Antibacterial activities of persimmon extracts relate with their hydrogen peroxide concentration.

Persimmon, a deciduous tree of the family Ebenaceae, is found throughout East Asia and contains high levels of tannins. This class of natural compounds exhibit favorable toxicity profiles along with bactericidal activity without the emergence of resistant bacteria, suggesting potential medical applications. Consistent with these observations, persimmon leaves show antibacterial activity. However, the mechanism of persimmon antibacterial activity remains unknown. In the present work, we demonstrate that the antibacterial activity of persimmon reflects the generation of reactive oxygen from tannins. The identification and quantification of reactive oxygen generated from persimmon and the level of antibacterial activity were determined.

Development of a highly sensitive chemiluminescent assay for hydrogen peroxide under neutral conditions using acridinium ester and its application to an enzyme immunoassay.

We developed a highly sensitive chemiluminescent (CL) assay for hydrogen peroxide using 10-methyl-9-(phenoxycarbonyl) acridinium fluorosulfonate (PMAC) that produced chemiluminescence under neutral conditions and applied it to an enzyme immunoassay (EIA). One picomole of hydrogen peroxide could be detected using the optimized PMAC-CL method and 6.2 × 10(-20) mol ß-D-galactosidase (ß-gal) could be detected by combining an indoxyl derivative substrate and the proposed PMAC-CL method. This highly sensitive CL ß-gal assay was applied to an EIA for thyroid-stimulating hormone (TSH) using ß-gal as a label enzyme; 0.02-100.0 µU/mL TSH in human serum could be assayed directly and with high reproducibility.

[Determination of glycarbylamide based on formation of nickel chelate].

A new and simple analytical method for glycarbylamide (GB) based on the formation of nickel chelate was developed. The proposed method is as follows: sample solution is mixed with 0.08 mmol/L nickel nitrate in 0.2 mol/L carbonate buffer (pH 9.0), and the absorbance is measured at 290 nm. Under the optimal conditions, GB could be determined in the concentration range from 0.13 microg/mL to 2.6 microg/mL (r = 0.9999). Using this method for HPLC post column reaction, GB levels in chicken liver extracts could be determined. The recovery of GB was 79.4% (RSD=2.6%, n=3) and the quantitation limit was 30 ng/g. The apparent molar extinction coefficient (epsilon) of the GB-nickel complex was 8.5 x 10(3). The molar ratio of the complex is GB: nickel ion = 2:1.

Determination of reactive oxygen generated from natural medicines and their antibacterial activity.

Extracts of 16 natural medicine powders (Galla chinensis, Malloti cortex, Cassiae semen, Sophorae radix, Myricae cortex, Crataegi fructus, Gambir, Mume fructus, Geranii herba, Phellodendri cortex, Coptidis rhizoma, Swertiae herba, and Cinnamomi cortex) were assayed for reactive oxygen concentrations using the peroxyoxalate chemiluminescent detection system. High luminescence intensity was observed in Galla chinensis, Geranii herba, Malloti cortex, Myricae cortex, and Cinnamomi cortex. Additional experiments identified the reactive oxygen species as hydrogen peroxide. Galla chinensis generated 2.4×10-4 mol/L hydrogen peroxide from a 1 mg/mL solution. In bacterial growth tests, Galla chinensis extract had antibacterial activity against Escherichia coli, Staphylococcus aureus, Bacteroides thetaiotaomicron, Campylobacter sputorum biovar sputorum, Streptococcus salivarius thermophilus, Lactobacillus casei, and Bifidobacterium longum infantis. This antibacterial activity was decreased by the addition of catalase. It revealed that hydrogen peroxide which Galla chinensis produced participated in antibacterial activity.

Chemiluminescence assay for tetrahydrobiopterin based on the generation of hydrogen peroxide using isoluminol-microperoxidase in the presence of 1-methoxy PMS.

We developed a novel highly sensitive chemiluminescence (CL) method for BH(4). The principle of the proposed method is based on active oxygen formation induced by 1-methoxy-5-methyl phenazinium methyl sulphate (1-methoxy PMS) in the presence of dissolved oxygen. Furthermore, active oxygen is determined by a CL assay involving the luminol reaction with microperoxidase. In this report, we examined the mechanism of formation and identified the reactive oxygen species derived from BH(4) employing 1-methoxy PMS. Additionally, optimum conditions for the CL assay of BH(4) were established.