Eucalyptus globulus fruit extract alleviates MASLD via modulation of the IRE1α/XBP1s pathway.

BACKGROUND

The incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) is on the rise, while pharmacotherapeutic options remain limited. Eucalyptus globulus fruit is an herbal medicine with empirical lipid-modulating properties. However, its therapeutic potential against MASLD remains uninvestigated.

PURPOSE: Assess the anti-MASLD efficacy of E. globulus fruit extract (EgE), identify its major active constituent, and uncover underlying mechanisms.

METHODS

EgE was evaluated for lipid-lowering activity in free fatty acid (FFA)-stimulated hepatocytes, and assessed for therapeutic effects in two mouse models of MASLD. Phytochemical investigation was conducted to characterize its major constituents. The underlying mechanism was investigated using transcriptomics, drug affinity responsive target stability (DARTS), pathway inhibition/knockdown assays, molecular docking, etc.

RESULTS

EgE markedly decreased FFA-elevated lipid content in vitro. Consistently, it substantially ameliorated glucose and lipid metabolic disorders, attenuated hepatic steatosis, and mitigated associated pathological liver injury in vivo. Hepatic transcriptomic profiling revealed marked enrichment of lipid metabolism and endoplasmic reticulum stress (ERS) pathways, and subsequent mechanistic studies further identified EgE as an IRE1α regulator that activates the adaptive IRE1α/XBP1s signaling, thereby restraining pathological ERS. Macrocarpal A (MA) was identified as the primary bioactive component. It binds the h1 pocket of IRE1α to increase its dimeric form, elevate XBP1s levels, and thereby exert lipid-lowering efficacy.

CONCLUSION

EgE exhibits potent anti-MASLD effects by activating the adaptive IRE1α/XBP1s axis, representing a promising novel therapeutic candidate for MASLD management. Its major constituent MA directly engages the h1 pocket of IRE1α to increase dimeric IRE1α - a previously unrecognized binding mode.