Valeriana spp.: Biological Activities and New In vitro and In vivo Perspectives

Background: Valerian extract is widely used in dietary supplements as well as in conventional, traditional and alternative medicines. It is one of the most used herbal plants for the treatment of several disorders, mainly related to the digestive and the nervous systems. Dozens of chemical constituents with pharmacological and therapeutic properties were identified in essential oils and/or other extracts of valerian’s roots, rhizomes and aerial parts. This review summarizes and updates the current knowledge about the pharmacological properties of valerian, highlighting the most recent clinical, in vitro and in vivo findings, and intends to identify and propose future directions for further research regarding the effective biological effects of Valeriana spp. Methods: This review analyzed the scientific literature published in PubMed, Science Direct and Web of Science. Results: Some reports are contradictory or inconclusive, probably due to the presence of chemically distinct chemotypes within a species of Valeriana or to different approaches adopted in different studies. Also, there are a number of studies showing that co-administration of herbal supplements and drugs may promote pharmacokinetic and pharmacodynamic herb-drug interactions. Conclusion: It is of utmost importance to clarify the state of the art related to Valeriana spp. therapeutic properties and their effects on metabolism.