The renal protective effects of Anoectochilus roxburghii polysaccharose on diabetic mice induced by high-fat diet and streptozotocin

PPAR gamma agonistic activity of dillapiole: protective effects against diabetic nephropathy

Using structural similarity approach we identified dillapiole, a phenylpropanoid, the main component of Piper aduncum L. and Anethum graveolens L. essential oils as potential PPARγ agonist. Molecular docking revealed that dillapiole binds to the active site of PPARγ, similar to pioglitazone binding. In silico ADME studies showed that dillapiole has high water solubility and GI absorption. Dillapiole was also observed to be partial agonist of PPARγ receptors with EC50 of 43.95 µM. In BHK-21 cells cultured under hyperglycaemic conditions, dillapiole administration reduced oxidative stress and prevented decrease in histone H3 acetylation (k9/14) levels. In HFD + STZ induced diabetic mice, dillapiole treatment for 7 days was able to improve renal functions and decrease plasma glucose level to 138.39 ± 12.36 mg/dl along with decreasing total cholesterol (29%), triglycerides (48.8%), LDL (24.7%), and VLDL (65%) levels in serum. These results show that dillapiole is a potential PPARγ-agonist and thus needs to explore further.

The effects of aerobic exercise on liver function, insulin resistance, and lipid profiles in prediabetic and type 2 diabetic mice

BACKGROUND AND AIMS

The purpose of the current study was to evaluate the expression of gluconeogenesis and insulin resistance key genes; including insulin receptor substrate 1 (Irs1), a serine/threonine protein kinase (Akt), forkhead box class-O 1 (FoxO1) and phosphoenolpyruvate carboxykinase (Pepck) genes, and lipid profiles following either a standard or a high-fat diet (HFD) and either an aerobic exercise or non-exercise intervention in prediabetic and type 2 diabetic (T2DM) mice.

METHODS

24 male mice were randomly assigned to two groups fed with a normal diet (ND) or a HFD for 12 weeks. The mice in each group were again randomly assigned to two groups to create four groups in total: 1. Prediabetes-exercised (Prediabetes-Exe), 2. Prediabetes-non exercised (Prediabetes-Non exe), 3. Healthy-exercised (Healthy-Exe), and 4. Healthy-non exercised (Healthy-Non exe). Eighteen additional male mice were fed with the HFD for 8 weeks, after which streptozotocin (STZ) was administered. The mice were then fed the HFD for an additional 4 weeks. These T2DM mice were then randomly divided into two groups: 1. Diabetes-exercised (Diabetic-Exe), and 2. Diabetes-Non exe. The three Exe groups all exercised on a treadmill for 8 weeks for 5 sessions/week. After the last training session, liver tissue was extracted, and the expression of Irs1, Akt, FoxO1, and Pepck genes was measured using real time quantitative Polymerase chain reaction tests. Lipid profiles were measured in serum and in the liver.

RESULTS

The expression of both Irs1 and Akt was significantly increased in the Healthy-Exe, Prediabetes-Exe, and Diabetes-Exe groups as compared to the Healthy-Non exe, Prediabetes-Non exe, and Diabetes-Non exe groups (p < 0.001). Additionally, the expression of FoxO1 (p < 0.05) and Pepck (p < 0.001) decreased significantly in the Prediabetes-Exe, and Diabetes-Exe groups as compared to the Prediabetes-non exe, and Diabetes-Non exe groups. Aerobic exercise did not lead to reductions in FoxO1 or Pepck expression in the Healthy-Exe mice.

CONCLUSIONS

Eight weeks of aerobic exercise (5 sessions/week) significantly increased the expression of key genes that are important for maintaining glucose homeostasis and improving insulin resistance (Irs1 and Akt), and decreased expression of genes that are important for decreasing gluconeogenesis in the liver (FoxO1 and Pepck) in healthy, prediabetic, and T2DM mice. The lipid profiles improved in healthy, prediabetic, and T2DM mice.

