Fraxini cortex (Qinpi): reframing a traditional heat-clearing botanical drug as a systemic immune-metabolic regulator

Fraxini Cortex (Qinpi), a traditional Chinese medicine used for millennia for "Qingre" (heat-clearing), is now being re-evaluated in the context of modern immunology and systems pharmacology. Its traditional applications in treating inflammatory conditions hint at a broader, systemic regulatory capacity. This review proposes that Fraxini Cortex functions as a systemic immune-metabolic regulator. We aim to synthesize existing evidence through this novel lens, hypothesizing that its therapeutic potential stems from the synergistic ability of its constituents to target pivotal hubs at the interface of immune response and cellular metabolism. We conducted a comprehensive literature review encompassing the phytochemistry, pharmacology, pharmacokinetics, and clinical evidence of Fraxini Cortex. Phytochemically, Fraxini Cortex is rich in coumarins (e.g., esculetin, esculin), secoiridoids, and phenylethanoid glycosides. Pharmacologically, its mechanisms extend beyond mere anti-inflammation. Crucially, we propose that its constituents reprogram tumor metabolism by targeting the glycolytic enzyme GPI (e.g., oleuropein); execute an anti-virulence strategy against MRSA by inhibiting Sortase A (e.g., esculetin); and correct uric acid and glucose-lipid metabolic disorders by modulating urate transporters (URAT1/GLUT9/ABCG2) and insulin signaling (e.g., fraxin and esculin). This hypothesis is based on the convergence of evidence showing that these multi-target actions are integrated by its capacity to suppress core inflammatory pathways (NF-κB, MAPK) while activating antioxidant defenses (Nrf2), thereby promoting the resolution of inflammation and tissue homeostasis. Pharmacokinetic challenges, notably low oral bioavailability of key coumarins, are being addressed by novel drug delivery systems. Preliminary clinical studies support its benefits in psoriasis and gouty arthritis. In conclusion, we propose that Fraxini Cortex exemplifies how a traditional "heat-clearing" botanical drug can be reinterpreted as a multi-target regulator of immune-metabolic homeostasis. Future research should focus on validating this paradigm using omics technologies, developing bioavailability-enhanced formulations, and conducting rigorous clinical trials for immune-metabolic diseases. This shift in perspective may accelerate the translation of Fraxini Cortex and similar botanical drugs into standardized, evidence-based immunomodulatory therapies.