2,7"-Phloroglucinol-6,6'-bieckol protects INS-1 cells against high glucose-induced apoptosis

Protection of pancreatic beta cells against high glucose-induced toxicity by astaxanthin-s-allyl cysteine diester: alteration of oxidative stress and apoptotic-related protein expression

Purpose: High glucose (HG)-induced oxidative stress is associated with apoptosis in pancreatic β-cells. The protective effect of astaxanthin-s-allyl cysteine diester (AST-SAC) against HG-induced oxidative stress in pancreatic β-cells (βTC-tet cell line) in in vitro was studied.Materials and Methods: βTC-tet cell line was exposed to HG in the presence and absence of AST-SAC. Various parameters such as cell viability, reactive oxygen species generation, mitochondrial membrane potential, DNA fragmentation and expression of proteins involved in apoptosis [p53, B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X (Bax), cytochrome c and caspase 3] were studied.Results: Pre-treatment of βTC-tet cells with AST-SAC (4, 8 and 12 μg/ml) in the presence of HG (25 mM) protected the viability of the cells in a dose-dependent manner. AST-SAC treatment mitigated the oxidative stress thereby preventing the mitochondrial dysfunction, DNA damage and apoptosis in βTC-tet cells against HG toxicity. Treatment with AST-SAC prevented the increased expression of p53 under HG conditions. Further, AST-SAC treatment maintained the level of pro-apoptotic (Bax, cleaved caspase-3 and cytochrome c) and anti-apoptotic (Bcl-2) proteins to that of the control level under HG exposed conditions in βTC-tet cells.Conclusion: Altogether, AST-SAC alleviated HG-induced oxidative damage and apoptosis in pancreatic β-cells by enhancing the antioxidant status and altering apoptotic-related protein expression.

Protection of β-pancreatic cells from dysfunctionality of insulin using vitexin by apoptosis of INS-1 cells

AIMS

This study was performed to explore the possible beneficial effects of vitexin on high glucose (HG)-induced cytotoxicity in pancreatic β-cells.

METHODS

INS-1 pancreatic β-cell line has used this study. HG-induced (33 Mm) exposed INS-1 cell death; the apoptosis INS-1 cells treated vitexin 10, 20, 40, and 80 µg/mL for 24 hours. The anti-apoptosis properties were evaluated by MTT assay, glucose-stimulated insulin secretion assay, biochemical assay, annexin-V-FITC staining and western blot analysis.

RESULTS

These findings demonstrate that vitexin treatment improved the HG-exposure, reduced the INS-1 cell viability and significantly enhanced glucose-stimulated insulin secretion in a dose-dependent manner. The antioxidant studies revealed that vitexin treatment significantly decreased lipid peroxidation and reactive oxygen species and increased antioxidant level of INS-1 cell line in 24 hrs. The findings of the study suggested that in the vitexin treatment group, pancreatic apoptosis and Bax protein expression reduced significantly. At the same time, Bcl-2 protein expression increased, and NF-κB protein in HG-induced INS-cells was inhibited.

CONCLUSION

Therefore, our results suggest that vitexin can be successfully used to regulate the expression of Bcl-2 family proteins, reduce lipid peroxidation and to improve the secretion of antioxidants in pancreatic β-cell lines.

Antioxidant Effect of Tyr-Ala Extracted from Zein on INS-1 Cells and Type 2 Diabetes High-Fat-Diet-Induced Mice

Type 2 diabetes mellitus (T2DM) is associated with an oxidative milieu that often leads to adverse health problems. Bioactive peptides of zein possess outstanding antioxidant activity; however, their effects on hyperglycemia-related oxidative stress remain elusive. In the present study, the dipeptide Tyr-Ala (YA), a functional peptide with typical health benefits, was applied to alleviate oxidative stress in pancreatic islets under hyperglycemic conditions. By detecting viability, antioxidant ability, and insulin secretion in INS-1 cells, YA showed excellent protection of INS-1 cells from H2O2 oxidative stress, erasing reactive oxygen species (ROS) and promoting insulin secretion. Moreover, by Western blotting, we found that YA can regulate the PI3K/Akt signaling pathway associated with glycometabolism. After establishing a T2DM mice model, we treated mice with YA and measured glucose, insulin, hemoglobin A1C (HbA1c), total cholesterol (TC), triglyceride (TG), and malonaldehyde (MDA) levels and activities of superoxide dismutase (SOD) and glutathione (GSH) from blood samples. We observed that YA could reduce the production of glucose, insulin, HbA1c, TC, TG, and MDA, in addition to enhancing the activities of SOD and GSH. YA could also repair the function of the kidneys and pancreas of T2DM mice. Along with the decline in fasting blood glucose, the oxidative stress in islets was alleviated in T2DM mice after YA administration. This may improve the health situation of diabetic patients in the future.

