Zhankuic Acid A Isolated from Taiwanofungus camphoratus Is a Novel Selective TLR4/MD-2 Antagonist with Anti-Inflammatory Properties

Abstract

TLR4, a membrane receptor that functions in complex with its accessory protein myeloid differentiation factor-2 (MD-2), is a therapeutic target for bacterial infections. Taiwanofungus camphoratus is highly valued as a medicinal mushroom for cancer, hypertension, and inflammation in traditional medicine. Zhankuic acid A (ZAA) is the major pharmacologically active compound of T. camphoratus. The mechanism of action of T. camphoratus or ZAA has not been fully elucidated. We analyzed the structure of human TLR4/MD-2 complex with ZAA by X-score and HotLig modeling approaches. Two Abs against MD-2 were used to verify the MD-2/ZAA interaction. The inflammation and survival of the mice pretreated with ZAA and injected with LPS were monitored. The modeling structure shows that ZAA binds the MD-2 hydrophobic pocket exclusively via specific molecular recognition; the contact interface is dominated by hydrophobic interactions. Binding of ZAA to MD-2 reduced Ab recognition to native MD-2, similar to the effect of LPS binding. Furthermore, ZAA significantly ameliorated LPS-induced endotoxemia and Salmonella-induced diarrhea in mice. Our results suggest that ZAA, which can compete with LPS for binding to MD-2 as a TLR4/MD-2 antagonist, may be a potential therapeutic agent for gram-negative bacterial infections.

Differential Modulation of Lipopolysaccharide-Induced Inflammatory Cytokine Production by and Antioxidant Activity of Fomentariol in RAW264.7 Cells

“…The anti-inflammatory activities of crude extracts of medicinal mushrooms have been demonstrated in previous studies using [ 3 4 5 6 7 ]. Recently, considerable efforts have been focused on the isolation of single compounds with potent and unique biological activities [ 8 9 10 11 ]. Fomes formetarius is a bracket fungus commonly known as horse's hoof fungus, which has been used as a traditional medicine in China and Korea for centuries to treat various disease conditions including cancers and disorders of the gastrointestinal tract [ 12 ].…”

Zhankuic acid A as a novel JAK2 inhibitor for the treatment of concanavalin A-induced hepatitis

“…Therefore, both the TLR4/MD-2 and JAK2 activation play a role in LPS induced endotoxemia. Modeling approaches indicate the interaction between ZAA and TLR4/MD2 is a highly hydrophobic recognition, which is confirmed by Native PAGE assay [40]. ZAA also interacts with JH1 domain of JAK2 by three H-bonds and several hydrophobic interactions according to HotLig prediction, which evidenced by Native PAGE assay and immunoblotting.…”

“…ZAA also belongs to this type of small molecule triterpenoid drugs. A previous study has demonstrated that ZAA is an LPS antagonist of NF-kB activation in response to inflammatory stimuli [40]. Whether the suppression of STAT3 by ZAA is associated with its observed inhibitory effects on NF-kB pathway needs further investigation.…”

Zhankuic Acids A, B and C from Taiwanofungus camphoratus Act as Cytotoxicity Enhancers by Regulating P-Glycoprotein in Multi-Drug Resistant Cancer Cells

“…In addition, our results showed that the combination of Zhankuic acid compounds with chemotherapeutic drugs could also enhance the cytotoxicity in drug-sensitive cell line HeLaS3, indicating there are other molecular mechanisms for cytotoxicity. ZA-A was reported to have anti-inflammatory functions such as the inhibition of ROS produced by fMLF-or PMA-activated peripheral human neutrophils [29], or modulating the production of NO, iNOS, COX2, TNF-α and IL-6, in macrophages [30]. The relationship between anti-inflammation and the cytotoxic effects of ZA-A deserves further experiment investigation to understand the diverse pharmacological roles of ZA-A.…”