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BACKGROUND: Currently, it is acknowledged that vitamin E, insulin sensitizers and anti-diabetic drugs are used to manage non-alcoholic fatty liver disease (NAFLD), however, these therapeutic interventions harbour adverse side effects. Pioglitazone, an anti-diabetic drug, is currently the most effective therapy to manage NAFLD. The use of natural medicines is widely embraced due to the lack of evidence of their negative side effects. Rooibos has been previously shown to decrease inflammation and oxidative stress in experimental models of diabetes, however, this is yet to be explored in a setting of NAFLD. This study was aimed at investigating the effects of an aspalathin-rich green rooibos extract (Afriplex GRTTM) against markers of hepatic oxidative stress, inflammation and apoptosis in an in vitro model of NAFLD. METHODS: Oleic acid [1 mM] was used to induce hepatic steatosis in C3A liver cells. Thereafter, the therapeutic effect of Afriplex GRTTM, with or without pioglitazone, was determined by assessing its impact on cell viability, changes in mitochondrial membrane potential, intracellular lipid accumulation and the expression of genes and proteins (ChREBP, SREBF1, FASN, IRS1, SOD2, Caspase-3, GSTZ1, IRS1 and TNF-α) that are associated with the development of NAFLD. RESULTS: Key findings showed that Afriplex GRTTM added to the medium alone or combined with pioglitazone, could effectively block hepatic lipid accumulation without inducing cytotoxicity in C3A liver cells exposed oleic acid. This positive outcome was consistent with effective regulation of genes involved in insulin signaling, as well as carbohydrate and lipid metabolism (IRS1, SREBF1 and ChREBP). Interestingly, in addition to reducing protein levels of an inflammatory marker (TNF-α), the Afriplex GRTTM could ameliorate oleic acid-induced hepatic steatotic damage by decreasing the protein expression of oxidative stress and apoptosis related markers such as GSTZ1 and caspase-3. CONCLUSION: Afriplex GRTTM reduced hepatic steatosis in oleic acid induced C3A liver cells by modulating SREBF1, ChREBP and IRS-1 gene expression. The extract may also play a role in alleviating inflammation by reducing TNF-α expression, suggesting that additional experiments are required for its development as a suitable therapeutic option against NAFLD. Importantly, further research is needed to explore its antioxidant role in this model.
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Hepatopatia Gordurosa não Alcoólica , Humanos , Hepatopatia Gordurosa não Alcoólica/metabolismo , Caspase 3/metabolismo , Ácido Oleico/farmacologia , Pioglitazona/uso terapêutico , Fator de Necrose Tumoral alfa/metabolismo , Fígado/metabolismo , Metabolismo dos Lipídeos , Inflamação/metabolismo , Insulina/metabolismo , Dieta Hiperlipídica , Glutationa Transferase/metabolismoRESUMO
Lipid overload or metabolic stress has gained popularity in research that explores pathological mechanisms that may drive enhanced oxidative myocardial damage. Here, H9c2 cardiomyoblasts were exposed to various doses of palmitic acid (0.06 to 1 mM) for either 4 or 24 h to study its potential physiological response to cardiac cells. Briefly, assays performed included metabolic activity, cholesterol content, mitochondrial respiration, and prominent markers of oxidative stress, as well as determining changes in mitochondrial potential, mitochondrial production of reactive oxygen species, and intracellular antioxidant levels like glutathione, glutathione peroxidase and superoxide dismutase. Cellular damage was probed using fluorescent stains, annexin V and propidium iodide. Our results indicated that prolonged exposure (24-hours) to palmitic acid doses ≥ 0.5 mM significantly impaired mitochondrial oxidative status, leading to enhanced mitochondrial membrane potential and increased mitochondrial ROS production. While palmitic acid dose of 1 mM appeared to induce prominent cardiomyoblasts damage, likely because of its capacity to increase cholesterol content/ lipid peroxidation and severely suppressing intracellular antioxidants. Interestingly, short-term (4-hours) exposure to palmitic acid, especially for lower doses (≤ 0.25 mM), could improve metabolic activity, mitochondrial function and protect against oxidative stress induced myocardial damage. Potentially suggesting that, depending on the dose consumed or duration of exposure, consumption of saturated fatty acids such as palmitic acid can differently affect the myocardium. However, these results are still preliminary, and in vivo research is required to understand the significance of maintaining intracellular antioxidants to protect against oxidative stress induced by lipid overload.
