From Claims to Evidence: Re-Evaluating the Molecular Pharmacology of Cirsium japonicum.

Cirsium japonicum Fisch. ex DC. has long been used in traditional East Asian medicine and has attracted increasing attention because of its diverse pharmacological activities, including antioxidant, anti-inflammatory, antifibrotic, metabolic regulatory, and anticancer effects. Although numerous studies have investigated its phytochemical composition and biological activities, current evidence has largely been organized according to individual compounds or disease categories, providing limited insight into the shared molecular mechanisms underlying its pleiotropic actions. In this review, we critically re-evaluate the molecular pharmacology of C. japonicum using an evidence-oriented framework that distinguishes experimentally supported mechanisms from pharmacological associations and emerging hypotheses. Rather than accepting changes in signaling proteins or downstream biomarkers as sufficient evidence of mechanism, we assess the strength of evidence based on reproducibility, pathway-specific interventions, genetic or pharmacological validation, and direct target engagement. Current evidence indicates that nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant responses and nuclear factor kappa B (NF-κB)-associated inflammatory responses represent the most consistently observed pathway associations, although direct molecular targets and causal pathway dependency remain insufficiently established. Evidence for AMPK/PI3K-Akt-associated metabolic regulation and TGF-β/Smad-associated antifibrotic responses is comparatively more limited. In contrast, modulation of apoptosis and autophagy is currently supported primarily by indirect or context-dependent observations. We further discuss how multiple phytochemicals converge on interconnected signaling networks regulating oxidative stress, inflammation, metabolism, tissue remodeling, and cell fate, thereby providing a systems-level explanation for the broad therapeutic potential of C. japonicum. Finally, we highlight the need for standardized phytochemical characterization, rigorous target validation, multi-omics integration, and artificial intelligence-assisted systems biology to establish causal molecular mechanisms and accelerate the translational development of evidence-based phytopharmaceuticals.