Green tea contains up to 30% polyphenolic compounds (of the dry weight) in the form of proanthocyanidins, tannins, catechins, and so on. Let's take a look at the hydrolyzable tannins - also known as proanthocyanidins (polymer chains of flavonoids) - and the subgroup called procyanidins.
A quick reminder about flavonoids: 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.
Proanthocyanidins are colourless molecules also called oligoflavonoids, condensed polyphenols, or hydrolyzable tannins. They called the latter because they can be hydrolyzed (the molecule is split by water into different compounds) in an acidic environment to produce anthocyanidins, which are coloured.
They play a role in the stabilization of collagen and maintenance of elastin in the skin. They are being studied as water retention reducers, and capillary protectors. They can help the body to produce histamine to prevent allergic reactions. And they are powerful anti-oxidants - they are about 20 times more powerful than Vitamin C and 50 times more powerful than Vitamin E.
Procyanidins are part of the proanthocyanidins group, and occur as esters of gallic acid in green and black tea and grapes. They are quite unstable, reacting chemically in acid or base solutions, reacting thermally, and oxidizing easily. They are considered to have anti-viral, anti-microbial, and anti-HIV properties, as well as anti-oxidizing through free radical scavenging.
So what does this all mean for us as formulators? Green tea's polyphenols are awesome! (I've used that word too many times today!) They offer lots of great anti-oxidants. They may help with inflammation and water retention. They provide increased wound and burn healing, as well as the maintenance of collagen and elastin in our skin.
We need to add green tea to our cool down phase so we don't mess with the thermal stability of the procyanidins, whether we're using a liquid or powdered extract. You also don't want to put green tea extract in something incredibly acidic (something with a ton of AHAs or other acids) or something incredibly basic (a solution made of lye...which would be an insane product!).
It seems obvious this is an ingredient we want in our lotions and other creations, but it could be beneficial for things like foot care products with all the anti-fungal and anti-bacterial qualities. We can use it in a powdered form for a foundation or finishing powder to offer anti-inflammatory and anti-reddening products. Or put it in a toner for those same qualities (as well as the astringency, which we'll see tomorrow).
Join me tomorrow for more fun with green tea extract!