Yangonin

Yangonin blocks tumor necrosis factor-α-induced nuclear factor-κB-dependent transcription by inhibiting the transactivation potential of the RelA/p65 subunit.[Pubmed: 22510965]

J Pharmacol Sci. 2012;118(4):447-54.

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, immunity, and apoptosis. In our search for NF-κB inhibitors from natural resources, we identified Yangonin from Piper methysticum as an inhibitor of NF-κB activation.
METHODS AND RESULTS:
In the present study, we demonstrate that Yangonin potently inhibits NF-κB activation through suppression of the transcriptional activity of the RelA/p65 subunit of NF-κB. This compound significantly inhibited the induced expression of the NF-κB-reporter gene. However, this compound did not interfere with tumor necrosis factor-α (TNF-α)-induced inhibitor of κBα (IκBα) degradation, p65 nuclear translocation, and DNA-binding activity of NF-κB. Further analysis revealed that Yangonin inhibited not only the induced NF-κB activation by overexpression of RelA/p65, but also transactivation activity of RelA/p65. Moreover, Yangonin did not inhibit TNF-α-induced activation of p38, but it significantly impaired activation of extracellular signal-regulated kinase 1/2 and stress-activated protein kinase/c-Jun NH(2)-terminal kinase. We also demonstrated that pretreatment of cells with this compound prevented TNF-α-induced expression of NF-κB target genes, such as interleukin 6, interleukin 8, monocyte chemotactic protein 1, cyclooxygenase-2 and inducible nitric oxide.
CONCLUSIONS:
Taken together, Yangonin could be a valuable candidate for the intervention of NF-κB-dependent pathological conditions such as inflammation.

Characterization of three small molecule inhibitors of enterovirus 71 identified from screening of a library of natural products.[Pubmed: 28412182 ]

Antiviral Res. 2017 Jul;143:85-96.

Enterovirus 71 (EV-A71) is a major cause of hand, foot, and mouth disease (HFMD). Infection with EV-A71 is more often associated with neurological complications in children and is responsible for the majority of fatalities, but currently there is no approved antiviral therapy for treatment.
METHODS AND RESULTS:
Here, we identified auraptene, formononetin, and Yangonin as effective inhibitors of EV-A71 infection in the low-micromolar range from screening of a natural product library. Among them, formononetin and Yangonin selectively inhibited EV-A71 while auraptene could inhibit viruses within the enterovirus species A. Time of addition studies showed that all the three inhibitors inhibit both attachment and postattachment step of entry. We found mutations conferring the resistance to these inhibitors in the VP1 and VP4 capsid proteins and confirmed the target residues using a reverse genetic approach. Interestingly, auraptene- and formononetin-resistant viruses exhibit cross-resistance to other inhibitors while Yangonin-resistant virus still remains susceptible to auraptene and formononetin. Moreover, auraptene and formononetin, but not Yangonin protected EV-A71 against thermal inactivation, indicating a direct stabilizing effect of both compounds on virion capsid conformation. Finally, neither biochanin A (an analog of formononetin) nor DL-Kavain (an analog of Yangonin) exhibited anti-EV-A71 activity, suggesting the structural elements required for anti-EV-A71 activity.
CONCLUSIONS:
Taken together, these compounds could become potential lead compounds for anti-EV-A71 drug development and also serve as tool compounds for studying virus entry.

Kavalactone yangonin induces autophagy and sensitizes bladder cancer cells to flavokawain A and docetaxel via inhibition of the mTOR pathway.[Pubmed: 28630390]

Kavalactones and the endocannabinoid system: the plant-derived yangonin is a novel CB? receptor ligand.[Pubmed: 22525682]

Pharmacol Res. 2012 Aug;66(2):163-9.

METHODS AND RESULTS:
To investigate the possible interactions between kavalactone-based molecules and proteins of the endocannabinoid system and provide novel and synthetically accessible structural scaffolds for the design of cannabinoid receptor ligands sharing pharmacological properties with kavapyrones, a preliminary SAR analysis was performed on five commercially available natural kavalactones and nine kavalactone-analogues properly synthesized. These compounds were investigated for assessing their cannabinoid receptor binding affinity and capability of inhibiting the activity of the two major metabolic enzymes of the endocannabinoid system, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Among the molecules tested, only Yangonin exhibited affinity for the human recombinant CB? receptor with a K(i)=0.72 μM and selectivity vs. the CB? receptor (K(i)>10 μM). None of the compounds exhibited strong inhibitory effects on the two enzymes analyzed.
CONCLUSIONS:
The CB? receptor affinity of Yangonin suggests that the endocannabinoid system might contribute to the complex human psychopharmacology of the traditional kava drink and the anxiolytic preparations obtained from the kava plant.

J Biomed Res. 2017 Jun 20.

Consumption of kava (Piper methysticum Forst) has been linked to reduced cancer risk in the South Pacific Islands. Kavalactones are major bioactive components in kava root extracts, which have recently demonstrated anti-cancer activities. However, molecular mechanisms of kavalactones' anti-cancer action remain largely unknown.
METHODS AND RESULTS:
We have identified two kavalactones, Yangonin and 5' 6'-dehydrokawain, as potent inducers of autophagic cell death in bladder cancer cells. The effect of Yangonin inducing autophagy is associated with increased expression of beclin and ATG5. In addition, Yangonin increases the expression of LKB1 and decreases the phosphorylation of Akt, PRAS40, rpS6, p70S6K and 4E-BP1, leading to increased binding of 4E-BP1 to m7 GTP. The growth inhibitory effects of Yangonin were attenuated inTSC1 or LKB1 knockout mouse embryonic fibroblasts, suggesting that TSC1 and LKB1 expression may contribute to optimal growth inhibition by Yangonin. Furthermore, Yangonin reduces the viability of bladder cancer cell lines derived from different stages of human bladder cancer, and acts synergistically with apoptosis-inducing agents such as docetaxel and flavokawain A.
CONCLUSIONS:
Our results support a novel anti-bladder cancer mechanism by Yangonin and further studies are needed to assess the potential use of Yangonin for bladder cancer prevention and treatment.