Inhibition of chemiluminescence

Inhibition of chemiluminescence of luminol-hypochlorite system. The hypochlorite is electrogenerated online by constant-current electrolysis 5 X 10-8 No data No data Pharmaceuticals 2007 129... 

DEVELOPMENT OF A CHEMILUMINESCENCE DETECTION OF HERBICIDES RELATIVE TO THE MEDIATED INHIBITION OF THYLAKOIDS IN A ji-FLUIDIC SYSTEM... 

A method of detecting herbicides is proposed the photosynthetic herbicides act by binding to Photosystem II (PS II), a multiunit chlorophyll-protein complex which plays a vital role in photosynthesis. The inhibition of PS II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase (HRP). The sensing device proposed combines the production and detection of hydrogen peroxide in a single flow assay by combining all the individual steps in a compact, portable device that utilises micro-fluidic components. 

SOD in Figure 5 demonstrates the effect of superoxide dismutase on PCL. Its effect is characterized by an inhibition of the chemiluminescence intensity without having an impact on the lag phase. According to McCord and Frido-vich [27] (50% test signal inhibition), 1 activity unit in this system refers to approximately 100 ng of the enzyme preparation of the Sigma Co. 

Mummichog, Fundulus heteroclitus 1000-20,000 Dose-dependent inhibition of peak chemiluminescence in phagocytes after incubation for 20 h 67... 

Anderson, R.S. and L.L. Brabacher. 1992. In vitro inhibition of medaka phagocyte chemiluminescence by pentachlorophenol. Fish Shellfish Immunol. 2 299-310. 

Final evidence for the involvement of a ground-state complex with [21] on the catalytic chemiluminescence pathway comes from the inhibition of the special catalysis by the addition of donor molecules capable of competitive complexation. Both the rate constant for the reaction of [21] catalyzed by MgTPP and the initial chemiluminescence intensity are decreased markedly by the addition of diethyl ether and even more dramatically by the addition of pyridine. This inhibition of catalysis apparently derives from complexation of the diethyl ether or pyridine to MgTPP. The added donor competes with [21] for the formation of the weak ground state complex, thereby inhibiting the otherwise effective catalysis. The special catalysis of ZnTPP and MgTPP is thus fully consistent with and readily accommodated by the CIEEL mechanism. 

The Glow of Phosphorus—Effect of Pressure upon Oxidation of Phosphorus— Velocity of the Reaction—Effect of Temperature—Production of Ozone— Inhibition of the Glow—Nature of the Chemiluminescence—Ionisation by the Glow—The Emission Spectrum. 

A stopped flow chemiluminescence method capable of assaying 120 samples per hour was based on inhibition of the reaction between luminol and iodine [144],... 

Kinetic analysis of luminol-dependent chemiluminescence demonstrated that a solution of berbamine (20 pM) was found to inhibit the generation of various types of reactive oxygens by guinea-pig neutrophils. The results of these and other experiments suggest that berbamine inhibits the active oxygen generation via the stabilization of plasma membrane and the inhibition of phospholipid-dependent protein kinase (PKC) and NADPH oxidase activation [178]. 

The free-radical-scavenging activity of compounds was evaluated in the TEAC and CL assays. The first measures the relative abiUty of antioxidant substances to scavenge the radical cation 2,2 -azinobis(3-ethylbenzothiozoline-6-sulfonate) (ABTS" ) as compared to a standard amount of the synthetic antioxidant Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid). The CL assay measures the inhibition of iodophenol-enhanced chemiluminescence by a horseradish peroxidase/perborate/luminol system. Trolox was used as the reference antioxidant. The results showed that xanthones exhibited free-radical-scavenging activity at potency levels comparable to those of reference antioxidant compounds quercetin and rutin, while the benzophenone and phloroglucinol type compoimds had more moderate activities [87]. 

Alapont AG, Zamora LL Calatyd JM. Indirect determination of paracetamol in pharmaceutical formulations by inhibition of the system luminol-H202- Fe(CN)6 chemiluminescence. JPharmBiomed 1999 21 311-7. 

