Resveratrol long-term treatment differentiates INS-1E beta-cell towards improved glucose response and insulin secretion

Insights into the Therapeutic and Pharmacological Properties of Resveratrol as a Nutraceutical Antioxidant Polyphenol in Health Promotion and Disease Prevention

Resveratrol (3, 5, 4'-trihydroxystilbene) is a polyphenolic derivative with herbal origin. It has attracted considerable attention in recent decades. Many studies have revealed the benefits of Resveratrol over several human disease models, including heart and neurological diseases, nephroprotective, immune regulation, antidiabetic, anti-obesity, age-related diseases, antiviral, and anticancer in experimental and clinical conditions. Recently, the antioxidant and anti-inflammatory activities of Resveratrol have been observed, and it has been shown that Resveratrol reduces inflammatory biomarkers, such as tissue degradation factor, cyclooxygenase 2, nitric oxide synthase, and interleukins. All of these activities appear to be dependent on its structural properties, such as the number and position of the hydroxyl group, which regulates oxidative stress, cell death, and inflammation. Resveratrol is well tolerated and safe even at higher pharmacological doses and desirably affects cardiovascular, neurological, and diabetic diseases. Consequently, it is plausible that Resveratrol can be regarded as a beneficial nutritional additive and a complementary drug, particularly for therapeutic applications. The present review provides an overview of currently available investigations on preventive and therapeutic characteristics and the main molecular mechanisms of Resveratrol and its potent derivatives in various diseases. Thus, this review would enhance knowledge and information about Resveratrol and encourage researchers worldwide to consider it as a pharmaceutical drug to struggle with future health crises against different human disorders.

Metabolo-epigenetic interplay provides targeted nutritional interventions in chronic diseases and ageing

Epigenetic modifications are chemical modifications that affect gene expression without altering DNA sequences. In particular, epigenetic chemical modifications can occur on histone proteins -mainly acetylation, methylation-, and on DNA and RNA molecules -mainly methylation-. Additional mechanisms, such as RNA-mediated regulation of gene expression and determinants of the genomic architecture can also affect gene expression. Importantly, depending on the cellular context and environment, epigenetic processes can drive developmental programs as well as functional plasticity. However, misbalanced epigenetic regulation can result in disease, particularly in the context of metabolic diseases, cancer, and ageing. Non-communicable chronic diseases (NCCD) and ageing share common features including altered metabolism, systemic meta-inflammation, dysfunctional immune system responses, and oxidative stress, among others. In this scenario, unbalanced diets, such as high sugar and high saturated fatty acids consumption, together with sedentary habits, are risk factors implicated in the development of NCCD and premature ageing. The nutritional and metabolic status of individuals interact with epigenetics at different levels. Thus, it is crucial to understand how we can modulate epigenetic marks through both lifestyle habits and targeted clinical interventions -including fasting mimicking diets, nutraceuticals, and bioactive compounds- which will contribute to restore the metabolic homeostasis in NCCD. Here, we first describe key metabolites from cellular metabolic pathways used as substrates to "write" the epigenetic marks; and cofactors that modulate the activity of the epigenetic enzymes; then, we briefly show how metabolic and epigenetic imbalances may result in disease; and, finally, we show several examples of nutritional interventions - diet based interventions, bioactive compounds, and nutraceuticals- and exercise to counteract epigenetic alterations.

DYRK1A inhibitors leucettines and TGF-β inhibitor additively stimulate insulin production in beta cells, organoids, and isolated mouse islets

The decreased β-cell mass and impaired β-cell functionality are the primary causes of diabetes mellitus (DM). Nevertheless, the underlying molecular mechanisms by which β-cell growth and function are controlled are not fully understood. In this work, we show that leucettines, known to be DYRK1A kinase inhibitors, can improve glucose-stimulated insulin secretion (GSIS) in rodent β-cells and isolated islets, as well as in hiPSC-derived β-cells islets. We confirm that DYRK1A is expressed in murine insulinoma cells MIN6. In addition, we found that treatment with selected leucettines stimulates proliferation of β-cells and promotes MIN6 cell cycle progression to the G2/M phase. This effect is also confirmed by increased levels of cyclin D1, which is highly responsive to proliferative signals. Among other leucettines, leucettine L43 had a negligible impact on β-cell proliferation, but markedly impair GSIS. However, leucettine L41, in combination with LY364947, a, a potent and selective TGF-β type-I receptor, significantly promotes GSIS in various cellular diabetic models, including MIN6 and INS1E cells in 2D and 3D culture, iPSC-derived β-cell islets derived from iPSC, and isolated mouse islets, by increased insulin secretion and decreased glucagon level. Our findings confirm an important role of DYRK1A inhibitors as modulators of β-cells function and suggested a new potential target for antidiabetic therapy. Moreover, we show in detail that leucettine derivatives represent promising antidiabetic agents and are worth further evaluation, especially in vivo.

