Anti-Acne Potential of Quercus salicina Extract: Inhibition of Cutibacterium acnes Growth and Virulence

Acne vulgaris is a prevalent inflammatory skin disorder mediated by Cutibacterium acnes, a key etiological factor.In this study, the anti-acne properties of the ethyl acetate fraction of Quercus salicina Blume (QsB-EE) against C. acnes were investigated.The QsB-EE fraction was separated into subfractions (E1-E6) using preparative HPLC.Antimicrobial and antivirulence activities were evaluated via bacterial growth, biofilm, and lipase activity assays.Virulence gene expression was assessed using qRT-PCR, and bioactive compounds were identified by LC-MS/MS.The QsB-EE demonstrated significant antimicrobial (MIC 125 μg/ml) and strong anti-virulence effects.The E1 fraction was the most potent, exhibiting the lowest MIC (16 μg/ml), highest biofilm inhibition (86.19% at 1,000 μg/ml), and highest lipase inhibition (93.72% at 10 μg/ml).In addition, mechanistic studies confirmed that E1 significantly downregulated the expression of key virulence genes: ppa0149 (biofilm), gehA (lipase), and hyl (hyaluronidase).LC-MS/MS identified (+)-catechin as the major compound in E1, alongside kaempferol and quercetin in E5.Although further in vivo studies are warranted to evaluate the therapeutic efficacy, our findings suggest that QsB-EE possesses promising anti-acne potential by targeting C. acnes virulence factors through the active compounds concentrated in the E1 fraction.