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High-fat diet (HFD) feeding in rodents has become an essential tool to critically analyze and study the pathological effects of obesity, including mitochondrial dysfunction and insulin resistance. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) regulates cellular energy metabolism to influence insulin sensitivity, beyond its active role in stimulating mitochondrial biogenesis to facilitate skeletal muscle adaptations in response to HFD feeding. Here, some of the major electronic databases like PubMed, Embase, and Web of Science were accessed to update and critically discuss information on the potential role of PGC-1α during metabolic adaptations within the skeletal muscle in response to HFD feeding in rodents. In fact, available evidence suggests that partial exposure to HFD feeding (potentially during the early stages of disease development) is associated with impaired metabolic adaptations within the skeletal muscle, including mitochondrial dysfunction and reduced insulin sensitivity. In terms of implicated molecular mechanisms, these negative effects are partially associated with reduced activity of PGC-1α, together with the phosphorylation of protein kinase B and altered expression of genes involving nuclear respiratory factor 1 and mitochondrial transcription factor A within the skeletal muscle. Notably, metabolic abnormalities observed with chronic exposure to HFD (likely during the late stages of disease development) may potentially occur independently of PGC-1α regulation within the muscle of rodents. Summarized evidence suggests the causal relationship between PGC-1α regulation and effective modulations of mitochondrial biogenesis and metabolic flexibility during the different stages of disease development. It further indicates that prominent interventions like caloric restriction and physical exercise may affect PGC-1α regulation during effective modulation of metabolic processes.
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Resistência à Insulina , Doenças Mitocondriais , Animais , Dieta Hiperlipídica , Músculo Esquelético/metabolismo , Modelos Animais , Doenças Mitocondriais/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismoRESUMO
There is an increasing interest in the use of nutraceuticals and plant-derived bioactive compounds from foods for their potential health benefits. For example, as a major active ingredient found from cruciferous vegetables like broccoli, there has been growing interest in understanding the therapeutic effects of sulforaphane against diverse metabolic complications. The past decade has seen an extensive growth in literature reporting on the potential health benefits of sulforaphane to neutralize pathological consequences of oxidative stress and inflammation, which may be essential in protecting against diabetes-related complications. In fact, preclinical evidence summarized within this review supports an active role of sulforaphane in activating nuclear factor erythroid 2-related factor 2 or effectively modulating AMP-activated protein kinase to protect against diabetic complications, including diabetic cardiomyopathy, diabetic neuropathy, diabetic nephropathy, as well as other metabolic complications involving non-alcoholic fatty liver disease and skeletal muscle insulin resistance. With clinical evidence suggesting that foods rich in sulforaphane like broccoli can improve the metabolic status and lower cardiovascular disease risk by reducing biomarkers of oxidative stress and inflammation in patients with type 2 diabetes. This information remains essential in determining the therapeutic value of sulforaphane or its potential use as a nutraceutical to manage diabetes and its related complications. Finally, this review discusses essential information on the bioavailability profile of sulforaphane, while also covering information on the pathological consequences of oxidative stress and inflammation that drive the development and progression of diabetes.
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Previously we reported that a high fat, high sugar (HFHS) diet induced adiposity, hyperinsulinaemia, hyperleptinaemia, hypertriglyceridaemia and increased liver mass in male Wistar rats. In the present study, the mechanisms underlying the increased liver mass were further elucidated by assessing hepatic lipid accumulation and the expression and methylation status of key metabolic genes using histology, quantitative real-time PCR and pyrosequencing, respectively. The HFHS diet induced hepatic steatosis, increased hepatic triglycerides (1.8-fold, p < 0.001), and increased the expression of sterol regulatory element-binding transcription factor 1 (Srebf1) (2.0-fold, p < 0.001) and peroxisome proliferator-activated receptor gamma (Pparg) (1.7-fold, p = 0.017) in the liver. The expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (Pgc1a) was decreased (2.6-fold, p < 0.010), which was accompanied by hypermethylation (p = 0.018) of a conserved CpG site in the promoter of Pgc1a in HFHS fed rats compared to controls. In silico analysis identified putative binding sites for CCAAT/enhancer-binding protein beta (C/EBPß) and hepatocyte nuclear factor 1 (HNF1) within proximity to the hypermethylated CpG. As Pgc1a is a co-activator of several transcription factors regulating multiple metabolic pathways, hypermethylation of this conserved CpG site in the promoter of Pgc1a may be one possible mechanism contributing to the development of hepatic steatosis in response to a HFHS diet. However, further work is required to confirm the role of Pgc1a in steatosis.
