A review of Rhododendron molle: traditional uses, clinical applications, phytochemistry, pharmacology, toxicology, pharmacokinetics and quality control.

Rhododendron molle, a member of the Ericaceae family, is a well-known medicinal plant in traditional Chinese medicine and ethnomedicine known as Yangzhizhu. As an important botanical drug, R. molle is characterized by "efficacy-toxicity duality". This review aims to provide a comprehensive and up-to-date overview of R. molle, encompassing its traditional medicinal uses, clinical applications, phytochemistry, pharmacology, toxicology, pharmacokinetics, and quality control in recent years. Information on R. molle was collected from scientific journals, classical books on traditional Chinese herbal medicine, and reports through library and electronic searches (PubMed, Google Scholar, Web of Science, CNKI, and other authoritative databases. R. molle is distributed in regions of China, and is used for treating pain, rheumatoid arthritis, cardiovascular disease, and gastrointestinal disorders. Approximately 349 chemical metabolites have been identified from R. molle, including diterpenoids, triterpenoids, flavonoids, lignans, and other metabolites. Among these metabolites, diterpenoids are recognized as the main bioactive metabolites, showing significant analgesic, anti-inflammatory, immunomodulatory, and cardiovascular effects. However, it is important to note that R. molle exhibits neurotoxicity, cardiotoxicity, hepatotoxicity, with its toxicity being linked to its primary diterpenoids. Rhodojaponin II and rhodojaponin III are generally selected as indicators for the quantitative determination of R. molle. Therefore, R. molle represents a valuable yet highly toxic botanical drug, while its traditional uses are supported by modern pharmacological evidence, further research is needed to clarify the mechanisms underlying its toxic effects and to establish scientific strategies for detoxification and quality control.