Bioactive Phenolics from Vinegar–Egg Accelerates Acute Wound Healing by Activation of Focal Adhesion and Mitogen-Activated Protein Kinase Signaling

Background/Objectives: Vinegar–egg is a traditional health-promoting beverage prepared by soaking eggs in vinegar. While both eggs and vinegar are common dietary components with well-documented nutritional and pharmacological activities, eggs treated with vinegar have been rarely studied. This study aims to identify and characterize bioactive compounds in vinegar–egg and investigate their potential wound-healing activities. Methods: The vinegar–egg extract was analyzed using liquid chromatography–mass spectrometry (LC–MS) and column chromatography, including HPLC purification, which led to the isolation of four phenolic compounds. Results: These compounds were identified as 4-hydroxybenzoic acid (1), vanillic acid (2), methyl syringate (3), and leptosperin (4) using ESI-MS, UV, and NMR spectroscopic data. Among the isolates, 4-hydroxybenzoic acid (1) and vanillic acid (2) demonstrated wound-healing properties in mouse embryonic fibroblast (MEF) cells. None of the compounds, 4-hydroxybenzoic acid (1), vanillic acid (2), methyl syringate (3), or leptosperin (4), exhibited cytotoxicity in PC12, AGS, MEF, or MDA-MB-231 cells. Notably, 4-hydroxybenzoic acid (1) enhanced cell motility by 2.59-fold and cell invasion by 1.20-fold, while vanillic acid (2) increased cell motility by 2.69-fold and cell invasion by 1.23-fold. Western blot analysis revealed that treatment with 4-hydroxybenzoic acid (1) and vanillic acid (2) increased the phosphorylation of focal adhesion kinase (p-FAK) and matrix metalloproteinase 2 (MMP-2). Furthermore, both compounds elevated the phosphorylation of p38, a key regulator in wound-healing pathways. Conclusions: These findings demonstrate that 4-hydroxybenzoic acid (1) and vanillic acid (2) accelerate wound healing through the activation of focal adhesion and mitogen-activated protein kinase (MAPK) signaling pathways. These results highlight vinegar–egg as a promising therapeutic candidate for wound healing.