Friday, February 7, 2014

Can polyphenols found in oils penetrate our skin?

Polyphenols are found in our oils in three major ways - flavonoids, lignans, and tannins. They are the structural backbone for most anti-oxidants found in plants. Flavonoids behave as anti-oxidants on our skin and in our bodies by scavenging the free radicals produced at our cell membranes. It is thought (meaning there aren't enough studies or nothing conclusive) the flavonoids offer anti-inflammatory benefits by inhibiting pro-inflammation mediators in our bodies, such as prostaglandins. Some flavonoids have anti-biotic, anti-fungal, and anti-reddening qualities.

Related posts:
Polyphenols: An overview
Polyphenols: A closer look

Synopsis of a study from the International Journal of Cosmetic Science. Oct2013, Vol. 35 Issue 5, p491-501. 11p.

Objective: Polyphenols are natural antioxidants, which can inhibit oxidative chain reactions in human skin and prevent therefore some skin diseases and premature ageing. A prerequisite of this behaviour is their permeation through the skin barrier, in particular the stratum corneum (SC). In this study, we investigated the skin permeation kinetic of polyphenols, incorporated to semisolid emulsions, and the release of polyphenols from the emulsions.

Methods: Mixtures of model substances, consisting of catechin, epigallocatechin gallate (EGCG), resveratrol, quercetin, rutin and protocatechuic acid (PCA), were formulated into o/w emulsions with different oil phase content. The in vitro experiments were carried out in Franz-type diffusion cells by means of ex vivo pig skin and a cellulose membrane.

Results: The increased oil content in the emulsion led to a significant decrease in initial release coefficients (Kr), diffusion coefficients within the formulation (Dv) and skin permeation coefficients (Kp), respectively. The study considered the dependence of Kr on molecular weight and lipophilicity of polyphenolics. For both more hydrophilic and more lipophilic substance groups, the values for Kr were inverse proportional to molecular weight. For catechin, quercetin, rutin, resveratrol and PCA, a good correlation between Kp and Kr parameters was obtained. The most permeable substance was PCA (Kp = 1.2·10−3 cm h−1), and the least permeable was quercetin (Kp = 1.5·10−5 cm h−1).

Conclusion: All substances could pass the SC barrier and were found mostly in the epidermis and dermis, confirming the potential of polyphenols as anti-ageing active cosmetic ingredients.

From another study (Citation: Skin Pharmacology & Physiology. Nov2009, Vol. 22 Issue 6, p299-304. 6p) the conclusion was that "it can be concluded that EGCG and quercetin from green tea and G. biloba extracts vehiculated in cosmetic formulations presented good skin penetration and retention, which can favor their skin effects". In other words, ECGC and quercetin penetrate the skin.

Wow! In other words, polyphenols like catechin, EGCG, resveratrol, quercetin, rutin, and PCA in lotions permeated our skin! Once in, they can behave as anti-oxidants that scavenge free radicals!

So it's safe to say that the polyphenols we find in our oils can penetrate our skin and work from the inside as anti-oxidants.

Join me tomorrow as we review what we've learned this week and what it all means!


Unknown said...

Good morning Susan,
Well, you done did it!! I have a new habit!!! Your email is the first one I read in the morning and boy, do I ever appreciate them!!! So much learning to do and so easy when you teach. Thank you for this last series,I am learning a lot!!!

Anonymous said...

Hi Susan -

Wow. Totally enjoyed this series and am looking forward to the review! (Much more enlightened reading than the Irish Times!)

Any thoughts on essential oils as skin penetration enhancers? I've been doing some research and found a study which suggests that eucalyptus and chenopodium caused a 30-fold increase in drug permeability coefficient, and ylang ylang was mildly effective with an 8-fold increase. (International Journal of Pharmaceuticals, 1989, vol. 57, issue 2, pages R7-R9) I wondered about the efficacy with oils…

Interestingly, I also found research that avocado oil actually penetrates the skin more deeply than many other plant oils including olive and almond oils. (Valette, G & E Sobrin, Pharm Acta. Helv. 38910:710-6 (1963) This study is a bit dated… by 50+ years so I'm on the hunt for some other research. The text 'Carrier oil for aromatherapy and massage' L Price (4th Ed) not the oil 'has a reputation for having a higher degree of penetration into the epidermis than most carrier oils'… I'm not sure if this has it's roots in folk wisdom? Which I'm not quick to dismiss!


Susan Barclay-Nichols said...

Hi Christine. Thanks for your kind words. It's nice to know that someone out there loves this stuff as much as I do!

Hi Rene! I remember seeing something about essential oils and penetration enhancement and writing about it, but I can't find that post at this time. If you find more, please send it along as it's quite interesting reading! (I'm putting it on my list of things to research as well!) I think you might have a typo after you quote the 4th ed book as it says "not the oil...." Which oil was studied?