Comparative Evaluation of Tamoxifen and Red Clover Extract on Reproductive and Hepatic Function in Female Trichogaster trichopterus: A Translational Endocrine Toxicology Study

Background & Objectives: Tamoxifen, a classic Selective Estrogen Receptor Modulator (SERM), regulates estrogen signaling in a tissue-dependent manner. Phytoestrogenic compounds such as red clover (Trifolium pratense), which activate estrogenic pathways via receptor agonism, are increasingly explored for their potential in hormone-related conditions. This study aimed to compare the endocrine and hepatic effects of tamoxifen and red clover extract in a validated vertebrate model, the female three-spot gourami ( Trichogaster trichopterus ). Methods A total of 120 adult female gourami were randomly assigned to eight groups, receiving intramuscular injections of tamoxifen (10, 50, 100 mg/kg), red clover extract (25, 75, 150 mg/kg), vehicle, or no treatment over 18 days. Reproductive (GSI, hormone levels, ovarian histology) and hepatic (HSI, ALT/AST levels, liver histology, TEM) parameters were assessed. Results Tamoxifen induced dose-dependent reductions in gonadosomatic index and levels of estradiol, progesterone, and testosterone, accompanied by elevated ALT and AST and histopathological liver changes. In contrast, red clover extracts increased GSI and sex hormones without hepatic damage. Histological and ultrastructural analyses confirmed arrested ovarian development and hepatic degeneration in tamoxifen-treated fish, while red clover–treated fish showed follicular maturation and preserved liver architecture. Conclusions The opposing profiles of tamoxifen and red clover underscore their distinct estrogen-modulatory mechanisms. Tamoxifen’s anti-estrogenic and hepatotoxic actions raise concerns about long-term use, while red clover demonstrated favorable reproductive stimulation and hepatic safety. These findings support red clover’s potential as a safer phytoestrogenic alternative for hormone regulation and provide a foundation for future translational research in women’s health.