Vitamin E induces regular structure and stability of human insulin, more intense than vitamin D3

Single and mixed associations of composite antioxidant diet on triglyceride-glucose index

BACKGROUND

Although the relationship between oxidative stress and insulin resistance (IR) has been established, the associations of the composite dietary antioxidant index (CDAI) and its components with the surrogate index of insulin resistance (IR), triglyceride-glucose index (TyG), is still not clear.

METHODS

This study analyzed the cross-sectional data of the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2018. Multivariate linear regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were used to analyze the associations of the CDAI and its components with the TyG. In addition, subgroup analysis and several sensitivity analyses were conducted.

RESULTS

A total of 14,673 participants with complete data were included, with a median age of 50 years and 7,257 women (49%). Multivariate linear regression showed that after full adjustment, the CDAI was significantly negatively associated with the TyG [β: -0.005, 95% CI: (-0.008, -0.002), p = 0.002]. The model in which six nutrients were mutually corrected showed that vitamin E (per-SD increase) was most strongly associated with the TyG [β: -0.062, 95% CI: (-0.074, -0.050), p < 0.0001]. In the WQS model, the WQS index of the antioxidant diet was negatively associated with the TyG (β: -0.060; P < 0.0001). Similar effects were observed in the BKMR analysis. Notably, in the WQS and BKMR models, vitamin E became the most influential component. In addition, in the subgroup analysis, the association between the CDAI and the TyG in overweight or obese and diabetic populations was significantly weaker.

CONCLUSION

Antioxidant diets, especially vitamin E, are significantly negatively correlated with TyG. This study emphasizes the important value of supplementing vitamin E to improve IR. However, patients with poor weight management and diabetes seem to benefit less from antioxidant diets.

"MD" method for the precise analysis of the O-acetyl-mannan structure and disclosure of the role in the conformational stability of insulin

Among the diversified glycan modifications, acylation is one of the most abundant. This modification could be responsible for many of the properties of glycans, such as structural stability and specificity for biological activity. To obtain better insight into the effects of acetylation of glycans on the structure and thermostability of insulin, it is critical to investigate glycans with a high degree of acetylation. An in-depth study of three functional glycans named acetyl-mannan from Dendrobium devonianum (DDAM) was conducted herein by efficient enzymatic depolymerization, and the effect of glycosidic bonds on acetylation modification sites was studied through a molecular dynamics (MD) method, as well as its positive effect on insulin secretion, glucose uptake, and the thermal stability of tertiary structures in vitro. Further study indicated that DDAMs play a hypoglycemic role by sparking the thermostability of the insulin conformation. The hypoglycemic activity displayed a positive correlation with the degree of acetylation in DDAMs. In this work, through the MD method, we confirmed the structure characteristics of DDAMs and provided accurate data support for the structure-activity relationship analysis. Thus, these findings demonstrated that DDAMs might be an exceptional leading compound for the stability of insulin drug.

Profiling of insulin and resveratrol interaction using multi-spectroscopy and molecular docking study

Background

Resveratrol, a phenolic compound, has various medicinal properties, including anticancer, anti-diabetic, antioxidant, anti-inflammatory, etc. Diabetes is a killing disease, especially for people who cannot maintain a healthy lifestyle. People with diabetes need additional information about a supplement that can prevent and treat diabetes. The present study aims to investigate the interaction of insulin with resveratrol using fluorescence spectroscopy, UV–Vis spectroscopy, CD spectropolarimeter, and molecular docking methods. As an outcome of this study, we expect to understand the contribution of resveratrol in insulin resistance.

