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

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 ® ).