Assoc. Prof. HUYNH VAN BA PhD.,MD
Head of Department of Dermato-Venereology
Can Tho University of medicine and pharmacy
Vice President, Vietnamese Society of Dermatology and Venereology
ABSTRACT
Antioxidants are popular skin care ingredients that can help neutralize free radicals, help protect healthy cells from damage caused by free radicals. Antioxidants include some vitamins (such as vitamins C and E), some minerals (such as selenium), and flavonoids, which are found in plants. The best sources of antioxidants are fruits and vegetables. Botanically derived antioxidants and natural extracts are frequently used for skin lightening due to their skin brightening and anti-inflammatory effects. Silymarin, arbutin, Aloe vera, niacinamide, ascorbic acid, green tea,…… are some of the more common agents seen in cosmeceutical products.
Hydroxy acids (HAs) is also a natural anti-oxidant, represent a class of compounds which have been widely used in a number of cosmetic and therapeutic formulations in order to achieve a variety of beneficial effects for the skin. We review and discuss the most frequently used classes of these compounds, such as α-hydroxy acids, β-hydroxy acids, polyhydroxy acids, and bionic acids, and describe their applications as cosmetic and therapeutic agents. HAs play an important role in cosmetic formulations, as well as in many dermatologic applications, such as in treating photoaging, acne, ichthyosis, rosacea, pigmentation disorders, and psoriasis.
Alpha-hydroxy acids (AHAs) include glycolic, lactic, mandelic, tartaric, malic and citric acids. Lactic and glycolic acids are most commonly used in dermatologic therapy and are found at various concentrations and pH levels in a myriad of formulations, including cleansers, shampoos, lotions, creams, gels, masks and peeling agents. Dermatologic conditions for which AHAs are utilized include xerosis, acne vulgaris, rosacea and photoaging.
Mechanism of action: AHAs diminish the strength of intercellular bonding, thereby weakening corneocyte cohesion and leading to exfoliation. AHAs tend to influence corneocyte cohesion at lower, newly forming levels of the cornified layer.
A new generation of AHAs, called polyhydroxy acids (PHAs), was discovered that provide similar effects as AHAs but do not cause the sensory irritation responses. PHAs have been found to be compatible with clinically sensitive skin, rosacea and atopic dermatitis. PHAs provide additional humectant and moisturization properties, enhance stratum corneum barrier function, therefore increasing the skin’s resistance.
Keywords: Salicylic acid, Hydroxy acids, polyhydroxy acids, Postinflammatory hyperpigmentation, antioxidants.
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