A fast and efficient method for screening and evaluation of hypoglycemic ingredients of Traditional Chinese Medicine acting on PTP1B by capillary electrophoresis

As a pivotal enzyme that regulates dephosphorylation in cell activities and participates in the insulin signaling pathway, protein tyrosine phosphatase 1B (PTP1B) is considered to be an important target for the therapy of diabetes. In this work, a rapid and efficient inhibitor screening method of PTP1B was established based on capillary electrophoresis (CE), and used for screening and evaluating the inhibition effect of Traditional Chinese Medicine on PTP1B. Response Surface Methodology was used for optimizing the conditions of analysis. After method validation, the enzyme kinetic study and inhibition test were performed. As a result, the IC50 of PTP1B inhibitors Ⅳ and ⅩⅧ were consistent with reported values measured by a conventional method. It was found that the extracts of Astragalus membranaceus (Fisch) Bunge and Morus alba L. showed prominent inhibition on the activity of PTP1B, which were stronger than the positive controls. Meanwhile, on top of the excellent advantages of CE, the whole analysis time is less than 2 min. Thus, the results demonstrated that a fast and efficient screening method was successfully developed. This method could be a powerful tool for screening inhibitors from complex systems. It can also provide an effective basis for lead compound development in drug discovery.

Status of research on natural protein tyrosine phosphatase 1B inhibitors as potential antidiabetic agents: Update

Protein tyrosine phosphatase 1B (PTP1B) is a crucial therapeutic target for multiple human diseases comprising type 2 diabetes (T2DM) and obesity because it is a seminal part of a negative regulator in both insulin and leptin signaling pathways. PTP1B inhibitors increase insulin receptor sensitivity and have the ability to cure insulin resistance-related diseases. However, the few PTP1B inhibitors that entered the clinic (Ertiprotafib, ISIS-113715, Trodusquemine, and JTT-551) were discontinued due to side effects or low selectivity. Molecules with broad chemical diversity extracted from natural products have been reported to be potent PTP1B inhibitors with few side effects. This article summarizes the recent PTP1B inhibitors extracted from natural products, clarifying the current research progress, and providing new options for designing new and effective PTP1B inhibitors.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XXII. Structurally diverse diterpenoids from the leaves and twigs of the endangered conifer Torreya jackii and their bioactivities

A phytochemical investigation on the MeOH extract of the leaves and twigs of the endangered conifer Torreya jackii Chun led to the isolation and characterization of 21 structurally diverse diterpenoids. Among them, six are previously undescribed, including four abietane-type (torreyins A-D, resp.) and two labdane-type diterpenoids (torreyins E and F). Their structures and absolute configurations were determined by a combination of spectroscopic methods, calculated/experimental electronic circular dichroism (ECD) data, and single-crystal X-ray diffraction analyses. In particular, torreyins A-C are rare 11,12-seco-abietane type diterpenoids possessing a dilactone moiety, and their biosynthetic pathway starting from a co-occurring abietane derivative (i.e., cyrtophyllone B) was briefly proposed. Among the isolates, 7-oxo-dehydroabietic acid and 15-methoxy-7,13-abietadien-18-oic acid showed considerable inhibitory effects against acetyl-coenzyme A carboxylase 1 (ACC1) and protein tyrosine phosphatase 1 B (PTP1B), with IC₅₀ values of 3.1 and 6.8 μM, respectively.

Crude extract and isolated bioactive compounds from Notholirion thomsonianum (Royale) Stapf as multitargets antidiabetic agents: in-vitro and molecular docking approaches

Background

Diabetes mellitus is a common disease effecting the lifestyles of majority world population. In this research work, we have embarked the potential role of crude extracts and isolated compounds of Notholirion thomsonianum for the management diabetes mellitus.

Methods

The crude extracts of N. thomsonianum were initially evaluated for α-glucosidase, α-amylase and antioxidant activities. The compounds were isolated from the activity based potent solvent fraction. The structures of isolated compounds were confirmed with NMR and MS analyses. The isolated compounds were tested for α-glucosidase, α-amylase, protein tyrosine phosphatase 1B (PTP1B) and DPPH activities. The molecular docking studies were carried out to find the binding interactions of isolated compounds for α-glucosidase, α-amylase and PTP1B.

Results

Initially, we screened out crude extracts and subfractions of N. thomsonianum against different in-vitro targets. Among all, Nt.EtAc was observed a potent fraction among all giving IC₅₀ values of 67, 70, < 0.1, 89 and 16 μg/mL against α-glucosidase, α-amylase, DPPH, ABTS and H₂O₂ respectively. Three compounds (Nt01, Nt02 and Nt03) were isolated from Nt.EtAc of N. thomsonianum. The isolated compounds Nt01, Nt02 and Nt03 exhibited IC₅₀ values of 58.93, 114.93 and 19.54 μM against α-glucosidase, while 56.25, 96.54 and 24.39 μM against α-amylase respectively. Comparatively, the standard acarbose observed IC₅₀ values were 10.60 and 12.71 μM against α-glucosidase, α-amylase respectively. In PTP1B assay, the compounds Nt01, Nt02 and Nt03 demonstrated IC₅₀ values of 12.96, 36.22 and 3.57 μM in comparison to the standard ursolic acid (IC₅₀ of 3.63 μM). The isolated compounds also gave overwhelming results in DPPH assay. Molecular docking based binding interactions for α-glucosidase, α-amylase and PTP1B were also encouraging.

