Antidiabetic effect of nepodin, a component of Rumex roots, and its modes of action in vitro and in vivo

The impact of solute carrier proteins on disrupting substance regulation in metabolic disorders: insights and clinical applications

Carbohydrates, lipids, bile acids, various inorganic salt ions and organic acids are the main nutrients or indispensable components of the human body. Dysregulation in the processes of absorption, transport, metabolism, and excretion of these metabolites can lead to the onset of severe metabolic disorders, such as type 2 diabetes, non-alcoholic fatty liver disease, gout and hyperbilirubinemia. As the second largest membrane receptor supergroup, several major families in the solute carrier (SLC) supergroup have been found to play key roles in the transport of substances such as carbohydrates, lipids, urate, bile acids, monocarboxylates and zinc ions. Based on common metabolic dysregulation and related metabolic substances, we explored the relationship between several major families of SLC supergroup and metabolic diseases, providing examples of drugs targeting SLC proteins that have been approved or are currently in clinical/preclinical research as well as SLC-related diagnostic techniques that are in clinical use or under investigation. By highlighting these connections, we aim to provide insights that may contribute to the development of improved treatment strategies and targeted therapies for metabolic disorders.

Impact of macrophage differentiation on hematopoietic function enhancement by Shenzhu ErKang Syrup

Shenzhu Erkang Syrup (SZEK) is a traditional Chinese medicine that improves spleen and stomach function, tonifying the Qi and activating the blood; however, its therapeutic effects in hematopoietic dysfunction and their underlying mechanism remain unexplored. In this study, mice were given cyclophosphamide (100 mg/kg) by intraperitoneal injections for three days to produce hematopoietic dysfunction model. We investigated the hematopoietic effect and mechanism of SZEK in mice with hematopoietic dysfunction via histopathological examination, flow cytometry, enzyme-linked immunosorbent assay, and Western blotting combined with intestinal flora and serum metabolomics analysis. In mice with hematopoietic dysfunction, SZEK (gavage, 0.3 mL/25 g) alleviated pathological damage to the bone marrow and spleen; increased the number of naïve cells (Lin-), hematopoietic stem cells (Lin-Sca-1+c-Kit+), long-term self-renewing hematopoietic stem cells (Lin-Sca-1+c-Kit+CD48-CD150+), B lymphocytes (CD45+CD19+), and macrophages (CD11b+F4/80+) in the bone marrow; and reduced inflammation. Preliminary intestinal flora and serum metabolome analyses indicated that the pro-hematopoietic mechanism of SZEK was associated with macrophage differentiation. Further validation revealed that SZEK promoted hematopoiesis by decreasing the number of M2 macrophages and inhibiting the secretion of negative hematopoietic regulatory factors in mice with hematopoietic dysfunction.

Isolation and biological activities of compounds from Rumex vesicarius L. and their use as a component of a synbiotic preparation

The study evaluated prebiotic potential and the enzyme inhibition of extracts and isolated compounds of Rumex vesicarius (ruby dock), family Polygonaceae. Eight known compounds were identified in the roots of R. vesicarius. Extracts and compounds (1-8) increased the growth rate of Escherichia coli Nissle 1917 differentially compared to controls. The highest prebiotic index (PI) and activity score was recorded for EcN in the presence of compound 4, followed by, in descending order, petroleum ether, ethyl acetate, and total methanol extracts. The compounds and extracts reduced protease, α-amylase, and angiotensin-converting enzyme activities. This inhibitory activity was positively correlated with PI, P_score, µ_u, and Y_max. These findings suggest that R. vesicarius is a good source of potential prebiotic and can boost beneficial bacteria. It may also be considered promising for treatment of diabetes mellitus, controlling weight, and regulating blood pressure.

Overview of the Biological Activity of Anthraquinons and Flavanoids of the Plant Rumex Species

Rumex confertus belongs to the genus Rumex and is classified as an invasive parasitic plant in agriculture. Despite other Rumex species being widely used in herbal medicine due to their antimicrobial, antioxidant, antitumor, and anti-inflammatory effects, there are almost no information about the potential of Rumex confertus for the treatment of various diseases. In this review we analyzed scientific articles revealing properties of Rumex plant’s substances against cancer, diabetes, pathogenic bacterial invasions, viruses, inflammation, and oxidative stress for the past 20 years. Compounds dominating in each composition of solvents for extraction were discussed, and common thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) methods for efficient separation of the plant’s extract are included. Physico-chemical properties such as solubility, hydrophobicity (Log P), pKa of flavonoids, anthraquinones, and other derivatives are very important for modeling of pharmacokinetic and pharmacodynamics. An overview of clinical studies for abounded selected substances of Rumex species is presented.

