Acne Blemishes: Effective Active Ingredients to Combat Them.

The S.F.D. (French Society of Dermatology) reports that 15 million people in France are affected by acne problems, including 3.3 million aged over 15 years. This skin disorder can appear on the face as well as certain parts of the body (chest, back, buttocks...). The primary reason for consultation with a dermatologist, acne can sometimes lead to a lack of self-confidence and significant psychological distress.

This chronic inflammatory disease develops at the level of the pilosebaceous follicles: the sebaceous glands secrete sebum that is either too thick or in excess, which clogs the openings. This is referred to as dysseborrhea. In this fat-rich environment, a bacterium usually present in small amounts on the skin, Cutibacterium acnes, proliferates, which triggers an inflammatory response on the skin's surface.

Several factors contribute to acne flare-ups: stress, pollution, hormonal fluctuations, and poor lifestyle choices (lack of sleep, smoking, unbalanced diet, inadequate hygiene...).

• Hydroxy Acids:

Hydroxy acids are a large family of molecules. Within this family, we find alpha-hydroxy acids (A.H.A.), beta-hydroxy acids (B.H.A.), and poly-hydroxy acids (P.H.A.). Although different, all of these are effective against acne.

1. The A.H.A.s:

A.H.A.s generally come from fruits, hence their name "fruit acids". The molecules of this family have numerous benefits for the skin, but it is their keratolytic power that gives them a formidable activity against acne. Indeed, A.H.A.s, through their keratolytic action, eliminate dead cells on the skin's surface by weakening the lipid bonds between the cells of the horny layer. This allows for the gradual removal of pore blockages and promotes the evacuation of sebum.

A.H.A.s contain a key molecule used in cosmetics, theglycolic acid. In addition to its keratolytic properties, this active ingredient has sebum-regulating properties that are very beneficial in treating acne. Indeed, glycolic acid helps combat the abnormal accumulation of sebum in the skin's enlarged pores, which leads to the formation of acne lesions. Known as the smallest of the A.H.A.s., glycolic acid is able to easily penetrate the layers of the skin. It thus works on the surface but also in depth.

Studies have reported that glycolic acid also exhibits a bactericidal activity of interest in an acidic pH environment around 3 to 4.5, even at low concentrations (< 10%). It thus helps to inhibit the proliferation of the Cutibacterium acnes bacteria on the skin of patients suffering from common acne, particularly by disrupting the integrity of the bacterial cell membrane.

Thelactic acid is another A.H.A. frequently used in cosmetics. Lactic acid is gentle compared to other AHAs. Generally, it is recommended for individuals with sensitive skin who are looking to perform a gentle exfoliation. This molecule, being larger in size than glycolic acid, will penetrate less deeply into the epidermis and will therefore be less irritating than the latter. Lactic acid is therefore an excellent alternative for skin that has not tolerated products with glycolic acid. However, it possesses the same keratolytic properties as glycolic acid, making it effective against acne.

1. The B.H.A.s:

The primary molecule in the B.H.A. family is thesalicylic acid. This active ingredient has various properties that allow it to combat acne.

Salicylic acid activates skin regeneration. Thanks to its keratolytic properties, it removes dead cells from the skin's surface and inhibits the pore blockage that causes acne. Thus, it effectively fights against the appearance of blackheads and tightens pores for a brightened and unified complexion.

Note : Salicylic acid has a strong affinity for sebum and therefore penetrates deeply into the skin's pores.

The surface of the epidermis can be colonized by harmful microorganisms that disrupt the microbiota and lead to redness, irritation, or sometimes painful pimples. Thanks to its antiseptic properties, salicylic acid prevents the growth and proliferation of harmful bacteria, such as Cutibacterium acnes, a microorganism responsible for the inflammatory reactions of acne.

Acne-prone skin is often a source ofdiscomfort. Pimples can cause tingling, itching, and burning sensations. The soothing virtues of salicylic acid alleviate symptoms related to inflammation. Indeed, salicylic acid plays a role in the arachidonic acid cascade and inhibits the synthesis of prostaglandins E2, molecules responsible for inflammatory and painful effects. In the treatment of acne, it thus soothes painful pimples and visibly reduces redness.

1. The P.H.A.s:

Regarded as the new generation of A.H.A.s, they are renowned for theirkeratolytic effects,meaning they eliminate dead cells (a process known as desquamation), which boosts cell renewal. This desquamation allows for deep pore cleansing, thus limiting the appearance of imperfections.

They also possessmoisturizing properties and humectants.This is due to the numerous hydroxyl functions they contain (OH-) at the level of their chemical structures. These structures capture water molecules and prevent transepidermal dehydration, thereby strengthening the skin barrier.

Unlike A.H.A. and B.H.A., P.H.A. are suitable for all skin types, even those that are sensitive. Indeed, due to their high molecular weights, they remain on the surface of the epidermis. This explains their good skin tolerance compared to other acids that penetrate more deeply into the epidermis.

There are numerous P.H.A.s, but the gluconolactone and lactobionic acid are the most commonly used.

Upon contact with the skin, P.H.A.s will have a keratolytic action by eliminating dead cells on the skin's surface and unclogging pores. This allows sebum to distribute more evenly across the skin surface. Consequently, Cutibacterium acnes will proliferate less, which will reduce the occurrence of pimples.

Furthermore, P.H.A.s have moisturizing and humectant properties. Contrary to what one might think, skin hydration is crucial even in the case of acne. It helps to prevent transepidermal dehydration and restore the skin barrier, in order to protect the skin from external aggressions and soothe the skin.