Quantitative, in situ visualization of intracellular insulin vesicles in pancreatic beta cells

Characterizing relationships between Zn²⁺, insulin, and insulin vesicles is of vital importance to the study of pancreatic beta cells. However, the precise content of Zn²⁺ and the specific location of insulin inside insulin vesicles are not clear, which hinders a thorough understanding of the insulin secretion process and diseases caused by blood sugar dysregulation. Here, we demonstrated the colocalization of Zn²⁺ and insulin in both single extracellular insulin vesicles and pancreatic beta cells by using an X-ray scanning coherent diffraction imaging (ptychography) technique. We also analyzed the elemental Zn²⁺ and Ca²⁺ contents of insulin vesicles using electron microscopy and energy dispersive spectroscopy (EDS) mapping. We found that the presence of Zn²⁺ is an important characteristic that can be used to distinguish insulin vesicles from other types of vesicles in pancreatic beta cells and that the content of Zn²⁺ is proportional to the size of insulin vesicles. By using dual-energy contrast X-ray microscopy and scanning transmission X-ray microscopy (STXM) image stacks, we observed that insulin accumulates in the off-center position of extracellular insulin vesicles. Furthermore, the spatial distribution of insulin vesicles and their colocalization with other organelles inside pancreatic beta cells were demonstrated using three-dimensional (3D) imaging by combining X-ray ptychography and an equally sloped tomography (EST) algorithm. This study describes a powerful method to univocally describe the location and quantitative analysis of intracellular insulin, which will be of great significance to the study of diabetes and other blood sugar diseases.

Ethyl acetate fraction of Fagara zanthoxyloides root-bark possess antidiabetic property against alloxan-induced diabetes and its complications in Wistar rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Fagara zanthoxyloides Lam., an African traditional medicinal plant, is used for treatment of malaria and diabetes.

AIM

To investigate the antidiabetic property of ethyl acetate fraction of F. zanthoxyloides root-bark (EAFFZRB) on alloxan-induced diabetic rats.

MATERIALS AND METHODS

Extraction, isolation, preliminary phytochemical analysis, and acute toxicity study of ethanol extract and fractions of F. zanthoxyloides root-bark were achieved using standard methods. Phyto-constituents in EAFFZRB were identified using HPLC technique. Forty-eight male Wistar rats (140-185 g) were randomized into 6 groups (n = 8). Groups 1 and 2 served as normal and negative controls, respectively. Diabetes was induced in test groups (2-6) using 150 mg/kg body weight (b.w) Alloxan monohydrate. Rats in groups 4-6 received of 200, 400 and 600 mg/kg b.w. EAFFZRB orally, respectively, for 21 days. Group 3 rats received 5 mg/kg b.w Glibenclamide. The effect of EAFFZRB on alterations in hematological, biochemical, and histological indices of study rats were assessed.

RESULTS

Extraction of 3500 g ethanol extract yielded 15.71 g EAFFZRB. HPLC fingerprint of EAFFZRB indicated presence of luteolin, rutin, quercetin, apigenin, cinnamic acid and catechin. Diabetes triggered significant (p < 0.05) alterations in b.w., hematological, biochemical and histological indices of test rats relative to normal control. Treatment with EAFFZRB (LD₅₀ = 3807.9 mg/kg b.w.) resulted in remarkable improvements in altered b.w. changes, hematological, biochemical and histological parameters of diabetic rats.

CONCLUSION

The study demonstrated the antidiabetic potential of EAFFZRB, providing scientific basis for traditional use of the plant in treatment of diabetes and its complications.