Antidiabetic Effect of Taxifolin in Cultured L6 Myotubes and Type 2 Diabetic Model KK-Ay/Ta Mice with Hyperglycemia and Hyperuricemia

Muscle is the largest tissue in our body and plays an important role in glucose homeostasis and hence diabetes. In the present study, we examined the effects of taxifolin (TXF) on glucose metabolism in cultured L6 muscle cells (myotubes) and in type 2 diabetic (T2D) model KK-A^y/Ta mice. TXF dose-dependently increased glucose uptake (GU) in L6 myotubes under the condition of insulin absence. This increase in GU was partially, but significantly canceled by TXF treatment in combination with either LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), which phosphorylates protein kinase B (Akt) or Compound C, an inhibitor of 5’-adenosine monophosphate-activated protein kinase (AMPK). Furthermore, TXF was demonstrated to activate (=phosphorylate) both Akt and AMPK, and promote glucose transporter 4 (GLUT4) translocation to the plasma membrane from cytosol of L6 myotubes via both PI3K/Akt and AMPK signaling pathways. Based on these in vitro findings, we conducted an in vivo experiment in KK-A^y/Ta mice with hyperglycemia and hyperuricemia. Fasting plasma glucose, insulin, uric acid levels and an index of insulin resistance (HOMA-IR) increased significantly in the T2D model mice compared with normal ones. Such rises in the T2D state were significantly suppressed by oral administration of TXF for four weeks. These results suggest that TXF is a potent antihyperglycemic and antihyperuricemic phytochemical in the T2D state.

Comparison of Phytochemical Profile and Bioproperties of Methanolic Extracts from Different Parts of Tunisian Rumex roseus

The genus Rumex (Polygonaceae) is distributed worldwide and the different species belonging to it are used in traditional medicine. The present study aimed at the evaluation of the phytochemical profile and the biochemical properties of methanolic extracts from different parts (roots, stems, and leaves) of Rumex roseus, a wild local Tunisian plant traditionally used as food.  The phytochemical analysis on the extracts was performed using standard colorimetric procedures, HPLC-DAD, and HPLC-DAD-ESI-MS; then, several in vitro cell-free assays have been used to estimate their antioxidant/free radical scavenging capability (TAC-PM, DPPH, TEAC, FRAP, ORAC, SOD-like activity, and HOCl-induced albumin degradation). Additionally, anti-inflammatory effect of these extracts was evaluated in an in vitro model of acute intestinal inflammation in differentiated Caco-2 cells. The results showed that the methanolic extracts from stems and, especially, leaves contain substantial amounts of flavones (apigenin and luteolin, together with their derivatives), while the extract from roots is characterized by the presence of tannins and quinic acid derivatives. All the extracts appeared endowed with excellent antioxidant/free radical scavenging properties. In particular, the extract from roots was characterized by a remarkable activity, probably due to its different and peculiar polyphenolic composition. Furthermore, both Rumex roseus roots and stems extracts demonstrated an anti-inflammatory effect in intestinal epithelial cells, reducing TNF-α-induced gene expression of IL-6 and IL-8. In conclusion, R. roseus methanolic extracts have shown to be potential sources of bioactive compounds to be used in the prevention and treatment of pathologies related to oxidative stress and inflammation.

Efficient and modified 2-NBDG assay to measure glucose uptake in cultured myotubes

Under type-2 diabetes, insulin resistance develops in skeletal muscles as a key defect and to study the disorder, its manifestation, and possible solution, measurement of glucose uptake is a fundamental necessity. Of various approaches (i.e. scintillation counting, flow cytometry, fluorometry and spectrophotometry) fluorescent labelled glucose analogue, 2-NBDG solution is the most popular one. Although 2-NBDG based assay is the most widely used approach in various cells including skeletal muscle, even then all available protocols possess huge variability which impacts the overall data reproducibility. Moreover, starvation (use of glucose/serum free medium), one of the prerequisite condition for glucose uptake assay, itself induces stress specifically during longer pre-incubation periods and alters muscle cell metabolism and morphology, but the fact has not been duly considered. Therefore in the present article, using specific skeletal muscle cells i.e. C2C12 myotubes, we have re-established the conditions like pre-incubation time period, concentrations of insulin, glucose and serum/BSA while maintaining the cultured myotubes in morphologically healthy state. Our lab standardized protocols were observed to be effective in studying insulin resistance condition induced by diverse stresses (oxidative & inflammation) in myotubes. Comparative study conducted with already established protocols demonstrates that the present method is more efficient, effective and better improvised for studying glucose uptake in C2C12.