Isolation, structural and bioactivities of polysaccharides from Anoectochilus roxburghii (Wall.) Lindl.: A review

Anoectochilus roxburghii (Wall.) Lindl. (A. roxburghii), a valuable herbal medicine in China, has great medicinal and edible value. Polysaccharides, as one of the main active components of A. roxburghii, comprise glucose, arabinose, xylose, galactose, rhamnose, and mannose in different molar ratios and glycosidic bond types. By varying the sources and extraction methods of A. roxburghii polysaccharides (ARPS), different structural characteristics and pharmacological activities can be elucidated. ARPS has been reported to exhibit antidiabetic, hepatoprotective, anti-inflammatory, antioxidant, antitumor, and immune regulation activities. This review summarizes the available literature on the extraction and purification methods, structural features, biological activities, and applications of ARPS. The shortcomings of the current research and potential focus in future studies are also highlighted. This review provides systematic and current information on ARPS to promote their further exploitation and application.

Therapeutic effect and mechanism of polysaccharides from Anoectochilus Roxburghii (Wall.) Lindl. in diet-induced obesity

BACKGROUND

Recent studies have shown that polysaccharides from Anoectochilus roxburghii (Wall.) Lindl. (ARPs) can reduce blood glucose levels, ameliorate oxidative stress and inflammation. However, whether ARPs have a beneficial effect on diet-induced obesity remain to be determined.

PURPOSE

This study aims to investigate the effect and mechanism of ARPs in improving obesity and metabolic disorders induced by high-fat diet (HFD).

METHODS

In this study, 6-week-old male mice were fed with HFD or chow diet for 13 weeks, and a dietary supplementation with ARPs was carried out. Glucose tolerance test and insulin tolerance test were performed to measure the glucose tolerance and insulin sensitivity. Adipose tissue and liver were isolated for analysis by qRT-PCR, Western blotting, hematoxylin-eosin staining and immunostaining.

RESULTS

At week 13, body weight and fat mass were significantly increased by HFD, but ARPs supplementation abolished these phenotypes. Compared with HFD group, thermogenic genes including Ucp-1, Pgc-1α, Prdm16 and Dio2 in adipose tissue were up-regulated in ARPs-treated mice. In addition, ARPs decreased liver lipid accumulation by reducing lipid synthesis and increasing oxidation. Meanwhile, dyslipidemia and insulin resistance induced by HFD were improved by ARPs. Mechanistically, ARPs can promote fat thermogenesis via AMPK/SIRT1/PGC-1α signaling pathway.

CONCLUSION

Dietary supplementation of ARPs can protect mice against diet-induced obesity, fatty liver and insulin resistance. Our study reveals a potential therapeutic effect for ARPs in regulating energy homeostasis.

Bioassay-guided study of the anti-inflammatory effect of Anoectochilus burmannicus ethanolic extract in RAW 264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus species is a small terrestrial orchid found in tropical and subtropical rain forest. These orchids are traditionally used extensively in China, Taiwan, and Vietnam due to their medicinal properties and therapeutic benefits. They are employed for treatment in different systems, such as stomach disorders, chest pain, arthritis, tumor, piles, boils, menstrual disorders, and inflammation. Aqueous extract of Anoectochilus burmannicus (AB) has been previously reported to exhibit anti-inflammatory activities, however there is a lack of evidence regarding its bioactive compounds and the mechanism of its actions.

AIM OF THE STUDY

The objectives of this study were to identify the anti-inflammatory compound(s) in an ethanolic extract of AB and to determine its anti-inflammatory mechanisms in LPS-stimulated macrophages and also its safety.

MATERIALS AND METHODS

The ethanolic extract of AB (ABE) was prepared and subsequently subjected to polarity-dependent extraction using n-hexane and ethyl acetate, which would result in isolation of the n-hexane (ABH), ethyl acetate (ABEA), and residue or aqueous (ABA) fractions. The AB fractions were investigated to determine total phenolic and flavonoid content, antioxidant capacity, toxicity, and safety in RAW 264.7 macrophages, human PBMCs, and RBCs. After extraction anti-inflammation screening of each extract was performed by nitric oxide (NO) production assay. The active fractions were further examined for their effect on proinflammatory mediators. In addition, kinsenoside content in the active fractions was identified using LC-MS/MS. Cellular toxicity and genotoxicity of AB were also tested using the wing spot test in Drosophila melanogaster.

