Genus Bupleurum: a review of its phytochemistry, pharmacology and modes of action

Objectives Radix Bupleuri represents one of the most successful and widely used herbal drugs in Asia for treatment of many diseases over the past 2000 years. Thorough studies have been carried out on many species of this genus and have generated immense data about the chemical composition and corresponding biological activity of extracts and isolated secondary metabolites. In this work, we review the chemistry and pharmacology of the genus Bupleurum and explore the relationships between the pharmacological effects and the chemical composition of these drugs. Key findings Early studies on the genus Bupleurum had focused only on the traditional uses of the plants in the treatment of inflammatory disorders and infectious diseases. After chemical profiling, several groups of secondary metabolites were characterized with relevant biological activity: triterpene saponins (saikosaponins), lignans, essential oils and polysaccharides. As a result, present interest is now focused on the bioactivity of the isolated triterpene saponins acting as immunomodulatory, anti-inflammatory and antiviral agents, as well as on the observed ant-iulcer activity of the polysaccharides and anti-proliferative activity of different lignans. Many saikosaponins exhibited very potent anti-inflammatory, hepatoprotective and immunomodulatory activities both in vivo and in vitro. Conclusions Further investigations and screenings are required to explore other Bupleurum species, to evaluate the clinical safety and possible interactions with other drugs or herbs. Standardization of Bupleuri extracts is crucial for them being integrated into conventional medicine due to large chemical and biological variations between different species and varieties.