Rumex japonicus Houtt.: A phytochemical, pharmacological, and pharmacokinetic review

Rumex japonicus Houtt. (RJH-Yang Ti) RJH has been used as a folk medicine in East Asian countries for thousands of years. It has a wide range of therapeutic effects in terms of anti-microorganic, anti-oxidant, anti-inflammatory, and antitumor effects. Therefore, it is urgent to thoroughly review the existing knowledge for this herb from phytochemical, pharmacological, and pharmacokinetic perspectives. "Yang Ti" and its English, botanical and pharmaceutical names used as keywords to perform database search which included the Encyclopaedia of traditional Chinese Medicines, PubMed, EMBASE, AMED, CINAHL, Cochrane Library, MEDLINE, Science Direct, Scopus, Web of Science, and China Network Knowledge Infrastructure. Forty-five compounds identified from RJH. Besides, the therapeutic effects of RJH have been summarized as well. The root of RJH contains derivatives of anthraquinones, phytosterols, nepodin, oxanthrone c-glycosides, phenolic acid, cinnamic acid, flavonoid, epoxynaphthoquinol, triterpenoids, methoxynaphthalene, trihydroxybenzene, anthracene-9,10-dione, and other compounds. The extract of RJH and its chemical compounds showed the potentials as a complementary agent to exert antioxidant, antimicrobial, antisepsis, anticancer, anti-haematological disease, anti-dermatological disease, and antidiabetic activities. For the record, there is no study conducted on RJH regarding its pharmacokinetic aspect. Notably, Emodin may require additional attention due to its multiple organ toxicity concerns.

Inhibition of Biofilm Formation by Candida albicans and Polymicrobial Microorganisms by Nepodin via Hyphal-Growth Suppression

Candida albicans is an opportunistic pathogenic yeast and is responsible for candidiasis. It readily colonizes host tissues and implant devices, and forms biofilms, which play an important role in pathogenesis and drug resistance. In this study, the antibiofilm, antihyphal, and antivirulence activities of nepodin, isolated from Rumex japonicus roots, were investigated against a fluconazole-resistant C. albicans strain and against polymicrobial-microorganism-biofilm formation. Nepodin effectively inhibited C. albicans biofilm formation without affecting its planktonic cell growth. Also, Rumex-root extract and nepodin both inhibited hyphal growth and cell aggregation of C. albicans. Interestingly, nepodin also showed antibiofilm activities against Candida glabrata, Candida parapsilosis, Staphylococcus aureus, and Acinetobacter baumannii strains and against dual biofilms of C. albicans and S. aureus or A. baumannii but not against Pseudomonas aeruginosa. Transcriptomic analysis performed by RNA-seq and qRT-PCR showed nepodin repressed the expression of several hypha- and biofilm-related genes (ECE1, HGT10, HWP1, and UME6) and increased the expression of several transport genes (CDR4, CDR11, and TPO2), which supported phenotypic changes. Moreover, nepodin reduced C. albicans virulence in a nematode-infection model and exhibited minimal cytotoxicity against the nematode and an animal cell line. These results demonstrate that nepodin and Rumex-root extract might be useful for controlling C. albicans infections and multispecies biofilms.

Three New Malyngamides from the Marine Cyanobacterium Moorea producens

Three new compounds of the malyngamide series, 6,8-di-O-acetylmalyngamide 2 (1), 6-O-acetylmalyngamide 2 (2), and N-demethyl-isomalyngamide I (3), were isolated from the marine cyanobacterium Moorea producens. Their structures were determined by spectroscopic analysis and chemical derivatization and degradation. These compounds stimulated glucose uptake in cultured L6 myotubes. In particular, 6,8-di-O-acetylmalyngamide 2 (1) showed potent activity and activated adenosine monophosphate-activated protein kinase (AMPK).

Hyperuricemia in type 2 diabetic model KK-Ay/Ta mice: a potent animal model with positive correlation between insulin resistance and plasma high uric acid levels

Objective

Hyperuricemia is recognized as a main cause of gout. Accumulating clinical evidence suggests that hyperuricemia is strongly associated with insulin resistance and abnormal glucose metabolism. However, there seem no proper animal models for investigating such associations. Ideal animal model is considered to be hyperuricemic as well as diabetic. Selecting the KK-A^y/Ta mouse model, the relationship between hyperuricemia and insulin resistance has been studied to characterize such an animal model.

