The Genus Erysimum (Brassicaceae): A Comprehensive Review of Its Diversity in Asia, Traditional Uses, Phytochemistry, and Pharmacological Potential

The genus Erysimum (Brassicaceae) comprises more than 150 species distributed mainly across Europe, Central Asia, East Asia, the Middle East, North Africa and North America, many of which are traditionally used for treating cardiovascular, respiratory, and inflammatory disorders. Plants of this genus are rich in various groups of secondary metabolites, including cardenolides, glucosinolates and isothiocyanates released from them, sterols, phenolic compounds such as flavonoids and tannins, and other secondary metabolites. This review synthesizes its unique phytochemical profile, characterized by the coexistence of ancestral glucosinolates and independently evolved cardenolides. Over 100 cardenolide structures based on 15 aglycones have been reported from Erysimum, although the structural characterization of several compounds remains inconsistent or incomplete, with some glycosides still absent in major chemical databases. A variety of pharmacological activities have been documented for extracts and isolated constituents, including cardiotonic, anti-inflammatory, antioxidant, antimicrobial, and cytotoxic effects, supporting the therapeutic potential of the genus. Ecologically, the genus employs a two-tiered defense strategy where strophanthidin-based compounds deter butterfly oviposition and digitoxigenin-based compounds repel larval feeding. This review summarizes current knowledge on the taxonomy, distribution, phytochemical composition, and biological activities of Erysimum species, with a focus on cardenolide diversity, structural ambiguities, and research gaps that require further investigation.