Conclusions

In the light of current results, it is obvious that N. thomsonianum is potential medicinal plant for the treatment of hyperglycemia. Overall, Nt.EtAc was dominant fraction in all in-vitro activities. Three compounds Nt01, Nt02 and Nt03 were isolated from ethyl acetate fraction. The Nt03 specifically was most potent in all in-vitro assays. The molecular docking studies supported our in-vitro results. It is concluded that N. thomsonianum is a rich source of bioactive antidiabetic compounds which can be further extended to in-vivo based experiments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03443-7.

Effects of sleeve gastrectomy on bone mass, microstructure of femurs and bone metabolism associated serum factors in obese rats

BACKGROUND

Sleeve gastrectomy (SG) is a profoundly effective operation for severe obese patients, but is closely associated with bone mass loss. Previous studies have reported changes of various serum factors which may be associated with bone mass loss after SG. However, those results are contradictory. In this study, we assessed the effects of SG on bone mass, microstructure of femurs, and changes in bone turnover markers (BTMs), serum adipokines, inflammatory factors and gastrointestinal hormones after SG in high-fat diet (HFD) induced obese rats.

METHODS

Eight-week-old male Sprague-Dawley (SD) rats were fed with HFD to induce obesity. Then, SG and sham surgery were performed in anesthetized obese rats. SD rats in control group were fed with standard chow. Microstructure of femurs was scanned and analyzed by micro-computed tomography in control group, HFD sham group and HFD SG group. Serum inflammatory factors, adipokines markers, gastrointestinal hormones and BTMs were also measured.

RESULTS

Bone mineral density (BMD) of trabecular bone in both HFD sham group and HFD SG group were remarkably decreased compared with control group. All serum BTMs were significantly higher in HFD SG group than HFD sham group. In the meantime, serum levels of several important inflammatory factors, gastrointestinal hormones and adipokines such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, monocyte chemoattractant protein-1(MCP-1), ghrelin, insulin and leptin in HFD SG group were remarkably reduced compared with HFD sham group, whereas glucagon-like peptide-1 (GLP-1), adiponectin, fibroblast growth factor (FGF)-19 and FGF-21 were dramatically increased after SG. Protein tyrosine phosphatase 1B (PTP1B) was significantly increased in the HFD sham group than control group. Spearman's correlation analysis indicated that serum osteocalcin (OC) and 25-hydroxy vitamin D₃ (25(OH)D₃) were positively correlated with BMD of trabecular bone, whereas serum PTP1B and TNF-α were negatively related to BMD of trabecular bone.

CONCLUSIONS

SG aggravates bone mass loss and activates bone remodeling in obese rats. Levels of BTMs, adipokines, inflammatory factors, and gastrointestinal hormones could be affected by SG in obese rats. Serum PTP1B level might be associated with abnormal bone mass in obese rats.

Astragaloside IV inhibits protein tyrosine phosphatase 1B and improves insulin resistance in insulin-resistant HepG2 cells and triglyceride accumulation in oleic acid (OA)-treated HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Astragaloside IV (AST IV) is the active component of Astragalus membranaceus (Fisch.) Bunge, which regulates lipid and carbohydrate metabolism and improves insulin resistance. In this study, we investigated the effects of AST IV on insulin resistant cells and a non-alcoholic fatty liver disease (NAFLD) model induced by high-concentration insulin or oleic acid (OA) in HepG2 cells, as well as the associated regulatory markers.

METHODS

First, the target of AST IV was predicted via pharmacophore model matching and molecular docking. Then, enzyme kinetics experiments were conducted in vitro to determine the effect of AST IV on the target protein. Next, AST IV's toxicity was tested on HepG2 cells in vitro, through an insulin resistance model and an NAFLD model, by high-concentration insulin or OA, respectively. To explore the effects of AST IV on insulin resistance and lipid metabolism, we detected the related indexes of glucose and lipid metabolism through commercially available kits. Relevant proteins were also detected by Western blot to provide future direction for study.

RESULTS

Our preliminary results of pharmacophore model matching and molecular docking suggested that AST IV and protein tyrosine phosphatase 1B (PTP1B) can be well-combined through hydrogen bonding. Further, the enzyme kinetics experiment showed that AST IV was an effective and specific inhibitor to PTP1B. We found that the protein level of PTP1B in HepG2 cells was significantly increased after treating with high-concentration insulin or OA. Additionally, the intervention of AST IV significantly increased glucose consumption in an insulin resistance model and reduced the content of triglyceride (TG), total cholesterol (TC), and free fatty acid (FFA) in the NAFLD model. Moreover, the 2-N-(7-nitrobenze-2-oxa-1, 3 diazol-4-yl) (2-NBDG) uptake rate in the NAFLD model was also greatly improved. These results validated the effects of AST IV on improving insulin resistance and lipid accumulation. Furthermore, Western blot results illustrated that AST IV suppressed PTP1B and increased levels of phosphorylated insulin receptor (p-IR) and phosphorylated insulin receptor substrate-1 (p-IRS-1) in insulin-resistant HepG2 cells, while also decreasing protein levels of PTP1B and sterol element regulatory binding protein-1c (SREBP-1c) in the NAFLD model.

