"Sunny kisses" or a cause for concern: Perm scientists share everything you need to know about freckles.

Freckles are areas of skin characterized by an increased concentration of the pigment melanin, which is synthesized by specific cells known as melanocytes and transferred to neighboring skin cells that form its foundation (keratinocytes). This process gives the skin a certain hue. If a melanocyte produces more melanin than those in adjacent areas, darker patches—freckles—form on the body. The number of such cells in the area where "sun kisses" appear remains normal, distinguishing them from moles, which are clusters of these cells.

In addition to the skin, melanin is also found in hair, the retina of the eye, the brain, the adrenal glands, and pigmented parts of the body, such as lips and nipples.

– The synthesis of melanin is triggered by exposure to ultraviolet radiation. Melanin is produced through a multi-step process that begins with the oxidation of the amino acid tyrosine, followed by the formation of polymeric forms of the pigment. The key enzyme in melanin synthesis is tyrosinase, and its activity determines the amount of pigment produced, – explains Anna Akhova, an associate professor at the Department of Chemistry and Biotechnology at Perm Polytechnic University and a candidate of biological sciences.

How does melanin protect the skin from the sun?

– Humans have several types of melanin, the main ones being eumelanin, which ranges in color from brown to black, and pheomelanin, which is yellow or red in tone. The ratio of these melanin types determines the shade of body parts, while the amount of pigment affects the intensity of coloring. For instance, brunettes have a high concentration of eumelanin, while blondes have less, and redheads have a small amount of eumelanin along with pheomelanin, – clarifies biologist Anna Akhova from Perm Polytechnic University.

Pheomelanin gives the skin a yellowish and pinkish tint, while more eumelanin results in darker skin. Sun exposure stimulates the production of both types of melanin (evidenced by skin reddening and/or tanning), but only eumelanin can absorb UV radiation, thereby protecting cellular structures, including DNA, from its damaging effects.

Why do red-haired individuals have freckles more often than others?

The activity of melanin synthesis by melanocytes varies among different ethnic groups, leading to different baseline skin tones. In some people and animals, melanin is produced in very small amounts or not at all, a phenomenon known as "albinism." Freckles are a result of and a protective response to ultraviolet radiation and can be found in individuals of any skin color, but are more common in those with fair skin. Darker skin contains more eumelanin, which has photoprotective effects, making it less susceptible to damage from sunlight.

– In red-haired individuals with fair skin, a mutation often disrupts the process of switching melanocytes from synthesizing pheomelanin to producing eumelanin. As a result, the latter, which has photoprotective properties, is not synthesized in sufficient quantities, making their skin more vulnerable to the negative effects of ultraviolet radiation, – notes Anna Akhova.

When can freckles be a cause for concern?

The question of whether health problems can directly cause the appearance of freckles requires clarification. Freckles themselves are not an indication of any disease. However, certain conditions can indirectly affect skin pigmentation, and it is important to consider them.

— Recently, there has been a significant increase in the number of people experiencing hyperpigmentation—an intensification of skin coloration due to disruptions in the process of melanogenesis. Although in most cases, such pigmented spots as freckles are not dangerous, their abundance may indicate heightened sensitivity and reactivity of the skin, as well as potentially signal an increased risk of developing skin cancer, – states Ekaterina Bankovskaya, an associate professor at the Department of Chemical Technologies at Perm Polytechnic University and a candidate of pharmaceutical sciences.

Medications commonly associated with drug-induced hyperpigmentation include hormonal, antiarrhythmic, antimicrobial, antiepileptic drugs, cytostatics (a class of drugs that affect cell division), and heavy metals.

Freckles are a seasonal phenomenon but can linger

— There are two main categories of freckles: ephelides and solar lentigines. Ephelides are a term of Greek origin that refers to flat spots measuring 1–2 mm, which tan to a slightly reddish or light brown color and typically appear during sunny months. Lentigines are larger pigmented spots that most often develop on areas of skin that have been sunburned. They are usually darker than ordinary freckles and do not fade in winter, – explains Ekaterina Bankovskaya.