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Dyslipidemia is one of the major risk factors for the development of cardiovascular disease (CVD) in patients with type 2 diabetes (T2D). This metabolic anomality is implicated in the generation of oxidative stress, an inevitable process involved in destructive mechanisms leading to myocardial damage. Fortunately, commonly used drugs like statins can counteract the detrimental effects of dyslipidemia by lowering cholesterol to reduce CVD-risk in patients with T2D. Statins mainly function by blocking the production of cholesterol by targeting the mevalonate pathway. However, by blocking cholesterol synthesis, statins coincidently inhibit the synthesis of other essential isoprenoid intermediates of the mevalonate pathway like farnesyl pyrophosphate and coenzyme Q10 (CoQ10). The latter is by far the most important co-factor and co-enzyme required for efficient mitochondrial oxidative capacity, in addition to its robust antioxidant properties. In fact, supplementation with CoQ10 has been found to be beneficial in ameliorating oxidative stress and improving blood flow in subjects with mild dyslipidemia.. Beyond discussing the destructive effects of oxidative stress in dyslipidemia-induced CVD-related complications, the current review brings a unique perspective in exploring the mevalonate pathway to block cholesterol synthesis while enhancing or maintaining CoQ10 levels in conditions of dyslipidemia. Furthermore, this review disscusses the therapeutic potential of bioactive compounds in targeting the downstream of the mevalonate pathway, more importantly, their ability to block cholesterol while maintaining CoQ10 biosynthesis to protect against the destructive complications of dyslipidemia.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Dislipidemias , Inibidores de Hidroximetilglutaril-CoA Redutases , Humanos , Ubiquinona/uso terapêutico , Ubiquinona/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Ácido Mevalônico , Colesterol , Doenças Cardiovasculares/tratamento farmacológico , Doenças Cardiovasculares/etiologia , Dislipidemias/complicações , Dislipidemias/tratamento farmacológicoRESUMO
Background: The focus on traditional and complementary medicine for supplementation and treatment of diseases is high. Aspalathus linearis commonly known as Rooibos showed several beneficial effects, this led to the standardized production of a pharmaceutical grade green rooibos extract (Afriplex TM GRT) with enhanced polyphenolic content. The aim of this study was to assess toxicity of Afriplex TM GRT in HepG2/C3A cells and Sprague Dawley rats. Methods: Afriplex GRT TM (0.1, 1, 10, 100, or 1000 µg/mL) in DMSO was added to the media to the final 0.01% DMSO for treatment of HepG2/C3A for 1, 24 and 48 hrs followed by MTT and ATP assays. Sprague Dawley rats were grouped to Control, Afriplex TM GRT treated (10, 100 and 300 mg/kg); and acute (24hrs tetrachloromethane (CCl 4) injected hepatotoxicity control). Serum biochemistry, histology and Western blot analysis on liver were performed. Results: Afriplex TM GRT significantly reduced cell viability at 100 and 1000µg/mL after 48 hrs. Acute CCl 4 treatment significantly increased serum alanine aminotransferase in rats. The highest extract treatment of 300 mg/kg significantly elevated aspartate amino transferase. There was severe macro vesicular in the CCl 4 group whereas mild to moderate micro vesicular steatosis was seen in the 300 mg/kg Afriplex TM GRT treated group. Highest extract treatment significantly reduced NFkB expression on Western blot analysis. Conclusion: The beneficial effects of pharmaceutical grade Afriplex GRT TM are concentration and dosage based. Afriplex GRT TM exerts its beneficial effects via NFkB as demonstrated by the dose dependent reduction of NFkB on Western blot analysis. More work need to be done to explore the exact mechanism that occurs in the NFkB pathway.