RESULTS

The data showed that ABEA had the highest phenolic content and level of antioxidant activities. ABE, ABEA, and ABA, but not ABH, significantly inhibited the LPS-stimulated NO production in the macrophages. Both ABEA and ABA reduced LPS-mediated expression of TNF-α, IL-6, iNOS, and COX-2 at both mRNA and protein levels. Besides, only ABEA notably diminished the LPS-stimulated p65 phosphorylation required for nuclear translocation and transcriptional activation of the nuclear factor-κB (NF-κB). Interestingly, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed ABA contained a high level of kinsenoside, a likely anti-inflammatory compound, while ABE and ABEA might require other compounds in combination with kinsenoside for the inhibition of inflammation. It was shown that all active fractions were neither cytotoxic nor genotoxic.

CONCLUSION

Our study demonstrated that the hydrophilic fractions of AB exhibit anti-inflammatory activity in LPS-stimulated macrophages. The mechanism used by the AB involves the scavenging of free radicals and the reduction of proinflammatory mediators, including IL-1β, IL-6, TNF-α, NO, iNOS and COX-2. The anti-inflammatory action of AB involves the suppression of the NF-κB signaling pathway by some unknown component(s) present in ABEA. This study found that kinsenoside is a major active compound in ABA which could be used as a biomarker for the quality control of the plant extraction. This study provides convincing significant information in vitro regarding the anti-inflammatory mechanism and preliminary evidence of the safety of Anoectochilus burmanicus. Therefore, the knowledge acquired from this study would provide supportive evidence for the development and standardization of the use of the extract of this plant as alternative medicine or functional food to prevent or treat non-communicable chronic diseases related to chronic inflammation.

Modulation and bioinformatics screening of hepatic mRNA-lncRNAs (HML) network associated with insulin resistance in prediabetic and exercised mice

Background

Insulin resistance is associated with prediabetes and further progression to type 2 diabetes mellitus (T2DM). This study aims to investigate novel hepatic lncRNAs associated with key genes in insulin resistance in prediabetes.

Methods

In the bioinformatics phase, we have collected screened a pool of lncRNAs and mRNAs according to their potential association to prediabetic condition. We performed pathway analysis of mRNAs, using DAVID tool based on KEGG repository data. Then, we used Python programming language to get a subset of lncRNAs located in 50 kb proximity with high-fat (HF)-responsive mRNAs. In the experimental phase, prediabetic mice model was established by the treatment of HF diets for 12 weeks. After this treatment, HF-fed animals were divided into two groups of endurance exercised or sedentary, both continuing on the HF diet for 8 weeks. Besides, a group of diabetic mice was treated using a HF diet for 8 weeks followed by injection with STZ solution and then a HF diet for another 4 weeks.

Results

We found three genes having paired lncRNAs annotated in insulin resistance pathway. Their hepatic expression levels were altered in prediabetic condition as upregulation of Srebf1 was associated with GM38501, upregulation of Pck1 was associated with Ctcflos and GM36691, downregulation of Cpt1b was associated with GM44502. All of these expression patterns were replicated in diabetic mice, correlated positively with their predicted lncRNAs. Interestingly, exercise reversed their expression patterns.

Conclusions

We suggest that the expression pattern of the hepatic mRNA-lncRNA (HML) network in prediabetic state undergoes similar modification to that of diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00600-0.

Characterization of Anoectochilus roxburghii polysaccharide and its therapeutic effect on type 2 diabetic mice

Anoectochilus roxburghii is a traditional herb in China that can be potentially used to treat diabetes. A novel polysaccharide ARLP-W was isolated from Anoectochilus roxburghii by chromatography on DEAE-52 cellulose. Chemical analysis indicated that ARLP-W (8.1 × 10⁴ Da) was mainly composed of mannose and glucose. The main linkages of glycosidic bonds of ARLP-W were β-1, 4-Manp and α-1, 4-Glcp. The terminal Glcp was connected to Manp-via O-3. RT-qPCR and western blotting analysis showed that ARLP-W caused a significant reduction in the levels of the key gluconeogenesis enzymes phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase (G6Pase) in the liver. The results of the insulin resistance tests indicated that ARLP-W increased glucose absorption. These results indicate that ARLP-W has a good therapeutic effect on type 2 diabetes and can assist with further development and application treatment of diabetes.

