The protective effect of silk fibroin on high glucose induced insulin resistance in HepG2 cells

Identification and molecular mechanism of novel hypoglycemic peptide in ripened pu-erh tea: Molecular docking, dynamic simulation, and cell experiments

Ripened pu-erh tea is known to have beneficial hypoglycemic properties. However, it remains unclear whether the bioactive peptides produced during fermentation are also related to hypoglycemic potential. This study aimed to identify hypoglycemic peptides in ripened pu-erh tea and to elucidate their bioactive mechanisms using physicochemical property prediction, molecular docking, molecular dynamics simulations, and cell experiments. Thirteen peptides were identified by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, AADTDYRFS (AS-9) and AGDGTPYVR (AR-9) exhibited high α-glucosidase inhibitory activity, with half-maximal inhibitory concentration (IC50) values of 0.820 and 3.942 mg/mL, respectively. Molecular docking and dynamics simulations revealed that hydrogen bonding, hydrophobic interactions, and van der Waals forces assist peptides AS-9 and AR-9 in forming stable and tight complexes with α-glucosidase. An insulin-resistance (IR)-HepG2 cell model was established. AS-9 was non-toxic to IR-HepG2 cells and significantly increased the glucose consumption capacity, hexokinase, and pyruvate kinase activities of IR-HepG2 cells (p < 0.05). AS-9 alleviated glucose metabolism disorders and ameliorated IR by activating the IRS-1/PI3K/Akt signaling pathway and increasing the expression levels of MDM2, IRS-1, Akt, PI3K, GLUT4, and GSK3β genes. In addition, no hemolysis of mice red blood cells red blood cells occurred at concentrations below 1 mg/mL. This work first explored hypoglycemic peptides in ripened pu-erh tea, providing novel insights for enhancing its functional value.

Uncovering the key pharmacodynamic material basis and possible molecular mechanism of Xiaoke formulation improve insulin resistant through a comprehensive investigation

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoke formulation (XKF) has been utilized in clinical practice for decades in China as a treatment option for mild to moderate type 2 diabetes. However, there is still a need for systematic research to uncover the key pharmacodynamic material basis and mechanism of XKF.

AIM OF THE STUDY

Aim of to investigate the distribution and metabolism of XKF in normal and insulin resistant (IR) mice were different, and elucidate its key pharmacodynamic material basis and mechanism of action.

MATERIALS AND METHODS

Ultra performance liquid chromatography/time of flight mass spectrometry technology was employed to investigate the differences in XKF absorption, distribution, and metabolism between normal and IR mice across blood, liver, feces, and urine samples. Further, network pharmacology was used to predict target proteins and their associated signaling pathways. Then, molecular docking was utilized to validate the activity of key pharmacodynamic components and targets. Finally, IR HepG2 cells were used to detect the glucose consumption under the action of key pharmacodynamic material basis. In addition, the expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and phospho-protein kinase B (p-AKT) was determined using western blotting.

RESULTS

The study demonstrates significant distinctions in plasma and liver number and abundance of alkaloids, organic acids, flavonoids, iridoids and saponins between normal and IR mice when XKF was administered. Further analysis has shown that the representative components of XKF, including berberine, chlorogenic acid, calycosin, swertiamarin and astragaloside IV have significantly different metabolic pathways in plasma and liver. Prototypes and metabolites of these components were rarely detected in the urine and feces of mice. According to the network pharmacological analysis, these differential components are predicted to improve IR by targeting key factors such as SRC, JUN, HRAS, NOS3, FGF2, etc. Additionally, the signaling pathways involved in this process include PI3K-AKT pathway, GnRH signaling pathway, and T cell receptor signaling pathway. In addition, in vitro experiments indicate that berberine and its metabolites (berberine and demethyleneberine), chlorogenic acid and its metabolites (3-O-ferulic quinic acid and 5-O-ferulic quinic acid), calycosin and swertiamarin could improve IR in IR-HepG2 cells by elevating the expression of PI3K and AKT, leading to an increase in glucose consumption.