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Diabetes, a prevalent metabolic condition with a wide range of complications, is fast becoming a global health crisis. Herbal medicine and enhanced extracts are some of the therapeutic options used in the management of diabetes mellitus. The plant-derived molecules and their suitable structure modification have given many leads or drugs to the world such as metformin used as an antidiabetic drug. The stem extract of Sclerocarya birrea has been reported as a potent antidiabetic (glucose uptake) agent. However, the bioactive compounds have not been reported from S. birrea for treatment of diabetes. In this study, the spray-dried aqueous leaf extracts of S. birrea were investigated as an antidiabetic agent using a 2-deoxy-glucose (2DG) technique showing good stimulatory effect on glucose uptake in differentiated C2C12 myocytes with % 2DG uptake ranging from 110-180% that was comparable to the positive control insulin. Three compounds were isolated and identified using bioassay-guided fractionation of the spray-dried aqueous extract of S. birrea leaves: myricetin (1), myricetin-3-O-ß-D-glucuronide (2) and quercetin-3-O-ß-D-glucuronide (3). Their chemical structures were determined using NMR and mass spectrometric analyses, as well as a comparison of experimentally obtained data to those reported in the literature. The isolated compounds (1-3) were studied for their stimulatory actions on glucose uptake in differentiated C2C12 myocytes. The three compounds (1, 2 and 3) showed stimulatory effects on the uptake of 2DG in C2C12 myocytes with % 2DG uptake ranging from 43.9-109.1% that was better compared to the positive control insulin. Additionally, this is the first report of the flavonoid glycosides (myricetin-3-O-ß-D-glucuronide) for antidiabetic activity and they are the main bioactive compound in the extract responsible for the antidiabetic activity. This result suggests that the S. birrea leaves have the potential to be developed for treatment of diabetes.
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Anacardiaceae , Diabetes Mellitus , Hipoglicemiantes/química , Extratos Vegetais/química , Anacardiaceae/química , Insulina , Diabetes Mellitus/tratamento farmacológico , Glucose/metabolismoRESUMO
This study was one of the first to detect Omicron sublineages BA.4 and BA.5 in wastewater from South Africa. Spearman rank correlation analysis confirmed a strong positive correlation between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral RNA in wastewater samples and clinical cases (r = 0.7749, P < .0001). SARS-CoV-2 viral load detected in wastewater, resulting from the Delta-driven third wave, was significantly higher than during the Omicron-driven fourth wave. Whole-genome sequencing confirmed presence of Omicron lineage defining mutations in wastewater with the first occurrence reported 23 November 2021 (BA.1 predominant). The variant spread rapidly, with prevalence of Omicron-positive wastewater samples rising to >80% by 10 January 2022 with BA.2 as the predominant sublineage by 10 March 2022, whilst on 18 April 2022 BA.4 and BA.5 were detected in selected wastewater sites. These findings demonstrate the value of wastewater-based epidemiology to monitor the spatiotemporal spread and potential origin of new Omicron sublineages.
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COVID-19 , SARS-CoV-2 , COVID-19/epidemiologia , Humanos , Prevalência , RNA Viral/genética , SARS-CoV-2/genética , África do Sul/epidemiologia , Águas ResiduáriasRESUMO
The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic capacity is limited in defined communities, posing a challenge in tracking and tracing new infections. Monitoring student residences, which are considered infection hotspots, with targeted wastewater surveillance is crucial. This study evaluated the efficacy of SARS-CoV-2 targeted wastewater surveillance for outbreak mitigation at Stellenbosch University's student residences in South Africa. Using torpedo-style passive sampling devices, wastewater samples were collected biweekly from manholes at twelve Stellenbosch University Tygerberg (SUT) campus and Stellenbosch University-Main (SUM) campus student residences. The surveillance led to an early warning detection of SARS-CoV-2 presence on campus, followed by an informed management strategy leading to restriction of student activities on campus and a delay in the onset of the third wave that was experienced throughout the country. Moreover, the study highlighted the extent of possible infections at defined locations even when a low number of confirmed coronavirus disease 2019 (COVID-19) cases were reported. The study also tracked the surge of the Delta and Omicron variants in the student residences using the Thermo Fisher TaqMan® RT-qPCR genotyping assay.
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COVID-19 , SARS-CoV-2 , COVID-19/epidemiologia , Humanos , SARS-CoV-2/genética , Esgotos , África do Sul/epidemiologia , Estudantes , Águas Residuárias , Vigilância Epidemiológica Baseada em Águas ResiduáriasRESUMO
There are three main types of diabetes, namely, type 1 diabetes, type 2 diabetes (T2D), and diabetes in pregnancy (gestational diabetes) [...].
