Why is this niacinamide serum turning brown?

Formulating

Why is this niacinamide serum turning brown?

Posted by DeedeeUkulele on October 1, 2022 at 3:23 am

Is one of the actives oxidizing? I can’t seem to find anything on Google regarding niacinamide/tranexamic acid/NAG turning brown. This sample was made in August.

Actives:
5% niacinamide
5% tranexamic acid
2% n-acetyl glucosamine
0.5% allantoin

Water, Propanediol, Aristoflex AVC, Optiphen Plus, EDTA

pH 6.0-6.5

Bill_Toge replied 2 years, 1 month ago 5 Members · 10 Replies
10 Replies

Abdullah

Member
October 1, 2022 at 11:02 am

Are those dots mold?
DeedeeUkulele

Member
October 1, 2022 at 11:22 am

Abdullah said:

Are those dots mold?

No, it’s just the dots on the paper underneath.
DRBOB@VERDIENT.BIZ

Member
October 1, 2022 at 3:52 pm

This looks like Mallard reaction taking place over time between free glucose in AG and amine group in Tranexamic acid .Try a knockout to confirm.
DeedeeUkulele

Member
October 2, 2022 at 1:34 am

DRBOB@VERDIENT.BIZ said:

This looks like Mallard reaction taking place over time between free glucose in AG and amine group in Tranexamic acid .Try a knockout to confirm.

Oh, that’s very interesting. Okay, will try a knockout and get back here with an update. Thank you!

Btw, this link (https://pubmed.ncbi.nlm.nih.gov/26114422/) states that glucosamine degrades at 37°C. Assuming it really is Maillard reaction, does that mean the NAG in the serum is all but useless in the presence of tranexamic acid?
DRBOB@VERDIENT.BIZ

Member
October 3, 2022 at 2:40 pm

not sure -just made changes substituting for functional equivalency when needed.
Bill_Toge

Member
October 3, 2022 at 8:47 pm

like many amines, tranexamic acid oxidises and turns yellow/brown over time
PhilGeis

Member
October 3, 2022 at 9:23 pm

@DeedeeUkulele
Please note Glucosamine instability @37C in the cited article appears to be in context of come concentration of ammonia and phosphate buffered to an (in abstract) pH. Can’t access the paper itself - any idea what these other specifcs were?
DeedeeUkulele

Member
October 4, 2022 at 1:29 am

Bill_Toge said:

like many amines, tranexamic acid oxidises and turns yellow/brown over time

Thank you, I wasn’t aware of that. I didn’t think it was the tranexamic acid because I didn’t find any data on it specifically turning brown.
DeedeeUkulele

Member
October 4, 2022 at 1:32 am

PhilGeis said:

@DeedeeUkulele
Please note Glucosamine instability @37C in the cited article appears to be in context of come concentration of ammonia and phosphate buffered to an (in abstract) pH. Can’t access the paper itself - any idea what these other specifcs were?

Thanks for pointing that out. Admittedly, I was just quickly looking for data to confirm that NAG oxidizes under certain conditions. Unfortunately, I don’t have access to the paper myself.
Bill_Toge

Member
October 5, 2022 at 8:20 pm

DeedeeUkulele said:

Bill_Toge said:

like many amines, tranexamic acid oxidises and turns yellow/brown over time

Thank you, I wasn’t aware of that. I didn’t think it was the tranexamic acid because I didn’t find any data on it specifically turning brown.

it’s a very common phenomenon with amine-containing organic compounds dissolved in water

for instance, at my last place we had an old sample of 90% monoethanolamine that had turned dark orange due to oxidation; when I ordered a fresh sample, it was completely colourless and had a much sharper odour