CONCLUSION

The key pharmacodynamic material basis of XKF, such as berberine and its metabolites (berberrubine and demethyleneberberine), chlorogenic acid and its metabolites (3-O-feruloylquinic acid and 5-O-feruloylquinic acid), calycosin and swertiamarin influence the glucose metabolism disorder of IR-HepG2 cells by regulating the PI3K/AKT signalling pathway, leading to an improvement in IR.

Synthesis, optimization, and cell response investigations of natural-based, thermoresponsive, injectable hydrogel: An attitude for 3D hepatocyte encapsulation and cell therapy

For the purpose of developing a 3D vehicle for the delivery of hepatocytes in cell therapy, the improved system of crosslinker and new gelling agent combinations consisting of glycerophosphate and sodium hydrogen carbonate have been employed to produce injectable, thermoresponsive hydrogels based on chitosan and silk fibroin. Adjusting the polymer-to-gelling agent ratio and utilizing a chemical crosslinker developed hydrogel scaffolds with optimal gelling time and pH. Applying sodium hydrogen carbonate neutralizes chitosan while keeping its thermoresponsive characteristics and decreases glycerophosphate from 60% to 30%. Genipin boosts the mechanical properties of hydrogel without affecting the gel time. Due to their stable microstructure and lower amine availability, genipin-containing materials have a low swelling ratio, around six compared to eight for those without genipin. Hydrogels that are crosslinked degrade about half as fast as those that are not. The slowerr degradation of Silk fibroin compared to chitosan makes it an efficient degradation inhibitor in silk-containing formulations. All of the optimized samples showed less than 5% hemolytic activity, indicating that they lacked hemolytic characteristics. The acceptable cell viability in crosslinked hydrogels ranges from 72% to 91% due to the decreasing total salt concentration, which protects cells from hyperosmolality. The pH of hydrogels and their interstitial pores kept most encapsulated cells alive and functioning for 24 h. Urea levels are higher in the encapsulation condition compared to HepG2 cultivated alone, and this may be due to cell-matrix interactions that boost liver-specific activity. Urea synthesis in genipin crosslinked hydrogels increased dramatically from day 1 (about 4 mg dl^-1) to day 3 (approximately 6 mg dl^-1), suggesting the enormous potential of these hydrogels for cell milieu preparation. All mentioned findings represent that the optimized system may be a promising candidate for liver regeneration.

Assessment of Novel Oligopeptides from Rapeseed Napin (Brassica napus) in Protecting HepG2 Cells from Insulin Resistance and Oxidative Stress

Oligopeptides (Thr-His-Leu-Pro-Lys (THLPK), His-Pro-Leu-Lys (HPLK), Leu-Pro-Lys (LPK), His-Leu-Lys (HLK), and Leu-His-Lys (LHK)) are newly identified from rapeseed napin (Brassica napus) protein-derived hydrolysates with the capability of upregulating glucose transporter-4 (GLUT4) expression and translocation. However, whether each of them enhances GLUT4 expression and translocation and their specific mechanisms remain unclear. Here, we assess the effects of the oligopeptides against insulin resistance (IR) and oxidative stress in hepatocytes and screen out the most antidiabetic one. Specifically, compared with other oligopeptides, LPK not only remarkably elevated glucose consumption to 8.45 mmol/L protein; superoxide dismutase (SOD) activity to 319 U/mg protein; GLUT4 expression and translocation; and phosphorylated level of insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt) (P < 0.05) but also remarkably attenuated the reactive oxygen species (ROS) level to 2255, lactate dehydrogenase (LDH) activity to 20.5 U/mg protein, malondialdehyde (MDA) content to 241 nmol/mg protein, and NO content to 1302 μmol/mL protein (P < 0.05). These findings demonstrated that antidiabetic oligopeptide LPK possessed the most potential to protect HepG2 cells from IR and oxidative stress via activating IRS-1/PI3K/Akt/GLUT4 and regulating common oxidative markers in vitro.

A diarylheptanoid compound from Alpinia officinarum Hance ameliorates high glucose-induced insulin resistance by regulating PI3K/AKT-Nrf2-GSK3β signaling pathways in HepG2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Alpinia officinarum Hance, a perennial natural medicine-food herb, has been traditionally used to treat colds, stomachache, and diabetes for thousands of years. 1,7-Diphenyl-4E-en-3-heptanone (DPH5), a diarylheptanoid isolated from the rhizome of A. officinarum has been reported to be safe and to have antioxidant and hypoglycemic effects, suggesting its potential in the treatment of insulin resistance (IR).

