Glycolic acid, also known as hydroxyacetic acid, hydroxyethanoic acid, or cane acid, is the simplest structure and the smallest molecular-weight member of the AHAs family.

Mechanism 1: Inhibition of Cutibacterium acnes Growth

Cutibacterium acnes can promote the release of pro-inflammatory factors such as IL-1、IL-8、IL-12 and TNF-α, triggering inflammatory responses in the skin and driving the aggregation and proliferation of keratinocytes, which contributes to acne formation. In addition, C. acnes can directly stimulate keratinocyte clustering and proliferation, further aggravating acne. GLA can inhibit the growth of C. acnes, thereby helping alleviate acne symptoms.

Mechanism 2: Inhibition of the NF-κB Pathway

NF-κB (nuclear factor kappa-B) is a protein complex involved in cellular responses to various stimuli, including inflammation, immune regulation, apoptosis, and stress responses. Excessive activation of NF-κB can lead to persistent inflammatory reactions.

Topical application of GLA can suppress the UVB-activated NF-κB signaling pathway, thereby reducing the production of inflammatory factors such as IL-1β, IL-6, IL-8, COX-2, TNF-α, and MCP-1. This ultimately leads to a reduction in inflammatory responses.

Mechanism 3: Upregulation of DNA Methyltransferase (DNMT) Expression

GLA can upregulate the expression of DNA methyltransferases (DNMTs), which subsequently reduces the expression of inflammasome components (NLRC4 and ASC) in keratinocytes. This leads to the disassembly of the inflammasome and decreases the release of downstream inflammatory factors. As a result, GLA exhibits anti-inflammatory effects.

Mechanism 4: Reducing Intercellular Adhesion Among Keratinocytes

GLA can activate serine proteases and steroid sulfatases (SP & STS), which act on intercellular desmosomes to reduce adhesion between keratinocytes, thereby promoting their shedding. This desquamation also facilitates the removal of epidermal melanin, improving hyperpigmentation. In addition, the accelerated turnover stimulates skin repair mechanisms and promotes collagen regeneration, ultimately helping to reduce fine lines.

In summary, through the dual pathways of inhibition and promotion, AC-GLA not only improves acne, inflammation, and hyperpigmentation, but also enhances overall skin structure and quality, making it a highly effective ingredient with both scientific backing and practical value.