Purification, structure and conformation characterization of a novel glucogalactan from Anoectochilus roxburghii

Anoectochilus roxburghii (AR) has been used in food, medicine and ornamental industries for a long time. Anion exchange resin was proposed to purify the sub-fraction of water-extracted AR polysaccharide (ARPP-70), and a homogeneous polysaccharide ARPP-70a was obtained. The structural features of ARPP-70a were characterized using gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, and high performance size exclusion chromatograph coupled with multi-angle laser light scattering (HPSEC-MALLS). The relative weight average molecular weight for ARPP-70a was determined to be 14.8 kDa, and the molar ratio of glucose to galactose was 1.0:3.2. The structure of ARPP-70a was elucidated to be glucogalactan, with backbone comprising β-1,4-linked Galp and some α-1,4-linked Glcp. The conformation characteristics of ARPP-70a were supposed to exist as a random coil chain in 0.1 M NaNO₃ solution. Moreover, in vitro antioxidant activity assays revealed ARPP-70a exhibited appreciable antioxidant potential. To the best of our knowledge, this is the first study to obtain this type of glucogalactan, and provide systematic information on its structural and conformational properties. This study improved the understanding of the physicochemical characteristics of AR polysaccharide, which is beneficial for its further application in food and medicinal industry.

Combined Metabolome and Transcriptome Analyses Reveal the Effects of Mycorrhizal Fungus Ceratobasidium sp. AR2 on the Flavonoid Accumulation in Anoectochilus roxburghii during Different Growth Stages

Anoectochilus roxburghii is a traditional Chinese herb with high medicinal value, with main bioactive constituents which are flavonoids. It commonly associates with mycorrhizal fungi for its growth and development. Moreover, mycorrhizal fungi can induce changes in the internal metabolism of host plants. However, its role in the flavonoid accumulation in A. roxburghii at different growth stages is not well studied. In this study, combined metabolome and transcriptome analyses were performed to investigate the metabolic and transcriptional profiling in mycorrhizal A. roxburghii (M) and non-mycorrhizal A. roxburghii (NM) growth for six months. An association analysis revealed that flavonoid biosynthetic pathway presented significant differences between the M and NM. Additionally, the structural genes related to flavonoid synthesis and different flavonoid metabolites in both groups over a period of six months were validated using quantitative real-time polymerase chain reaction (qRT-PCR) and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The results showed that Ceratobasidium sp. AR2 could increase the accumulation of five flavonol-glycosides (i.e., narcissin, rutin, isorhamnetin-3-O-beta-d-glucoside, quercetin-7-O-glucoside, and kaempferol-3-O-glucoside), two flavonols (i.e., quercetin and isorhamnetin), and two flavones (i.e., nobiletin and tangeretin) to some degrees. The qRT-PCR showed that the flavonoid biosynthetic genes (PAL, 4CL, CHS, GT, and RT) were significantly differentially expressed between the M and NM. Overall, our findings indicate that AR2 induces flavonoid metabolism in A. roxburghii during different growth stages, especially in the third month. This shows great potential of Ceratobasidium sp. AR2 for the quality improvement of A. roxburghii.

The purification, structural characterization and antidiabetic activity of a polysaccharide from Anoectochilus roxburghii

Anoectochilus roxburghii, a traditional Chinese medicinal herb, has been widely used for treating numerous chronic diseases.

First demonstration of protective effects of purified mushroom polysaccharide-peptides against fatty liver injury and the mechanisms involved

Fatty liver (FLD) disease is a consequence of metabolic syndrome, which is a health problem worldwide with a phenomenal rise in prevalence. In this study, two hepatoprotective polysaccharide-peptides were extracted from the mushroom Auricularia polytricha followed by chromatographic fractionation of the extract on the ion exchanger DEAE-cellulose and gel filtration on Sephadex-200 to yield two purified fractions: APPI and APPII. The monosaccharide compositions, FT-IR, N-terminal sequences, internal peptide sequences and molecular weights of the two fractions were determined. Furthermore, their hepatoprotective effect on human hepatoma HepG2 cells in vitro and in an animal model of fatty liver disease was evidenced by the findings that APPI and APPII diminished lipid deposit in cells, blood and the liver, increased cellular antioxidant activity and viability, and protected the liver against injury. The mechanistic study revealed that APPI and APPII activated the adiponectin pathway, up-regulated expression of genes controlling free fatty acid (FFA) oxidation, such as AMPK, CPTl, ACOX1 and PPARα genes, enhanced lipid metabolism, preserved hepatic function, promoted the antioxidant defense system and reduced lipid peroxidation. Hence the bioactive compounds of A. polytricha could serve as therapeutic agents in the food and pharmaceutical industries.

