Zinc oxide, zinc gluconate, zinc PCA, zinc lactate... zinc in all its forms.

Thezinc oxide (ZnO) refers to a chemical ingredient that combines a zinc atom with an oxygen atom. It is obtained by oxidising metallic zinc vapour at high temperatures. The chemical reaction is written as follows.

2 Zn(solid) + O2 (gaseous) → 2 ZnO(solid)

This results, on one hand, in hexagonal and colourless crystals, or on the other hand, in loose white powder, following the refraction of light in the small crystals.

ZnO can also be obtained by incinerating zinc hydroxide, zinc nitrate, or zinc carbonate, according to the following reaction.

Zn (OH)2 (solid) → ZnO(solid) + H2O(liquid)

Zinc oxide is primarily a UV-protective filter. It is used in sunscreens, acting as a shield on the skin's surface. Indeed, it iseffective in blocking and deflecting UVA and UVB rays, thus protecting the skin from the harmful effects of the sun.

Beware, in some products, it may be of nanometric size. The health risks are as follows: psuspected percutaneous penetration, suspected reproductive toxicity, suspected genotoxicity, suspected carcinogenicity. Furthermore, regarding the environment, there is also suspected aquatic ecotoxicity. Despite this, this UV filter remains bio-compatible according to the COSMOS standard.

At Typology, we apply the precautionary principle and exclude nanoparticles from our formulations.

It should be noted, zinc oxide is also used as a pigment, you can find it on INCI lists under the name CI 77947.

Thezinc PCA is a zinc and PCA alloy (L-pyrrolidone carboxylic acid), used as amoisturising active ingredient. It is obtained by the reaction of pyrrolidone-carboxylic acid (PCA), specifically through the thermal cyclisation of glutamic acid (a plant-based amino acid, derived from beet molasses) with zinc oxide. Zinc PCA is known to be non-sensitising and gentle, thus making it suitable for sensitive skin. The PCA also plays a role inimproving the skin's absorption of zinc while promoting its hydration.

Zinc PCA possessesanti-inflammatory, antibacterial and healing propertiesthat are highly beneficial for acne. Indeed, it inhibits the growth of the bacteria responsible for acnePropionobacterium Acnes, which is the bacteria primarily involved in this skin condition. Moreover, this active ingredient reduces the activity of the sebaceous glands due to its anti-androgenic activity. Thus, it helps to regulate sebum production and prevent blemishes.

We have developed several treatments based on zinc PCA to limit the excess of sebum on the skin as well as the scalp.

• Thepurifying cleansing gelcontains 2% zinc PCA combined with bamboo extract. Bamboo naturally contains porous particles that absorb excess sebum on the skin. This high absorption capacity helps to reduce skin shine. Therefore, this compound is particularly recommended for combination to oily skin types.

• Specifically designed for oily skin, thematifying serumis concentrated in zinc PCA, azelaic acid (10%) of plant origin, and organic bamboo extract to reduce excess sebum. Of plant origin, azelaic acid is known for its anti-comedogenic and anti-bacterial effects. Indeed, this molecule works to unclog pores and reduce the formation of "open" comedones (otherwise known as blackheads). It also helps to combat the bacteria involved in acne.

• Due to its content of sebum-regulating and antibacterial actives, ourpurifying face creammade with 4% zinc PCA and bamboo extract is ideal for moderating sebum secretion, refining skin texture and preventing the appearance of unsightly blackheads. It should be applied daily to clean, dry skin and over yourface serum, using small circular movements during application until the cream is fully absorbed. However, this cream is not recommended for pregnant and breastfeeding women due to the essential oils it contains.

• Our local blemish serum is concentrated at 2% in salicylic acid. It is also enriched with zinc (1%), a sebum-regulating and antimicrobial trace element. It is applied locally, in small amounts after your daily face serums . Generally, one drop is sufficient for an isolated spot. The first results will be observable after three days. Potentially sensitising, we recommend applying this productonly in the evening.

• Formulated without talc, silicones and nanoparticles, our translucent mattifying loose powder targets shiny and oily skin. A true hybrid product between skincare and makeup, it contains up to 1% of zinc PCA. This element helps to absorb excess sebum for an immediate and lasting matte finish, thus helping to prolong the wear of tinted treatments. It also includes 0.1% ofhyaluronic acid (INCI name: Sodium Hyaluronate): this hygroscopic compound can hold up to 1,000 times its weight in water, making it a powerful skin care ingredient for instant hydration.

• For oily dandruff, the purifying hair serum helps to get rid of it permanently, it is necessary to rely on sebum-regulating active ingredients. Our purifying scalp treatment is composed of 4% of zinc PCA and nettle extract which are known for their purifying and sebum-regulating properties. In addition to this, it contains essential oils of peppermint andeucalyptus globulus which, thanks to their antibacterial and antifungal virtues, help to purify the scalp by fighting against the proliferation of microorganisms responsible for dandruff.

Zinc lactate is a soluble form of zinc with organoleptic properties. It contains 23.4% mineral zinc and can be obtained in various ways, the first of which is through the saturation of lactic acid. This involves the decomposition of calcium lactate using either diluted sulphuric acid or an oxalic acid solution. The second method is through double decomposition: transforming calcium lactate into potassium lactate and then combining it with zinc acetate and potassium lactate to produce zinc lactate.

Zinc lactate is primarily used in toothpastes, due to its anti-plaque action. Highly effective as an anti-microbial, it is also found in many deodorants where it reduces or masks unpleasant body odours, as well as in numerous anti-blemish products.

Zinc gluconate is a compound with the chemical formula C12H22O14Zn. It is the zinc salt of gluconic acid, an ionic active ingredient formed of two gluconate anions for each zinc cation.

C6H12O6 + O2 → C6H11O6OH [ZnO] → (C6H11O6O) 2Zn + H2O

Beyond its role in the metabolism of proteins, lipids, and carbohydrates, this active ingredient is used in cosmetics for its antiseptic and healing functions (it aids the body in transforming essential fatty acids used by the skin for healing). These benefits are particularly appreciated by combination to oily skin types. Furthermore, its sebum-regulating action inhibits the activity of 5-alpha-reductase, an enzyme involved in the synthesis of sebum in the sebaceous glands. Thanks to its antimicrobial action, it is also found in toothpastes as well as deodorants and antiperspirants.

• KERI J. E. & al. The role of zinc in the treatment of acne: A review of the literature. Dermatology and Therapy (2017).

• KALINOWSKA-LIS U. & al. Zinc-containing compounds for personal care applications. International Journal of Cosmetic Science (2018).