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Diabetes Mellitus Tipo 2 , Diabetes Gestacional , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Gestacional/tratamento farmacológico , Feminino , Alimentos , Humanos , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/uso terapêutico , GravidezRESUMO
Enzalutamide, a nonsteroidal antiandrogen, significantly prolonged the survival of patients with metastatic castration-resistant prostate cancer (CRPC). However, patients receiving enzalutamide frequently develop drug resistance. Rooibos (Aspalathus linearis) is a shrub-like leguminous fynbos plant endemic to the Cedarberg Mountains area in South Africa. We evaluated the possibility of using a pharmaceutical-grade green rooibos extract (GRT, containing 12.78% aspalathin) to suppress the proliferation and survival of enzalutamide-resistant prostate cancer (PCa) cells. Treatment with GRT dose-dependently suppressed the proliferation, survival, and colony formation of enzalutamide-resistant C4-2 MDV3100r cells and PC-3 cells. Non-cancerous human cells were more resistant to GRT treatment. GRT suppressed the expression of proteins involved in phosphoinositide 3-kinase (PI3K)-Akt signaling, androgen receptor (AR), phospho-AR (Ser81), cyclin-dependent kinase 1 (Cdk1), c-Myc and Bcl-2 but increased the expression of apoptotic proteins. Overexpression of c-Myc antagonized the suppressive effects of GRT, while knockdown of c-Myc increased the sensitivity of PCa cells to GRT treatment. Expression level of c-Myc correlated to resistance of PCa cells to GRT treatment. Additionally, immunofluorescence microscopy demonstrated that GRT reduced the abundance of AR proteins both in nucleus and cytoplasm. Treatment with cycloheximide revealed that GRT reduced the stability of AR. GRT suppressed protein expression of AR and AR's downstream target prostate specific antigen (PSA) in C4-2 MDV3100r cells. Interestingly, we observed that AR proteins accumulate in nucleus and PSA expression is activated in the AR-positive enzalutamide-resistant PCa cells even in the absence of androgen. Our results suggested that GRT treatment suppressed the cell proliferation and survival of enzalutamide-resistant PCa cells via inhibition of c-Myc, induction of apoptosis, as well as the suppression of expression, signaling and stability of AR. GRT is a potential adjuvant therapeutic agent for enzalutamide-resistant PCa.
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Aspalathus , Neoplasias de Próstata Resistentes à Castração , Aspalathus/metabolismo , Benzamidas , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Humanos , Masculino , Nitrilas , Feniltioidantoína , Fosfatidilinositol 3-Quinases , Antígeno Prostático Específico/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/patologia , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismoRESUMO
Oxidative stress and lipotoxicity effects on pancreatic ß cells play a major role in the pathogenesis of type 2 diabetes (T2D). Flavonoids and antioxidants are under study for their cytoprotective effects and antidiabetic potential. In this study, we aimed to compare the protective effect of the Rooibos components aspalathin, isoorientin, 3-hydroxyphloretin (3-OH) and green Rooibos extract (GRT) itself, and exendin-4 and N-acetylcysteine (NAC) as reference molecules, against lipotoxicity and oxidative stress. The insulin-producing ß cell line INS1E was exposed to hydrogen peroxide or streptozotocin (STZ) to induce oxidative stress, and palmitate to induce lipotoxicity. Cell viability was assessed by a MTS cell viability assay. Antioxidant response and antiapoptotic gene expression was performed by qRT-PCR. Glucose transporter 2 (GLUT 2) transporter inhibition was assessed through 2-NBDG uptake. GRT and the flavonoids aspalathin and 3-hydroxyphloretin offered significant protection against oxidative stress and lipotoxicity. GRT downregulated expression of pro-apoptotic genes Txnip and Ddit3. The flavonoids aspalathin and 3-hydroxyphloretin also downregulated these genes and in addition upregulated expression of antioxidant response genes Hmox1, Nqo1 and Sod1. Isoorientin gave no cytoprotection. Cytoprotection by Rooibos components was significantly higher than by NAC or exendin-4. Rooibos components strongly protect INS1E ß cells against diabetogenic stress. Cytoprotection was associated with the upregulation of antioxidant response genes of the NRF2/KEAP1 pathway or suppression of the TXN system. The Rooibos molecules offered better protection against these insults than exendin-4 and NAC, making them interesting candidates as ß cell cytoprotectants for therapeutic or nutraceutical applications.