Therapeutic effects of polysaccharides from Anoectochilus roxburghii on type II collagen-induced arthritis in rats

Anoectochilus roxburghii, a famous Chinese herbal medicine, has been commonly used for the treatment of liver disease, diabetes, and rheumatoid arthritis. Our study aimed to investigate the anti-rheumatoid arthritis effects of A. roxburghii polysaccharides (ARP), using the rat's model of type II collagen-induced arthritis (CIA). ARP was prepared by alcohol sedimentation and structurally characterized based on combined chemical, chromatographic and spectroscopic methods. High Performance Size Exclusion Chromatography-Multiangle Laser Light Scattering-Refrative Index (HPSEC-MALLS-RI) analysis revealed that ARP includes two peaks, and the weight-average molecular weight (Mw) of the principal one was estimated as 5.90 kDa with a relative content of 98.2%. Pharmacological results exhibited that ARP significantly decreased the arthritis index and ameliorated the inflammatory cell infiltration and the synovial tissue destruction in CIA rats. Additionally, ARP possessed significant NO production inhibitory effects and antioxidant activity. Further anti-inflammatory mechanism investigations indicated that ARP significantly inhibited the activation of nuclear factor κB (NF-κB) pathway by suppressing the phosphorylation of IκB and p65, which subsequently down-regulated the mRNA expressions of IL-1β and IL-6 in LPS-stimulated RAW 264.7 cells. These findings suggested that ARP has great potential in the development of functional foods and dietary supplements for the treatment of rheumatoid arthritis.

Effects of supplemental lighting with different light qualities on growth and secondary metabolite content of Anoectochilus roxburghii

Background

Anoectochilus roxburghii is a widespread herbaceous plant with high medicinal value. Wild A. roxburghii resources face extinction due to their slow growth rate and over exploitation. The growing market demand has led to advances in the field of artificial planting of A. roxburghii. Methods to increase the economic benefits of cultivation and the production of medicinal ingredients are very useful.

Methods

A. roxburghii was exposed to red light, blue light (BL), yellow light (YL), green light, or white light as supplemental lighting at night (18:00-02:00) in a greenhouse or were left in darkness (control, CK) to investigate the effects of various light qualities on growth indices, photosynthetic pigments, chlorophyll fluorescence, root vitality, stomatal density, soluble proteins, sugars, and the accumulation of secondary metabolites.

Results

Supplementation of BL had a positive effect on A. roxburghii growth and secondary metabolite accumulation. Leaf number, stem diameter, fresh weight, dry weight, chlorophyll a content, and secondary metabolite (total flavonoids, total polyphenols) content increased significantly. YL treatment showed significantly higher soluble sugar and polysaccharide contents than the control.

Discussion

BL treatment was conducive to promoting the growth and accumulation of secondary metabolites (total flavonoids, total polyphenols); YL treatment significantly increased the content of soluble sugar and polysaccharides more than the control. Polysaccharides and total flavonoids are important medicinal ingredients of Anoectochilus, so future research will focus on the combination of blue and YL.

