Natural Products & Plant Materials
Phellodendron Compound Obakulactone Eases Joint Swelling and Tissue Damage in Rat Model of Rheumatoid Arthritis
An animal study reported that a triterpenoid from the traditional medicinal herb Phellodendron bark lowered inflammatory signalling by inducing degradation of the fatty acid metabolism enzyme ACOT1.
A study reported that obakulactone, a tetracyclic triterpenoid derived from the traditional medicinal herb Phellodendron bark (Phellodendri cortex), reduced joint swelling and tissue damage in rats with a model of rheumatoid arthritis. The paper by Chinese researchers (Hongda Liu, Xijun Wang and colleagues) appeared in volume 56 of the journal Engineering, and its publisher, Higher Education Press, introduced the findings through ScienceDaily.
21 days of dosing at three dose levels
The team gave obakulactone to rats with arthritis induced by complete Freund's adjuvant at three doses, 50, 100 and 200 mg/kg per day, for 21 days. Joint swelling decreased, and cartilage and synovial structures were comparatively well preserved. T cells and macrophages that had flooded the joint tissue decreased, and the macrophages shifted toward an anti-inflammatory profile. Blood inflammation markers such as IL-6 and TNF-α and arthritis markers fell in proportion to the dose.
The fatty acid metabolism enzyme ACOT1 was identified as the mechanism of action. The explanation is that obakulactone binds directly to ACOT1 and promotes its degradation through the ubiquitin-proteasome pathway, restoring a disrupted balance of unsaturated fatty acids and calming the JAK-STAT and PI3K-AKT signalling in synovial fibroblasts. What sets this study apart is that it pinpointed the target protein of a single compound from Phellodendron bark.
These results were obtained in rats and cultured cells, and effects and safety in people have not been confirmed. Drinking a decoction of Phellodendron bark and an experiment giving a purified compound at tens to hundreds of mg per kg of body weight are different things, and the findings cannot be used as grounds for patients with rheumatoid arthritis to replace their existing treatment.
- Phellodendron-derived obakulactone given to CFA-induced arthritis rats at 50, 100 and 200 mg/kg/day for 21 days
- Less joint swelling, cartilage damage and immune cell infiltration; dose-dependent drops in IL-6 and TNF-α
- Target is ACOT1: direct binding, then ubiquitin-proteasome degradation, then restored unsaturated fatty acid balance
Limitations These are results from rat and cell experiments. Efficacy and safety in people have not been confirmed, and they are not grounds for replacing existing treatment.
Original research
- Liu H, Yang L, Yang Y, Tang H, et al.; Wang X (corresponding) · Higher Education Press (publisher of Engineering) / Chinese researchers. Natural compound may fight rheumatoid arthritis at its source (paper: Obakulactone Alleviates Rheumatoid Arthritis by Promotion of ACOT1 Degradation via the Ubiquitin‒Proteasome Pathway and Restoration of Unsaturated Fatty Acid Homeostasis). Engineering. DOI: 10.1016/j.eng.2025.10.029
Copyright in the original research belongs to its publisher and authors.