We investigated the toxicity, psychotropic side effects and anxiolytic potential of an Echinacea angustifolia extract that produced promising effects in laboratory tests performed earlier. Rats were studied in the elevated plus-maze, conditioned fear, open-field, object recognition and conditioned place preference tests. Toxicity was studied in rats after intragastric administration. The preparation decreased anxiety in the elevated plus-maze and ameliorated contextual conditioned fear. No lethality or behavioural signs of discomfort were noticed in rats treated with 1000 and 3000 mg/kg Echinacea angustifolia. The extract was without effect in tests of locomotion (open-field), memory (object recognition) and rewarding potential (conditioned place preference) within a wide dose range. A pharmacological formulation based on the same E. angustifolia extract was tested in human subjects. One or two tablets per day were administered for 1 week to healthy volunteers scoring high on the State-Trait Anxiety Inventory (STAI). The tablets contained 20 mg of the plant extract. Data were collected using a structured self-assessment diary technique. The high dose (2 tablets per day) decreased STAI scores within 3 days in human subjects, an effect that remained stable for the duration of the treatment (7 days) and for the 2 weeks that followed treatment. The lower dose (1 tablet per day) did not affect anxiety significantly.
- State-Trait Anxiety Inventory
- conditioned fear
- elevated plus-maze
- side effects
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