Everything You Need To Know About Mandelic Acid

It is an aromatic ingredient belonging to the AHA family.

It has a molecular weight of 152.147 g/mol.

It is derived from the hydrolysis of a bitter almond extract.

It was first discovered by the German pharmacist Ferdinand Ludwig WINCKLER in 1831.

It was used in particular in medicines for urinary tract infections due to its antibacterial activity.

It has exfoliating, anti-bacterial, anti-inflammatory and antioxidant properties.

It is associated with less stinging and burning than other low molecular weight AHAs.

It is an ideal peeling agent for sensitive skin.

Of molecular form C8H8O3, mandelic acid is an aromatic ingredient belonging to the AHA family (alpha-hydroxy acids). It is a white, crystalline solid with a light fragrance. Soluble in polar organic solvents and weakly in water, mandelic acid is an arylalkyl AHA containing a phenyl group attached to the α-carbon. It was discovered in 1831 by a German pharmacist, Ferdinand Ludwig WINCKLER, by heating amygdalin, an extract of bitter almond, with dilute hydrochloric acid. Its name comes from the German "Mandel" which means "almond".

Since the early 1900s, mandelic acid has been used in the treatment of urinary tract infections as an antiseptic agent in the medical community. It is also used as a precursor for the production of semi-synthetic penicillins and cephalosporins, anti-obesity agents and pharmaceuticals with anti-HIV or anti-leukemia activities.

Its interest in skin care stems from its dual action having both cosmetic and antibacterial properties. The role of mandelic acid is also to remove dead cells from the surface of the epidermis. It differs from other AHAs by its size. Indeed, it is a large molecule (MW = 152.147 g/mol), a characteristic common to PHAs (polyhydroxy acids): it is twice the size of glycolic acid. Its penetration into the epidermis is therefore slow and uniform, and not as deep as other fruit acids. Its progressive, slow and gentle mode of action explains its tolerance by sensitive skin.

Mandelic acid is usually extracted from the bitter almond, the non-edible fruit of the wild almond tree. The biosynthesis of mandelic acid is done by hydrolysis of mandelonitrile, an aromatic compound present in the nucleus, with the help of nitrilase enzymes, without the formation of "free" amino intermediates. Mandelic acid can also be isolated from Aesculus indica fruit extract.

However, it is not always of natural origin. Indeed, it has also been shown that it can be obtained by biotechnology. Synthetically, it can be produced by microbial fermentation of glucose using a genetically modified strain of Saccharomyces cerevisiae yeast expressing the hydroxymandelate synthase enzyme from Amycolatopsis orientalis.

Versatile, mandelic acid has gained ground as a skin care product due to its many benefits.

• Anti-bacterial: Compared to other AHAs, mandelic acid has a significant antibacterial effect. Studies have found that mandelic acid has the ability to inhibit the growth of certain strains of Escherichia coli, Proteus mirabilis, Klebsiella pneumonia, Enterococcus spp., Staphylococcus aureus, Bacillus proteus and Aerobacter aerogenes at concentrations as low as 0.5% and 1% in pH 4.0 - 4.5 media. This antibacterial activity depends on the pH of the medium: if the pH increases, this inhibitory effect decreases. It thus contributes to the prevention of skin eruptions.

• Anti-inflammatory: In addition to this, it has anti-inflammatory properties, thus preventing the appearance of new inflammations. It helps to fade the marks left by pimples, known as post-inflammatory erythema. It also effectively exfoliates the surface of the skin without drying it out or causing redness.

• Antioxidant: By neutralizing free radicals and reducing their content in skin cells, it helps protect the skin from reactive oxygen species. These can be factors of premature skin aging.

• Exfoliant: It allows a superficial peeling of the skin. Its mechanism? It eliminates calcium ions in the epidermis from the cell adhesion structures by chelation. When disturbed, it causes a cellular desquamation of the upper layers of the epidermis, which favors the growth of cells and inhibits their differentiation.

Regenerating, purifying and gentle, mandelic acid has all the qualities needed to be the ideal active ingredient. It is suitable for dull complexions, hyperpigmented skin, skin prone to imperfections, and skin showing signs of aging.

By breaking the cohesive bonds of the corneocytes just above the granular layer of the skin, mandelic acid improves and evens out the complexion. It reduces pigmentation, "camouflages" dilated pores, and blurs the appearance of signs of aging (wrinkles, loss of elasticity). This is possible because it slightly activates the production of collagen and stimulates the natural synthesis of hyaluronic acid. It smoothes the skin texture by erasing skin irregularities, and keeps the skin moisturized, restoring its suppleness.

