Reproductive Toxicity of Sudan IV-Adulterated Palm Oil in Male Wistar Rats: Hormonal, Oxidative and Testicular Effects

Abstract

Sudan IV (S4D) is a synthetic azo dye prohibited for use in food because of its carcinogenic and mutagenic potential, yet it has been detected as an adulterant in edible palm oil. Despite evidence of systemic toxicity, information on its effects on male reproductive function remains limited. This study investigated the reproductive toxicity of S4D-adulterated palm oil in male Wistar rats, focusing on endocrine disruption, antioxidant responses, and inflammatory alterations as potential pathways of testicular injury. Forty-three male Wistar rats weighing 150–200 g were used, with 30 rats randomly assigned to five groups (n = 6). Groups 2–4 received S4D at 100, 200, and 400 mg/kg body weight, respectively, dissolved in unadulterated palm oil and administered orally by gavage once daily for 28 days. Groups 1 and 5 served as normal and palm-oil controls, respectively. Serum reproductive hormones, testicular antioxidant enzymes, inflammatory cytokines, sperm characteristics, and testicular histopathology were assessed. S4D exposure produced dose-dependent reductions in testosterone, follicle-stimulating hormone, sperm count and motility, with increased sperm abnormalities and progressive testicular architectural damage. Superoxide dismutase, catalase and glutathione peroxidase activities increased with dose, suggesting a compensatory antioxidant response to chemical stress, while tumour necrosis factor-alpha increased and interleukin-10 decreased. Histopathological examination revealed spermatogenic arrest and interstitial haemorrhage, particularly at higher doses. These findings indicate that repeated oral exposure to S4D-adulterated palm oil may impair male reproductive function through interacting endocrine, oxidative, and inflammatory disturbances. The findings highlight the potential reproductive-health implications of illegal Sudan IV adulteration of edible palm oil and support strengthened food-safety surveillance and further investigation of chronic exposure and underlying molecular mechanisms.