Goodbye, freckles!

To reduce skin pigmentation and the number of freckles, sunscreen products as well as whitening agents are used. It is advisable to combine these with professional cosmetic procedures (peeling) aimed at reducing melanin production and exfoliating the skin’s stratum corneum.

— Procedures aimed at removing the skin's stratum corneum include chemical peels, cryodestruction, and dermabrasion. Melanin reduction can be achieved using lasers and modern IPL (intense pulsed light) techniques. This technology is used in aesthetic medicine for a wide range of procedures, from hair removal and photo-rejuvenation to alleviating dermatological conditions such as acne. The foundation of IPL involves using a powerful lamp that generates an intense, visible, and near-infrared, broad-spectrum light pulse ranging from 400 to 1200 nm. This light selectively targets specific structures and chromophores (such as melanin), heating them to the point of destruction, after which they are absorbed by the body, – notes Ekaterina Bankovskaya, an associate professor at the Department of Chemical Technologies at Perm Polytechnic University and a candidate of pharmaceutical sciences.

In the fight against hyperpigmentation, cosmetology offers a wide array of technologies, including carbon dioxide lasers, alexandrite, krypton, neodymium, and erbium lasers. The CO2 laser operates by removing or vaporizing melanin-containing tissues. It is quite effective; however, its use can lead to serious complications, including the development of new hyperpigmentation, hypopigmentation, and scarring, including keloids. The rehabilitation period following the procedure can be prolonged, lasting up to 2-3 months.

The mechanism of action of other lasers involves lightening through fragmentation and dispersion of melanin. Each type of laser is used depending on the wavelength for treating specific kinds of hyperpigmentation. Lasers with shorter wavelengths penetrate less deeply and are used for removing superficial pigmented skin lesions, such as freckles. For deeper treatments, lasers with longer wavelengths, such as neodymium (1064 nm) and erbium (2940 nm), are applied.

These cosmetic procedures can quickly yield good results; however, they are all expensive, time-consuming, and may lead to various complications.

— Currently, researchers are searching for tyrosinase inhibitors to treat skin conditions associated with hyperpigmentation (melasma, age spots). Vitamin C and flavonoids can inhibit the activity of this enzyme in vitro. Therefore, it is suggested that these substances may influence the formation of freckles, – adds Anna Akhova.

Will SPF cream help?

— Numerous studies confirm the effectiveness of sunscreens in the prevention and treatment of pigmented spots, including freckles. Sunscreens should have a high SPF factor (at least 50), and they must be used throughout the treatment period, regardless of the season, which is crucial for preventing recurrent hyperpigmentation. The cream should be applied 15–20 minutes before going outside and reapplied every 2–3 hours, especially after swimming or sweating, – advises Ekaterina Bankovskaya, an associate professor at the Department of Chemical Technologies at Perm Polytechnic University and a candidate of pharmaceutical sciences.

Traditional methods

To combat hyperpigmentation and accelerate the regeneration of the epidermis, substances that enhance the exfoliation of the stratum corneum are used. These include alpha-hydroxy acids (glycolic, lactic, tartaric, mandelic, citric, malic) and retinol.

— Glycolic acid in low concentrations is found in grapes, sugar beets, sugar cane, and green plants. Lactic acid is present in cheeses, yogurt, cottage cheese, fatty kefir, buttermilk, and baked goods, such as rye bread and wheat flour bread of the first grade, as well as in pickled and salted vegetables. Mandelic acid is found in bitter almonds, elderberries, peach, plum, and cherry pits, – notes the scientist.

Citric acid is found in citrus fruits (lemons, oranges, limes), berries (strawberries, raspberries, gooseberries, cranberries), pineapples, cherries, tomatoes, some types of peppers, artichokes, and lettuce. Malic acid is present in unripe apples, grapes, rowan berries, barberries, raspberries, oranges, mandarins, lemons, tomatoes, and rhubarb.

In folk medicine, a paste made from almond flowers and