Free radical scavenging and metal chelation by Tinospora cordifolia, a possible role in radioprotection.

Aqueous extract of T. cordifolia inhibited Fenton (FeSO4) reaction and radiation mediated 2-deoxyribose degradation in a dose dependent fashion with an IC50 value of 700 microg/ml for both Fenton and radiation mediated 2-DR degradation. Similarly, it showed a moderate but dose dependent inhibition of chemically generated superoxide anion at 500 microg/ml concentration and above with an IC50 value of 2000 microg/ml. Aqueous extract inhibited the formation of Fe2+-bipiridyl complex and formation of comet tail by chelating Fe2+ ions in a dose dependent manner with an IC50 value of 150 microg/ml for Fe2+-bipirydyl formation and maximally 200 microg/ml for comet tail formation, respectively. The extract inhibited ferrous sulphate mediated lipid peroxidation in a dose-dependent manner with an IC50 value of 1300 microg/ml and maximally (70%) at 2000 microg/ml. The results reveal that the direct and indirect antioxidant actions of T. cordifolia probably act in corroboration to manifest the overall radioprotective effects.

Plasma Paraquat Concentration in Acute Paraquat Poisoning

BACKGROUND: Paraquat is a bipyridyl compound, and when ingested, concentrated paraquat can cause either rapid death from multisystem failure and cardiovascular shock or delayed death from progressive pulmonary fibrosis. Paraquat is poorly absorbed by inhalation, but when ingested orally, severe illness can occur. Death usually occurs within 2 days if more than 50mg/kg of paraquat is ingested. The most important prognostic indicator is the quantity of paraquat absorbed, as shown by the plasma paraquat concentration. However, in Korea, there are few, if any, institutes that can measure the plasma paraquat concentration, and the prognostic indication depends mostly on the description given by the patients and their families about the amount of paraquat ingested, which is often underestimated or overestimated. For these reasons, we tried to compare the plasma paraquat concentrations with amount of paraquat described by patients or their families. METHODS: We reviewed the medical records of 59 patients with acute paraquat poisoning from February 1998 through February 1999. The paraquat concentrations in plasma were measured at Presbyterian Medical Center by using high performance liquid chromatography. RESULTS: There was a striking discrepancy between the plasma paraquat concentration and the ingested amount described by the patients or their families. CONCLUSION: We recommend that the plasma paraquat concentration be measured in patients being treated for acute paraquat poisoning.

Spectrophotometric determination of tannins in tea samples using alpha and alpha'-dipyridyl and tiron

Tannins are determined spectrophotometrically in Indian, Kenyan and Ceylon tea samples using direct and indirect methods In the direct method excess amount of Fe[III] is added to tea sample followed by alpha, alpha ['] -bipyridyl at pH 4.4 and the absorbance of Fe [II]- alpha, alpha ['] -bipyridyl complex is measured at 522 mm. In the indirect method an excess amount of Fe[III] is added to the sample followed by Tiron reagent and the absorbance of the formed Fe[III]-Tiron complex is measured at 620 nm

Lethal interaction between hydrogen peroxide and o-phenanthroline in Escherichia coli

The iron chelator o-phenanthroline enhances the lethal effect of H2O2 about four hundred times in Escherichia coli when both substances are added simultaneously to the culture mediu. If o-phenanthroline is added for increasing periods of time prior to the addition of H2O2, there is a shift from this lethal interaction to protection by the chelator about seven hundred times. It is known that the Fe2+ -o-phenanthroline(I) and Fe2+ -o-phenanthroline(II) complexes are formed quickly whereas the final and more stable Fe2+ -o-phenanthroline(III) complex is formed slowly, Moreover, the mono and bis complexes react with H2O2 to produce OH., whereas the tris complex is stable towards H2O2. Therefore, the lethal effect could be explained by the kinetics of reaction of o-phenanthroline with intracellular Fe2+, i.e., the mono and bis complexes are more reactive than intracellular Fe2+

Iron-regulated outer-membrane proteins of strains of avian septicemic Escherichia coli

1. Outer-membrane protein patterns of Escherichia coli recovered from the peritoneal cavities of infected guinea pigs and grown in medium M9 containing 2,2'-dipyridyl were studied by polyacrylamide gel electrophoresis (SDS-PAGE) to determine whether in vivo conditions of growth affected the expression of these bacterial surface proteins. 2. Eleven strains of septicemic E. coli studied in vitro under conditions of iron restriction expressed iron-regulated outer-membrane proteins, mainly the protein of approximately 74 kDa, whereas avirulent strains grown under similar conditions did not present the 74-kDa protein. 3. These results show the distribution of iron-regulated outer-membrane proteins among avian E. coli and suggest that the protein of approximately 74 kDa may be important for the virulence of these strains.

Cholesterol side-chain cleavage by immobilized cells of Rhodococcus equi DSM 89-133.

Side-chain cleavage of sterol and extracellular cholesterol oxidase activity were investigated using viable cells of R. equi DSM 89-133 immobilized in polyacrylamide gel. In batch culture, immobilized cells were active in side-chain cleavage of cholesterol for more than 30 days. Free or immobilized cells were incapable of side-chain cleavage in the absence of 2,2' dipyridyl; cholesterol oxidase was, however, produced in both the cases. Maximal activity of the immobilized cells was 60 to 70% of the free cells.

A case of erythema multiforme due to contact of paraquat(gramoxone) / 대한피부과학회지

Paraquat is the most important bipyridyl herbicide, acting as a norselective herbicide with somewhat unique properties. The major acute local cutaneous side effects reslt from the caustic properties of paraquat, which produce local ulceration of the epithelial surface. Blistering of the skin and cracking and even loss of the fingernails have been reported. Its systemic taxic ties also include pulmonary fibrosis, cardiac failure, renal failure, and hepatotoxicity. We report a case of erytlema multiforme with transient heat-toxicity due to percutanious absorption of paraquat. A 31-year-old farmer was admitted to our de artment because of target-like bullous erythema on both thighs and buttocks following accidenta contact with paraquat. The histopathologic findings show d spongiesis, exocytosis, intercellular dema in the epidermis, degeneration of dermo-epidermal junction and inflammatory cell infiltrations in the dermis especially papillary and perivascular area.