Senotherapeutic Potential of Araliadiol in Senescent Human Dermal Fibroblasts: An In Vitro Study Using Three Senescence Models

<b>Background/Objectives</b>: With the rapid aging of the global population, the interest in therapies for age-related diseases has increased substantially. The skin is particularly important, as aging-related changes are visible and negatively impact quality of life. Therefore, the identification of senotherapeutic candidates that are effective against skin aging is of considerable importance. Given the cost and reproducibility limitations of existing senescence models, this study established three dermal fibroblast senescence models induced by etoposide, hydrogen peroxide, and ultraviolet A, representing intrinsic and extrinsic aging. Furthermore, considering the adverse effects of current photoaging treatments, such as tretinoin and methoxsalen, we investigated the senotherapeutic potential of araliadiol, a plant-derived compound, in these models. <b>Methods</b>: Senescence induction and validation were assessed using trypan blue-based cell counting, senescence-associated β-galactosidase (SA-β-gal) staining, and adenosine triphosphate content assays. The senotherapeutic potential of araliadiol was further evaluated using quantitative reverse transcriptase-polymerase chain reaction, Western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay. <b>Results</b>: Compared with non-senescent fibroblasts, senescent cells exhibited increased SA-β-gal positivity, elevated intracellular reactive oxygen species levels, and upregulated p16 and p21 expression. The senolytic agent ABT-737 selectively induced apoptosis in senescent fibroblasts but not in non-senescent fibroblasts, validating the models. Araliadiol showed no senolytic activity but demonstrated potential senomorphic effects, including reduced expression of senescence-associated secretory phenotype (SASP) genes (<i>IL1β</i>, <i>IL6</i>, <i>IL8</i>, <i>CCL2</i>, and <i>CXCL1</i>) and NF-κB p65 phosphorylation, suppression of MMP-1 (up to 2.35-fold reduction) and MMP-3 (up to 30.53-fold reduction) expression and AP-1 activation, and increased extracellular procollagen type I content (up to 18.35% increase). <b>Conclusions</b>: Araliadiol exerted senomorphic-but not senolytic-effects across three validated dermal fibroblast senescence models, supporting its potential as a natural topical therapeutic agent for mitigating skin aging.