L-Arginine and Taurine interactions

Dear colleagues, my current project includes two compounds – L-Arginine and Taurine. Are those two amino acids going to interact in the water solution? Since Taurine is zwitterion, what should I expect in the presence of Arginine? Do these compounds form salts or any other complexes? Please, advise. I would be grateful for any suggestions.  


Comments

  • PharmaPharma Member, Pharmacist
    Arginine is a strong base and an amino acid = zwitterionic (technically speaking, taurine is an amino acid too... at least an amino acid metabolite)
    -> You are likely preferring to add an acid to adjust pH
    -> No issues between the two, neither un-pH-adjusted nor pH-adjusted
  • vitalysvitalys Member
    @Pharma , Thank you for your explanation. Yes, Taurine is considered as an amino acid. So, they can exist together in a product intact, aren't they? What is going to happen with zwitterion of Taurine then? Both compounds have different pKa. 
    I just have made a water solution of these amino acids in equimolar ratio. The solution had remained clear and colorless in the beginning but after two hours it became yellow. What could cause this yellowing? 
  • PharmaPharma Member, Pharmacist
    Which form of arginine did you use? If free base... I guess the high pH did lead to degradation (of either or both) and partial deprotonation of the ammonium part of taurine. Taurine is fairly stable and remains zwitterionic under more 'normal' conditions. Also, arginine salts are quite stable in water. Dunno how stable arginine free base is, though.
  • vitalysvitalys Member
    @Pharma, I really appreciate your swift response. Yes, the thing is I use the base. That is why I have assumed the possible interaction with Taurine. Yes, I agree, the arginine salts are stable as well as a free base solutions and I like some of them in different formulations. So it turns out now that I need to try some neutralized form of Arginine ( with lactic acid, for instance) to make the mix with Taurine stable in one solution and further in the formulation. This product is going to be used for the very special diabetic foot care (not a treatment) and my customer(a podiatric clinic) would like to explore the benefits of those two amino acids along with other actives in a form of a cream.
    Again, thank you for you valuable help, @Pharma It is always a pleasure to read your posts. :smile:
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