Result

The fluorescence spectroscopy results showed that the peak intensity of insulin emission decreased with resveratrol. The interaction of insulin with resveratrol involved a combination of static and dynamic quenching effects. Temperature changes caused the binding constant (K) and the binding site (n) unstable. The interaction occurred through hydrogen bonding, van der Waal, and was hydrophobic. The results of UV–Vis spectroscopy showed that the addition of resveratrol caused a peak in a blueshift, and the absorbance was hyperchromic. Also, there was a reduction in electron transition and the extinction coefficient. The CD spectropolarimeter results showed that the addition of resveratrol affected the secondary structure of insulin. The amount of α-helix and β-sheet slightly change and increase in the secondary structure’s length. The molecular docking study showed that resveratrol interacts via hydrogen bonding with glycine and asparagine. van der Waal interactions occurred in asparagine, phenylalanine, and cysteine. The interaction of electrons occurred through the π orbitals of resveratrol with tyrosine A and B. The binding energy of molecules interaction happened spontaneously on a hydrophobic surface.

Conclusion

Profiling the interaction of insulin and resveratrol shows that resveratrol can stabilize insulin structure and prevent insulin resistance in diabetes.

Metabolomics based biomarker identification of anti-diabetes and anti-obesity properties of Malaysian herbs

BACKGROUND

Today, obesity affects over one-third of the global population and is hugely considered the Industrial Revolution's side effect. This multi-factorial disease is continuously spreading across developing countries, including the Middle East and Southeast Asia region, where Malaysia and Darussalam Brunei are the most affected. The sedentary lifestyle and availability of surplus foods have dramatically increased the number of individuals with type 2 diabetes in these countries. Thus, an adequate medical strategy must be developed urgently to address and remedy these diseases. Natural sources have been attracting attention, especially in Malaysia, where most land areas are under plant cover. Metabolomics, as a prophylactic technique, has been used extensively in Malaysia to investigate the potential use and benefits of herbs to combat obesity and diabetes.

AIM OF REVIEW

This review aims to explain the application of the metabolomics approach in the study of anti-diabetes and anti-obesity activity of Malaysian herbs to identify the stand-up point for future advancement in using these herbs as a primary source for drug exploration.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review provides an overview of using metabolomics technique in studying the anti-diabetes and anti-obesity activity of Malaysian herbs. Specific emphasis is given to the changed metabolites in both in vivo and in vitro treatment of Malaysia herbs that might be future drugs for treating diabetes and obesity.

Progress in Simulation Studies of Insulin Structure and Function

Insulin is a peptide hormone known for chiefly regulating glucose level in blood among several other metabolic processes. Insulin remains the most effective drug for treating diabetes mellitus. Insulin is synthesized in the pancreatic β-cells where it exists in a compact hexameric architecture although its biologically active form is monomeric. Insulin exhibits a sequence of conformational variations during the transition from the hexamer state to its biologically-active monomer state. The structural transitions and the mechanism of action of insulin have been investigated using several experimental and computational methods. This review primarily highlights the contributions of molecular dynamics (MD) simulations in elucidating the atomic-level details of conformational dynamics in insulin, where the structure of the hormone has been probed as a monomer, dimer, and hexamer. The effect of solvent, pH, temperature, and pressure have been probed at the microscopic scale. Given the focus of this review on the structure of the hormone, simulation studies involving interactions between the hormone and its receptor are only briefly highlighted, and studies on other related peptides (e.g., insulin-like growth factors) are not discussed. However, the review highlights conformational dynamics underlying the activities of reported insulin analogs and mimetics. The future prospects for computational methods in developing promising synthetic insulin analogs are also briefly highlighted.

