Photoprotective agents
Last reviewed: 23.04.2024
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Photoprotection is a broad concept, implying a complex of measures aimed at reducing the impact of UFOs. First of all, the use of exogenous and endogenous photoprotectors is shown.
Exogenous photoprotection, or sunscreen, is available in the form of an emulsion (cream), spray, oil. Modern requirements for an "ideal" photoprotective agent include good tolerability, non-toxicity, effective protection against UVA and UVB simultaneously, high sunscreen factor (at least 40), photostability, water resistance, comfort in use. Many researchers emphasize the importance of using chemical filters, compared to screens.
Modern sunscreen preparations are subdivided into means with preferential protection from UVB, from UVA and combined (UVA + UVB).
Means with primary protection from VVB were first available to dermatologists. They began to be manufactured in an industrial way in the world from the end of the 30s of the last century. At present, this group includes PABA (PABA, or RAWA) and its derivatives, salicylic acid esters (salicylates), cinnamic acid esters (cinnamates), and other compounds. Salicylates include the long-known compound phenyl salicylate (salol), as well as three methyl cyclohexyl salicylate (homosalate, Neo Heliopan HMS, etc.), octylsalicylate (Neo Heliopan OS), methylanthranilate (Neo Heliopan MA), 4-methylbenzylidenecampor (Emolex 6300, Uvinul MBC 95, etc.), benzalidene camphor sulphonic acid (Mexoryl SL), octyltriazone (Uvimtl E-150). Cinnamates are ethylhexylmethoxycinnamate-EMC (Parsol MCX, Neo Heliopan AV, Escalol 557, etc.), octocrylene (Neo Heliopan 303, Parsol 5000, etc.), isoamyl-p-methoxycinnamate (Neo Heliopan E-1000).
Means with preferential protection against UVA are represented by butyl methoxydibenzoylmethane (avobenzone, or Parsol 1789. Eusolex 9020, Uvinul VMVM). Among them, special attention should be paid to such newly synthesized agents as terephthalidene-dicamporic sulfonic acid-TDSA (Mexoryl SX, etc.).
Combined preparations include mainly various benzophenones (hydroxybenzone, dioxibenzone, benzophenone, etc.). Recently, new high-performance compounds with combined protection have appeared on the market: drometrizoltrisiloxane (DTS) -Mexoryl XL, as well as bis-ethyl hexyloxyphenolmethoxyphenyltriazine (BF.MT) -Tinosorb S and methylene-bis-benzotriazolyltetramethylbutylphenol (MWVT) -Tinosorb M.
To assess the effectiveness of protection from UVB, use is made of a factor such as sun protection factor (sun protective factor, or SPF). The SPF assessment method is standardized and implemented in accordance with the strictly established rules of the international organization COLIPA, EC (The buropean Cosmetic Toiletry and Perfumery Association). It is expressed in primes and demonstrates the degree of protection from the corresponding rays. SPF is the ratio of the minimum erythema dose (ED, J / cm2) that occurs when the skin is irradiated with a photoprotector, to a minimum erythematous dose without a photoprotector:
SPF = min ED with photoprotector / min ED without photoprotector
In accordance with the new classification of photoprotective agents approved by COLIPA, funds are allocated with ultra-protection (SPF> 50, denoted 50+), with increased protection (SPF = 30-50) and with high protection (SPF = 20-30).
However, recent studies have shown that sunscreens with a high SPF score provide not an equivalent degree of protection against UVA rays. The importance of using agents with high anti-ray protection factors has already been proven. Since rays A are not erythemogenic, the degree of protection against UVA can not be determined by the sunscreen factor. Currently, several indicators are used, based on the severity of delayed and delayed skin pigmentation, which arises in response to the action of these rays on the skin protected and unprotected by the photoprotector (1PD - immediate pigme / jM darkening, PPD - persistent pigment darkening).
Modern photoprotectors are subdivided by the mechanism of action into chemical (filters) and mineral (screens). Chemical filters provide photochemical protection by absorbing certain types of energy, and the screens reflect it, partially adsorbing (especially radiation B). At the same time, chemical filters are the most preferred. This group includes paraminobenzoic acid, salicylates, cinnamates, benzophenones, avobenzone (Parsol 1789), DTS (Mexoryl XL), and other compounds. The screens include titania, zinc oxide, red iron oxide and other compounds.
Sunscreen products include day cream for the face, for the body. There are also sunscreen products for the lips, eye contour. In recent years, sunscreens have been widely added to various cosmetic preparations for hair care. As a rule, they are designed for hair care during a holiday at sea and are designed to protect the hair from both ultraviolet exposure and from contact with salt water. They are added to the form of a gel, an aerosol, a foam, a hair cream.
It should also be remembered that wearing a hat or hat on a sunny day provides the hair and skin of the scalp with a defense similar to a sunscreen factor (SPF) of 5-7.
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