Study on the protection of water extracts of Polygoni Multiflori Radix and Polygoni Multiflori Radix Praeparata against NAFLD and its mechanism.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygoni Multiflori Radix (PMR) and Polygoni Multiflori Radix Praeparata (PMRP) that is used after processing are two well-known traditional Chinese medicines. PMRP is traditionally reported to have lipid-reducing activity as recorded in Chinese Pharmacopoeia. AIM OF THE STUDY: This study aims to observe the alleviation of Polygoni Multiflori Radix Praeparata water extract (PMRPWE) and Polygoni Multiflori Radix water extract (PMRWE) against nonalcoholic fatty liver disease (NAFLD), and its potential engaged mechanism and the main active ingredients. MATERIALS AND METHODS: The contents of 2,3,5,4'-tetrahydroxy-stilbene-2-O-ß- D-glucoside (TSG), emodin and physcion in PMRWE and PMRPWE were measured by using high-performance liquid chromatography (HPLC). NAFLD was induced in rats by high-fat diet (HFD) feeding for 8 weeks. At the same time, rats were orally given with PMRWE (70, 140, 280 mg/kg) or PMRPWE (70, 140, 280 mg/kg) every day. Serum and liver biochemical parameters, hepatic gene expression and enzymatic activity were detected. Cellular lipids accumulation in human normal liver L-02 cells was induced by 0.5 mM non-esterified fatty acid (NEFA). RESULTS: The results of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), liver reactive oxygen species (ROS) and hematoxylin-eosin (H&E) observation showed that PMRWE and PMRPWE both alleviated liver injury in HFD-fed rats. The results of liver triglyceride (TG), total cholesterol (TC) and NEFA amounts, and liver Oil Red O staining evaluation showed that PMRWE and PMRPWE both reduced hepatic lipids accumulation in HFD-fed rats. The results of 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY) fluorescence staining and cellular TG content showed that both PMRWE and PMRPWE reduced NEFA-induced cellular lipids accumulation in L-02 cells. PMRWE and PMRPWE increased liver mRNA expression of some signals involved in mitochondrial ß oxidation, including the key enzyme carnitine palmitoyltransferase 1A (CPT1A). Moreover, PMRWE and PMRPWE increased the decreased liver CPT1A enzymatic activity in HFD-fed rats. Etomoxir (ETO), a CPT1A inhibitor, weakened the lipid-lowering activity of PMRWE and PMRPWE in vitro. Additionally, the main compounds in PMRWE and PMRPWE including TSG, emodin, physcion and resveratrol all reduced cellular lipids accumulation induced by NEFA in L-02 cells. CONCLUSIONS: PMRWE and PMRPWE alleviated NAFLD through promoting mitochondrial ß oxidation by enhancing liver CPT1A activity. Stilbenes (including TSG, polydatin and resveratrol) and anthraquinones (including physcion, emodin and rhein) may be the main active compounds contributing to the lipid-lowering activity provided by PMRWE and PMRPWE.

(-)-Epicatechin attenuates hepatic sinusoidal obstruction syndrome by inhibiting liver oxidative and inflammatory injury.

Hepatic sinusoidal obstruction syndrome (HSOS) is a rare liver disease with considerable morbidity and mortality. (-)-Epicatechin (EPI) is a natural flavonol. This study aims to investigate the protection of EPI against monocrotaline (MCT)-induced HSOS and its engaged mechanism. Results of serum alanine/aspartate aminotransferases (ALT/AST) activities, total bilirubin (TBil) and bile acids (TBA) amounts, liver histological evaluation, scanning electron microscope observation and hepatic metalloproteinase-9 (MMP-9) expression all demonstrated the protection by EPI against MCT-induced HSOS in rats. EPI attenuated liver oxidative injury induced by MCT. EPI enhanced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased the expression of its downstream antioxidant genes in rats. Molecular docking results implied the potential interaction of EPI with the Nrf2 binding site in kelch-like ECH-associated protein-1 (Keap1). The EPI-provided protection against MCT-induced HSOS was diminished in Nrf2 knock-out mice when mice were treated with MCT for 24 h but not for 48 h. However, EPI reduced the increased liver myeloperoxidase (MPO) activity, hepatic infiltration of immune cells, pro-inflammatory cytokines expression and nuclear factor κB (NFκB) activation in both wild-type and Nrf2 knock-out mice when mice were treated with MCT for 48 h. EPI reduced the elevated serum heat shock protein 60 (HSP60) content, and reversed the decreased mitochondria expression of HSP60 and Lon in livers from MCT-treated rats. Furthermore, the MCT-induced HSOS was markedly alleviated in mice treated with anti-HSP60 antibody. Taken together, this study demonstrates that EPI attenuates MCT-induced HSOS by reducing liver oxidative injury via activating Nrf2 antioxidant pathway and inhibiting liver inflammatory injury through abrogating NFκB signaling pathway initiated by HSP60.

