Protective Effects of Schinus terebinthifolius Leaf Supercritical Fluid Extract Against UVC-Induced Oxidative Stress: A Com-Prehensive Gene Expression Study

Ultraviolet (UV) exposure accelerates skin aging by inducing oxidative stress, extracellular matrix (ECM) degradation, and epidermal barrier dysfunction. This study investigated the protective effects of Brazilian pepper tree (SB), neem (SD), and Vietnamese coriander (PP) leaf extracts obtained by supercritical fluid extraction (SFE) using CO₂ with ethanol as a co-solvent against radiation-induced cellular damage. Among these, SB yielded the greatest amount of extract and exhibited the highest levels of phenolic and flavonoid constituents, including naringin, epicatechin gallate, and rosmarinic acid. These compounds, identified through HPLC profiling, were associated with strong inhibition of collagenase, elastase, and hyaluronidase, and exhibited potent antioxidant activity in the DPPH assay. Under UVC-induced oxidative stress in HaCaT keratinocytes, SB markedly enhanced the mRNA expression of key genes involved in ECM integrity (<i>COL1A1</i>, 3.04 ± 0.15-fold), epidermal barrier and hydration (<i>FLG</i>, 4.66 ± 0.17-fold; <i>HAS1</i>, 1.90 ± 0.14-fold), and cellular defense mechanisms (<i>SIRT1</i>, 3.83 ± 0.54-fold), demonstrating superior efficacy to reference antioxidants (EGCG and ascorbic acid) in upregulating key barrier genes like FLG. Overall, the findings highlight SB as the extract with the most comprehensive photoprotective properties and support the use of SFE-derived botanical extracts as promising agents for natural and photoprotective skincare applications.