Involvement of the TGFβ1- ILK-Akt signaling pathway in the effects of hesperidin in type 2 diabetic nephropathy

Diabetic nephropathy is one of the manifestations of systemic microangiopathy in diabetes. Hesperetin, a natural flavanone glycoside compound in citrus fruits, has been demonstrated to exert hypoglycemic effects and protect kidney in experimental diabetic animals. The current study was aimed to investigate the mechanisms underlying the hypoglycemic effects of hesperetin in high-fat/streptozocin (STZ)-induced diabetic nephropathy. The results showed that mice in whom hesperetin was administered for 4 weeks attenuated the increased fasting blood glucose and impaired glucose tolerance ability that was observed in high-fat/STZ mice. In addition, we found that hesperetin ameliorated the abnormalities of biochemical parameters in serum, liver, and kidney of mice with diabetic nephropathy. Hesperetin also rescued the irregular distortions in glomerular basement membrane and expanded mesangial regions. Moreover, hesperetin repaired the function of podocyte by increasing renal nephrin expression and decreasing renal alpha-smooth muscle actin expression. Furthermore, hesperetin inhibited the expression of transforming growth factor-β1 (TGF-β1) and its downstream effectors integrin-linked kinase (ILK) and Akt. In conclusion, our study implies that hesperetin produced protective effects in diabetic nephropathy possibly by suppressing TGF-β1-ILK-Akt signaling.

Anoectochilus roxburghii: A review of its phytochemistry, pharmacology, and clinical applications

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii (Orchidaceae), also known as Jinxianlian (Simplified Chinese: ) and Jinxianlan (Simplified Chinese: ), is valued in many Asian countries, where this plant species is used for medicinal, culinary, and ornamental purposes. As a food, A. roxburghii is widely used as a treatment booster and medicine because of its various beneficial properties; these include, most notably, the curative effects of heat dissipation and cooling of blood, elimination of dampness, detoxification, and immunity enhancement.

AIM OF THIS REVIEW

This review aims to provide up-to-date information on the phytochemistry, pharmacology, and clinical applications of A. roxburghii.

MATERIALS AND METHODS

Relevant information on A. roxburghii was obtained by an online search of worldwide-accepted scientific databases (Web of Science, ScienceDirect, Elsevier, Springer, NCBI, ACS Publications, CNKI, and Wanfang data).

RESULTS

Phytochemical investigations have revealed that the major chemical constituents of A. roxburghii are polysaccharides, flavonoids, glycosides, organic acids, volatile compounds, steroids, triterpenes, alkaloids, and nucleosides. These compounds have been proven to be the main bioactive substances responsible for pharmacological activities such as antidiabetic, antilipemic, anti-inflammatory, antiviral, liver protective, renal protective, immunomodulatory, abirritant, sedative, and antineoplastic effects.

CONCLUSIONS

A variety of dosage forms of A. roxburghii are currently being applied to patients suffering from hyperuricemia, type 2 diabetes mellitus, chronic hepatitis B, Helicobacter pylori infection, cough-variant asthma, and other conditions. Nevertheless, further research is needed to clarify A. roxburghii absorption, distribution, metabolic, and excretion pathways. Moreover, the toxicology in A. roxburghii and A. formosanus are also in urgent need of research, especially long-term in vivo chronic toxicity tests need to be carried out.

The vascular protective effects of Anoectochilus roxburghii polysaccharose under high glucose conditions

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii has been used as a health food and a herb for treatment diabetes in China for hundreds years. Anoectochilus roxburghii polysaccharose (ARP) is the major active component of the plant.

AIM OF THE STUDY

The present study investigated the vascular protection of ARP in vivo and in vitro experiments.

MATERIALS AND METHODS

Hypoglycemic activity of ARP was examined in diabetic mice. Moreover, the further vascular protective effects in vitro were investigated in human umbilical vein endothelial cells (HUVECs) stimulated by high glucose (HG, 35mM).

RESULTS

Compared with untreated diabetic mice, ARP (100 or 300mg/kg) caused a significant decrease in blood glucose levels. Histological examination showed that ARP ameliorated endothelial damage to some extent, especially ARP at dosage of 300mg/kg. In vitro assay, pretreatment with ARP (10, 20 and 30μg/mL) markedly inhibited generations of reactive oxygen species (ROS), monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) in HG-induced HUVECs. ARP pretreatment not only suppressed HG-induced matrix metalloproteinases (MMPs) activity via increasing the expression of the tissue inhibitors of MMPs (TIMPs), but also adjusted the MMPs/TIMPs balance to maintain homeostasis of vascular structure. Moreover, pretreatment with ARP could significantly reduce p-NF-κB p65, p-p38 MAPK expression levels in HG-induced HUVECs.

