Synergistic effect of a novel oxymatrine-baicalin combination against hepatitis B virus replication, α smooth muscle actin expression and type I collagen synthesis in vitro

Metabolites from traditional Chinese botanical drugs with anti-hepatitis B virus activity - a review

Hepatitis B virus (HBV)-related liver disease poses a major threat to human health worldwide. Although interferon and nucleoside analogues are commonly administered for treating chronic HBV infection, their use is limited by considerable side effects, drug resistance and incapacity for HBV elimination. Hence, novel HBV therapeutics are urgently required. For numerous years, traditional Chinese botanical drugs have been widely used to treat HBV-related diseases. The natural metabolites derived from these traditional drugs exhibit significant anti-HBV effects and serve as potential novel drugs for treating HBV. For overall understanding the therapeutic potential of these metabolites, the anti-HBV effects and mechanisms of action of 107 natural metabolites are summarized in this article. Mechanistically, these natural metabolites exert their anti-HBV effects by influencing the expression and function of host and/or viral genes, which differs from the mechanism of action of nucleoside analogues. Indeed, combining natural metabolites with nucleoside analogues can exert synergistic effects. Accordingly, natural metabolites or their chemically modified derivatives represent potential novel drugs and adjuvants for anti-HBV treatment.

Antiviral responses versus virus-induced cellular shutoff: a game of thrones between influenza A virus NS1 and SARS-CoV-2 Nsp1

Following virus recognition of host cell receptors and viral particle/genome internalization, viruses replicate in the host via hijacking essential host cell machinery components to evade the provoked antiviral innate immunity against the invading pathogen. Respiratory viral infections are usually acute with the ability to activate pattern recognition receptors (PRRs) in/on host cells, resulting in the production and release of interferons (IFNs), proinflammatory cytokines, chemokines, and IFN-stimulated genes (ISGs) to reduce virus fitness and mitigate infection. Nevertheless, the game between viruses and the host is a complicated and dynamic process, in which they restrict each other via specific factors to maintain their own advantages and win this game. The primary role of the non-structural protein 1 (NS1 and Nsp1) of influenza A viruses (IAV) and the pandemic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respectively, is to control antiviral host-induced innate immune responses. This review provides a comprehensive overview of the genesis, spatial structure, viral and cellular interactors, and the mechanisms underlying the unique biological functions of IAV NS1 and SARS-CoV-2 Nsp1 in infected host cells. We also highlight the role of both non-structural proteins in modulating viral replication and pathogenicity. Eventually, and because of their important role during viral infection, we also describe their promising potential as targets for antiviral therapy and the development of live attenuated vaccines (LAV). Conclusively, both IAV NS1 and SARS-CoV-2 Nsp1 play an important role in virus-host interactions, viral replication, and pathogenesis, and pave the way to develop novel prophylactic and/or therapeutic interventions for the treatment of these important human respiratory viral pathogens.

Role of baicalin as a potential therapeutic agent in hepatobiliary and gastrointestinal disorders: A review

Baicalin is a natural bioactive compound derived from Scutellaria baicalensis, which is extensively used in traditional Chinese medicine. A literature survey demonstrated the broad spectrum of health benefits of baicalin such as antioxidant, anticancer, anti-inflammatory, antimicrobial, cardio-protective, hepatoprotective, renal protective, and neuroprotective properties. Baicalin is hydrolyzed to its metabolite baicalein by the action of gut microbiota, which is further reconverted to baicalin via phase 2 metabolism in the liver. Many studies have suggested that baicalin exhibits therapeutic potential against several types of hepatic disorders including hepatic fibrosis, xenobiotic-induced liver injury, fatty liver disease, viral hepatitis, cholestasis, ulcerative colitis, hepatocellular and colorectal cancer. During in vitro and in vivo examinations, it has been observed that baicalin showed a protective role against liver and gut-associated abnormalities by modifying several signaling pathways such as nuclear factor-kappa B, transforming growth factor beta 1/SMAD3, sirtuin 1, p38/mitogen-activated protein kinase/Janus kinase, and calcium/calmodulin-dependent protein kinase kinaseβ/adenosine monophosphate-activated protein kinase/acetyl-coenzyme A carboxylase pathways. Furthermore, baicalin also regulates the expression of fibrotic genes such as smooth muscle actin, connective tissue growth factor, β-catenin, and inflammatory cytokines such as interferon gamma, interleukin-6 (IL-6), tumor necrosis factor-alpha, and IL-1β, and attenuates the production of apoptotic proteins such as caspase-3, caspase-9 and B-cell lymphoma 2. However, due to its low solubility and poor bioavailability, widespread therapeutic applications of baicalin still remain a challenge. This review summarized the hepatic and gastrointestinal protective attributes of baicalin with an emphasis on the molecular mechanisms that regulate the interaction of baicalin with the gut microbiota.

