, lucigenin-chemilumines-cence, and luminal-chemiluminescence levels. The value of Tj of red blood cell hemolysis and the lag phase of LDL oxidation increased in barley-treated group compared with the control. Ninety percent of the intimal surface of the thoracic aorta was covered with atherosclerotic lesions in the... 

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