Pharmacological and Toxicological Study of Maytenus ilicifolia Leaf Extract Part II-Clinical Study (Phase I). Maytenus ilicifolia is a plant widely used in South American folk medicine as an effective anti-dyspeptic agent, and the aim of this study was to evaluate their clinical and toxicological effects in healthy volunteers in order to establish its maximum safe dose. We selected 24 volunteers (12 women and 12 men) between 20 and 40 years of age and put them through clinical/laboratory screening and testing to ascertain their psychomotor functions (simple visual reaction, speed and accuracy, finger tapping tests). M. ilicifolia tablets were administered in increasing weekly dosages, from an initial dose of 100 mg to a final dose of 2000 mg. The volunteers'' clinical and biochemical profiles and psychomotor functions were evaluated weekly, and they also completed a questionnaire about any adverse reactions. All subjects completed the study without significant changes in the evaluated parameters. The most cited adverse reactions were xerostomia (dry mouth syndrome) (16.7%) and polyuria (20.8%), with reversal of these symptoms without any intervention during the study. The clinical Phase I study showed that the administration of up to 2000 mg of the extract was well tolerated, with few changes in biochemical, hematological or psychomotor function parameters, and no significant adverse reactions. Copyright © 2017 John Wiley & Sons, Ltd.