Background: Tumor growth is associated with systemic oxidative stress and inflammatory signaling, including altered cyclooxygenase expression. Resistance exercise and pineapple-derived bioactive compounds, particularly bromelain, may improve antioxidant defense and modulate inflammatory pathways. This study evaluated the independent and combined effects of resistance exercise and pineapple extract supplementation on hepatic Cox1/Cox2 expression, serum catalase activity, and lipid peroxidation in B16F10 melanoma-bearing mice.

Methods: Thirty-two male C57BL/6 mice were inoculated with B16F10 melanoma and randomly assigned to four groups: tumor-bearing control, resistance exercise, pineapple extract (300 mg/kg/day by oral gavage), and resistance exercise plus pineapple extract. Interventions began one week after tumor inoculation and continued for six weeks. Resistance training was performed three times weekly using a progressive ladder-climbing protocol. At the endpoint, serum catalase activity and malondialdehyde (MDA) concentration were measured, and hepatic Cox1 and Cox2 mRNA expression were quantified by quantitative real-time PCR using Gapdh as the reference gene.

Results: Both resistance exercise and the combined intervention significantly increased the hepatic Cox1/Cox2 expression ratio compared with the control group (p = 0.0107 and p = 0.0003, respectively), whereas pineapple extract alone did not significantly alter this ratio. Catalase activity was significantly elevated in all intervention groups, with the greatest increase observed after combined exercise and pineapple extract supplementation (p < 0.0001 versus control). Serum MDA concentration was significantly reduced by resistance exercise, pineapple extract, and the combined intervention relative to control (p = 0.0229, p = 0.003, and p = 0.0003, respectively).