Читать книгу Cosmeceuticals - Группа авторов - Страница 51

Alpha, beta, and polyhydroxy acids have been utilized and well documented through research and literature for decades. They are extremely useful in both medical and cosmetic applications, working to treat a wide variety of skin issues while functioning to preserve youthful skin characteristics. The hydroxy acids (HAs) are similar in structure to each other, each bringing forth their unique mechanisms of action and applications. In chemical peels, HAs are used on their own in addition to solutions where two or more are combined to produce the desired results. In other cosmeceuticals they are useful for superficial exfoliation and moisturization, and when used in combination with injectables like neuromodulators or dermal fillers, their results are enhanced and beautifully displayed. When used with topical prescriptions they can provide properties to make the patient feel more comfortable, like adding moisture to lessen a burning sensation. More information is emerging about the benefits of each HA now more than ever, which bodes well for the future in terms of being able to prescribe and recommend the most precise treatment options for patients, and in turn, advancing and improving results.

© 2021 S. Karger AG, Basel

Hydroxy acids (HAs) are no strangers to the world of cosmeceuticals, as they have been widely used for decades for a variety of reasons on the skin. Alpha HA (AHA), a naturally occurring compound found in many fruits, is a carboxylic acid with one hydroxyl group attached to the alpha position of the carboxyl group [1]. Through the mechanism of gentle cleavage, the bonds between keratinocytes break, inducing fresh collagen to form. AHAs are well known for their efficacy in treating fine lines and wrinkles, seborrheic or actinic keratoses, verrucae vulgares, psoriasis, acne, xerosis, ichthyosis, and hyperpigmentation [1]. A few well-known examples of AHAs include glycolic acid, lactic acid, and mandelic acid [2].

Much like the AHAs, beta HAs (BHAs) are similarly structured but instead of the hydroxyl group attachment to the alpha position of the carboxyl group, attachment is to the beta position of the carboxyl group. BHAs utilize the same mechanism of action as AHAs, but it is valuable to note that while AHAs are water soluble and penetrate to the dermis, BHAs are lipid-soluble and penetrate only to the epidermis and pilosebaceous unit [3], meaning the latter are more effective when treating oily skin types due to their capability of penetrating through sebaceous follicles [4]. The most notable BHA is salicylic acid, in addition to its related entities including sodium salicylate and willow bark extract [2].

A third group of HAs are polyhydroxy acids (PHAs), which are differentiated by their unique carboxylic acid molecular structure which is comprised of 2⁺ hydroxyl groups. The hydroxyl groups are attached to either the carbon atoms or an alicyclic chain. It should be noted that at least one of the hydroxyl groups must be attached at the alpha position of the carboxyl group [5]. PHAs have been purported to be less irritating to the skin than AHAs and BHAs in cosmeceuticals due to their larger molecular size, in addition to their surface-level penetration capability versus a deeper level that AHAs and BHAs are able to reach [3]. PHAs are humectants which allow for greater moisturization efficacy when compared to AHAs and BHAs, and they also contain antioxidant/chelation characteristics [5]. Polyhydroxy bionic acids are another group related to PHAs and HAs, with the differentiating feature of having an extra sugar molecule which is attached to the PHA. They act through analogous mechanisms of action by gently exfoliating the stratum corneum and, consequently, smoothing the skin [5]. Gluconolactone is one of the more prominent examples from the PHA family, commonly found in many skincare products and cosmeceuticals. Gluconolactone effectively reinforces the skin barrier while maintaining the HA’s anti-aging property of exfoliation to improve the skin’s texture and quality [2].