Anxiolytic-like effect of essential oils extracted from Lippia alba and Lippia citriodora

Introduction: Essential oils from natural plants are widely use around the world to relief mental conditions. The aim of this investigation was to determine the anxiolytic-like effect of essential oils extracted from Lippia alba and Lippia citriodora. Methods: The oil was extracted by hydro-distillation for 3 hours using a modified Clevenger-type apparatus and then chemical composition was investigated by gas chromatography analysis (GC) and gas chromatography-mass spectrometry (GC-MS). Moreover, a randomized experimental trial was conducted, where 95 participants were divided into 3 groups, comprising a waiting list control group and two experimental groups treated with essential oils by inhalation. The anxiety index was evaluated by State-Trait Anxiety Inventory (STAI). Measures were taken two times: pretest and posttest. Results: chemical analysis showed that carvone was the main component (64.5%) for Lippia alba essential oil and geranial (39.8%) for Lippia citriodora. State and Trait anxiety scores showed a decrease in posttest study phase in comparison with pretest in all experimental groups (p<0.05). Cohen's D and Hedges’ G scores show a large size effect in state anxiety for experimental group treated with Lippia alba while moderate changes were found for the rest of variables in all experimental groups. Conclusion: the essential oils extracted from Lippia alba and Lippia citriodora may be useful as a mean to counteract anxiety, specifically state anxiety showing short-terms benefits.