Interaction between phloretin and insulin: a spectroscopic study

Diabetes is among the top ten deadly diseases in the world. It occurs either when the pancreas does not produce enough insulin (INS) or when the body cannot effectively use the insulin it produces. Phloretin (PHL) has a biological effect that can treat diabetes. A spectroscopic study was carried out to explore the interaction between phloretin and insulin. UV/Vis spectroscopy, fluorescence spectroscopy, and circular dichroism spectropolarimeter were used in the study. UV/Vis spectra showed that the interaction between PHL and INS produced strong absorption at a wavelength of 282 nm. The fluorescence analysis results showed that the excitation and emission occurred at 280-nm and 305-nm wavelengths, respectively. Temperature changes did not affect INS emissions. However, the interaction of PHL–INS caused a redshift at 305 to 317 nm. Temperature affected the binding constant (Ka) and the binding site (n). Ka decreased with increasing temperature and increased the binding site. The thermodynamic parameters such as enthalpy (ΔH0) and entropy (ΔS0) each had a value of − 16,514 kJ/mol and 22.65 J/mol·K. PHL and INS interaction formed hydrogen bonds and hydrophobic interaction. The free energy (ΔG0) recorded was negative. PHL and INS interactions took place spontaneously. The quenching effect was dynamic and static. KD values were greater than KS. The higher the temperature, the less was KD and KS. The appearance of two negative signals on circular dichroism (CD) spectropolarimeter implies that phloretin could induce regional configuration changes in insulin. The addition of PHL has revealed that the proportion of α-helix in the insulin stabilizes its structure. Phloretin’s stabilization and enhancement of the α-helix structural configuration in insulin indicate that phloretin can improve insulin resistance.

Antioxidant, Anti-Inflammatory, and Metabolic Properties of Tocopherols and Tocotrienols: Clinical Implications for Vitamin E Supplementation in Diabetic Kidney Disease

Diabetes mellitus is a metabolic disorder characterized by the development of vascular complications associated with high morbidity and mortality and the consequent relevant costs for the public health systems. Diabetic kidney disease is one of these complications that represent the main cause of end-stage renal disease in Western countries. Hyperglycemia, inflammation, and oxidative stress contribute to its physiopathology, and several investigations have been performed to evaluate the role of antioxidant supplementation as a complementary approach for the prevention and control of diabetes and associated disturbances. Vitamin E compounds, including different types of tocopherols and tocotrienols, have been considered as a treatment to tackle major cardiovascular outcomes in diabetic subjects, but often with conflicting or even negative results. However, their effects on diabetic nephropathy are even less clear, despite several intervention studies that showed the improvement of renal parameters after supplementation in patients with diabetic kidney disease. Then we performed a review of the literature about the role of vitamin E supplementation on diabetic nephropathy, also describing the underlying antioxidant, anti-inflammatory, and metabolic mechanisms to evaluate the possible use of tocopherols and tocotrienols in clinical practice.

Activation of human insulin by vitamin E: A molecular dynamics simulation study

Lack of perfect insulin signaling can lead to the insulin resistance, which is the hallmark of diabetes mellitus. Activation of insulin and its binding to the receptor for signaling process initiates via B-chain C-terminal hinge conformational change through an open structure to "wide-open" conformation. Observational studies and basic scientific evidence suggest that vitamin D and E directly and/or indirectly prevent diabetes through improving glucose secretion and tolerance, activating calcium dependent endopeptidases and thus improving insulin exocytosis, antioxidant effect and reducing insulin resistance. On the contrary, clinical trials have yielded inconsistent results about the efficacy of vitamin D supplementations for the control of glucose hemostasis. In this work, best binding modes of vitamin D₃ and E on insulin obtained from AutoDock Vina were selected for Molecular Dynamic, MD, study. The binding energy obtained from Molecular Mechanics- Poisson Boltzman Surface Area, MM-PBSA method, revealed that Vitamins D₃ and E have good affinity to bind to the insulin and vitamin E has higher binding energy (-46 kj/mol) by engaging more residues in binding site. Distance and angle calculation results illustrated that vitamin E changes the B-chain conformation and it causes the formation of wide-open/active form of insulin. Vitamin E increases the Val^B12-Tyr^B26 distance to ∼15 Å and changes the hinge angle to ∼65°. Consequently, essential hydrophobic residues for binding to insulin receptor exposed to surface in the presence of vitamin E. However, our data illustrated that vitamin D₃ cannot change B-chain conformation. Thus our MD simulations propose a model for insulin activation through vitamin E interaction for therapeutic approaches.