Preserved organ function and redox homeostasis following repeated oral exposure to Quercus suber acorn shell extract in female FVB/n mice

Acorn shells (AS), a by-product of Quercus suber acorn processing, are rich in phenolic compounds with recognized bioactivities. However, their incorporation into food or nutraceutical formulations requires in vivo safety assessment under physiologically relevant exposure conditions. This study evaluated the effects of a hydroethanolic AS extract following repeated oral intake in female FVB/n mice over 25 days. The extract’s phenolic profile was characterized by HPLC-DAD-ESI-MS/MS. Nineteen animals (8-12 weeks old) were randomly assigned to four groups receiving drinking water containing 0, 100, 200 and 500μg/mL of extract. Animal welfare, food and water intake, and body weight were monitored throughout the study. At the end, animals were euthanised via anesthetic overdose, after which blood was collected for biochemical analysis, organs were weighed, and liver and kidney processed for histology and oxidative stress analysis. The extract was dominated by phenolic acids and hydrolysable tannins, primarily gallic/ellagic acid derivatives. No toxicity signs or mortality were recorded, and food and water intake remained similar across groups. Body weight and food and water intakes were unaffected, whereas an increase in liver, spleen, and left kidney relative weight was observed in the 200μg/mL dose ( p <0.05). Biochemical parameters were also preserved between groups, though the 200μg/mL group showed reduced renal lipid peroxidation ( p <0.05). Histological examination revealed no treatment-related hepatic or renal lesions. Overall, these findings indicate that repeated oral exposure to AS extract does not compromise systemic homeostasis under the tested conditions, supporting further exploration as a sustainable source of bioactive compounds as functional dietary ingredients. • Repeated oral exposure to acorn shell extract resulted in preserved organ function • Hepatic and renal architecture remained intact across all tested doses • Ellagic and gallic acid derivatives dominated the extract phenolic profile • Intermediate dose (200 μg/mL) reduced renal lipid peroxidation • Acorn shell is a phenolic-rich bioresource for development of functional products