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

Zhang W, Tian G, Feng S, Wong JH, Zhao Y, Chen X, Wang H, Ng TB - Sci Rep (2015)

Bottom Line: Pickles are popular in China and exhibits health-promoting effects.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Agrobiotechnology and Department of Microbiology, China Agricultural University, Beijing 100193, China.

ABSTRACT
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.

No MeSH data available.


Changes of blood nitrite level in rats.(a) rats receiving NiR extracts; (b) rats receiving capsules containing the nitrite reductase. Arrows represent time point at which nitrite was administered. Results are presented as mean ± SD (n = 12).
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f4: Changes of blood nitrite level in rats.(a) rats receiving NiR extracts; (b) rats receiving capsules containing the nitrite reductase. Arrows represent time point at which nitrite was administered. Results are presented as mean ± SD (n = 12).

Mentions: Based on the ratio of conversion between the dosage for human and dosage for rats, the dose of NaNO2 lethal to rats was 420 mg/kg. NaNO2 was introduced by intragastric administration into rats at the dose of 7 mg/100 g body weight to raise the nitrite level. Blood nitrite level was determined after administration of different amounts of the NiR. The results are shown in Fig. 4a. It can be seen that there was a peak in the control rats which reached a maximum 25 minutes after intragastric administration of NaNO2. Then the peak gradually became smaller in size. In the experimental group that received B. edulis NiR, there was a shift in the peak which attained a maximum 45 minutes after intragastric administration. This shift and the smaller peak were most likely due to the elimination of nitrite by the NiR in B. edulis. As the dosage of NiR administered was elevated, the peak of blood nitrite level disappeared. Reduction of nitrite took place before 100 minutes even with the higher dose of NiR, which can be attributed to gastric degradation.


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

Zhang W, Tian G, Feng S, Wong JH, Zhao Y, Chen X, Wang H, Ng TB - Sci Rep (2015)

Changes of blood nitrite level in rats.(a) rats receiving NiR extracts; (b) rats receiving capsules containing the nitrite reductase. Arrows represent time point at which nitrite was administered. Results are presented as mean ± SD (n = 12).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4597360&req=5

f4: Changes of blood nitrite level in rats.(a) rats receiving NiR extracts; (b) rats receiving capsules containing the nitrite reductase. Arrows represent time point at which nitrite was administered. Results are presented as mean ± SD (n = 12).
Mentions: Based on the ratio of conversion between the dosage for human and dosage for rats, the dose of NaNO2 lethal to rats was 420 mg/kg. NaNO2 was introduced by intragastric administration into rats at the dose of 7 mg/100 g body weight to raise the nitrite level. Blood nitrite level was determined after administration of different amounts of the NiR. The results are shown in Fig. 4a. It can be seen that there was a peak in the control rats which reached a maximum 25 minutes after intragastric administration of NaNO2. Then the peak gradually became smaller in size. In the experimental group that received B. edulis NiR, there was a shift in the peak which attained a maximum 45 minutes after intragastric administration. This shift and the smaller peak were most likely due to the elimination of nitrite by the NiR in B. edulis. As the dosage of NiR administered was elevated, the peak of blood nitrite level disappeared. Reduction of nitrite took place before 100 minutes even with the higher dose of NiR, which can be attributed to gastric degradation.

Bottom Line: Pickles are popular in China and exhibits health-promoting effects.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Agrobiotechnology and Department of Microbiology, China Agricultural University, Beijing 100193, China.

ABSTRACT
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.

No MeSH data available.