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How to slow down or prevent tranexamic acid color change (yellow/brown)?
I have two tranexamic acid(TA) serums (3% TA), one from Paula’s Choice and the other from Regimen Lab. They have both yellowed/browned. I have read on this forum that TA oxidizes easily because of its amine group and I think it is responsible for the color change in both products.
I want to make my own TA serum, so is there a way to avoid this? (Like by adding antioxidants or chelators such as EDTA/Lactobionic Acid? Does ph impact stability of TA?)
Any advice about formulating with tranexamic acid would be much appreciated! Thank you
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5 Replies
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In terms of formulation, I suggest using EDTA to chelate with heavy metal ions and inorganic sulfite salts for anti-oxidation. You should not use phenolic compounds for preservation because tranexamic acid will be oxidized faster (phenolic compounds are oxidized to quinone, quinone will damage tranexamic acid by Schiff base reaction). I did an experiment with my own comparison of preservative agents, using HPLC for quantification of tranexamic acid, and got the that results. Sealed vial caps and refrigerated storage also limit oxidation of tranexamic acid. My last word is, you cannot completely prevent the color change of tranexamic acid serum.
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Can Phenoxyethanol be a good choice??
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The pH does not play much of a role because at the usual pH of cosmetic products of 5-6, the amino group of tranexamic has been protonated almost completely, making it more difficult to participate in the redox reaction.
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Oxidation of a phenolic antioxidant to a quinone requires very specific conditions, like a strong oxidizing agent and a very low or very high pH, both conditions being not so common in cosmetics. Also, that the compound is solubilized in water (phenolics can have different solubilities, but the aromatic ring of course doesn’t help).
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Yepp, thank you for your reply. Actually, the mechanism I propose is because I deduced from my university chemistry knowledge, it may not be correct, but surely tranexamic acid is incompatible with phenolic preservatives, because I have experimented.
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