Baicalin Induces a Potent Innate Immune Response to Inhibit Respiratory Syncytial Virus Replication via Regulating Viral Non-Structural 1 and Matrix RNA

Respiratory syncytial virus (RSV) infection is the most frequent cause of hospitalization in pediatric patients. Current systemic treatment and vaccines are not curative and re-infection is often associated with a more drastic incidence of the disease. Baicalin is a flavonoid isolated from Scutellaria baicalensis with potent anti-viral characteristics, namely against RSV. However, its precise mechanism of action remains unclear. Here, using in vitro methods and an in vivo murine model of RSV infection, we showed that baicalin inhibits RSV replication induces translational upregulation of type I interferons (IFNs), IFN-α and IFN-β, and reverses epithelial thickening in lung tissues. Moreover, baicalin inhibits transcription of the RSV non-structural proteins NS1 and NS2. Molecular docking and surface plasmon resonance-based affinity analysis showed that baicalin also binds to the α3 helix of the NS1 protein with an affinity constant of 1.119 × 10⁻⁵ M. Polysome profiling showed that baicalin inhibits translation of the RSV matrix protein (M) RNA. Baicalin mediates increased release of the ribosomal protein L13a from the large ribosomal subunit, where the extra ribosomal subunit L13a inhibits M RNA translation. These results comprehensively establish the multiple mechanisms by which baicalin induces a potent innate immune response against RSV infection.

Antiviral Properties of Baicalin: a Concise Review

Baicalin is one of the bioactive flavonoid glycosides isolated from the dried root of Scutellaria baicalensis Georgi, Lamiaceae, with antiviral properties. In recent years, the antiviral activity of baicalin has been widely investigated to explore its molecular mechanism of action. In this mini-review, the molecular mechanisms of action of baicalin as an antiviral agent are evaluated, which included three categories: the inhibition or stimulation of JAK/STAT, TLRs, and NF-κB pathways; up or down modulation of the expression levels of IFN, IL, SOCS1/3, PKR protein, Mx1 protein, and AP-1 protein; and inhibition of cell apoptosis caused by virus infection. In addition, clinical studies of baicalin are also discussed. This literature search suggested that baicalin can serve as a potential candidate for the development of a novel broad-spectrum antiviral drug.

Baicalin Alleviates Lipopolysaccharide-Induced Liver Inflammation in Chicken by Suppressing TLR4-Mediated NF-κB Pathway

As a kind of potent stimulus, lipopolysaccharide (LPS) has the ability to cause cell damage by activating toll-like receptor(TLR)4, then nuclear factor kappa B (NF-κB) translocates into the nucleus and changes the expression of related inflammatory genes. Baicalin is extracted from Radix Scutellariae, which possesses anti-inflammation, antioxidant and antibacterial properties. However, the effects of it on LPS-induced liver inflammation have not been fully elucidated. This study aims to investigate the anti-inflammatory effects of Baicalin on the LPS-induced liver inflammation and its underlying molecular mechanisms in chicken. The results of histopathological changes, serum biochemical analysis, NO levels and myeloperoxidase activity showed that Baicalin pretreatment ameliorated LPS-induced liver inflammation. ELISA and qPCR assays showed that Baicalin dose-dependently suppressed the production of IL-1β, IL-6, and TNF-α. Furthermore, the mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were significantly decreased by Baicalin. TLR4 is an important sensor in LPS infection. Molecular studies showed that the expression of TLR4 was inhibited by Baicalin pretreatment. In addition, Baicalin pretreatment inhibited NF-kB signaling pathway activation. All results demonstrated the protective effects of Baicalin pretreatment against LPS-induced liver inflammation in chicken via negative regulation of inflammatory mediators through the down-regulation of TLR4 expression and the inhibition of NF-kB activation.

The Antiviral Effect of Baicalin on Enterovirus 71 In Vitro

Baicalin is a flavonoid compound extracted from Scutellaria roots that has been reported to possess antibacterial, anti-inflammatory, and antiviral activities. However, the antiviral effect of baicalin on enterovirus 71 (EV71) is still unknown. In this study, we found that baicalin showed inhibitory activity on EV71 infection and was independent of direct virucidal or prophylactic effect and inhibitory viral absorption. The expressions of EV71/3D mRNA and polymerase were significantly blocked by baicalin treatment at early stages of EV71 infection. In addition, baicalin could decrease the expressions of FasL and caspase-3, as well as inhibit the apoptosis of EV71-infected human embryonal rhabdomyosarcoma (RD) cells. Altogether, these results indicate that baicalin exhibits potent antiviral effect on EV71 infection, probably through inhibiting EV71/3D polymerase expression and Fas/FasL signaling pathways.

Baicalein, Ethyl Acetate, and Chloroform Extracts of Scutellaria baicalensis Inhibit the Neuraminidase Activity of Pandemic 2009 H1N1 and Seasonal Influenza A Viruses

This study rated antiviral activity of Scutellaria baicalensis Georgi (S. baicalensis) extracts against influenza A virus subtypes, for example, pandemic 2009 H1N1, seasonal H1N1 and H3N2. Ethyl acetate (EtOAc) and chloroform extracts inhibited in vitro neuraminidase (NA) enzymatic activity and viral replication more than methanol (MeOH) extract. EtOAc extract demonstrated NA inhibition IC50 values ranging from 73.16 to 487.40 μg/mL and plaque reduction IC50 values ranging from 23.7 to 27.4 μg/mL. Chloroform extract showed antiviral activities with plaque reduction IC50 values ranging from 14.16 to 41.49 μg/mL Time-of-addition assay indicated that EtOAc and chloroform extracts also significantly inhibited virus yields after infection. HPLC analysis demonstrated that baicalin was dominant in the MeOH extract; baicalein and chrysin were rich in the EtOAc and chloroform extracts. Molecular simulation revealed baicalein hydrogen bonding with Glu277 as well as hydrophobic and Van der Waals interactions with Ile222, Arg224, Ser246, and Tyr347 in NA1 active sites of NA1. Baicalein inhibited in vitro replication of influenza A viruses pandemic 2009 H1N1 (IC50 = 0.018 μM) and seasonal 2007 H1N1 using plaque reduction assays. A combination of low-dose baicalein with other anti-influenza agents could be applicable for development of alternative remedies treating influenza A virus infection.

Current understanding on antihepatocarcinoma effects of xiao chai hu tang and its constituents

Xiao Chai Hu Tang (XCHT), a compound formula originally recorded in an ancient Chinese medical book Shanghanlun, has been used to treat chronic liver diseases for a long period of time in China. Although extensive studies have been demonstrated the efficacy of this formula to treat chronic hepatitis, hepatic fibrosis, and hepatocarcinoma, how it works against these diseases still awaits full understanding. Here, we firstly present an overview arranging from the entire formula to mechanism studies of single herb in XCHT and their active components, from a new perspective of "separation study," and we tried our best to both detailedly and systematically organize the antihepatocarcinoma effects of it, hoping that the review will facilitate the strive on elucidating how XCHT elicits its antihepatocarcinoma role.

San-Huang-Xie-Xin-Tang extract suppresses hepatitis C virus replication and virus-induced cyclooxygenase-2 expression

Chronic hepatitis C virus (HCV) infection is associated with chronic inflammation of liver, which leads to the development of cirrhosis and hepatocellular carcinoma (HCC). Because of severe side effects and only a 50-70% cure rate in genotype 1 HCV-infected patients upon current standard treatment with pegylated interferon-α plus ribavirin, new therapeutic regimens are still needed. San-Huang-Xie-Xin-Tang (SHXT) is a transitional Chinese herbal formula, composed of Rhei rhizoma, Scutellaria radix and Coptidis rhizome, and possesses anti-inflammatory effect. Here, we describe a (+)-catechin-containing fraction extracted from SHXT, referred as SHXT-frC, exhibited effective inhibition of HCV replication, with selectivity index value (SI; CC50 /EC50) of 84, and displayed synergistic anti-HCV effects when combined with interferon-α, HCV protease inhibitor telaprevir or polymerase inhibitor 2'-C-methylcytidine. The activation of factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) signalling pathway has particular relevance to HCV-associated HCC. SHXT-frC treatment also caused a concentration-dependent decrease in the induction of COX-2 and NF-κB expression caused by either HCV replication or HCV NS5A protein. Collectively, SHXT-frC could be an adjuvant treatment for patients with HCV-induced liver diseases.

Qushi Huayu Decoction (祛湿化瘀方) inhibits protein and gene expression of cathepsin B in HepG2 cells induced by free fatty acids

OBJECTIVE

To study the experimental efficacy of Qushi Huayu Decoction (祛湿化瘀方,QHD) on, protein and gene expression of cathepsin B (ctsb) in HepG2 cells induced by free fatty acids (FFAs).

METHODS

The model of HepG2 steatosis and tumor necrosis factor-α (TNF-α) secretion was induced by long-chain FFAs. HepG2 cells were divided into 4 groups: control group (group C), model group (group M), low-dose QHD group (group L) and high-dose QHD group (group H). Long-chain FFAs were added to groups M, L and H. The 10% blank-control serum was added to group C and M, while 5% and 10% QHD-containing sera were added to group L and H, respectively. The levels of serum TNF-α and cellular triglyceride (TG) were detected. Cellular p-IκB and ctsb expression were detected using Western blot and PCR. The expression and distribution of ctsb were observed by immunofluorescence.

RESULTS

After incubating with FFA for 24 h, TG deposition in HepG2, TNF-α content in cell supernatant, the protein expression of cellular ctsb and P-IκB, as well as mRNA expression of ctsb increased markedly in group M compared with group C (P<0.05, P<0.01). Compared with group M, TG deposition, the expression of cellular ctsb, P-IκB and ctsb mRNA in groups L and H, as well as TNF-α content in group H, decreased significantly (P<0.05). Cell immunochemical fluorescence studies showed that ctsb was released from lysosomes and distributed in the cytoplasm extensively and diffusedly after being stimulated with FFA. In this study, these above-mentioned changes were inhibited markedly in groups L and H.

CONCLUSION

QHD might have a direct inhibitory effect on the ctsb target in the FFA-ctsb-TNFα pathway of hepatic lipotoxicity.

Effect of oxymatrine on the replication cycle of hepatitis B virus in vitro

AIM: To determine the antiviral mechanism or target of oxymatrine against hepatitis B virus (HBV).

METHODS: HepG2.2.15 cells were incubated with culture medium containing 500 μg/mL of oxymatrine for 2 and 5 d. The surface antigen of HBV (HBsAg) and e antigen of HBV (HBeAg) in supernatant were determined by ELISA. HBV DNA in supernatant, and intracellular covalently closed circular DNA (cccDNA), relaxed circular DNA (rcDNA) and pregenomic RNA (pgRNA) were quantified by specific real-time polymerase chain reaction (PCR) or reverse transcription (RT)-PCR.

RESULTS: Treatment with oxymatrine for 2 d and 5 d reduced the production of HBV by the cell line, as indicated by the decline of HBsAg (22.67%, t = 5.439, P = 0.0322 and 22.39%, t = 5.376, P = 0.0329, respectively), HBeAg (55.34%, t = 9.859, P = 0.0101 and 43.97%, t = 14.080, P = 0.0050) and HBV DNA (40.75%, t = 4.570, P = 0.0447 and 75.32%, t = 14.460, P = 0.0047) in the supernatant. Intracellular cccDNA was also markedly reduced by 63.98% (t = 6.152, P = 0.0254) and 80.83% (t = 10.270, P = 0.0093), and intracellular rcDNA by 34.35% (t = 4.776, P = 0.0413) and 39.24% (t = 10.050, P = 0.0097). In contrast, intracellular pgRNA increased by 6.90-fold (t = 8.941, P = 0.0123) and 3.18-fold (t = 7.432, P = 0.0176) after 500 μg/mL of oxymatrine treatment for 2 d and 5 d, respectively.

CONCLUSION: Oxymatrine may inhibit the replication of HBV by interfering with the process of packaging pgRNA into the nucleocapsid, or inhibiting the activity of the viral DNA polymerase.