Effects of Coffee Grounds Extract on Scalp Health and Skin Barrier Function

Environmental stressors such as pollution, excessive cleansing, and microbial imbalance are major contributors to scalp and skin barrier dysfunction, often leading to inflammation and chronic scalp disorders. This study aimed to evaluate the biological activities of spent coffee grounds extract (CGE) as a functional ingredient for scalp health and skin barrier enhancement. Given the growing demand for mild and sustainable active ingredients, CGE, an upcycled by-product of the coffee industry, was investigated across multiple in vitro models. CGE significantly inhibited Malassezia furfur-derived lipase activity in a dose-dependent manner, thereby reducing the generation of irritant free fatty acids. In LPS-stimulated RAW264.7 macrophages, CGE suppressed the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂), demonstrating anti-inflammatory efficacy comparable to the iNOS inhibitor 1400W and the cyclooxygenase-2 inhibitor, celecoxib. In HaCaT-HSD11β1 reporter cells, CGE significantly inhibited HSD11β1 promoter activity, suggesting a role in modulating stress hormone–mediated barrier impairment. Furthermore, CGE promoted hyaluronic acid synthesis in keratinocytes and exhibited potent antioxidant activity in the DPPH radical scavenging assay. Collectively, these findings indicate that CGE contributes to scalp improvement and skin barrier protection through anti-inflammatory, antioxidant, barrier-regulatory, and moisturizing effects. As a sustainable by-product of the coffee industry, CGE may be applicable as a natural functional material for cosmetic and scalp care applications, providing both efficacy and environmental benefits.