Phenolic Composition and Protective Effects of Actinidia arguta Leaves Extracts on UVB-irradiated HaCaT Cells Prepared with Different Ethanol Concentrations

This study aimed to analyze the major bioactive compounds in the leaves of Actinidia arguta (hardy kiwi) and to evaluate their potential as functional materials by comparing marker compound content and cell-protective effects under different solvent extraction conditions. Dried Actinidia arguta leaves (AAL) were extracted using reflux extraction with 100% ethanol, 50% ethanol, or distilled water as solvents. The extracts were then concentrated under reduced pressure and lyophilized. High-performance liquid chromatography (HPLC) was employed to quantitatively analyze four marker compounds neochlorogenic acid, chlorogenic acid, ferulic acid, and isoquercitrin. Human keratinocyte (HaCaT) cells were irradiated with ultraviolet B (UVB, 25 mJ/cm²) and subsequently treated with the extracts at concentrations of 50, 100, and 200 μg/mL. Cell viability was determined using the MTT assay. The extraction yield was highest in the 50% ethanol extract (AAL 50E, 31.92%), followed by the 100% ethanol extract (AAL 100E, 15.98%) and the distilled water extract (AAL D.W, 10.25%). HPLC analysis showed excellent linearity with R²values above 0.9995, and the limits of detection (LOD) and limits of quantification (LOQ) confirmed the reliability of the analytical method. The total phenolic compound content was highest in the AAL 50E extract, reaching 0.531 ± 0.011%. In the HaCaT cell assay, UVB-induced cytotoxicity was effectively alleviated by AAL 50E in a dose-dependent manner, with the 200 μg/mL treatment showing the highest cell viability (93.9 ± 3.5%). In contrast, the AAL D.W extract showed a lower protective effect (61.8 ± 4.9% at 200 μg/mL) but still exhibited an increasing trend in cell viability. Overall, Actinidia arguta leaf extracts exhibited notable phenolic content and protective effects against UVB-induced damage in HaCaT cells. In particular, the 50% ethanol extract (AAL 50E) contained the highest levels of phenolic compounds and demonstrated concentration-dependent recovery of cell viability, suggesting its potential as a functional material for mitigating UV-induced cellular damage.