AHAs (Alpha Hydroxy Acids) primarily act by virtue of their exfoliating properties, which involve the disruption of intercellular adhesions between corneocytes, the outermost layer of skin cells, leading to the elimination of dead skin cells and the facilitation of cell turnover. Notably, glycolic acid, extensively investigated among AHAs, has been found to augment desquamation by stimulating the activity of enzymes implicated in the degradation of corneodesmosomes, the structures responsible for maintaining the integrity of the stratum corneum. This process engenders the removal of superficial damaged layers, unveiling a smoother and more vibrant skin texture.
Beyond their exfoliative role, AHAs also play a pivotal role in stimulating collagen synthesis, a crucial determinant of skin elasticity and firmness. Research studies have established that AHAs, such as glycolic acid and lactic acid, can induce upregulation of collagen production in the dermis, the deeper layer of the skin. This stimulation transpires through diverse mechanisms, encompassing the activation of fibroblasts, heightened expression of collagen-related genes, and modulation of signalling pathways implicated in collagen synthesis. Consequently, the employment of AHAs can contribute to the reduction of fine lines, wrinkles, and overall skin texture.
AHAs have also been shown to enhance the skin’s barrier function and hydration. AHAs promote the synthesis of epidermal lipids, such as ceramides and cholesterol, which assume a vital role in upholding a healthy skin barrier, acting as a protective shield against external aggressors and maintaining moisture balance. By fortifying the barrier function, AHAs assist in averting trans-epidermal water loss and maintaining optimal hydration levels in the skin. This attribute holds particular significance for individuals with dry or dehydrated skin, as AHAs can aid in the restoration and retention of moisture, thereby yielding a smoother and well-hydrated complexion.
The combination of AHAs and beta-hydroxy acids (BHAs) represents a compelling synergy in skincare formulations, exhibiting remarkable potential for enhancing overall skin health and addressing various dermatological concerns. AHAs, such as glycolic acid and lactic acid, work predominantly on the skin’s surface by exfoliating dead skin cells and promoting cellular turnover, while BHAs, notably salicylic acid, penetrate deeper into the pores, aiding in the treatment of acne.
The complementary actions of AHAs and BHAs offer a multifaceted approach to skincare, yielding synergistic effects that can result in improved skin texture, tone, and clarity. Recent research endeavours have delved into the mechanisms of action of AHAs. Lupu et al. investigated a topical formulation containing both AHAs and BHAs, along with anti-inflammatory and antibacterial molecules. Following a 28-day regimen, a substantial decrease in the number of dilated infundibula, infundibula filled with keratotic material, and infundibula with thickened bright borders were observed. These findings offer promising prospects for ameliorating various inflammatory skin conditions, such as rosacea.
AHAs have also been shown to modulate the expression of genes implicated in skin pigmentation, leading to an overall reduction in melanin synthesis and an improvement in hyperpigmentation. In a systematic review investigating treatments for lentigines, a common form of hyperpigmentation, 58% of individuals experienced a complete or partial response following chemical peels with AHA/BHAs. These findings further underscore the multifaceted mechanisms by which AHAs exert their beneficial effects on the skin.
Overall, the mechanisms of action of AHAs on the skin encompass exfoliation, stimulation of collagen synthesis, enhancement of the skin’s barrier function and hydration, as well as anti-inflammatory and depigmenting effects. By employing these mechanisms, we can harness the therapeutic potential of AHAs for a broad spectrum of dermatological conditions, including textural skin changes and photoaging, hyperpigmentation, and inflammatory skin disorders.
This is not my own work, but taken from:
Karwal, K.; Mukovozov, I. Topical AHA in Dermatology: Formulations, Mechanisms of Action, Efficacy, and Future Perspectives. Cosmetics 2023, 10, 131. https://doi.org/10.3390/cosmetics10050131
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