AIM OF THE STUDY

Aim of to investigate the protective effect of DPH5 on IR and elucidate its underlying mechanism of action.

MATERIALS AND METHODS

HepG2 cells were used as the research objects. Glucose uptake and reactive oxygen species (ROS) levels in high glucose-induced insulin-resistant HepG2 cells were assessed using flow cytometry. Glucose consumption and the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were analyzed using the corresponding assay kits. The expression of mRNA and proteins related to insulin signaling, glucose metabolism, and antioxidant factor, including insulin receptor substrate-1 (IRS1), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), translocation of glucose transporter-4, glycogen synthase kinase-3β (GSK3β), glucokinase (GCK), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), nuclear factor-erythroid 2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NADPH quinoneoxidoreductase (NQO1), and glutathione peroxidase (GSH-Px) was determined using real-time quantitative polymerase chain reaction and western blotting. Furthermore, molecular docking was performed to determine the spatial mechanism of DPH5 on the key targets PI3K, AKT, Nrf2, and GSK3β.

RESULTS

DPH5 could improve IR that manifested as increased glucose uptake and glucose consumption in insulin-resistant HepG2 cells. Moreover, DPH5 could enhance antioxidant capacity by activating Nrf2/HO-1 elements, including increasing Nrf2, HO-1, SOD, NQO1, and GSH-Px expression and reducing MDA, ROS, and JNK levels, thereby improving oxidative stress and ultimately alleviating IR. Additionally, DPH5 could promote the expression of IRS1, PI3K, AKT, GSK3β, GCK, and PK, and downregulate the expression of PEPCK and G6pase, thereby accelerating glucose utilization and enhancing insulin sensitivity. The mechanism underlying the effect of DPH5 in alleviating IR was related to the PI3K/AKT- and Nrf2/HO-1-mediated regulation of the GSK3β signaling pathway, and the results were further confirmed using the specific inhibitors LY294002 and ML385. Results from molecular docking indicated that there were different regulatory sites and interacting forces between DPH5 and PI3K, AKT, Nrf2, and GSK3β; however, the binding force was relatively strong.

CONCLUSIONS

DPH5 improved oxidative stress and glucose metabolism via modulating the PI3K/AKT-Nrf2-GSK3β pathway, thereby ameliorating IR. Overall, our findings suggest the potential of DPH5 as a natural medicine to treat type-2 diabetes mellitus.

Bombyx mori cocoon as a promising pharmacological agent: A review of ethnopharmacology, chemistry, and biological activities

Silk cocoon, naturally produced by silkworms scientifically named Bombyx mori L. (Lepidoptera, Bombycidae), is one of the well-known medicinal agents with several therapeutic activities. The present study aims to review the various aspects of the silk cocoon, including chemical composition, traditional uses, biological and biotechnological activities, and toxicological issues, to provide a scientific source for scholars. For this purpose, Electronic databases including PubMed, Scopus, Google Scholar, Web of Science, and traditional literature, were searched up to December 2021. According to the historical data, silk farming is acknowledged as one of the most ancient agricultural findings. The silk is generally composed of 75-83% fibroin, 17-25% sericin, and 1-5% non-sericin components, including secondary metabolites, wax, pigments, carbohydrates, and other impurities. Flavonoids, especially quercetin and kaempferol, alkaloids, coumarin derivatives, and phenolic acids, are among the secondary metabolites isolated from the silk cocoon. In recent years the biological properties of the silk cocoon, especially its major proteins, namely fibroin and sericin, have drawn special attention. Scientific literature has investigated several pharmacological effects of the silk cocoon and its ingredients, including cardioprotective, antioxidant, anticancer, antidiabetic, antihyperlipidemia, gastroprotective, as well as ameliorated skin health activities. In addition, it has been extensively taken into consideration in drug delivery and tissue engineering study fields. Furthermore, its toxicity is in acceptable range.

