Received February 16, 2026
Accepted March 02, 2026

Objective: Resorcinol bis(diphenyl phosphate) (RDP) is a widely used organophosphate flame retardant, yet data on its reproductive toxicity are limited. This study evaluated the gonadotoxic effects of RDP and the protective potential of ethanolic Citrus sinensis peel extract (EECS) in male Wistar rats. Methods: Twenty-eight rats were randomized into four oral treatment groups: control, RDP (500 mg/kg), EECS (600 mg/kg), and RDP+EECS, administered for 14 days. Results: RDP exposure significantly impaired sperm quality and reduced circulating testosterone levels. Testicular dysfunction was accompanied by qualitative histoarchitectural distortion, oxidative stress, inflammatory responses, and apoptosis. Co-administration of EECS ameliorated these effects, improving sperm parameters and antioxidant status and reducing inflammatory and apoptotic markers. Conclusion: RDP induces testicular dysfunction through oxidative-inflammatory and mitochondrial pathways, whereas EECS exerts protective effects via antioxidant and anti-inflammatory mechanisms. These findings suggest that EECS may be a promising agent against RDP-induced reproductive toxicity.