Senomorphic Activity of a Novel Standardized Propolis Extract in Human Dermal Fibroblasts: Molecular Insights into Clinically Proven Anti-Wrinkle Efficacy

Background We recently demonstrated in a randomized controlled trial (RCT) that a Standardized Propolis Extract (SPE), produced via a patented non-alcoholic PEG 400/lecithin process, achieves significant clinical anti-wrinkle efficacy (34% wrinkle depth reduction). The present study investigates the underlying molecular mechanisms, specifically its potential senomorphic activity—the ability to modulate the Senescence-Associated Secretory Phenotype (SASP) without inducing cell death. Objective To evaluate the senomorphic activity of this chemically defined SPE (standardized to 1318.43 µg/g total phenolic markers) in an in vitro model of oxidative stress-induced senescence, providing molecular insights into its clinically observed anti-aging effects. Methods Human Dermal Fibroblasts (HDFs) were pre-treated with SPE (0.01%, 0.05%) or Rapamycin (3µM, reference senomorphic control). Senescence was induced via a validated stress-induced premature senescence (SIPS) protocol (200µM H₂O₂, 2 hours). Gene expression for senescence markers (CDKN2A/p16, CDKN1A/p21), SASP cytokines (IL-6, IL-8), and cell cycle regulators (CDK4, CDK2, CCNE1) was quantified by qPCR. An exploratory study on Mesenchymal Stem Cells (MSCs) assessed SA-β-galactosidase activity qualitatively. Results The 0.05% SPE demonstrated potent senomorphic activity, significantly suppressing the key SASP marker IL-6 (FC: -7.78, p = 0.003)—comparable to the Rapamycin control (FC: -8.1, p = 0.003). Uniquely, SPE induced transcriptional upregulation of CDK4 (FC: +6.71, p = 0.002) and CDKN1A/p21 (FC: +2.33, p = 0.005), effects not observed with Rapamycin. In exploratory MSC experiments, SPE qualitatively reduced SA-β-gal staining. Conclusion This first-in-class standardized propolis extract demonstrates distinct senomorphic activity, suppressing the inflammatory SASP (IL-6) while inducing transcriptional modulation of pro-regenerative pathways (CDK4). These molecular findings provide mechanistic insights consistent with the extract's clinically proven anti-wrinkle efficacy, supporting its positioning as an evidence-based active ingredient for dermo-cosmetic formulations targeting inflammaging.