Therapeutic Potential of Seaweed-Derived Bioactive Compounds for Cardiovascular Disease Treatment

Cardiovascular diseases are closely related to hypertension, type 2 diabetes mellitus, obesity, and hyperlipidemia. Many studies have reported that an unhealthy diet and sedentary lifestyle are critical factors that enhance these diseases. Recently, many bioactive compounds isolated from marine seaweeds have been studied for their benefits in improving human health. In particular, several unique bioactive metabolites such as polyphenols, polysaccharides, peptides, carotene, and sterol are the most effective components responsible for these activities. This review summarizes the current in vitro, in vivo, and clinical studies related to the protective effects of bioactive compounds isolated from seaweeds against cardiovascular disorders, including anti-diabetic, anti-hypertensive, anti-hyperlipidemia, and anti-obesity effects. Therefore, this present review summarizes these concepts and provides a basis for further in-depth research.

Flavonoids-rich extract from Bidens bipinnata L. protects pancreatic β-cells against oxidative stress-induced apoptosis through intrinsic and extrinsic pathways

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicinal, Bidens bipinnata L. has been used to treat many diseases with a long history in China. The anti-diabetic effects of extract from B. bipinnata have been demonstrated in the previous reports.

AIM OF THE STUDY

The protective effects of flavonoids-rich extract from B. bipinnata (BBTF) on cell damage induced by H₂O₂ in pancreatic β cell and its potential mechanisms were evaluated.

MATERIALS AND METHODS

MTT, ROS production, nuclear staining and flow cytometry assays were adopted to determine the effects of BBTF on cell viability, production of ROS and cell apoptosis in H₂O₂-treated INS-1 cell. Cell apoptosis-related proteins expressions were detected by Western blot assay.

RESULTS

Pre-treatment of BBTF could significantly increase INS-1 cell viability, inhibit the production of intracellular ROS and reduced the characteristic features of cell apoptosis induced by H₂O₂ in INS-1 cells. The studies of the underlying mechanism showed that BBTF could regulate Bax and Bcl-2 proteins expressions, suppress the phosphorylation of JNK, ERK and p38, as well as down-regulate Fas and FasL proteins expressions induced by H₂O₂. The expressions of caspase-8, caspase-9 and caspase-3 were therefore decreased.

CONCLUSION

The results indicated that flavonoids-rich extract from B. bipinnata could be a natural agent in diabetic prevention and therapy.

Vitexin restores pancreatic β-cell function and insulin signaling through Nrf2 and NF-κB signaling pathways

Chronic hyperglycemia induces pancreatic β-cell dysfunction through several cell signaling pathways. The β-cell loss by apoptosis appears to play a crucial role in the onset and progression of diabetes. This study was aimed to investigate the role of vitexin against high glucose-induced β-cells apoptosis and the underlying mechanisms involved therein. INS-1 cells were pretreated with vitexin (20 and 40 μM) followed by high glucose (33 mM) exposure and the cytotoxicity was assessed by MTT. The effect of vitexin on nuclear factor erythroid 2-related factor 2 (Nrf2) and NF-kB signaling molecules have been studied. Vitexin-mediated stimulation of Nrf2 was assessed. Vitexin protected the cells against high glucose toxicity in a concentration-dependent manner. Vitexin improved insulin signaling as analyzed by the levels of functional proteins in the insulin pathways, viz., insulin receptor (IR), insulin receptor substrate (IRS)-1 and IRS-2, glucose transporter -2, and glucose-stimulated insulin secretion. Vitexin improved the high glucose-induced nuclear transcription factor system by suppressing Rel A, Rel B, P50/p105, and IκB expression resulting in decreased cell apoptosis, further confirmed by the reduction in the percentage of Annexin-V positive cells. Our data suggest that vitexin improves insulin secretion by activating key proteins, including NF-κB and Nrf2 in β-cells regulating apoptosis.

