Protective Effects of Eriobotrya japonica Fruit Extract Against UVB-Induced Damage in Human Keratinocytes

This study was conducted against the background that modern environmental factors, particularly chronic ultraviolet(UV) exposure, promote oxidative stress and photoaging of the skin, and aimed to explore the potential of natural-derived ingredients for photoprotective strategies by evaluating the antioxidant activity and skin-protective effects of loquat (Eriobotrya japonica (Thunb.) Lindl.) fruit extracts as functional materials. Loquat fruits were reflux-extracted with 100% ethanol (EJF 100E), 50% ethanol (EJF 50E), and distilled water (EJF D.W.), followed by vacuum concentration and freeze-drying to prepare powdered samples. Antioxidant activities were assessed by DPPH and ABTS radical scavenging assays, and total phenolic and total flavonoid contents were quantified. Additionally, photoprotective efficacy was evaluated by measuring cell viability in HaCaT keratinocytes after ultraviolet B(UVB, 25 mJ/cm2) exposure. Antioxidant assays showed dose-dependent increases in DPPH and ABTS scavenging activity in the order EJF 50E > EJF 100E > EJF D.W. Total phenolic content was highest in EJF 50E, whereas total flavonoid content was highest in EJF 100E. Under UVB exposure conditions that reduced cell viability to approximately 54.6%, treatment with EJF 50E restored cell viability in a dose-dependent manner, reaching over 80% at the highest concentration. In contrast, EJF D.W. displayed a tendency toward decreased viability with increasing concentration and did not exhibit protective effects. The loquat fruit extracts demonstrated antioxidant activity and cellular protection, suggesting their potential application as skin protective materials to mitigate UVB induced photoaging. This study provides foundational data on the functional evaluation and optimal extraction conditions of loquat extracts and suggests their applicability for functional cosmetics and health supplements.