CONCLUSION

This study demonstrated that AST IV inhibited PTP1B and effectively improved insulin resistance in insulin-resistant HepG2 cells and triglyceride accumulation in OA-treated HepG2 cells.

Multiflorumisides HK, stilbene glucosides isolated from Polygonum multiflorum and their in vitro PTP1B inhibitory activities

A phytochemical study on a 70% EtOH extract of dried roots of Polygonum multiflorum resulted in the isolation of four undescribed stilbene glucosides, namely multiflorumisides HK (1-4). The structures of the natural products were elucidated by 1D and 2D nuclear magnetic resonance (NMR) as well as mass spectroscopy analyses. Among them, multiflorumiside J (3) and multiflorumiside K (4) belong to rare tetramer stilbene glucosides. Moreover, the in vitro inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) were evaluated and the putative biosynthetic pathway was proposed. Notably, compounds 1-4 showed the inhibitory activity against PTP1B with the IC₅₀ values of 1.2, 1.7, 1.5 and 4.6 μm, respectively. Based on the obtained results, stilbene glucosides could be the potential PTP1B inhibitors of P. multiflorum.

Protein tyrosine phosphatase 1B (PTP1B) is required for cardiac lineage differentiation of mouse embryonic stem cells

Protein tyrosine phosphatase 1B (PTP1B) has been shown to regulate multiple cellular events such as differentiation, cell growth, and proliferation; however, the role of PTP1B in differentiation of embryonic stem (ES) cells into cardiomyocytes remains unexplored. In the present study, we investigated the effects of PTP1B inhibition on differentiation of ES cells into cardiomyocytes. PTP1B mRNA and protein levels were increased during the differentiation of ES cells into cardiomyocytes. Accordingly, a stable ES cell line expressing PTP1B shRNA was established. In vitro, the number and size of spontaneously beating embryoid bodies were significantly decreased in PTP1B-knockdown cells, compared with the control cells. Decreased expression of cardiac-specific markers Nkx2-5, MHC-α, cTnT, and CX43, as assessed by real-time PCR analysis, was further confirmed by immunocytochemistry of the markers. The results also showed that PTP1B inhibition induced apoptosis in both differentiated and undifferentiated ES cells, as presented by increasing the level of cleaved caspase-3, cytochrome C, and cleaved PARP. Further analyses revealed that PTP1B inhibition did not change proliferation and pluripotency of undifferentiated ES cells. Taken together, the data presented here suggest that PTP1B is essential for proper differentiation of ES cells into cardiomyocytes.

Novel chromenedione derivatives displaying inhibition of protein tyrosine phosphatase 1B (PTP1B) from Flemingia philippinensis

Protein tyrosine phosphatase 1B (PTP1B) is an important target to treat obesity and diabetes due to its key roles in insulin and leptin signaling. The MeOH extracts of the root bark of Flemingia philippinensis yielded eight inhibitory molecules (1-8) capable of targeting PTP1B. Three of them were identified to be novel compounds, philippin A (1), philippin B (2), and philippin C (3) which have a rare 3-phenylpropanoyl chromenedione skeleton. The other compounds (4-8) were known prenylated isoflavones. All compounds (1-8) inhibited PTP1B in a dose dependent manner with IC50s ranging between 2.4 and 29.4μM. The most potent compound emerged to be prenylated isoflavone 5 (IC50=2.4μM). In kinetic studies, chromenedione derivatives (1-3) emerged to be reversible, competitive inhibitors, whereas prenylated isoflavones (5-8) were noncompetitive inhibitors.

Protein tyrosine phosphatase 1B (PTP1B): A key regulator and therapeutic target in liver diseases

Phosphorylation of tyrosine residues within proteins, which is controlled by the reciprocal action of protein tyrosine kinases and protein tyrosine phosphatases, plays a key role in regulating almost all physiological responses. Therefore, it comes as no surprise that once the balance of tyrosine phosphorylation is disturbed, drastic effects can occur. Protein tyrosine phosphatase 1B (PTP1B), a classical non-transmembrane tyrosine phosphatase, is a pivotal regulator and promising drug target in type 2 diabetes and obesity. Recently it has received renewed attention in liver diseases and represents an intriguing opportunity as a drug target by modulating hepatocyte death and survival, hepatic lipogenesis and so on. Here, the multiple roles of PTP1B in liver diseases will be presented, with respect to liver regeneration, drug-induced liver disease, non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma.