Hepatoprotective effect of chitooligosaccharides against tert-butylhydroperoxide-induced damage in Chang liver cells

Phospho-Chitooligosaccharides below 1 kDa Inhibit HIV-1 Entry In Vitro

Despite present antiviral agents that can effectively work against HIV-1 replication, side effects and drug resistance have pushed researchers toward novel approaches. In this context, there is a continued focus on discovering new and more effective antiviral compounds, particularly those that have a natural origin. Polysaccharides are known for their numerous bioactivities, including inhibiting HIV-1 infection and replication. In the present study, phosphorylated chitosan oligosaccharides (PCOSs) were evaluated for their anti-HIV-1 potential in vitro. Treatment with PCOSs effectively protected cells from HIV-1-induced lytic effects and suppressed the production of HIV-1 p24 protein. In addition, results show that PCOSs lost their protective effect upon post-infection treatment. According to the results of ELISA, PCOSs notably disrupted the binding of HIV-1 gp120 protein to T cell surface receptor CD4, which is required for HIV-1 entry. Overall, the results point out that PCOSs might prevent HIV-1 infection at the entry stage, possibly via blocking the viral entry through disruption of virus-cell fusion. Nevertheless, the current results only present the potential of PCOSs, and further studies to elucidate its action mechanism in detail are needed to employ phosphorylation of COSs as a method to develop novel antiviral agents.

Chemical synthesis of oligosaccharides and their application in new drug research

Oligosaccharides are the ubiquitous molecules of life. In order to translate human bioglycosylation into clinical applications, homogeneous samples of oligosaccharides and glycoconjugates can be obtained by chemical, enzymatic or other biological methods for systematic studies. However, the structural complexity and diversity of glycans and their conjugates present a major challenge for the synthesis of such molecules. This review summarizes the chemical synthesis methods of oligosaccharides, the application of oligosaccharides in the field of medicinal chemistry according to their related biological activities, and shows the great prospect of oligosaccharides in the field of pharmaceutical chemistry.

The Positive Influence of Polyphenols Extracted From Pueraria lobata Root on the Gut Microbiota and Its Antioxidant Capability

Pueraria lobata, an edible food and medicinal plant, is a rich source of bioactive components. In this study, a polyphenol-rich extract was isolated from P. lobata. Puerarin was identified, and the high antioxidant bioactivity of the P. lobata extract was evaluated using the methods of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), and hydroxyl free radical scavenging ratio. Additionally, the IC₅₀ values of DPPH, ABTS, and hydroxyl radical scavenging activities were 50.8, 13.9, and 100.4 μg/ml, respectively. Then, the P. lobata extract was administered to C57Bl/6J mice and confirmed to have a superior effect on enhancing the antioxidant status including improving superoxide dismutase activity, glutathione peroxidase peroxide activity, total antioxidant capacity activity, and malondialdehyde contents in vivo. Furthermore, the P. lobata extract had beneficial and prebiotic effects on the composition and structure of gut microbiota. Results showed that the P. lobata extract significantly increased the abundance of beneficial bacteria, involving Lactobacillaceae and Bacteroidetes, and decreased the abundance of Ruminococcaceae, Prevotellaceae, and Burkholderiaceae. Overall, our results provided a basis for using the P. lobata extract as a promising and potential functional ingredient for the food industry.

Chitooligosaccharides alleviate hepatic fibrosis by regulating the polarization of M1 and M2 macrophages

Regulating immune homeostasis by targeting liver macrophage polarization is a potential therapeutic strategy for hepatic fibrosis. Chitooligosaccharide (COS) is a bioactive oligosaccharide possessing potent immunomodulatory and hepatoprotective effects. In this study the hepatoprotective effect of COS on hepatic fibrosis was examined in mice and the underlying mechanisms were investigated. Herein, mice were induced to hepatic fibrosis using carbon tetrachloride (CCl₄) and concurrently treated with COS orally. Kupffer cells (KCs) were skewed towards M1 macrophage polarization by lipopolysaccharide (LPS) and towards M2 macrophage polarization by interleukin-4 (IL-4) in vitro, which were utilized for COS treatment. The results showed that mice were rescued from hepatic fibrosis by COS, marked by a reduction in the deposition of the extracellular matrix (ECM) and histological lesions. COS had an inhibitory effect on the polarization of M1 and M2 macrophages both in vivo and in vitro, characterized by the raised biomarker of the M1 and M2 macrophages slipping towards the basal levels. Furthermore, COS inhibited the JAK2/STAT1 pathways on M1 macrophages and the JAK1/STAT6 pathways on M2 macrophages in KCs. In summary, this study revealed a molecular mechanism for the impact of COS effectiveness on the polarization of liver macrophages, suggesting that is could be a possible intervention for hepatic fibrosis.

Anti-inflammatory activity of soluble chito-oligosaccharides (CHOS) on VitD3-induced human THP-1 monocytes

Chito-oligosaccharides (CHOS) are oligomers of D-glucosamine and N-acetyl-glucosamine. Anti-inflammatory activities of a wide variety of CHOS mixtures have previously been reported, mainly based on studies with mouse models and murine macrophages. Since the mouse and human immune systems are quite different, gaining insight into the activity of CHOS on human cell lines, using well-characterized CHOS mixtures, is of considerable interest. Bacillus subtilis chitosanase (BsCsn46A) can efficiently convert chitosan to mixtures of water soluble low molecular weight CHOS. Here, the anti-inflammatory activity of a properly characterized CHOS mixture was studied, using human THP-1 cells that were differentiated to mature monocytes using vitamin D3. Addition of CHOS reduced the production of multiple pro-inflammatory cytokines associated with bacterial lipopolyssacharide (LPS)-stimulated inflammation, in a dose-dependent manner and without affecting cell viability. Interestingly, only minimal effects of CHOS were observed in similar experiments with phorbol 12-myristate 13-acetate- (PMA-) differentiated, macrophage-like, THP-1 cells. Altogether, in addition to showing promising biological effects of well-characterized low molecular weight soluble CHOS in a human system, the present study also points at Vitamin D3-stimulated THP-1 cells as a favorable system for assessing the anti-inflammatory activity of bioactive compounds.

Characterization of a New Chitosanase from a Marine Bacillus sp. and the Anti-Oxidant Activity of Its Hydrolysate

Chitooligosaccharide (COS) has been recognized to exhibit efficient anti-oxidant activity. Enzymatic hydrolysis using chitosanases can retain all the amino and hydroxyl groups of chitosan, which are necessary for its activity. In this study, a new chitosanase encoding gene, csnQ, was cloned from the marine Bacillus sp. Q1098 and expressed in Escherichia coli. The recombinant chitosanase, CsnQ, showed maximal activity at pH 5.31 and 60 °C. Determination of CsnQ pH-stability showed that CsnQ could retain more than 50% of its activity over a wide pH, from 3.60 to 9.80. CsnQ is an endo-type chitosanase, yielding chitodisaccharide as the main product. Additionally, in vitro and in vivo analyses indicated that chitodisaccharide possesses much more effective anti-oxidant activity than glucosamine and low molecular weight chitosan (LMW-CS) (~5 kDa). Notably, to our knowledge, this is the first evidence that chitodisaccharide is the minimal COS fragment required for free radical scavenging.

Induction of Nrf2-mediated phase II detoxifying/antioxidant enzymes in vitro by chitosan-caffeic acid against hydrogen peroxide-induced hepatotoxicity through JNK/ERK pathway

Chemical modification of chitosan is a promising method for the improvement of biological activity. In this study, chitosan-caffeic acid (CCA) was prepared and its in vitro hepatoprotective ability against hydrogen peroxide-induced hepatic damage in liver cells was evaluated. Treatment with CCA (50-400 µg/mL) did not show cytotoxicity and also significantly (p < 0.05) recovered cell viability against 650 µM hydrogen peroxide-induced hepatotoxicity. CCA treatment attenuated reactive oxygen species generation and lipid peroxidation in addition to increasing cellular glutathione level in cultured hepatocytes. To validate the underlying mechanism, antioxidant and phase II detoxifying enzyme expressions, which are mediated by NF-E2-related factor 2 (Nrf2) activation, were analyzed and CCA treatment was found to increase the expression of superoxide dismutase-1 (SOD-1), glutathione reductase (GR), heme oxygenase-1 (HO-1), and NAD(P)H:quinine oxidoreductase 1 (NQO1). CCA treatment resulted in increased Nrf2 nuclear translocation. The phosphorylation of extracellular regulated kinase (ERK), c-Jun NH₂-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) by CCA treatment contributed to Nrf2 activation. Pharmacological blockade of ERK, JNK, and p38 MAPK revealed that SP600125 (JNK inhibitor) and PD98059 (ERK inhibitor) treatment reduced Nrf2 translocation into the nucleus while SB203580 (p38 inhibitor) exhibited weak inhibition. Collectively, CCA protects liver cells against hydrogen peroxide-induced injury and this ability is attributed to the induction of antioxidants and phase II detoxifying enzymes that are mediated by Nrf2 translocation via JNK/ERK signaling.

Characterization of the antioxidant fraction of Trapa japonica pericarp and its hepatic protective effects in vitro and in vivo

The ethanolic extract of Trapa japonica pericarp (TJP) and its various fractions were evaluated for their antioxidant potential. The ethyl acetate fraction (EF) from TJP exhibited significant antioxidant and protective effects against tert-butylhydroperoxide (t-BHP)-induced oxidative damage in vitro and in vivo. In vitro experimental results showed that the EF suppressed t-BHP-induced damage in Chang cells by inhibiting reactive oxygen species generation and regulating the mitochondrial membrane potential. Furthermore, western blot analysis showed that the EF effectively inhibited t-BHP-induced apoptosis by suppressing caspase-3, caspase-7, caspase-8, and caspase-9. In the in vivo study, the EF significantly prevented serum increases in glutamate oxaloacetate transaminase and glutamate pyruvate transaminase and hepatic malondialdehyde levels caused by t-BHP. Furthermore, the EF markedly increased hepatic superoxide dismutase, catalase, and glutathione levels. Histopathological examinations further confirmed that the EF could protect the liver from t-BHP-induced oxidative injury. These findings indicate that the EF could be developed as a therapy or to prevent hepatic injury.

Protective activity of kudzu (Pueraria thunbergiana) vine on chemically-induced hepatotoxicity: in vitro and in vivo studies

Background

Kudzu (Pueraria thunbergiana) root has long been used in Traditional Chinese Medicine. However, the vine of the kudzu plant has been considered waste material. This study aimed to investigate the hepatoprotective properties of the kudzu vine.

Methods

We created 0 %, 30 %, 70 %, and 95 % ethanolic kudzu vine extracts. The isoflavone contents of kudzu vine extract were quantified by high-performance liquid chromatography. Tertiary-butylhydroperoxide (t-BHP) was added to human liver-derived HepG2 cells, and the production of reactive oxygen species was measured in the presence and absence of kudzu vine extract. Antioxidant activity was evaluated in all kudzu vine extracts using a hydroxyradical scavenging assay. Thirty-five male Sprague–Dawley rats were divided into seven groups (n = 5); two groups were not given any extract or drug, one group was treated with 50 mg/kg silymarin orally for 5 days, and the remaining four groups were respectively treated with 100 mg/kg of 0 %, 30 %, 70 %, or 95 % ethanolic extract of kudzu vine orally once daily for 5 days. On day 5 the treatment groups and one untreated group were fed 0.75 ml/kg carbon tetrachloride (CCl₄) to induce liver damage. Blood and liver tissue samples were collected 24 h after CCl₄ administration for measurement of plasma alanine aminotransferase and aspartate aminotransferase, and concentration of malondialdehyde and glutathione in liver tissue.

Results

Puerarin was the most abundant isoflavone in kudzu vine extract. Kudzu vine extract significantly reduced the cytotoxicity and production of reactive oxygen species induced by t-BHP in a dose-dependent manner. Treatment with 0 % and 30 % ethanolic extracts of kudzu vine significantly lowered the plasma levels of alanine aminotransferase and aspartate aminotransferase in a CCl₄-induced hepatotoxicity rat model (P < 0.05). Glutathione was significantly elevated in the 30 % ethanolic extract-treated group (P < 0.05), while the malondialdehyde level in liver tissue was significantly decreased in the 0 % and 30 % ethanolic extract-treated groups (P < 0.05).

Conclusions

The kudzu vine is potentially highly beneficial in treating liver damage, as it scavenges reactive free radicals and boosts the endogenous antioxidant system.

Antioxidant activity and protective effect of extract of Celosia cristata L. flower on tert-butyl hydroperoxide-induced oxidative hepatotoxicity

This study was undertaken to evaluate the antioxidant potential and protective effects of Celosia cristata L. (Family: Amaranthaceae) flower (CCF) extracts on tert-butyl-hydroperoxide (t-BHP)-induced oxidative damage in the hepatocytes of Chang cells and rat livers. In vitro, CCF extracts exhibited protective effect through their radical scavenging ability to enhance cell viability, prevent reactive oxygen species (ROS) generation, and inhibit mitochondrial membrane depolarisation in t-BHP-induced hepatotoxicity in Chang cells. In vivo, oral feeding of CCF (100mg and 500mg/kg of body weight) to rats for five consecutive days before a single dose of t-BHP (2mmol/kg, i.p.) showed a significant (p<0.05) protective effect by lowering serum levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT). The extract decreased the hepatic levels of lipid peroxidation (MDA) and serum level of triglyceride (TG) against t-BHP-induced oxidative stress. These results indicate that CCF extract prevented oxidative stress-induced liver injury by enhancing hepatocyte antioxidant abilities.

Chitooligosaccharide and its derivatives: preparation and biological applications

Chitin is a natural polysaccharide of major importance. This biopolymer is synthesized by an enormous number of living organisms; considering the amount of chitin produced annually in the world, it is the most abundant polymer after cellulose. The most important derivative of chitin is chitosan, obtained by partial deacetylation of chitin under alkaline conditions or by enzymatic hydrolysis. Chitin and chitosan are known to have important functional activities but poor solubility makes them difficult to use in food and biomedicinal applications. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin prepared by enzymatic or chemical hydrolysis of chitosan. The greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivatives for various biomedical applications. In light of the recent interest in the biomedical applications of chitin, chitosan, and their derivatives, this review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives.

Antioxidant activity and protective effects of Trapa japonica pericarp extracts against tert-butylhydroperoxide-induced oxidative damage in Chang cells

In this study, the antioxidant properties of Trapa japonica pericarp extracts were evaluated through several biochemical assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH), alkyl radical scavenging activity, hydroxyl radical scavenging, ferric reducing antioxidant power (FRAP) assay, ABTS radical scavenging activity and oxygen radical absorbance capacity (ORAC). The antioxidant activities were compared with other natural and synthetic antioxidants. The results showed that higher radical scavenging activity and antioxidant capacity in FRAP than those of vitamin C as a positive control. T. japonica pericarp extracts have antioxidant properties through its ability to prevent tert-butylhydroperoxide (t-BHP)-induced toxicity which enhance the cell viability, reduce reactive oxygen species (ROS) production, inhibits of oxidative damage and mitochondria dysfunction in Chang liver cells. Therefore, based on these finding, it seems reasonable to suggest that T. japonica pericarp extracts has the potential to protect liver against t-BHP-induced cell damage and should be considered as a potential functional food.

Thymol from Thymus quinquecostatus Celak. protects against tert-butyl hydroperoxide-induced oxidative stress in Chang cells

The present work describes the protective effects of thymol isolated from Thymus quinquecostatus Celak. against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage through various experiments with Chang liver cells. Thymol significantly protected hepatocytes against t-BHP-induced cell cytotoxicity as demonstrated by increased viability. Furthermore, observation of Hoechst staining, annexin V/PI staining, and expression of Bcl-2 and Bax indicated that thymol inhibited t-BHP-induced Chang cell damage. Further, thymol inhibited the loss of mitochondrial membrane potential in t-BHP-treated Chang cells and prevented oxidative stress-triggered reactive oxygen species (ROS) and lipid peroxidation (malondialdehyde, MDA). Thymol restored the antioxidant capability of hepatocytes including glutathione (GSH) levels which were reduced by t-BHP. These results indicated that thymol prevents oxidative stress-induced damage to liver cells through suppression of ROS and MDA levels and increase of GSH level.

Effects of chitosan oligosaccharides on drug-metabolizing enzymes in rat liver and kidneys

To investigate the effect of chitosan oligosaccharides (COS) on drug-metabolizing enzymes in rat liver and kidneys, male Spraque-Dawley rats were fed a diet containing 1% or 3% COS for 5 weeks. The activities of cytochrome P450 (CYP) enzymes, UDP-glucurosyltransferase (UGT) and glutathione S-transferase (GST) in the liver and kidneys were determined. Significant decreases in microsomal CYP3A-catalyzed testosterone 6β-hydroxylation, CYP2C-catalyzed diclofenac 4-hydroxylation, and CYP4A-catalyzed lauric acid 12-hydroxylation in the liver of rats fed the COS diets were observed compared with those rats fed the control diet. Immunoblot analyses of CYP proteins showed the same trend as with enzyme activities. Increased glutathione content in liver was found in rats fed the 1% COS diet. Increased hepatic NADPH: quinone oxidoreductase 1 (NQO1) activity was found in rats fed the COS diets. In kidneys, COS had little or no effect on CYP enzyme activities. However, increased GST activity was observed in rats fed the COS diets. Moreover, a higher UGT activity was found in rats fed the 1% COS diet. Our results indicate that COS may suppress hepatic CYP enzymes and induce phase II detoxifying reactions in the liver and kidneys of rats.