Liquiritigenin and liquiritin alleviated MCT-induced HSOS by activating Nrf2 antioxidative defense system.

Hepatic sinusoidal obstruction syndrome (HSOS) is a serious and life-threatening liver disease. Liquiritigenin (LG) and liquiritin (LQ) are natural flavonoids distributed in Glycyrrhizae Radix et Rhizoma (Gan-cao). This study aims to investigate the protective effect and mechanism of LG and LQ against monocrotaline (MCT)-induced HSOS. Results of serum alanine/aspartate aminotransferases (ALT/AST) activities, liver histological evaluation and scanning electron microscope observation, and hepatic metalloproteinase-9 (MMP-9) expression demonstrated that LG and LQ both alleviated HSOS induced by MCT in rats. Results of hepatic reactive oxygen species (ROS), malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), oxidized glutathione (GSSG) and reduced glutathione (GSH) contents, glutathione reductase (GR) and superoxide dismutase (SOD) activities showed that LG and LQ attenuated MCT-induced liver oxidative stress injury. Furthermore, LG and LQ were found to promote Nrf2 nuclear translocation and lead to the increased expression of Nrf2 downstream antioxidative genes. Molecule docking analysis indicated the potential interaction of LG and LQ with Nrf2 binding site in the kelch-like ECH-associated protein-1 (Keap1) protein. Finally, Nrf2 knock-out mice were used. The results showed that LG and LQ both alleviated MCT-induced HSOS in wild-type mice, but such protection was totally diminished in Nrf2 knock-out mice. In conclusion, our study revealed that LG and LQ alleviated MCT-induced HSOS by inducing the activation of hepatic Nrf2 antioxidative defense system.

Natural product andrographolide alleviated APAP-induced liver fibrosis by activating Nrf2 antioxidant pathway.

As a well-known analgesic drug, acetaminophen (APAP) is commonly used to relieve pain for patients with chronic painful diseases. Our previous study has shown that long-term ingestion of APAP caused liver fibrosis in mice. This study further investigated the critical role of nuclear factor erythroid 2-related factor 2 (Nrf2) in regulating APAP-induced liver fibrosis in mice and the anti-fibrotic effect of natural compound andrographolide (Andro). Our results showed that hepatic collagen deposition and hepatic stellate cells (HSCs) activation induced by APAP were more serious in Nrf2 knock-out mice than in normal wild-type mice. Andro reduced HSCs activation in vitro, and also decreased hepatic collagen deposition and HSCs activation induced by APAP in mice. Andro alleviated liver oxidative stress injury induced by APAP in mice and reduced cellular formation of reactive oxygen species (ROS) in HSCs. Andro enhanced Nrf2 nuclear translocation and increased the expression of Nrf2 downstream antioxidant genes both in vitro and in vivo. Furthermore, the Andro-provided protection against APAP-induced liver fibrosis was diminished in Nrf2 knock-out mice. In summary, Nrf2 is critically involved in preventing liver fibrosis induced by long-term administration of APAP in mice, and Andro alleviates APAP-induced liver fibrosis by attenuating liver oxidative stress injury via inducing Nrf2 activation. This study points out the potential application of Andro in the treatment of liver fibrosis in clinic.

Baicalein and baicalin alleviate acetaminophen-induced liver injury by activating Nrf2 antioxidative pathway: The involvement of ERK1/2 and PKC.

Acetaminophen (APAP)-induced hepatotoxicity is the main cause of drug-induced liver injury. This study investigated the protection of baicalin and its aglycone baicalein against APAP-induced hepatotoxicity and its mechanism. Baicalein and baicalin alleviated APAP-induced hepatotoxicity both in vitro and in vivo. Moreover, this baicalin-provided protection was not diminished in hepatocytes or mice treated with ß-glucuronidase inhibitor. Results of liver glutathione (GSH) and reactive oxygen species (ROS) formation demonstrated the alleviation of baicalein and baicalin on APAP-induced liver oxidative stress injury. Baicalein and baicalin induced the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased the expression of its downstream antioxidant genes. Baicalein and baicalin-provided protection was diminished after the application of Nrf2 siRNA in hepatocytes and Nrf2 knock-out mice. Molecular docking results indicate the potential interaction of baicalein and baicalin with kelch-like ECH-associated protein-1 (Keap1). Baicalein and baicalin induced the sustained phosphorylation of extracellular regulated protein kinases (ERK)1/2 and protein kinase C (PKC). Moreover, ERK1/2 and PKC inhibitors both abrogated Nrf2 phosphorylation and its subsequent activation, and the protection against APAP-induced hepatotoxicity induced by baicalein and baicalin. In summary, baicalein and baicalin alleviate APAP-induced hepatotoxicity by activating Nrf2 via blocking the binding of Nrf2 with Keap1 and inducing Nrf2 phosphorylation. ERK1/2 and PKC are both critical for regulating the phosphorylation of Nrf2 induced by baicalein or baicalin.