Everything there is to know about Mandelic Acid.

Is an aromatic ingredient belonging to the AHA family.

has a molar mass of 152.147 g/mol.

Derived from the hydrolysis of a bitter almond extract.

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

It was particularly used in medications for urinary tract infections due to its bactericidal activity.

Has exfoliating, antibacterial, anti-inflammatory, and antioxidant properties.

Is associated with less tingling and burning than other low molecular weight AHAs.

Is an ideal peeling agent for sensitive skin.

With a molecular formula of C8H8O3, mandelic acid is an aromatic ingredient belonging to the AHA (alpha-hydroxy acids) family. It presents itself as a white, crystalline solid with a slight fragrance. Soluble in polar organic solvents and slightly 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 from bitter almonds, with diluted hydrochloric acid. Its name, in fact, 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 within the medical community. It is also used as a precursor for the production of semi-synthetic penicillins and cephalosporins, anti-obesity agents, and pharmaceutical products with anti-HIV or anti-leukaemic activities.

Its interest in skincare stems from its dual action, possessing both a well-established cosmeceutical and antibacterial activity. The role of mandelic acid also involves peeling off dead cells from the surface of the epidermis. It differs from other AHAs in its size. Indeed, it is a large molecule (MW = 152.147 g/mol), a characteristic common to PHAs (poly-hydroxy acids): it is twice as large as that 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 typically extracted from the bitter almond, a non-edible fruit of the wild almond tree. The biosynthesis of mandelic acid occurs through the hydrolysis of mandelonitrile, an aromatic compound present in the kernel, with the aid of nitrilase enzymes, without the formation of "free" amide intermediates. Mandelic acid can also be isolated from the fruit extract ofAesculus indica.

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

Versatile in nature, mandelic acid has gained ground as a skincare treatment due to its numerous benefits.

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

• Anti-inflammatory: in addition to this, it has anti-inflammatory properties, thus preventing the onset of new inflammations. Indeed, it helps to fade the marks left by spots, known aspost-inflammatory erythema. Moreover, it effectively exfoliates the skin's surface without drying it out or causing redness.

• Antioxidant: by neutralising free radicals and reducing their content in skin cells, it aids the skin in protecting itself from the action of reactive oxygen species, factors in premature skin ageing.

• Exfoliant: It allows for a superficial peeling of the skin. Its mechanism? It eliminates calcium ions in the epidermis from cellular adhesion structures through chelation. Disturbed, this leads to cellular desquamation of the upper layers of the epidermis, which promotes cell growth and inhibits their differentiation.

Regenerative, purifying and gentle, mandelic acid has all the qualities to be the ideal active ingredient for dull complexions, hyperpigmented skin, epidermis prone to blemishes, as well as skin showing signs of ageing.

By breaking the cohesive bonds of corneocytes just above the granular layer of the skin, mandelic acid improves and evens out the complexion by reducing pigmentation phenomena, "camouflaging" the dilated pores, blurring the appearance of signs of ageing (wrinkles, loss of elasticity) by slightly activating collagen production and stimulating the natural synthesis of hyaluronic acid, smooths the skin texture by erasing skin irregularities, and keeps the skin hydrated, restoring its suppleness.

Mandelic acid, like other AHAs, are non-toxic substances naturally present in plants. What sets it apart? It has a lower potential for skin irritation and that's why it's considered a better alternative to other AHAs. Indeed, the high molecular weight of mandelic acid gives it the unique property of being non-aggressive and non-irritating.

Although it generally does not present any side effects and is suitable for all skin types, in rare cases it can cause episodes of skin reaction : it can be a source of redness, tightness, tingling, sensations of heat... Furthermore, mandelic acid is photosensitising, meaning it can increase the skin's sensitivity to the sun.

Are there any specific usage precautions to be taken?

1. The ideal approach, before incorporating it into your daily routine, is to perform a skin test in the crook of your elbow or behind your ear.

2. It is recommended to apply it in the evening after the cleansing stage to prevent irritations and the onset of redness.

3. During the day, you must apply a sunscreen for the entire duration of use.

4. To minimise the risks of intolerance, it is recommended to apply a moisturising treatment. Even though it is considered mild, mandelic acid temporarily compromises the skin barrier.

5. It is advised not to combine it with treatments containing irritating active ingredients such as retinoids. Indeed, their combination can cause skin sensitivity, especially for delicate skin.

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

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

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

Formerly used exclusively by dermatological clinics for procedures such as chemical peels, it has now conquered the cosmetic industry and is present in skin care products intended for the general public. It caters to all skin types and tones, without the risk of hyperpigmentation and depigmentation.

With its unique benefits, themandelic acid (INCI name: Mandelic Acid) is incorporated into the formulation of two Typology skincare products.

• The peeling mask combining 10% AHA (mandelic acid, glycolic acid, lactic acid, tartaric acid) and 10% PHA (gluconolactone) is an exfoliating jelly. Also containing bisabolol and green tea extract (INCI name: Camellia Sinensis Leaf Extract), this night mask combines effectiveness and facial care in a formula respectful of the skin's balance. It reduces the size of enlarged pores, renews the skin and makes the complexion brighter.

  How to use it? In the evening, apply the gel mask once or twice a week on clean, dry skin, leave it on for 10 minutes and then rinse thoroughly with warm water.

• The exfoliating night cream offers a gentle, progressive micro-exfoliation of the skin by combining chemical exfoliation with glycolic acid and mandelic acid, and enzymatic exfoliation with the pink grapefruit extract (INCI name: Citrus Paradisi (Grapefruit) Fruit Extract). Its exfoliating and deep-cleansing effect helps to combat blackheads and enlarged pores night after night, and to restore the skin's radiance.

  How to use it? Only in the evening on previously cleansed skin, spread a small amount of the cream over the entire face and neck. Gently massage your skin using circular movements and let it absorb. 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 exfoliants are photosensitising, meaning they can trigger a skin reaction (risk of sunburn) when exposed to UV rays. It is therefore strongly recommended to use a sunscreen with a minimum SPF30 during the day and to limit sun exposure while using these treatments and for the entire duration of their use.

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• SARKAR R. & al. Glycolic acid peels versus salicylic–mandelic acid
  peels in active acne vulgaris and post-acne scarring and hyperpigmentation: a comparative study. Journal of the American Society for Dermatologic Surgery (2008).

• 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 the effectiveness and tolerability of glycolic acid, salicylic acid, mandelic acid, and phytic acid combination peels in melasma. Dermatologic Surgery (2016).

• BOLES E. & al. The engineering of hydroxymandelate synthases and the aromatic amino acid pathway allows for the 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. Quick Communication (2018).

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

• SAHU P. & al. Comparative study of the effectiveness 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.