Results

Male type 2 diabetic KK-A^y/Ta and age-matched normal C57BL/6J mice were maintained on a basal 20% casein diet for 35 days. Food intake, body weight gain, levels of plasma uric acid, glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglyceride in KK-A^y/Ta mice were significantly higher than those in normal mice. Plasma uric acid levels showed significant positive correlations with plasma glucose, insulin, HOMA-IR and triglyceride levels. These results suggest that the KK-A^y/Ta mouse strain is useful for studies on correlation between hyperuricemia and insulin resistance, and for those on effects of foods and their components on the relations.

Evaluation of raw nepodin extraction from Rumex japonicus and R. obtusifolius and their DNA polymorphisms

Nepodin, found in the roots of Rumex japonicus Houtt. (Polygonaceae), inhibits osteoclast differentiation and has an antidiabetic effect. We propose nepodin as an ingredient of new functional foods or as a drug candidate for reducing the risk of reduced locomotion resulting from diseases such as osteoporosis. Although there are no previous reports of R. obtusifolius L., which is found throughout Japan, having roots containing nepodin, we found nepodin in the roots of this species. Therefore, R. obtusifolius as well as R. japonicus was considered a candidate raw material for nepodin extraction. We also discuss the suitability of R. japonicus and R. obtusifolius as sources of raw nepodin for cultivation on the Ryukyu Islands. In this study, all specimens on the Ryukyu Islands were identified as R. japonicus. Conversely, all specimens on mainland Japan were R. obtusifolius. The DNA sequence of the chloroplast trnL-trnF intergenic spacer region and partial nuclear internal transcribed spacer was consistent with the identification of R. japonicus and R. obtusifolius by morphological characteristics of the perianth segments. Therefore, to avoid erroneous identification and misuse of the plant species used for extraction of raw materials, it is preferable to develop DNA markers for these two regions. The content of nepodin varied from undetectable to 0.34% of the fresh weight (%FW) in R. japonicus and from undetectable to 0.21%FW in R. obtusifolius. From a pharmacological perspective, as plants that might be suitable as raw materials for nepodin extraction, it became clear that both R. japonicus and R. obtusifolius can be used with the same expected extraction efficiency. Based on our findings, R. obtusifolius could not be confirmed as inhabiting the Ryukyu Islands. For this reason, to conserve the endemic genetic characteristics of the Ryukyu Islands and to prevent genetic pollution by R. obtusifolius, only R. japonicus should be cultivated on the Ryukyu Islands.

Antidiabetic effect of enterolactone in cultured muscle cells and in type 2 diabetic model db/db mice

Enterolactone (ENL) is formed by the conversion of dietary precursors like strawberry lignans via the gut microbiota. Urinary concentrations of lignan metabolites are reported to be significantly associated with a lower risk of Type 2 diabetes (T2D). In the present study, antidiabetic effect of ENL and its modes of action were studied in vitro and in vivo employing a rat skeletal muscle-derived cell line, L6 myocytes in culture, and T2D model db/db mice. ENL dose-dependently increased glucose uptake in L6 myotubes under insulin absent condition. This increase by ENL was canceled by compound C, an inhibitor of 5'-adenosine monophosphate-activated protein kinase (APMK). Activation (=phosphorylation) of AMPK and translocation of glucose transporter 4 (GLUT4) to plasma membrane in L6 myotubes were demonstrated by Western blotting analyses. Promotion by ENL of GLUT4 translocation to plasma membrane was also visually demonstrated by immunocytochemistry in L6 myoblasts that were transfected with glut4 cDNA-coding vector. T2D model db/db mice were fed the basal 20 % casein diet (20C) or 20C supplemented with ENL (0.001 or 0.01 %) for 6 weeks. Fasting blood glucose (FBG) levels were measured every week and intraperitoneal glucose tolerance test (IPGTT) was conducted. ENL at a higher dose (0.01 % in 20C) suppressed the increases in FBG levels. ENL was also demonstrated to improve the index of insulin resistance (HOMA-IR) and glucose intolerance by IPGTT in db/db mice. From these results, ENL is suggested to be an antidiabetic chemical entity converted from dietary lignans by gut microbiota.