Metformin improves high‑fat diet‑induced insulin resistance in mice by downregulating the expression of long noncoding RNA NONMMUT031874.2

Metformin (MET) is the first-line therapeutic option for patients with type 2 diabetes that has garnered substantial attention over recent years. However, an insufficient number of studies have been performed to assess its effects on insulin resistance and the expression profile of long noncoding RNAs (lncRNAs). The present study divided mice into three groups: Control group, high-fat diet (HFD) group and HFD + MET group. A high-throughput sequencing analysis was conducted to detect lncRNA and mRNA expression levels, and differentially expressed lncRNAs were selected. Subsequently, the differentially expressed lncRNAs were validated both in vivo and in vitro (mouse liver AML12 cells treated with Palmitic acid) models of insulin resistance. After validating randomly selected lncRNAs via reverse transcription-quantitative PCR a novel lncRNA, NONMMUT031874.2, was identified, which was upregulated in the HFD group and reversed with MET treatment. To investigate the downstream mechanism of NONMMUT031874.2, lncRNA-microRNA (miR/miRNA)-mRNA co-expression network was constructed and NONCODE, miRBase and TargetScan databases were used, which indicated that NONMMUT031874.2 may regulate suppressor of cytokine signaling 3 by miR-7054-5p. For the in vitro part of the present study, AML12 cells were transfected with small interfering RNA to knock down NONMMUT031874.2 expression before being treated with palmitic acid (PA) and MET. The results showed that the expression of NONMMUT031874.2 was significantly increased whereas miR-7054-5p expression was significantly decreased by PA treatment. By contrast, after knocking down NONMMUT031874.2 expression or treatment with MET, the aforementioned in vitro observations were reversed. In addition, it was also found that NONMMUT031874.2 knockdown and treatment with MET exerted similar effects in alleviating insulin resistance and whilst decreasing glucose concentration in AML12 cells. These results suggest that MET treatment can ameliorate insulin resistance by downregulating NONMMUT031874.2 expression.

Screening and identification of a novel antidiabetic peptide from collagen hydrolysates of Chinese giant salamander skin: Network pharmacology, inhibition kinetics and protection of IR-HepG2 cells

In this study, a novel peptide GPPGPA was screened from the collagen hydrolysates of Chinese giant salamander (Andrias davidianus) skin, and anti-diabetes mechanism was predicted by network pharmacology, and inhibitory...

Bovine lactoferrin and Lentinus edodes mycelia polysaccharide complex: The formation and the activity to protect islet β cells

The formation of complexes may be used for the development of delivery systems in foods field. The aim of this study was to explore the interaction mechanism between Lentinus edodes mycelia polysaccharide (LMP) and bovine lactoferrin (BLF), and the activity of LMP-BLF complex to inhibit oxidative stress in islet β cells. The interaction mechanisms of LMP with BLF were investigated with multi-spectroscopic techniques. The multi-spectroscopic analysis result showed that LMP bound with BLF by van der Waals force and hydrogen bond. The quenching mechanism of BLF with LMP was static quenching. Cell viability, reactive oxygen species (ROS) level, apoptosis and the related signaling pathways were detected with thiazolyl blue tetrazolium bromide (MTT) assay, 2,7-Dichlorofluorescin diacetate (DCFH-DA) staining, Hoechst 33258 staining and Western blot methods respectively. The complex alleviated apoptosis induced by hydrogen peroxide (H₂O₂), and inhibited oxidative stress via MAPK pathways in MIN6 cells. In addition, the complex was able to promote glucose uptake in HepG2 cells. These results will broaden our understanding of LMP-BLF complexes and the applications of polysaccharide-protein complexes in the foods field.

Hypoglycemic effects and modulation of gut microbiota of diabetic mice by saponin fromPolygonatum sibiricum

Polygonatum sibiricumis a medicinal and homologous plant grown in China. The saponin inPolygonatum sibiricumhas shown its good hypoglycemic performance, and it can be developed as functional foods and drugs with hypoglycemic effect.

Peptides from walnut (Juglans mandshurica Maxim.) protect hepatic HepG2 cells from high glucose-induced insulin resistance and oxidative stress

Schematic of the mechanism underlying the protection of hepatic HepG2 cells against high glucose-induced insulin resistance and oxidative stress by walnut-derived peptides.