Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

[Effect of sodium nitrite poisoning on the activity of enzymes of anti-oxidant protection and peroxidation processes in mouse erythrocytes]. / Vliianie intoksikatsii nitritom natriia na aktivnost' fermentov antioksidantnoi zashchity i protsessy peroksidatsii v éritrotsitakh myshi.

The intoxication of white mice with sodium nitrite results in the decrease of red cell superoxide dismutase (SOD) and catalase activity. The glutathione peroxidase activity is the same as in the control group. The level of red cell lipid peroxidation in the group of mice that receive sodium nitrite is higher as compared to the control group. After the intoxication the total activity of glucose-6-phosphate dehydrogenase and dehydrogenase of 6-phosphogluconate as well as the activity of glutathione reductase are higher than in the control group. The level of SH-groups and reduced glutathione is higher in the group of mice that receive sodium nitrite in comparison with the control group.

[Examination of dynamic changes of certain biochemical parameters in blood of rats poisoned with sodium nitrite]. / Badanie dynamiki zmian niektórych parametrów biochemicznych we krwi szczurów zatruwanych azotynem sodu.

In Wistar rats poisoned by daily addition of sodium nitrite to drinking water (1 g/dm3), determination was made of the dynamics of changes in: blood methemoglobin and 2,3-diphosphoglyceric acid levels, contents of protein and non-protein thiol groups in erythrocytes, blood glucose-6-phosphate dehydrogenase and peroxide dismutase activities, as well as plasma vitamin E and hydroxyproline levels, Determinations were performed after 15, 30, 45, 60, 75 and 90 days of poisoning. There occurred a linear relationship between the drop in glucose-6-phosphatase dehydrogenase activity and in vitamin E level, on one hand, and the duration of poisoning with sodium nitrite. Moreover, a significant rise of 2,3-diphosphoglyceric acid level in erythrocytes and a decrease in the non-protein thiol groups took place. Rhe results indicated that the determinations--in blood--of: methemoglobin, glucose-6-phosphate dehydrogenase activity in erythrocytes, and vitamin E in plasma or serum, could be included among the diagnostic tests performed (at the laboratories attached to industrial plants or making part of the industrial health service) for evaluation of the health hazard in the nitro-compound industry or in other nitrite contaminated working places.