A sensitive and simple chemiluminescent (CL) method for measuring antioxidant activity was developed. The determination of TEAC (Trolox equivalent antioxidant capacity) is based on the inhibition of CL intensity of luminol by an antioxidant. Antimicrobial activity was tested as a minimal inhibitory concentration (MIC) by broth microdilution method on gram-positive Enterococcus faecalis. Staphylococcus aureus) and gram-negative Pseudomonas aeruginosa, Escherichia coli) bacterial strains. 

Table 13. Singlet oxygen decontaminase activity 0/ Cu-chelales and erythrocuprein. The erythrocuprein concentration required to produce a 50% inhibition of the chemiluminescence was taken an enzyme unit for quantitating the singlet oxygen decontaminase activity. The assay mixture contained HEPES buffer, 0.1 M, pH 7.8 luminol, 0.3 mM crystalline K3CrO%, 0.3 mM the total volume was 5.1 ml. Counting was performed as described in the legend to Fig. 32...

Cu2+-Chelate Required equivalent of chelated copper to yield 50% inhibition of M902 induced chemiluminescence Moles X [106] Specific activity. Units x mole-1 X [10 5]... 

Fig. 1. Typical trace of the superoxide-depndent chemiluminescence detected in the presence of CLA. (A) Lang-lasting nature of chemiluminescence. (B) Inhibition of the chemiluminescence in the presence of Tiron.

Table 2. Antioxidant Activity of Argentine Aqueous Plant Extracts IC50 and 95% Confidence Interval for Inhibition of Hydroperoxide-initiated Chemiluminescence (CL) and the Production of Thiobarbituric Acid-reactive Substances (TBARS) in Rat Liver Homogenates...

Table 6. Inhibition of Lipid Peroxidation (Chemiluminescence and TBARS) and Free Radical-mediated DNA-sugar Damage Induced by the Presence of Fe (II) Salts (IC5o s) in Methanolic Extrncts and Isolated Compounds of Pothomorphe spp.

The antioxidant activity of alizarin was established in four different assays (1) suppression of light emission in the p-iodophenol enhanced chemiluminescent assay, (2) scavenging of superoxide anion (02 -) in a hypoxanthine-xanthine oxidase system, (3) protection of rat liver microsomes from lipid peroxidation by ADP/iron(II) ions, and (4) protection of bromobenzene-intoxicated mice from liver injury in vivo [141]. Alizarin was compared with Trolox (water soluble vitamin E), the flavonoid baicalin and green tea proanthocyanidins. In assay (1) the activity of alizarin was 76% of that of Trolox. In assay (2) the inhibition of 02 -induced chemiluminescence was 40%, 32%, 23% and 14% for Trolox, alizarin, green tea polyphenols and baicalin respectively. Alizarin was not significantly active in the lipid peroxidation assay but after baicalin the most active compound in the in vivo assay. This shows again the difficulty in the evaluation of antioxidant activity and the differences between in vitro and in vivo assays [141]. 

Similarly, L-arginine may provide some protection against graft atherosclerosis in heart transplant recipients via -NO-mediated inhibition of intimal cell proliferation (Drexler et al., 1994) and may attenuate the adhesion of monocytes to the EC surface in a dietary model of experimental atherosclerosis (Tsao et al., 1994). In contrast, other data suggest that NO production is actually enhanced in hypercholesterolemic vessels (Minor et al., 1990). Using chemiluminescent techniques. Minor et al. (1990) showed that the basal release of -NO and its metabolites was increased in the aortas of hypercholesterolemic rabbits. This implies that impaired relaxation responses are due to the rapid reaction of NO with other target molecules. 

The first report on the use of ion-exchange columns with chemiluminescence detection was that by Buiguera et aI.[Sl] on the determination of zinc and cadmium through inhibition of the cobalt catalyzed chemiluminescence generation from luminol. The chloro-complexes of zinc and cadmium were retained by an anion exchanger and eluted separately using sodium hydroxide and nitric acid. Apparently, preconcentration effects were not pursued. 

Van Dyke, K., Antonini, J.M., Wu, L., Ye, Z., and Reasor, M.J., The inhibition of silica-induced lung inflammation by dexamethasone as measured by bronchoalveolar lavage fluid parameters and peroxynitrite-dependent chemiluminescence, Hgenf5 Hcn on, 41,44 9, 1994. 

---