Effects of a hydroalcoholic extract of Turnera diffusa Willd. ex Schult., Turneraceae, in tests for adaptogenic activity

The objective of the present study was to assess whether Turnera diffusa Willd. ex Schult., Turneraceae, (TD), plant known in popular medicine as tonic and aphrodisiac, has other effects that are characteristic of an adaptogen substance, such as improvement of the memory and reduction of the damage caused by stress. We carried out an initial screening to detect a possible toxicity of the plant. In that phase of the study we used tests of observational screening; evaluation of acute toxicity; measurement of motor activity and motor coordination, and sleeping time induced by pentobarbital, and observed that the extract presented low toxicity and no stimulant or depressant effect on the animals. We then performed specific tests for the evaluation of an adaptogen effect. TD did not protect the stomach of the animals from the formation of ulcers, neither did it alter the plasmatic levels of adrenocorticotropic hormone (ACTH) and corticosterone of the animals submitted to immobilization and cold. As regards the evaluation of memory in passive avoidance, TD did not inhibit scopolamine-induced amnesia. Additionally, the hydroalcoholic extract presented low antioxidant activity in vitro. In the models used, TD produced no changes in relation to a possible adaptogen effect.