Thanks for that ref. Aren't old papers great? They also pointed out that mono-, di-, and tri-methyl compounds are common impurities in MB. I don't know if that's still true today; I suppose we could try a little homebrew paper chromatography. Anyway, yeah, it looks like you want pH 4.5 or so; probably best to just have some excess ascorbic acid around in order to keep it soluble. Once it hits your stomach, you won't have to worry any more. Or maybe it's safer to just take the oxidized MB, at least that way you know it's getting in.There's another catch though. Leucomethylene blue is only soluble in acidic solutions (pH below 4.5ish?). So you may need to use ascorbic acid as opposed to ascorbate.This means that (according to them, anyway) if you want whatever improvement ascorbate can give you, you can't just swallow a vitamin C tablet at the same time you take the MB. You need to pre-incubate the two compounds in solution for several hours first. Considering the small doses that we're using, we could probably use a large excess of ascorbate to accelerate the reaction. To be honest, I'm kind of baffled that this should take any time at all; this sort of redox reaction is usually very fast. Also, I would think that if you see the color change, then it's done. Note that these guys are trying to get a patent on the use of leucomethylene blue as a therapeutic agent, so they are probably inclined to make it sound tricky in order to flummox the hapless patent examiner. If someone happens to have some MB and some ascorbate handy, mix a little together and let us know what happens.It is highly likely that variability in oral absorbtion is determined largely by the efficiency of initial reduction in the GI tract. One way to achieve more reliable absorbtion is therefore be to pre-reduce methylene blue with ascorbic acid. We have shown from in vitro studies that this conversion is rather slow, so that it takes 3 hours to achieve 90% reduction of methylene blue in water in the presence of 2× mg ratio of ascorbic acid. Therefore, the dosage of methylene blue which is most likely to ensure reliable absorbtion will be 3.5 mg/kg/day of methylene blue pre-reduced for at least 3 hours in the presence of 7 mg/kg/day of ascorbic acid.
I wonder if putting a thin layer of ascorbic acid at the bottom of the diluted methylene blue solution would keep the pH sufficiently low.
http://jcs.biologist...26/113.full.pdf
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