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Aspalathus , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Antioxidantes/análise , Antioxidantes/farmacologia , Morte Celular , Diabetes Mellitus Tipo 2/tratamento farmacológico , Exenatida/farmacologia , Flavonoides/análise , Flavonoides/farmacologia , Proteína 1 Associada a ECH Semelhante a Kelch , Fator 2 Relacionado a NF-E2 , Estresse Oxidativo , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Substâncias Protetoras/farmacologiaRESUMO
Non-alcoholic fatty liver disease (NAFLD) is a spectrum of hepatic metabolic perturbations ranging from simple steatosis to steatohepatitis, cirrhosis and hepatocellular carcinoma. Currently, lifestyle modifications to reduce weight gain are considered the most effective means of preventing and treating the disease. The aim of the present study was to determine the therapeutic benefit of Sclerocarya birrea (Marula leaf extract, MLE) on hepatic steatosis. Obese db/db mice were randomly stratified into the obese control, metformin (MET) or MLE-treated groups. Mice were treated daily for 29 days, at which point all mice were euthanized and liver samples were collected. Hematoxylin and eosin staining was used for histological assessment of the liver sections, while qRT-PCR and Western blot were used to determine hepatic mRNA and protein expression, respectively. Thereafter, the association between methylenetetrahydrofolate reductase (Mthfr a key enzyme in one-carbon metabolism and DNA-methylation-induced regulation of gene transcription) and lipogenic genes was evaluated using Pearson's correlation coefficient. Mice treated with MLE presented with significantly lower body and liver weights as compared with the obese control and MET-treated mice (p ≤ 0.05). Further, MLE treatment significantly inhibited hepatic steatosis as compared with the obese control and MET-treated mice (p ≤ 0.05). The reduced lipid accumulation was associated with low expression of fatty acid synthase (Cpt1; p ≤ 0.05) and an upregulation of the fatty acid oxidation gene, carnitine palmitoyltransferase (Cpt1; p ≤ 0.01), as compared with the obese control mice. Interestingly, MLE treatment improved the correlation between Mthfr and Cpt1 mRNA expression (r = 0.72, p ≤ 0.01). Taken together, the results suggest that Marula leaf extracts may inhibit hepatic steatosis by influencing the association between Mthfr and genes involved in hepatic lipid metabolism. Further studies are warranted to assess DNA methylation changes in lipid metabolism genes.
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Anacardiaceae , Neoplasias Hepáticas , Hepatopatia Gordurosa não Alcoólica , Animais , Metabolismo dos Lipídeos , Fígado , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Obesidade/metabolismo , Extratos Vegetais/metabolismo , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , RNA Mensageiro/metabolismoRESUMO
Skeletal muscle insulin resistance and mitochondrial dysfunction are some of the major pathological defects implicated in the development of type 2 diabetes (T2D). Therefore, it has become necessary to understand how common interventions such as physical exercise and caloric restriction affect metabolic function, including physiological processes that implicate skeletal muscle dysfunction within a state of T2D. This review critically discusses evidence on the impact of physical exercise and caloric restriction on markers of insulin resistance and mitochondrial dysfunction within the skeletal muscle of patients with T2D or related metabolic complications. Importantly, relevant information from clinical studies was acquired through a systematic approach targeting major electronic databases and search engines such as PubMed, Google Scholar, and Cochrane library. The reported evidence suggests that interventions like physical exercise and caloric restriction, within a duration of approximately 2 to 4 months, can improve insulin sensitivity, in part by targeting the phosphoinositide 3-kinases/protein kinase B pathway in patients with T2D. Furthermore, both physical exercise and caloric restriction can effectively modulate markers related to improved mitochondrial function and dynamics. This was consistent with an improved modulation of mitochondrial oxidative capacity and reduced production of reactive oxygen species in patients with T2D or related metabolic complications. However, such conclusions are based on limited evidence, additional clinical trials are required to better understand these interventions on pathological mechanisms of T2D and related abnormalities.