Thus, the use of P.H.A.s for acne-prone skin is interesting as they act against blemishes gently, while respecting the skin barrier.

• Retinol:

The retinol (a derivative of vitamin A) is an active ingredient that has long been criticized due to its potentially irritating and drying effects on the skin. Today, subject to regulation, it is increasingly found in the composition of cosmetic products, primarily for its excellent benefits against signs of aging but also against acne.

Just like hydroxy acids, retinol has a keratolytic action that allows the removal of dead cells present on the surface of the epidermis. The pores are unclogged and the skin texture is refined, thus preventing the appearance of blackheads and/or comedones.

• Bakuchiol:

In 2007, the bakuchiol was used for the first time in cosmetics. Several studies have defined it as a natural alternative to retinol, hence its nickname of "bio-retinol" or "phyto-retinol". Bakuchiol thus effectively combats the signs of skin aging and acne with fewer side effects than retinol (irritations, stability issues, photosensitization, etc…).

For about a decade, studies have been focusing on the comprehensive anti-acne action of bakuchiol. This compound works on several levels.

Bakuchiol is an anti-inflammatory active ingredient. Inflammation is another issue for skin affected by acne. Unfortunately, there are few options available to directly alleviate the inflammation that accompanies acne. However, studies show that bakuchiol has strong inhibitory activity against COX-2, an enzyme that contributes to the formation of prostaglandins.

Bakuchiol combats the bacteria responsible for acne, Cutibacterium acnes. A study shows that bakuchiol exhibits excellent inhibitory activity against C.acnes, and it is very effective in inhibiting other microorganisms such as Staphylococcus and Candida.

Bakuchiol is a sebum-regulating active ingredient.Excess sebum clogs the skin's pores, allowing bacterial growth that leads to inflammation, infection, and visible acne. Bakuchiol works by reducing the secretion and thus the activity of an enzyme, 5-α-reductase. This enzyme converts testosterone into DHT, which binds to the androgen receptors of the sebaceous glands and triggers an excessive production of sebum.

Bakuchiol accelerates healing. It has been shown that acne-prone skin contains higher levels of matrix metalloproteinases (MMP) than so-called normal skin. These enzymes (primarily collagenase and elastase) degrade the matrix in the acne lesion and thus slow down the healing of skin affected by acne. Topical application of bakuchiol inhibits the activity of these enzymes, preventing them from hindering the healing of micro-lesions left by acne pimples.

• Zinc:

Zinc is an essential trace element for the body. It is present in meat as well as in certain plants after fermentation. A zinc deficiency would exacerbate inflammatory phenomena. It is included in skincare products in various forms such as zinc oxide, zinc gluconate, or zinc PCA.

Sebum-regulating active ingredient, zinc PCA helps to regulate sebum production and thus prevent imperfections. Zinc PCA is also known to limit the growth of microorganisms such as the Cutibacterium acnes. This bacteria is found in excess in acne-prone skin.

Thus, zinc PCA reduces inflammation, regulates sebum production, and limits bacterial proliferation.

• Azelaic Acid:

Naturally found in certain grains such as barley, theazelaic acid is classified among the dicarboxylic acids. It is found in medicinal treatments for acne, applied topically, usually at concentrations between 15 and 20%. In cosmetics, creams and serums rarely contain more than 10%. However, even at this concentration, its overall anti-blemish activity is relevant. It operates on several levels:

It regulates keratinization. The keratinization, or cell differentiation, is a maturation process of epithelial cells, which load up on keratin to result in dead cells that make up the horny layer. Thus, azelaic acid normalizes this process, resulting in a smoothed skin texture and limited obstruction of pores by dead cells, preventing the formation of blackheads and comedones.

It fights against bacteria. Thanks to its anti-bacterial properties, azelaic acid limits the proliferation of bacteria P. acnes and S. epidermidis, which are implicated in the inflammatory reactions of acne. Moreover, it acts specifically on these two microorganisms but does not have harmful effects towards the "good bacteria" present on the skin.

It limits inflammation. Azelaic acid reduces redness, as well as the marks left by blemishes: we're talking aboutpost-inflammatory erythema. Studies have shown that azelaic acid inhibits the secretion of pro-inflammatory cytokines, such as interleukins IL-1β and IL-6, and the transcription factor TNF-α. Furthermore, another study showed that azelaic acid promotes the regulation of kallikrein-5 in epidermal keratinocytes, which in turn lower cathelicidins, reducing inflammatory processes.

• Niacinamide:

Niacinamide is a water-soluble derivative of vitamin B3. It is essential for the proper functioning of the body as it is involved in the production of NAD and NADP, coenzymes recognized as energy transfer molecules. This vitamin has numerous benefits for the skin. It is particularly involved in preventing the harmful effects of free radicals emanating from sunlight, tobacco, and pollution. Niacinamide also regulates sebum production, inhibits the proliferation of bacteria such as C.Acnes and stimulates collagen synthesis. Moreover, it is a stable antioxidant, which withstands light and heat very well.

Niacinamide is a comprehensive anti-blemish agent, which works both before the formation of pimples and afterwards to reduce any potential marks and scars.

Upstream, this vitamin regulates the sebum level on the skin's surface, thereby preventing the pore blockage that leads to the formation of blackheads and comedones. Additionally, it performs a anti-bacterial function effective against the microorganisms responsible for the inflammatory reactions of acne such as P. acnes ;

Downstream, its virtues are soothing and help to decrease inflammation, thus reducing redness associated with blemishes.