Corydalis yanhusuo W. T. Wang: a comprehensive review of phytochemistry, vinegar processing and analgesic mechanisms

Corydalis yanhusuo W. T. Wang (C. yanhusuo) is a botanical source of diverse isoquinoline alkaloids with significant analgesic properties. Vinegar processing, a common post-harvest treatment, markedly alters its chemical profile and bioactivity. This review systematically analyzes the current phytochemical and pharmacological knowledge of C. yanhusuo, with a focus on the chemical modifications induced by vinegar processing. Evidence indicates that this treatment increases the content and/or bioavailability of key analgesic alkaloids, such as tetrahydropalmatine and dehydrocorydaline, and can lead to the formation of novel compounds. These chemical changes correlate with enhanced pharmacological effects through multi-target mechanisms, primarily involving the modulation of dopaminergic and opioid systems alongside the inhibition of neuroinflammatory pathways (such as the NLRP3 inflammasome). By integrating evidence of chemical alterations with mechanistic studies, and providing a stratified evaluation of the current evidence—distinguishing well-established mechanisms from those requiring further investigation—this review offers a comprehensive phytochemical rationale for the optimized application of C. yanhusuo. Furthermore, it identifies critical research gaps and future directions, including the systematic characterization of processing-specific chemical markers and the elucidation of alkaloid transformation pathways during vinegar processing, to support the development of safe, effective, and non-addictive analgesic agents.