Alpha-Arbutin and dark spots

ngarayeva001

Member

May 20, 2019 at 8:41 pm

Doesn’t do much

First: I don’t speak from experience regarding arbutin in cosmetics but from experience as a pharmacist with a PhD in pharmacognosy/phytochemistry: keep in mind that some things are true for both, others are quite different between scientific lab-work and real life

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Arbutin will hydrolyse under acidic conditions to form glucose and the more reactive hydroquinone especially at elevated temperatures. Arbutin and even more so hydroquinone are susceptible to oxidation (benzoquinone is formed) already under slightly alkaline conditions and/or UV irradiation which cause their degradation sometimes within minutes to form a dark coloured polymeric substance. This effect is pronounced when nucleophilic substances such as thiols (e.g. cysteine) and to a lesser extent primary amines (rare in cosmetics) and even certain alcohols (abundant in cosmetics) are present.

A slightly acidic environment (pH about 5-6) and room temperature keeps the hydroquinone moiety safe from degradation and isn’t too acidic to cause arbutin hydrolysis but acidic enough to prevent chemical reactions with other ingredients.

A problem with hydroquinone can be that it may start an autocatalytic oxidation of itself and of ascorbic acid if the latter is present at active concentrations (>1%) rather than just as antioxidant for “preservation” (~0.1-0.2%). Mind, arbutin & high ascorbic acid is a common skin bleaching combination. The phenomenon of hydroquinone and ascorbic acid degradation isn’t always predictable but can cause dark colours either homogeneously throughout the product or as spotty/patchy appearance due to the vicious cycle randomly starting in just a few places where by bad luck the reaction is kicked off. This reaction is again pronounced under high temperature, high alkalinity and UV-irradiation and “gets exponential” when (pro-)oxidants such as benzoyl peroxide or heavy metal ions for example from iron oxides are present. Notably, this degradation requires oxygen! EDTA and other strong metal chelates can help dealing with trace amounts of iron and vacuum-mixing and a non-transparent, airless pump dispenser should be of great advantage too. But sadly, the developing colour is visible at really low amounts and completely avoiding oxygen is nearly impossible. Avoiding susceptible ingredient combinations would be the better way to go.

Besides: A proper ingredient listing of your spotty product might shed more light on your issue

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F*** errr… EDIT: Today isn’t my best day ;( . I just realised that I misunderstood your question and wrote the whole thing in vain

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Here’s the useful part: Experience in the pharmacy with dark spots says that arbutin alone doesn’t suffice. Combinations of hydroquinone with other things might but therein it’s unpredictable to know which ingredient does what and to which extent. Besides, hydroquinone is skin permeable and “bleaches” whereas arbutin is said to inhibit melatonin formation and is very unlikely to reach high enough concentrations in the deeper areas of the skin where true pigment spots are produced.

Dtdang

Member

May 21, 2019 at 11:33 am

@Pharma, thanks for Comment

ngarayeva001

Member

May 21, 2019 at 12:58 pm

@Pharma, thank you very much! It’s very useful comment. I knew that aplha arbutin should be formulated within neutral pH, but I didn’t know how important it is. I also didn’t know about metals (I always add EDTA just in case but here it’s justified).

I am speaking as someone who used and wasn’t impressed with the result. Probably anecdotal evidence but it seems to me that it prevents skin from getting darker after sun exposure, but it doesn’t lighten what’s already there. I guess it might be true provided it’s mechanism of work.

Dtdang

Member

May 22, 2019 at 2:15 pm

@ngarayeva001 and @Pharma, I just found the information said that ethyl ascorbic acid and alpha-arbutin are good for dark spots. Do you ever experience on them?

ngarayeva001

Member

May 22, 2019 at 4:08 pm

I don’t have experience with ethyl ascorbic acid because it’s impossible to find it on the DIY market (please let me know if I am wrong). If you can find it, make sure it shouldn’t be formulated within low pH (see Pharma’s explanation on the Ph above). LAA serums should be formulated at a low pH to be active.

Pharma

Member

May 22, 2019 at 9:01 pm

Lipophilic ascorbic acid derivatives such as ascorbyl palmitate, tetrahexyldecyl ascorbate and also ethyl ascorbic acid penetrate skin better/deeper than pure ascorbic acid. In addition, the latter two are without charge and are “inactive”, they require activation by cellular enzymes to become active vitamin c and are therefore said to be superior for above application. I have zero experience with ethyl ascorbic acid and only a scientific one regarding ascorbyl palmitate (I love that stuff!). Theoretically, ethyl ascorbic acid should not interfere with anything in a cosmetic preparation, is the smallest molecule of all the “prodrug” derivatives and hence, in theory, the best of ’em all .

ngarayeva001

Member

May 22, 2019 at 9:11 pm

Oh it’s lipophilic! I didn’t know that. Very interesting ingredient. I wish I could buy it. Have some experience with tetrahexyldecyl ascorbate. I am not too impressed to be honest.

