Battle of Glycerol and Sorbitol. Which is the all-rounder?

This is a very interesting article. It is what it is. No B.S. No scaremongering.

What caught my attention is Sorbitol is invoked. Oh I love Sorbitol simply because most people gravitate towards Glycerol. Bwahahaha!

The way @Perry described, Sorbitol is my ideal sort of humectant. Not tacky/sticky, more hygroscopic than Glycerol. However, I remember that I read an article of Swiftcraftmonkey (Susan), she says Glycerol is not washed away due to some aquaporin thing. I have been wondering how come Glycerin is seemingly the only thing that gets absorbed that efficiently, it is not even cationic. I could not retrieve the article because she had made her entire site a paid one.

I then consulted the Internet University (including Google Scholar), but to no avail. This 'aquaporin' is too general as it exists all over our body. I could not find the effect of putting Glycerol specifically on skin and how it actually works.

Can Sorbitol penetrate aquaporin and be resorbed like Glycerol?
Sorbitol is twice the size of Glycerol. Does molecular weight matter in this instance?

Is that aquaporin very important?
I always thought that as long as the skin is kept moist with whatever (e.g., Petroleum Jelly) then healing naturally takes place as enzymes require some level of moisture to work. But then Glycerol comes in with the claim of speeding up healing, lipid regeneration, and all-that-you-know, all due to aquaporin-Glycerol relationship.
Can Sorbitol also do what Glycerol does minus the stickiness and extreme gloss?

Sorbitol is very inexpensive, at least for me. My heart is not hurt even when I indiscriminately replace Glycerol with Sorbitol.

Comments

  • PharmaPharma Member, Pharmacist
    edited November 13
    ... I have been wondering how come Glycerin is seemingly the only thing that gets absorbed that efficiently, it is not even cationic...

    ...Can Sorbitol penetrate aquaporin and be resorbed like Glycerol?
    Sorbitol is twice the size of Glycerol. Does molecular weight matter in this instance?...

    Is that aquaporin very important?...
    Cationic only gives compounds a 'gluey' characteristic, being without charge makes them more fat-soluble and hence better for assimilation/penetration.

    Yes, it can. And yes, size matters. There are many types of aquaporins. I don't know the molecular cut-off of these but since they are there to transport much more than just water between/into/out of cells, such as sugars, urea and even mineral ions, it's highly likely that sorbitol will be transported as well. Sure, there is an aquaporin family extra for glycerol and hence, glycerol might be favoured over sorbitol which has to use 'sugar' aquaporins (glycerol can use these too).
    I don't know how important they are in cosmetics... they're hyped, that much I can say :D !
    THAT might help.
  • Cst4Ms4Tmps4Cst4Ms4Tmps4 Member
    edited November 14
    @Pharma

    Thanks for confirming my confirmation bias.  XD

    Cationic's gluey characteristic due to the fact that the skin/hair slightly negatively charged, I presume.

    Ah. Nonpolar. This is another thing that amazes me. The skin seems to have affinity for nonpolar substances. Weird no charge and still has very high affinity with skin! I do not get it! Makes no sense.

    At first I thought must be sebum. But not possible because sebum is constantly 'pushing' things out. (I got this idea from HERE) I am talking on my behalf as I have oily/combination skin. Skin on the dry/drier side can be 'sucking' in things, advertisements call it 'thirsty'.  :D

    I suddenly remembered phospholipid bilayer. The skin is semi-permeable and it is selective to what goes in and out. The skin tends to have the hydrophobic tail sticking outside, and the hydrophilic head is inside cells keeping in water/moisture. So, this suddenly makes sense to me that the skin (at last the outer most part that I read about; stratum corneum) is hydrophobic. If hydrophilic we would swell big time and probably rot every time we shower.

    That makes sense until....I deliberately confuse myself. I found THIS. Hydrophilic head is on the outside! Not possible for lipids to love skin so much! My guess because is cell membrane, already within the body, not exposed to air like the skin, exposed to different kinds of insults and therefore evolved having different morphology.

    Come along glycoprotein and glycolipid might be the receptors for sugars and glycerol that you mentioned. I guess these 'open' up the channels and allow lipids to enter.

    Somehow that doesn't answer why skin/hair-lipid relationship takes precedence over skin/hair-water/moisture relationship.
    My mere mortal educated guess is based on evolution and biology. The answer is that's why we accumulate fat much easier than muscle. Yup, answered but still left unanswered as to why and how skin/hair and lipids are soulmates. LOL!

    And then I found some more images and facts (or theory). They show/say that surrounding skin cells is lipids a.k.a mortar.

    I do not know which one is the most accurate! All might be theories but I bet there is at least one that arrived scientific consensus. As my coolest and big balls (not many physicists dare to call a spade a spade and bother banishing pseudoscience and educating the public gratis) physics professor Donald Simanek once said:

    Theory in science is a word reserved for unifying laws and principles that have universal scope and are well tested and trusted.  Unfortunately the media often uses the word colloquially to label any speculative hypothesis, even those with flimsy foundations.

    Right now we have many competing speculations about all-embracing unifying principles, involving string theory, branes, multiple universes, black holes, white holes, wormholes in space, dark energy, dark matter, the MOND hypothesis, etc. etc. None of these deserve to be called anything more than elaborate speculative hypothesis. None of them have the universal acceptance to quality as established theories.

    I don't write about them for I take a "wait and see" attitude toward them. Maybe they will be resolved in 20 or 50 years. Some of them strain my credulity, but I readily admit that true physics does not have to be appealing, beautiful, intuitive or simple. It may well be ugly, messy and distasteful. Certainly physics does not have to conform to our naive common sense.

    Also, I think some of the folks who write popular books on these subjects are living on cloud 9, basking in the mathematics they consider "beautiful" and caring little for the nitty gritty task of experimental verification. They forget that mathematics is only a tool of science. We can easily invent mathematics that can marvelously describe worlds that simply do not exist. They need to "come down to earth". But that's only my opinion.

    Sorbitol's molecular weight is 182.17 g/mol should not be any more difficult to be taken in by the skin as it is within the 500 Dalton rule as far as skin is concerned.

    I feel Sorbitol is 'oily' very much like Propanediol and Propylene Glycol. I do not know the technicalities of it but looking at its structure it has 2 units of hydroxymethyl (CH2OH), and 4 units of I-dont-know-what-it-is, however it has 6 hydroxy groups.

    Probably it is the 2 hydroxymethyl groups that are responsible for the oily part. Glycerol also has 2 of that.
    Sorbitol and Glycerol are soluble in fat equally well, no one wins and no one loses. Yes?

    I read somewhere, long time ago, it says there is a limit to stickiness. Sorbitol has twice the amount of hydroxyl group than Glycerol, this makes Sorbitol less to no stickiness compared to Glycerol.
    Oddly, there will be a state when more hydroxy group the stickiness comes back.

    A Few -OH = Very sticky.

    More than a few -OH = Not very or not sticky.

    More than more than a few -OH = Very sticky.

    Bell curve came to my mind at that time.

    Truly weird how things can be. I cannot remember the reason (maybe there is no more explanation!), but I do know that it says nothing about the shielding effect (otherwise I won't seek ancient souls and be startled when you provoked that phrase before me. ROFL!).
  • @Pharma

    I forgot to add that the test did not test enough.

    They basically added back Glycerol after the tape stripping rather than adding other substances as comparison and see if that aquaglycerolporin also responds to others.

    That is probably the origin that makes Glycerol famous until this day and no body (the professionals and the experts) seems to test with other substances and get similar or same results.
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