The green tea extract: its benefits for the skin.

Recent studies have demonstrated thatgreen tea extract is capable ofinhibiting certain enzymes that play a role in skin ageing. These include metalloproteinases, which are involved in the proteolytic degradation of extracellular matrix proteins, hyaluronidase, which catalyses the hydrolysis of hyaluronic acids, and collagenase, which is responsible for breaking down the peptide bonds of collagen. By inhibiting these processes, green tea extract can delay skin ageing. However, the precise mechanisms through which it operates remain unknown to this day.

Green tea extract is also valued for its skin-hydrating virtues, which it derives from the catechins it contains. Studies in vitro have highlighted that these molecules increase the expression of genes related to NMFs (Natural Moisturising Factors). NMFs are a collection of hygroscopic substances located within the corneocytes of the epidermis. Their role is to ensure the hydration of the stratum corneum.

The moisturising effect of green tea extract has also been highlighted in vivo, during a study conducted on 24 volunteers. This showed that the daily application on the forearm of a moisturising cream containing 6% green tea extract for a month significantly increased theoverall hydration of the skin and its suppleness. By enhancing skin hydration, green tea extract not only contributes to its protection, but also to the prevention of dehydration fine lines.

The polyphenols found in green tea extract also enable it to protect cellular constituents from oxidative stress. Notably, they are capable of enhancing the activity of antioxidant enzymes, such as superoxide dismutase (SOD) and glutathione peroxidase (GPx). These are proteins essential to the mechanism of eliminating free radicals. Polyphenols can also bind to certain metals involved in the generation of these reactive species (copper, iron...). In doing so, polyphenols prevent them from producing free radicals.

Furthermore, studies have shown that these compounds have a protective effect on certain antioxidants such as vitamins C and E. Green tea extract is thus a highly valued natural ingredient for skin lacking radiance or heavily exposed to pollution. The protection it provides to DNA, cells and proteins in the body also contributes to the delay of skin ageing.

The anti-inflammatory properties of green tea extract are derived from its catechins, polyphenolic compounds that reduce the production of pro-inflammatory cytokines, such as interleukins 6 and 8 (IL-6 and IL-8) and tumour necrosis factor (TNF-α), which are responsible for pathological phenomena. Furthermore, catechins decrease the activity of nuclear factor kappa-B (NF-κB), a regulatory protein for several genes encoding inflammation proteins. Therefore, green tea extract is considered an interesting ingredient for combating redness and itching. It is regularly incorporated into treatments intended for acne-prone skin.

Thegreen tea extract is considered a friend to oily skin due to its mattifying and sebum-regulating properties. If we delve into the biological mechanisms, it is once again the catechins that are at work. They inhibit the activity of 5-alpha-reductase, an enzyme that catalyses the transformation of testosterone into dihydrotestosterone, which in turn activates the synthesis of sebum by the sebaceous glands. The mattifying effect provided by the green tea extract has also been evaluated in various in vivo studies. One of them notably showed that the daily application of a cream containing 3% green tea extract on the faces of 10 volunteers for 8 weeks resulted in a 60% reduction in their sebum production.

Green tea extract has photoprotective properties and helps to prevent issues ofhyperpigmentation. Scientists have indeed studied in vitro the effects of green tea catechins on melanogenesis and have shown that these molecules can inhibit the synthesis of the hormone α-MSH (α-melanocyte-stimulating hormone), a hormone activating certain melanocortin receptors. These receptors trigger the production of melanin. However, it is important to note that no study has been directly conducted on people with hyperpigmentation. Therefore, caution should be exercised regarding the anti-brown spot properties of green tea extract.

Green tea extract has proven antibacterial properties. Indeed, the polyphenols it contains are capable of limiting the growth of certain bacteria, such as Cutibacterium acnes, making it an excellent supplement for combating acne. Polyphenols work by preventing pathogenic bacteria from binding to the host cell membrane. Furthermore, researchers have suggested that they can inhibit quorum sensing, that is, communication between bacteria.

At Typology, we have incorporated green tea extract into our botanical blend with CBD. This treatment is suitable for all skin types, but is particularly adapted to sensitive and fragile skin, prone to redness (redness from hypersensitivity, redness due to the dilation of micro-vessels, and redness due to imperfections). Although they may have different causes, all skin redness share a common factor - skin inflammation.

This night serum soothes the skin and reduces the inflammation that causes various types of redness. It does this by combining the action of six botanical extracts with anti-inflammatory properties: cannabidiol (CBD), calendula oil macerate (Calendula Officinalis Flower Extract), hemp oil (Cannabis Sativa Seed Oil), black cumin oil (Nigella Sativa Seed Oil), sesame oil (Sesamum Indicum (Sesame) Seed Oil), and green tea extract (Camellia Sinensis Leaf Extract).

• CHO J. & al. Skin Protective Effect of Epigallocatechin Gallate. International journal of molecular sciences (2018).

• TENCOMNAO T. & al. A Review of the Role of Green Tea ( Camellia sinensis) in Antiphotoaging, Stress Resistance, Neuroprotection, and Autophagy. Nutrients (2019).

• KUKULA-KOCH W. & al. Applications of Tea ( Camellia sinensis) and its Active Constituents in Cosmetics. Molecules (2019).

• WILCZYNSKI S. & al. The Effects of Green Tea ( Camellia sinensis), Bamboo Extract ( Bambusa vulgaris) and Lactic Acid on Sebum Production in Young Women with Acne Vulgaris Using Sonophoresis Treatment. Healthcare (2022).