The genus Valeriana L.: ethnopharmacology, phytochemistry and biological activities—an updated review

Abstract The genus Valeriana L. is a large genus with its 436 accepted species distributed all over the world. Some members of the genus have been utilized in different folk medicines to cure many diseases especially anxiety, sleep disorders and epilepsy since remote times. Pharmacological studies on the extracts prepared mostly from below ground parts of some Valeriana species mainly from V. officinalis , V. jatamansi , and V . amurensis revealed their diverse bioactivities including, anxiolytic, antidepressant, anticonvulsant, anti-inflammatory, cytotoxic, and anticancer activities. Many secondary metabolites have been isolated and characterized from several Valeriana species that belong to mainly iridoid, sesquiterpene, lignan, flavonoid chemical classes. Bioactivity studies on the isolated iridoids, sesquiterpenes, and lignans derived from these species possess significant biological activities such as cytotoxic, anticancer, anti-inflammatory, neuroprotective, and antiviral activities. This comprehensive review aims to provide an overview of the traditional use and phytochemical composition of Valeriana species as well as the very recent bioactivities of secondary metabolites derived from these species. Recent in vitro, in vivo, and clinical studies are reviewed and discussed, particularly focusing on cytotoxic, anti-inflammatory, neuroprotective, and anti-viral activities of the isolated compounds from Valeriana species. Among the secondary metabolites, especially iridoids, sesquiterpenes, and lignans seem to be the compounds that are responsible for the pharmacological activities of extracts. Although promising results were reported for some secondary metabolites in in vitro studies, it is essential to perform in vivo and even clinical studies in order to discover new potential drug leads from this genus.