Ultrasound exposure ameliorates the hepatoprotective effect of herpetrione nanosuspension via oral delivery

Herpetrione, a New Type of PPARα Ligand as a Therapeutic Strategy Against Nonalcoholic Steatohepatitis

Non-alcoholic fatty liver disease, especially nonalcoholic steatohepatitis (NASH), is a leading cause of cirrhosis and liver cancer worldwide; nevertheless, there are no Food and Drug Administration-approved drugs for treating NASH until now. Peroxisome proliferator-activated receptor alpha (PPARα) is an interesting therapeutic target for treating metabolic disorders in the clinic, including NASH. Herpetrione, a natural lignan compound isolated from Tibetan medicine Herpetospermum caudigerum, exerts various hepatoprotective effects, but its efficacy and molecular mechanism in treating NASH have not yet been elucidated. Here, we discovered that herpetrione lessened lipid accumulation and inflammation in hepatocytes stimulated with oleic acid and lipopolysaccharide, and effectively alleviated NASH caused by a high-fat diet or methionine-choline-deficient diet by regulating glucolipid metabolism, insulin resistance, and inflammation. Mechanistically, RNA-sequencing analyses further showed that herpetrione activated PPAR signaling, which was validated by protein expression. Furthermore, the analysis of molecular interactions illustrated that herpetrione bound directly to the PPARα protein, with binding sites extending to the Arm III domain. PPARα deficiency also abrogated the protective effects of herpetrione against NASH, suggesting that herpetrione protects against hepatic steatosis and inflammation by activation of PPARα signaling, thereby alleviating NASH. Our findings shed light on the efficacy of a natural product for treating NASH, as well as the broader prospects for NASH treatment by targeting PPARα.

Development of herpetrione nanosuspensions stabilized by glycyrrhizin for enhancing bioavailability and synergistic hepatoprotective effect

The objective of this study was to develop novel herpetrione (HPE) nanosuspensions stabilized by glycyrrhizin (HPE NSs/GL) for enhancing bioavailability and hepatoprotective effect of HPE. HPE NSs/GL were prepared by wet media milling method and then systemically evaluated by particle size analysis, scanning electronic microscopy (SEM), X-ray powder diffraction (XRPD), dissolution test, pharmacokinetics, and hepatoprotective effect. HPE-NSs stabilized by poloxamer 407 (HPE NSs/P407) were also prepared and used as a reference for comparison. HPE NSs/GL and HPE-NSs/P407 with similar particle sizes around 450 nm and PDI less than 0.2 were successfully prepared and both of them appeared to be spherical under SEM. The XRPD results demonstrated that HPE in both HPE NSs/GL and HPE NSs/P407 was presented in the amorphous state and the addition of GL or P407 and the milling process didn't alter the physical state of HPE. The dissolution and pharmacokinetic studies demonstrated that HPE NSs/GL exhibited significant enhancement in drug dissolution (72.44% within 24 h) and AUC_0-t (24.91 ± 3.3 mg/L·h) as compared to HPE coarse suspensions (HPE CS, 34.19% & 13.07 ± 1.02 mg/L·h), but was similar with those of HPE NSs/P407 (80.06% & 26.75 ± 4.06 mg/L•h). Moreover, HPE NSs/GL exhibited significantly better hepatoprotective effect as compared to HPE CS and HPE NSs/P407 as indicated by the lowering of the elevated serum ALT and AST levels and the improvement of the hepatic morphology and architecture, which might be attributed to the improved bioavailability of HPE, and synergistic hepatoprotective effect of GL via alleviating inflammation evidenced by the significant decreased hepatic levels of inflammatory cytokines IL-1β, IL-6 and TNF-α. It could be concluded that GL might be an effective stabilizer for preparing HPE NSs, and HPE NSs/GL is a potential formulation strategy for improving oral bioavailability and hepatoprotective effect of HPE.

Dehydrodiconiferyl alcohol, a lignan from Herpetospermum pedunculosum, alleviates cholestasis by activating pathways associated with the farnesoid X receptor

BACKGROUND

In our previous study, we demonstrated the hepatoprotective effect of Herpetospermum pedunculosum in cholestatic rats. A bioassay-guided study also led to the identification and isolation of a lignan, dihydrodiconiferyl alcohol (DA) from the seeds of H. pedunculosum.

PURPOSE

To investigate whether DA could alleviate cholestasis and determine the mechanisms underlying such action.

METHODS

Male Sprague-Dawley (SD) rats were administered with DA (10, 20 or 40 mg/kg) intragastrically once daily for 7 days prior to treatment with α-naphthylisothiocyanate (ANIT) (60 mg/kg). We then evaluated the levels of a range of serum indicators, determined bile flow, and carried out histopathological analyses. Western blotting was then used to investigate the levels of inflammatory mediators and the Farnesoid X Receptor (FXR), proteins involved in the downstream biosynthesis of bile acids, and a range of transport proteins. Molecular docking was used to simulate the interaction between DA and FXR. Cell viability of human hepatocytes (L-02) cells was determined by MTT. Then, we treated guggulsterone-inhibited L-02 cells, Si-FXR L-02 cells, and FXR-overexpression cells with the FXR agonist GW4064 (6 μM) or DA (25, 50 and 100 μM) for 24 h before detecting gene and protein expression by RT-PCR and western blotting, respectively.

RESULTS

DA significantly attenuated ANIT-induced cholestasis in SD rats by reducing liver function indicators in the serum, increasing bile flow, improving the recovery of histopathological injuries in the liver, and by alleviating pro-inflammatory cytokines in the liver. DA also increased the expression levels of FXR and altered the levels of downstream proteins in the liver tissues, thus indicating that DA might alleviate cholestasis by regulating the FXR. Molecular docking simulations predicted that DA was as an agonist of FXR. In vitro mechanical studies further showed that DA increased the mRNA and protein expression levels of FXR, Small Heterodimer Partner 1/2, Bile Salt Export Pump, Multidrug Resistance-associated Protein 2, and Na+/taurocholate Co-transporting Polypeptide, in both guggulsterone-inhibited and Si-FXR L-02 cells. Moreover, DA enhanced the mRNA and protein expression of FXR, and its downstream genes and proteins, in L-02 cells containing an FXR-overexpression plasmid.

CONCLUSION

DA may represent an effective agonist for FXR has significant therapeutic potential for the treatment of cholestatic liver injury.