Brown Seaweeds for the Management of Metabolic Syndrome and Associated Diseases

Metabolic syndrome is characterized by the coexistence of different metabolic disorders which increase the risk of developing type 2 diabetes mellitus and cardiovascular diseases. Therefore, metabolic syndrome leads to a reduction in patients' quality of life as well as to an increase in morbidity and mortality. In the last few decades, it has been demonstrated that seaweeds exert multiple beneficial effects by virtue of their micro- and macronutrient content, which could help in the management of cardiovascular and metabolic diseases. This review aims to provide an updated overview on the potential of brown seaweeds for the prevention and management of metabolic syndrome and its associated diseases, based on the most recent evidence obtained from in vitro and in vivo preclinical and clinical studies. Owing to their great potential for health benefits, brown seaweeds are successfully used in some nutraceuticals and functional foods for treating metabolic syndrome comorbidities. However, some issues still need to be tackled and deepened to improve the knowledge of their ADME/Tox profile in humans, in particular by finding validated indexes of their absorption and obtaining reliable information on their efficacy and long-term safety.

In Vitro Evaluation of Chemically Analyzed Hypericum Triquetrifolium Extract Efficacy in Apoptosis Induction and Cell Cycle Arrest of the HCT-116 Colon Cancer Cell Line

Naturally derived drugs and plant-based products are attractive commodities that are being explored for cancer treatment. This in vitro study aimed to investigate the role of Hypericum triquetrifolium (50% ethanol: 50% water) extract (HTE) treatment on apoptosis, cell cycle modulation, and cell cycle arrest in human colon cancer cell line (HCT-116). HTE induced cell death via an apoptotic process, as assayed by an Annexin V-Cy3 assay. Exposing HCT-116 cells to 0.064, 0.125, 0.25, and 0.5 mg/mL of HTE for 24 h led to 50 ± 9%, 71.6 ± 8%, 85 ± 5%, and 96 ± 1.5% apoptotic cells, respectively. HCT-116 cells treated with 0.25 and 0.5 mg/mL HTE for 3 h resulted in 38.9 ± 1.5% and 57.2 ± 3% cleavage of caspase-3-specific substrate, respectively. RT-PCR analysis revealed that the HTE extract had no effect on mRNA levels of Apaf-1 and NOXA. Moreover, the addition of 0.125 mg/mL and 0.25 mg/mL HTE for 24 h was clearly shown to attenuate the cell cycle progression machinery in HCT-116 cells. GC/MS analysis of the extract identified 21 phytochemicals that are known as apoptosis inducers and cell cycle arrest agents. All the compounds detected are novel in H. triquetrifolium. These results suggest that HTE-induced apoptosis of human colon cells is mediated primarily through the caspase-dependent pathway. Thus, HTE appears to be a potent therapeutic agent for colon cancer treatment.

Voltammetric, spectroscopic, and cellular characterization of redox functionality of eckol and phlorofucofuroeckol-A: A comparative study

Interest in phlorotannins has increased in recent years largely due to antioxidant capacity, however, the redox mechanism of phlorotannins is still obscure. In the present study, the electrochemical oxidation mechanisms of eckol (EL) and phlorofucofuroeckol-A (PFF-A), two representative phlorotannin compounds, were comparatively analyzed in a wide pH range using cyclic and differential pulse voltammetry as well as spectroscopic assay. The voltammetric study revealed that EL and PFF-A were successively oxidized in three pH-dependent steps. Moreover, it was found that the PFF-A presented a stronger proton and electron transferring activity as compared to EL since PFF-A exhibited lower acid-base dissociation constant (pKa ) value and higher heterogeneous rate constant (kbh ) value in the first oxidation step. These property were further evidenced by comparison of direct antioxidant activity (i.e., superoxide anion and peroxide radicals) as well as indirect antioxidant activity (i.e., mRNA expression of two phase II enzymes) between EL and PFF-A. PRACTICAL APPLICATIONS: Phlorotannins from edible algae have been regarded as novel antioxidants those presented high application potential in food industry. Even though antioxidant activity of phlorotannin compounds have been widely investigated in both in vitro and in vivo studies, very few reports focused on electron transferring functionality which is chemical basis for antioxidant process. Herein, the oxidative mechanisms of two representative phlorotannins were comparatively analyzed using multiple electrochemical methods. This is hopefully to give information on the chemical meaning behind the antioxidant activity of dietary phlorotannins.

Potential Role of Seaweed Polyphenols in Cardiovascular-Associated Disorders

The beneficial effects of various polyphenols with plant origins on different cardiovascular-associated disorders, such as hypertension, diabetes mellitus type 2 and metabolic syndrome are well known. Recently, marine crude-drugs are emerging as potential treatments in many noncommunicable conditions, including those involving the cardiovascular system. Among the active compounds responsible for these activities, seaweed polyphenols seem to play a key role. The aim of the present review is to summarise the current knowledge about the beneficial effects reported for edible seaweed polyphenols in the amelioration of these prevalent conditions, focusing on both preclinical and clinical studies. This review will help to establish the basis for future studies in this promising field.