Sceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers

Jonathon Reay, Mark A. Wetherell, Emma Morton, James Lillis, Vladimir Badmaev

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Objective: To investigate the anxiolytic properties of a standardized extract of Sceletium tortuosum (trademarked―Zembrin®). Methods: Two studies utilized a placebo-controlled, double-blind, between-subject experimental design to investigate the effects of a single dose of Sceletium tortuosum (25 mg, Zembrin®) on laboratory stress/anxiety responding in 20 young healthy volunteers. To elicit feelings of stress/anxiety, participants completed 20 min of the multitasking framework in study 1 and a 5-min simulated public speaking task in study 2. Study 1 measured subjective experiences of mood at baseline, prestress induction, and poststress induction. Study 2 measured subjective experiences of anxiety and physiological indicators of stress (heart rate [HR] and galvanic skin response) at baseline, prestress induction, during stress induction, and poststress induction. Results: A series of analysis of covariances (baseline entered as the covariate) revealed no treatment effect in study 1; however, study 2 revealed subjective anxiety levels to be significantly lower in the Zembrin® group at the prestress induction point and a significant interaction between treatment and time on HR. Taken together, results indicate that a single dose of Zembrin® can ameliorate laboratory stress/anxiety responding in healthy volunteers. Conclusion: We provide the first tentative behavioral evidence to support the anxiolytic properties of Sceletium tortuosum (25 mg Zembrin®).

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalHuman Psychopharmacology
Issue number6
Publication statusPublished - 6 Aug 2020


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