Mandelic acid, like other AHAs, are non-toxic substances naturally present in plants. Its distinction? It has a lower potential for skin irritation, which is why it is considered a better alternative to other AHAs. Indeed, the high molecular weight of mandelic acid gives it the unique feature of being non-aggressive and non-irritating.

Although it has no side effects as a general rule and is suitable for all skin types, in rare cases it can cause episodes of skin sensitivity: it can cause redness, tightness, tingling, feelings of heat, etc. Moreover, the mandelic acid is photosensitizing, that is to say it can increase the sensitivity of the skin to the sun.

Are there particular precautions of use to be taken?

1. Ideally, before integrating it into your daily routine, you should do a skin test on the hollow of the elbow or behind the ear.

2. It is recommended to apply it in the evening after the cleaning step to avoid irritation and the appearance of redness.

3. During the day, you must wear sunscreen during the entire period of use.

4. To minimize the risk of intolerance, it is recommended to apply a moisturizer. Even though it is considered mild, mandelic acid temporarily compromises the skin barrier.

5. It is not recommended to combine it with skin care products containing irritating ingredients such as retinoids. Indeed, their association can cause a sensitivity of the skin, especially for the sensitive skin.

6. It is preferable to choose products containing anti-inflammatory and soothing active ingredients, in addition to mandelic acid.

7. It should not be applied around the eyes or on the lips, which are delicate areas.

The adverse effects of mandelic acid depend on its concentration in solution, the time the skin is exposed and the pH of the environment.

Once used exclusively by dermatological practices for chemical peels, for example, it has now entered the cosmetic industry and is present in skin care products intended for the general public and is suitable for all skin types and complexions, without the risk of hyperpigmentation and depigmentation.

With its unique benefits, mandelic acid (INCI name: Mandelic Acid) incorporates the formulation of two skin care products at Typology.

• The peeling mask combining 10% AHA (mandelic acid, glycolic acid, lactic acid, tartaric acid) and 10% PHA (gluconolactone) is an exfoliating gel. Also containing bisabolol and green tea extract (INCI name: Camellia Sinensis Leaf Extract), this night mask combines effectiveness and facial care in a formula that respects the skin's balance. It reduces the size of dilated pores, renews the skin and makes the complexion more radiant.
  How to use it? In the evening, apply the gel-mask once or twice a week to clean, dry skin, leave it on for 10 minutes and then rinse thoroughly with warm water.

• The exfoliating night cream offers a progressive and gentle micro-exfoliation of the skin by combining chemical exfoliation with glycolic acid and mandelic acid, and enzymatic exfoliation with pink grapefruit extract (INCI name: Citrus Paradisi (Grapefruit) Fruit Extract). Its exfoliating effect helps to fight night after night against blackheads and dilated pores, and to restore radiance to the complexion.
  How to use it? In the evening, on cleansed skin only, spread a dab of the cream over the entire face and neck. Massage your skin gently in circular movements and let it penetrate. Before using it daily, start with two applications per week, then gradually increase the frequency of use according to your skin's tolerance.

Fruit acid-based scrubs are photosensitizing, which means that they can cause a skin reaction (risk of sunburn) when exposed to UV rays. It is then strongly recommended to use a sunscreen SPF30 minimum during the day and to limit its exposure to the sun when using these care products and throughout the duration of its use.

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• ROTSZTEJN H. & al. Influence of azelaic and mandelic acid peels on sebum secretion in ageing women. Advances in Dermatology and Allergology (2013).

• GUPTA C. & al. Comparative evaluation of efficacy and tolerability of glycolic acid, salicylic acid, mandelic acid, and phytic acid combination peels in melasma. Dermatologic Surgery (2016).

• BOLES E. & al. Engineering of hydroxymandelate synthases and the aromatic amino acid pathway enables de novo biosynthesis of mandelic and 4-hydroxymandelic acid with Saccharomyces cerevisiae. Metabolic Engineering (2018).

• CULBERTSON E. J. & al. Effects of topical mandelic acid treatment on facial skin viscoelasticity. Rapid Communication (2018).

• ULLAH F. & al. Isolation of quercetin and mandelic acid from Aesculus indica fruit and their biological activities. BMC Biochemistry (2018).

• SAHU P. & al. Comparative study of efficacy and safety of 45% mandelic acid versus 30% salicylic acid peels in mild‐to‐moderate acne vulgaris. Journal of Cosmetic Dermatology (2019).

• SWIERGIEL A. H. & al. Antimicrobial properties of mandelic acid, gallic acid and their derivatives. Mini-Reviews in Medicinal Chemistry (2021).

• Food & Drugs Administration (FDA). Alpha hydroxy acids (2022).

• PubChem. Mandelic acid.