Brazilian sunberry (Solanum oocarpum Sendtn): Alkaloid composition and improvement of mitochondrial functionality and insulin secretion of INS-1E cells

Chronic high-glucose levels induce the generation of reactive oxygen species leading to mitochondrial dysfunction, which is one of the pathological triggers in the development of diabetes. This study investigated the alkaloid composition of two fruits of the genus Solanum, fruta-do-lobo (Solanum lycocarpum) and juá-açu (Solanum oocarpum), and their capacity to protect against oxidative damage and defective insulin secretion induced by chronic high-glucose levels. LC-MS and molecular network of fruit crude extracts reveals that juá-açu and fruta-do-lobo contain kukoamines and glycoalkaloids, respectively. Two purification processes were used to enrich those alkaloids. Fruta-do-lobo extract rich in glycoalkaloids showed a strong cytotoxicity effect, however the juá-açu enriched extract was able to protect mitochondrial functionality against glucotoxicity and stimulate insulin secretion even under conditions of hyperglycemia. These results are promising and suggest that juá-açu is a potential source of bioactive compounds for adjuvant/co-adjuvant therapy for diabetes.

Therapeutic Potential of Luteolin on Impaired Wound Healing in Streptozotocin-Induced Rats

Long-term hyperglycemia may lead to diabetic microvascular and macrovascular complications that can affect the peripheral vascular system, particularly in wound healing capacity. Impaired angiogenesis and delayed wound healing are significant clinically. Luteolin (3', 4', 5, 7-tetrahydroxyflavone) is a naturally occurring flavonoid that is ubiquitously found in plants. Recent evidence has shown that luteolin is an anti-inflammatory and anti-oxidative agent. However, the effect of systemic luteolin administration on diabetic wound restoration remains unclear. Herein, we explored the effectiveness of luteolin for improving delayed and impaired healing of skin wound and further clarified the underlying mechanisms. The results indicated that luteolin significantly attenuates blood glucose concentration, improves impaired healing and accelerates re-epithelization of skin wound in streptozotocin (STZ)-induced diabetic rats. Histopathological staining and immunoblotting revealed an inhibitory effect of luteolin on inflammatory cell and cytokine production. We also observed remarkable decreases in protein expressions of inflammatory factors including matrix metalloproteinase (MMP)-9, tumor necrosis factor (TNF)-α, interleukin (IL-6), and IL1-β and downregulation of nuclear factor (NF)-κB, as well as increases in anti-oxidative enzymes such as superoxide dismutase 1 (SOD1) and glutathione peroxidase (GSH-Px) induced by nuclear factor erythroid 2-related factor (Nrf)-2 following luteolin supplementation. Furthermore, luteolin decreased the expression of vascular endothelial growth factor (VEGF) and increased the expression of ubiquitin carboxy-terminal hydrolase (UCH)-L1, as evidenced by angiogenesis and neuronal regeneration in completely healed wound. In conclusion, systemic administration of luteolin promotes wound restoration by ameliorating inflammation and oxidative stress through the inactivation of NF-κB and upregulation of Nrf2 in STZ-induced diabetic rats.

The role of resveratrol in bone marrow-derived mesenchymal stem cells from patients with osteoporosis

The aim of the present study was to investigate the effects of resveratrol on BMSCs from patients with osteoporosis. The cell viability and proliferation of BMSCs after treatment with different concentrations of resveratrol was respectively observed by MTT assay and EdU staining. The apoptosis was assessed using by TUNEL staining and the pluripotency was analyzed by quantitative reverse transcription‐PCR (qRT‐PCR). The osteogenic differentiation and adipogenic differentiation were determined by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, oil red O (ORO) staining and qRT‐PCR analysis. MTT assay showed that Res at 40, 80, 100 μM markedly improved the cell proliferation of BMSCs from patients with osteoporosis. EdU staining indicated that Res treatment significantly accelerated the proliferation of BMSCs. In addition, the results of TUNEL staining revealed that Res at 40, 80, 100 μM inhibited the osteoporosis‐related apoptosis of BMSCs. qRT‐PCR analysis explored that Res treatment played a positive role in the pluripotency in BMSCs. ALP, ARS staining and qRT‐PCR demonstrated that Res promoted the differentiation of BMSCs into osteoblasts, especially at 80 μM. ORO staining and qRT‐PCR analysis proved that treatment of Res inhibited the adipogenesis of BMSCs isolated from patients with osteoporosis. Our findings suggested that Res can play a vital role in the cell viability, proliferation, apoptosis, pluripotency, osteogenesis and adipogenesis of BMSCs. And Res might be an efficient therapeutic approach for treating patients with osteoporosis.