CONCLUSIONS

The vascular protective effects of ARP might be associated with NF-κB and p38 MAPK pathway. ARP might be used as useful substance in the treatment of vasculopathy in diabetic patients.

Protective effect of a polysaccharide from Anoectochilus roxburghii against carbon tetrachloride-induced acute liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii (Wall.) Lindl. is traditionally used for the treatment of various types of chronic and acute hepatitis in China. Considering that Anoectochilus roxburghii polysaccharide (ARPT) is the main constituent of Anoectochilus roxburghii, the present study was designed to investigate the hepatoprotective effect of ARPT and its possible mechanism in carbon tetrachloride (CCl₄)-induced mice.

MATERIAL AND METHODS

The hepatoprotective activity of ARPT (150, 300 and 500mg/kg) were investigated on CCl₄-induced acute liver damage in mice. The activities of alanine transaminase (ALT), aspartate transaminase (AST) were determined in serum. The hepatic levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured in liver homogenates. The levels of cytochrome P450 sub family 2E1 (CYP2E1), tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-2 (MIP-2), KC (Murine IL-8 ortholog), transforming growth factor-beta1 (TGF-β1), Bcl-2 and Bax were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The expressions of CYP2E1, nuclear factor-kappa B (NF-κB) p65 and caspase-3 were evaluated by western blot assays. The hepatic levels of TNF-α, IL-6, MIP-2 and TGF-β1 were measured by enzyme-linked immunosorbent assay (ELISA). Furthermore, histopathological observation and terminal-deoxynucleoitidyl transferase mediated nick end labeling assay (TUNEL) were carried out on the separated livers of mice.

RESULTS

ARPT significantly decreased serum ALT and AST activities, hepatic MDA level, and markedly enhanced antioxidant enzyme (SOD, CAT and GSH-Px) activities and GSH level in hepatic tissue, in a dose-dependent manner, when compared to the model group. Histopathological observation revealed the hepatoprotective effect of ARPT against the damage. Furthermore, ARPT remarkably inhibited CYP2E1 mRNA expression, decreased NF-κB p65 expression and therefore to prevent the secretion of pro-inflammatory cytokines (TNF-α and IL-6) and chemokines (MCP-1, MIP-2 and KC), suppressed TGF-β1 expression and hepatocytes apoptosis. Moreover, ARPT could prevent DNA fragmentation based on TUNEL assay results.

CONCLUSION

These findings suggested that ARPT possessed hepatoprotective effect against CCl₄-induced hepatotoxicity in mice and the action might in part be through reducing oxidative stress, inflammation and apoptosis.

Water metabolism dysfunction via renin-angiotensin system activation caused by liver damage in mice treated with microcystin-RR

Microcystins (MCs) are a group of monocyclic heptapeptide toxins that have been shown to act as potent hepatotoxins. However, the observed symptoms of water metabolism disruption induced by microcystin-RR (MC-RR) or MCs have rarely been reported, and a relatively clear mechanism has not been identified. In the present study, male mice were divided into 4 groups (A: 140μg/kg, B: 70μg/kg,C: 35μg/kg, and D: 0μg/kg) and administered MC-RR daily for a month. On day 8 of treatment, an increase in water intake and urine output was observed in the high-dose group compared with the control, and the symptoms worsened with the repeated administration of the toxin until day 30. In addition, the urine specific gravity decreased and serum enzymes that can reflect hepatic damage increased in the high-dose group compared with the control (P<0.05). The mRNA level of angiotensinogen (AGT) in hepatocytes was upregulated to approximately 150% of the control (P<0.05), and the serum renin-angiotensin system (RAS) was activated in the high-dose group; however, signs of renal injury were not observed throughout the experiment. After the toxin treatment was completed, the high levels of the RAS and vasopressin in group A returned to normal levels within 1 week. As expected, the symptoms of polyuria and polydipsia also disappeared. Therefore, we propose that water metabolism dysfunction occurs via RAS activation caused by liver damage because the increased serum RAS levels in the experiment were consistent with the increased urine output and water intake in the mice during the observation period. In addition, we found for the first time that a RAS blocker could alleviate the observed polyuria and polydipsia and inactivate the high level of the RAS induced by MC-RR in a dose-dependent manner, which further supported our hypothesis.