Ethanolic extract of Hyptis mutabilis (Rich.) Briq.: An effective sedative and antioxidant agent in fish

The goal of this study was to evaluate the anesthetic potential of an ethanolic extract of Hyptis mutabilis and its effects on behavior, biochemistry, ionic balance, and oxidative stress biomarkers of silver catfish (Rhamdia quelen) after 24-h exposure. Additionally, its chemical composition was determined by high performance liquid chromatography coupled with a diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS) to identify its bioactive compounds. The concentration range of 50-500 mg L-1 induced only partial loss of equilibrium (14-2 min) in fish. There was quick recovery (about 5 min) with 50 and 100 mg L-1, while not all animals recovered within 30 min exposure to the higher concentrations. Fish exposed to 100 mg L-1 maintained a sedative level during the long-term experiment. There were lower plasma glucose and lactate levels in fish exposed to the extract compared with the control group (water). There were net Na+ and K+ influxes after exposure to the extract, while Cl- effluxes were observed in all groups (treated or not). Ammonia excretion decreased in animals exposed to extract, and creatinine elimination did not change. Fish exposed to 100 mg L-1 showed higher catalase and glutathione S-transferase activities in the kidney, while glutathione-dependent peroxidase activity increased in the liver. Lipid peroxidation in the kidney did not differ among experimental groups, while there were lower levels in the liver of juveniles exposed to the extract. There was no mortality or side effects in any of the experiments. Rosmarinic acid (53.76 +/- 0.13 mg g(-1) extract) and rutin (5.75 +/- 0.28 mg g(-1) extract) were identified in the extract based on standards. In conclusion, the ethanolic extract of H. mutabilis is a promising fish sedative at 100 mg L-1. Its use for long-term exposure showed a good safety margin and ability to prevent stress. Hence, it can be proposed for use in the transport of aquatic animals.

Automated summary

The study evaluated the anesthetic potential of an ethanolic extract of Hyptis mutabilis on silver catfish (Rhamdia quelen) and found promising sedative effects at 100 mg L-1. Long-term exposure showed good safety and stress prevention abilities, making it suitable for use in the transport of aquatic animals.