Fruit extract of Plinia trunciflora (O. Berg) Kausel reduces cortisol levels and exhibits antioxidant effects in Rhamdia quelen exposed to acute stress

ABSTRACT Rhamdia quelen is a species native to the Americas that plays a significant role in extractive fishing and aquaculture in southern Brazil. It has been recognized as one of the most promising species for fish farming due to its resilience to management practices, rapid growth, and good feed efficiency. However, the intensification of farming systems exposes fish to stressful conditions, leading to diseases, reduced production yields, and negative environmental impacts. The jaboticaba tree (Plinia trunciflora), indigenous to Brazil, produces fruits rich in anthocyanins with high antioxidant activity. This study aimed to investigate the effects of jaboticaba fruit extract on oxidative stress parameters and whole-body cortisol levels in R. quelen under acute stress. A dried hydroalcoholic extract was incorporated into the fish diet and administered for 15 days. Afterward, the fish underwent an acute stress protocol using a net chase model. The effects of the treatment were evaluated by assessing superoxide dismutase, catalase (CAT), glutathione S-transferase (GST), lipid peroxidation (LPO), and non-protein thiol group levels in the liver of R. quelen. The results indicated that the extract effectively prevented oxidative damage and mitigated the stress-induced increase in cortisol levels. This study represents the first instance of demonstrating that adding an extract to fish diets can counteract the damage caused by acute stress by activating antioxidant systems and alleviating stress responses.