Amalaki Rasayana, a Gallic Acid-Enriched Traditional Phytomedicine, Attenuates Left Ventricular Cardiac Remodeling Associated with Excess Extracellular Galectin-3 Through Modulation of Surface Engagement and Compartmentalization: A Non-Canonical Mechanism of Antioxidant Cardioprotection

Natural polyphenol-rich interventions are widely investigated for antioxidant protection, yet whether such interventions influence non-redox mechanisms of cardiac mechanoadaptation remains incompletely understood. Amalaki Rasayana (AR) is a traditional phytomedicine with antioxidant properties used for cardioprotection. Here, we investigated whether extracellular C-terminal-epitope-reactive Galectin-3 (Gal-3) species are associated with altered cardiomyocyte surface organization and mechanotransduction-associated signaling, and whether these responses are modulated by AR. In complementary mechanistic cardiomyocyte cell-culture experiments, we further examined whether gallic acid (GA), an analytically prominent and bioavailable constituent of AR, recapitulates selected AR-associated anti-hypertrophic effects. Using biologically aged and left ventricular pressure-overload rat models, followed by complementary in vitro cardiomyocyte mechanical-loading assays, biochemical and imaging approaches, and exploratory analyses of human serum and myocardial tissue, we examined epitope-resolved Gal-3 species, their compartmental distribution and surface-associated clustering, and associated mechanotransduction responses. Pressure overload increased extracellular and surface-associated C-terminal-epitope-reactive Gal-3 species, including a higher-molecular-weight population distinct from full-length Gal-3, accompanied by reduced intracellular Gal-3 and hypertrophic remodeling. C-terminal-epitope-enriched human serum induced surface-associated Gal-3 clustering and altered calcium responses, RhoA–ROCK1-F-actin organization, the NFATC2–MEF2A hypertrophic transcriptional axis, and nuclear stress responses. AR attenuated hypertrophic remodeling while shifting Gal-3 distribution away from extracellular and surface-associated C-terminal-epitope-reactive species toward intracellular retention. In complementary mechanical-loading experiments, GA recapitulated selected AR-associated effects. Additional mechanistic experiments supported roles for Gal-3 C-terminal-epitope (carbohydrate-recognition domain, CRD)-dependent surface engagement and Ser6-phosphorylation-sensitive regulation of intracellular Gal-3. Together, these findings support a potentially non-canonical, Gal-3-centered mechanism through which a polyphenol-rich antioxidant intervention may modulate pathological cardiac mechanoadaptation by regulating Gal-3 compartmentalization and surface engagement.