Dtdang

Member

May 22, 2019 at 10:39 pm

@Pharma, Thank you so much.
Would you please explain more details about cellular enzymes?
I hope that alpha-arbutin + ethyl ascorbic acid can help dark spots

Thanks again

Dtdang

Member

May 22, 2019 at 10:49 pm

@pharma, ngarayeva001
My hope is that:
Alpha arbutin & Ethyl ascorbic acid give dual approach by soothing skin to quell the inflammatory mediators that lead to upregulation of tyrosinase,
while also acting as a tyrosinase inhibitor to reduce melanin production.

Dtdang

Member

May 22, 2019 at 10:55 pm

@pharma, ngarayeva001
Another ingredient called retinol. It has superior benefits of anti-aging.
Is there any chemical reaction between retinol + ethyl ascorbic acid + alpha-arbutin?

Thanks in advance

Pharma

Member

May 23, 2019 at 8:02 pm

@Dtdang Ascorbic acid is not just an antioxidant (a reducing agent) but also a so called conjugated acid. The hydroxy group(-s) responsible for both actions can either be esterified with ethanol or with a carboxylic acids forming a fairly stable acid anhydride. This feature is quite exceptional but way off the point

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Anyway: Such a modified ascorbic acid is no longer acidic nor an antioxidant, it’s “dormant” and doesn’t degrade or react before reaching the interior of a cell. Once inside a cell (the modification makes it lipophilic, oil-soluble and hence cell permeable) it meets different enzymes, mostly lipases, which cleave off the protecting group liberating active ascorbic acid which becomes trapped within the cell where it can work its magic.

Retinol profits from the antioxidants which render it more stable. Else, there shouldn’t be any negative interactions.

Dtdang

Member

May 23, 2019 at 9:11 pm

@Pharma, thank you so much. I understand it now.

ngarayeva001

Member

May 24, 2019 at 12:52 pm

There is one thing to consider. Retinol is a skin sensitiser. As well as LAA in high concentrations. I wouldn’t recommend to have them in the same routine unless you are working with deriatives as mentioned above.
I saw formulas with encapsulated retinol and tetrahexyldecyl ascorbate.

Dtdang

Member

May 24, 2019 at 1:09 pm

@ngarayeva001 what does LAA mean? I don’t understand it. Would you explain.

ngarayeva001

Member

May 24, 2019 at 5:19 pm

L-Ascorbic Acid. All derivatives get converted into LAA in the skin.

Dtdang

Member

May 24, 2019 at 6:21 pm

Thanks

Dtdang

Member

May 24, 2019 at 6:21 pm

@ngarayeva001 thanks

Dtdang

Member

May 30, 2019 at 1:07 am

@Pharma, I have question: the modified ascorbic acid such as ethyl ascorbic acidenter the cell. After enzyme, ascorbic acid is off to protect the cell. Where does ethyl go?
thank you in advance.

Pharma

Member

May 30, 2019 at 7:39 am

@Dtdang That’s ethanol, your cell gets drunk :smiley: . Naw, likely not drunk because that small quantity of ethanol gets fully metabolised.

ngarayeva001

Member

May 30, 2019 at 10:16 am

@Pharma, now I will be imagining drunk cells all day long :smiley:
I want to thank you for your comments. It’s great to have someone who knows the science behind processes and is willing to share this knowledge with others (your previos comments on effect of the pH on alpha arbutin was very useful).

Dtdang

Member

May 30, 2019 at 2:21 pm

@Pharma, @ngarayeva001 thank you so much.
I will have the results: alpha-arbutin vs. alpha-arbutin + ethyl ascorbic acid soon. I will let you know.

@Pharma, I have a lot of basic questions. Would you please help me? You have great knowledge and sharing. I again appreciate you a lot.
our skin doesn’t absorb water? Only oils with small molecular weight can be absorbed through our skin? Because Most active ingredients are water soluble, therefore we need to choose oils(easy absorbed) and emulsifiers with small molecular weight => cream is easy to absorb to our skin?

ngarayeva001

Member

May 31, 2019 at 10:35 am

I don’t think you want emulsifier to penetrate your skin. Read about the 500 dalton rule and research propylene glycol and dimethyl isosorbide. Both are penetration enhancers. Having said that, I would be very careful, as the barrier function of our skin exists for a reason.

Dtdang

Member

May 31, 2019 at 11:58 am

@ngarayeva001, thanks
can you explain the penetrating processes of cream to skin?

Dtdang

Member

May 31, 2019 at 3:44 pm

@ngarayeva001, questions:
so what happens when cream was applied to the skin?
The emulsifiers combine the water and oils . The water and oils may contain the active ingredients. I read 500 dalton rules.
Thanks