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Diabetes Mellitus Tipo 2 , Resistência à Insulina , Restrição Calórica , Diabetes Mellitus Tipo 2/metabolismo , Exercício Físico/fisiologia , Humanos , Insulina/metabolismo , Resistência à Insulina/fisiologia , Mitocôndrias/metabolismo , Músculo Esquelético/metabolismoRESUMO
Rooibos (Aspalathus linearis), an indigenous South African plant and its major flavonoid, aspalathin, exhibited positive effects on glycemia and dyslipidemia in animal studies. Limited evidence exists on the effects of rooibos extract taken in combination with oral hypoglycemic and lipid-lowering medications. This study investigated the combined effects of a pharmaceutical grade aspalathin-rich green rooibos extract (GRT) with the sulfonylurea, glyburide, and atorvastatin in a type 2 diabetic (db/db) mouse model. Six-week-old male db/db mice and their nondiabetic lean db+ littermates were divided into 8 experimental groups (n=6/group). Db/db mice were treated orally with glyburide (5 mg/kg bodyweight), atorvastatin (80 mg/kg bodyweight) and GRT (100 mg/kg bodyweight) as mono- and combination therapies respectively, for 5 weeks. An intraperitoneal glucose tolerance test was conducted at 3 weeks of treatment. Serum was collected for lipid analyses and liver tissues for histological examination and gene expression. A significant increase in the fasting plasma glucose (FPG) of the db/db mice compared to their lean counterparts (from 7.98 ± 0.83 to 26.44 ± 1.84, p < 0.0001) was observed. Atorvastatin reduced cholesterol (from 4.00 ± 0.12 to 2.93 ± 0.13, p < 0.05) and triglyceride levels (from 2.77 ± 0.50 to 1.48 ± 0.23, p < 0.05). In db/db mice, the hypotriglyceridemic effect of atorvastatin was enhanced when combined with both GRT and glyburide (from 2.77 ± 0.50 to 1.73 ± 0.35, p = 0.0002). Glyburide reduced the severity and pattern of steatotic lipid droplet accumulation from a mediovesicular type across all lobular areas, whilst combining GRT with glyburide reduced the abundance and severity of lipid droplet accumulation in the centri- and mediolobular areas. The combination of GRT, glyburide and atorvastatin reduced the abundance and severity of lipid accumulation and the intensity score compared to the administered drugs alone. The addition of either GRT or glyburide in combination with atorvastatin had no effect on blood glucose or lipid profiles, but significantly reduced lipid droplet accumulation.
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It remains essential to decipher some of the pathological mechanisms that link obesity with deteriorating human health. Insulin resistance, due to enhanced free fatty acid substrate delivery, results in disrupted glucose homeostasis and altered mitochondrial oxidative capacity, which is a characteristic feature of an obese state. In fact, as a major site for regulating glucose homeostasis and energy production in response to insulin, the skeletal muscle has become an interesting target tissue to understand the impact of lipid overload on the development of insulin resistance and impaired mitochondrial respiratory function. In addition to systematically retrieving the discussed data, the current review brings an essential perspective in understanding the relevance of experimental models of lipid overload such as high fat diets in understanding the pathological link between insulin resistance and pathological changes in mitochondrial oxidative capacity. Importantly, inclusion of evidence from transgenic model highlights some of the unique molecular targets that are implicated in the development of insulin resistance and inefficient mitochondrial respiration processes within an obese state. Importantly, saturation with lipid products such as ceramides and diacylglycerols, especially within the skeletal muscle, appears to be instrumental in paving the path leading to worsening of metabolic complications. These metabolic consequences mostly interfere with the efficiency of the mitochondrial electron transport chain, leading to overproduction of toxic reactive oxygen species. Therefore, therapeutic agents that reverse the effects of lipid overload by improving insulin sensitivity and mitochondrial oxidative capacity are crucial for the management or even treatment of metabolic diseases.
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Resistência à Insulina , Ceramidas/metabolismo , Glucose/metabolismo , Humanos , Insulina/metabolismo , Mitocôndrias Musculares/metabolismo , Modelos Teóricos , Músculo Esquelético/metabolismo , Obesidade/metabolismo , Estresse OxidativoRESUMO
The current study investigated the physiological effects of flavonoids found in daily consumed rooibos tea, aspalathin, isoorientin, and orientin on improving processes involved in mitochondrial function in C2C12 myotubes. To achieve this, C2C12 myotubes were exposed to a mitochondrial channel blocker, antimycin A (6.25 µM), for 12 h to induce mitochondrial dysfunction. Thereafter, cells were treated with aspalathin, isoorientin, and orientin (10 µM) for 4 h, while metformin (1 µM) and insulin (1 µM) were used as comparators. Relevant bioassays and real-time PCR were conducted to assess the impact of treatment compounds on some markers of mitochondrial function. Our results showed that antimycin A induced alterations in the mitochondrial respiration process and mRNA levels of genes involved in energy production. In fact, aspalathin, isoorientin, and orientin reversed such effects leading to the reduced production of intracellular reactive oxygen species. These flavonoids further enhanced the expression of genes involved in mitochondrial function, such as Ucp 2, Complex 1/3, Sirt 1, Nrf 1, and Tfam. Overall, the current study showed that dietary flavonoids, aspalathin, isoorientin, and orientin, have the potential to be as effective as established pharmacological drugs such as metformin and insulin in protecting against mitochondrial dysfunction in a preclinical setting; however, such information should be confirmed in well-established in vivo disease models.
