Thuja occidentalis(Arbor vitae): A Review of its Pharmaceutical, Pharmacological and Clinical Properties

Abstract

Arbor vitae (Thuja occidentalisL.) is a native European tree widely used in homeopathy and evidence-based phytotherapy. Many reviews and monographs have been published on the herbal substance's description, mode of action and clinical use. However, no comprehensive evidence-based review is available. Therefore, our aim was to search MEDLINE databases and survey manufacturers for further details or unpublished data. This review presents the botany, ethnobotany and phytochemistry, especially the different contents of essential oil (Thujone) in relation to different extraction procedures of this medicinal plant.Thuja's antiviral action and immunopharmacological potential, such as stimulatory and co-stimulatory effects on cytokine and antibody production and activation of macrophages and other immunocompetent cells, have been evaluated in numerousin vitroandin vivoinvestigations. Although no controlled trials have been conducted onThuja occalone, many clinical studies have been performed with a herbal medicinal product containing a special extract ofThuja occand other immunostimulants, demonstrating its therapeutic efficacy and safety in respiratory tract infections.