eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2026-06-19 19 2 72315 article JaxongirIsmoiljono‘g‘liTuychiboyev 1 Nodira Gulomdjanovna Abdulladjanova 2 Rustamjon Rasuljonovich Makhmudov 2 Damira Turdibekovna Atabayeva 1 Zulkhumor Shukhradovna Mirzayeva 1 Farangiz Oybekqizi Alimova 1 Department of Biology, Chirchik State Pedagogical University, Chirchik, Uzbekistan Laboratory of Protein and Peptide Chemistry of the Institute of Bioorganic Chemistry named after A. Sadykov, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan. Department of Human and Animal Physiology, National University of Uzbekistan named after Mirzo Ulugbek, Tashkent, Uzbekistan. Hypothyroidism is a condition characterized by insufficient production of thyroid hormones and impaired adaptive mechanisms of the body to stress. The present study aimed to evaluate the corrective effects of plant-derived polyphenols on thyroid function and stress-related hormonal alterations in a Mercazolil-induced experimental model of hypothyroidism. In experimental hypothyroid rats, the phytosubstanceRutan, Providin, and Anakardin-2 were administered at doses of 50 and 100 mg/kg, as well as Dehydroquercetin at a dose of 5 mg/kg. The levels of free T₃, T₄, adrenaline, and cortisol in blood serum were determined using standard enzyme-linked immunosorbent assay  methods. Statistical analysis was performed using Python software, and the graphs were generated using Matplotlib.As a result of mercazolil administration, a significant decrease in free T₃, T₄, and adrenaline levels, along with an increase in cortisol concentration, was observed compared to the healthy control group (p < 0.05–0.001). This condition reflects a reduction in thyroid and sympathoadrenal system activity, accompanied by activation of the hypothalamic–pituitary–adrenal axis, which ensures the body’s adaptive mechanisms to stress. Treatment with polyphenols led to a dose-dependent normalization of hormonal parameters. In groups receiving the higher dose of 100 mg/kg, a significant restoration of free T₃, T₄, and adrenaline levels, as well as a reduction in cortisol concentration, was observed compared to the hypothyroid group. The most pronounced corrective effects were observed in the Providin and Dehydroquercetin groups, with the parameters reaching physiological levels.The obtained results confirm that plant-derived polyphenols exert corrective and restorative effects on thyroid function and the imbalance of the hypothalamic–pituitary–adrenal axis under experimental hypothyroid conditions. https://biomedpharmajournal.org/vol19no2/effects-of-plant-derived-polyphenols-on-thyroid-and-stress-related-hormonal-alterations-in-experimental-hypothyroidism/ Adrenaline Cortisol Hypothyroidism Tetraiodothyronine (T₄) Triiodothyronine (T₃)