Assuntos
Antimicina A/toxicidade , Aspalathus/química , Chalconas/farmacologia , Flavonoides/farmacologia , Glucosídeos/farmacologia , Luteolina/farmacologia , Mitocôndrias/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Animais , Antibacterianos/toxicidade , Linhagem Celular , Células Cultivadas , Camundongos , Mitocôndrias/metabolismo , Músculo Esquelético/citologia , Músculo Esquelético/metabolismo , Chá/químicaRESUMO
Our group has progressively reported on the impact of bioactive compounds found in rooibos (Aspalathus linearis) and their capacity to modulate glucose homeostasis to improve metabolic function in experimental models of type 2 diabetes. In the current study, we investigated how the dietary flavone, orientin, modulates the essential genes involved in energy regulation to enhance substrate metabolism. We used a well-established hepatic insulin resistance model of exposing C3A liver cells to a high concentration of palmitate (0.75 mM) for 16 hrs. These insulin-resistant liver cells were treated with orientin (10 µM) for 3 h to assess the therapeutic effect of orientin. In addition to assessing the rate of metabolic activity, end point measurements assessed include the uptake or utilization of glucose and palmitate, as well as the expression of genes involved in insulin signaling and regulating cellular energy homeostasis. Our results showed that orientin effectively improved metabolic activity, mainly by maintaining substrate utilization which was marked by enhanced glucose and palmitate uptake by liver cells subjected to insulin resistance. Interestingly, these effects can be explained by the improvement in the expression of genes involved in glucose transport (Glut2), insulin signaling (Irs1 and Pi3k), and energy regulation (Ampk and Cpt1). These preliminary findings lay an important foundation for future research to determine the bioactive properties of orientin against dyslipidemia or insulin resistance in reliable and well-established models of type 2 diabetes.
Assuntos
Flavonoides/farmacologia , Glucosídeos/farmacologia , Insulina/genética , Aspalathus/química , Linhagem Celular , Chalconas/farmacologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Flavonoides/metabolismo , Expressão Gênica/efeitos dos fármacos , Glucose/metabolismo , Glucosídeos/metabolismo , Hepatócitos/metabolismo , Humanos , Insulina/metabolismo , Proteínas Substratos do Receptor de Insulina/metabolismo , Resistência à Insulina/fisiologia , Fígado/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Extratos Vegetais/química , Transdução de Sinais/efeitos dos fármacos , Transcriptoma/efeitos dos fármacosRESUMO
Insulin resistance and mitochondrial dysfunction are characteristic features of type 2 diabetes mellitus. However, a causal relationship between insulin resistance and mitochondrial dysfunction has not been fully established in the skeletal muscle. Accordingly, we have evaluated the effect of antimycin A (AA), a mitochondrial electron transport chain complex III inhibitor, on mitochondrial bioenergetics and insulin signaling by exposing C2C12 skeletal muscle cells to its concentrations of 3.125, 6.25, 12.5, 25, and 50 µM for 12 h. Thereafter, metabolic activity, ROS production, glucose uptake, Seahorse XF Real-time ATP and Mito Stress assays were performed. Followed by real-time polymerase chain reaction (RT-PCR) and Western blot analysis. This study confirmed that AA induces mitochondrial dysfunction and promote ROS production in C2C12 myotubes, culminating in a significant decrease in mitochondrial respiration and downregulation of genes involved in mitochondrial bioenergetics (TFAM, UCP2, PGC1α). Increased pAMPK and extracellular acidification rates (ECAR) confirmed a potential compensatory enhancement in glycolysis. Additionally, AA impaired insulin signaling (protein kinase B/AKT) and decreased insulin stimulated glucose uptake. This study confirmed that an adaptive relationship exists between mitochondrial functionality and insulin responsiveness in skeletal muscle. Thus, therapeutics or interventions that improve mitochondrial function could ameliorate insulin resistance as well.