Disease relevance of Menadiol

• We have studied the effects of site-directed mutations in Escherichia coli nitrate reductase A (NarGHI) on heme reduction by a menaquinol analogue (menadiol) using the stopped-flow method [1].
• AIM: To evaluate the efficacy of oral menadiol compared to intravenous phytomenadione when correcting coagulopathies associated with cholestasis [2].
• With reduced menadione as the electron donor, an enzymatic activity of 101 nmol of NO per min per mg of protein was obtained with membrane fractions of Synechocystis wild-type cells [3].
• CONCLUSION: Oral menadiol appears to be an effective alternative to intravenous phytomenadione in the correction of coagulopathies associated with obstructive liver disease [2].
• By itself, menadiol was moderately toxic to HLN, but not to normal lymphocytes or non-small cell lung cancer [4].

High impact information on Menadiol

• Extracellular superoxide was generated due to reduced menadione diffusing across the plasma membrane and reacting with oxygen to generate superoxide in the medium [5].
• About 40% of the hemes are reduced by menadiol, but no reduction is observed upon treatment with H2 and hydrogenase, irrespective of the presence of cytochrome c3 [6].
• Phytomenadione or menadiol in the management of an elevated international normalized ratio (prothrombin time) [2].
• Whereas reduced cytochrome c was ineffective as electron donor, NO was reduced at a specific activity of 2.3 micromol/min per mg of protein in the presence of 2-methyl-1,4-naphthoquinol [7].
• Pre-treatment of cells with fura-2 acetoxymethyl ester, a Ca2+ chelator, reduced menadione-induced cell degeneration and lipid peroxidation but it did not block cellular glutathione depletion [8].

Chemical compound and disease context of Menadiol

• Since menadione is reduced by the two-electron reduction pathway to menadiol, the induction of this enzyme is likely to be an adaptive response of E. coli to partially alleviate the toxicity of menadione [9].

Biological context of Menadiol

• Semiquantitative histochemistry with minimal incubation revealed more favorable kinetics for the menadiol diphosphate method, especially when using NBT [10].
• Cell survival times with mechlorethamine, vincristine, and dexamethasone were converted from a range characteristic of drug resistance (ie, range observed in relapsed patients) to a range characteristic of drug sensitivity (ie, range observed in untreated patients) in the presence of menadiol [4].

Anatomical context of Menadiol

• Antioxidant activity of reduced menadione in solvent solution and in model membranes [11].
• Menadiol increased the cytotoxic effects of a number of standard agents in HLN but not in normal lymphocytes [4].

Associations of Menadiol with other chemical compounds

• These results show that menadione exerts an antioxidant effect through participation of microsomal DT-diaphorase by generating menadiol with a radical scavenging ability, while menadiol also has a prooxidant property [12].
• The antioxidant activity of reduced menadione was investigated and compared with that of alpha-tocopherol both in solvent solution and in large unilamellar vesicles by using azocompounds as free radical generators [11].
• An in vitro quinol dehydrogenase assay was developed to show that both NapG and NapH are essential for rapid electron transfer from menadiol to the terminal NapAB complex [13].

Analytical, diagnostic and therapeutic context of Menadiol

• The synthesis and purification of menadiol diphosphate are described, and it was shown to be sufficiently stable for qualitative and semiquantitative histochemistry, as well as for the immunohistochemistry of enzymes and cytoskeletal proteins with nonspecific alkaline phosphatase as the enzyme label [10].

References