cyanidin-3-O-β-glucoside Research Articles

Supplementation of Cyanidin-3-O-β-Glucoside Promotes Endothelial Repair and Prevents Enhanced Atherogenesis in Diabetic Apolipoprotein E–Deficient Mice1–3

Atherosclerosis is accelerated in diabetes mellitus mainly due to the reduced availability and function of endothelial progenitor cells (EPCs). The purpose of this study was to determine the protective effects of the anthocyanin cyanidin-3-O-β-glucoside (C3G) on EPC function and endothelial repair in diabetic apolipoprotein E–deficient (apoE−/−) mice. Diabetes mellitus was induced in 8-wk-old male apoE−/− mice with streptozotocin. Diabetic apoE−/− mice were fed the AIN-93 diet or an AIN-93 diet supplemented with C3G (0.2% wt:wt) for 6 wk. Sham-injected apoE−/− mice fed the AIN-93 diet served as nondiabetic controls. The endothelium-dependent relaxation response to acetylcholine in the aortas of C3G-fed mice was greater by 51% compared with diabetic mice fed the AIN-93 diet (P < 0.05) and was similar to that in nondiabetic apoE−/− mice. The capacity of in vitro adhesion to fibronectin, migration, and tube formation was significantly impaired in diabetic EPCs (decreased by 83, 61.9, and 74.5%, respectively, compared with nondiabetic controls; all P < 0.01), which was significantly rescued in response to C3G (increased by 3.9-, 2-, and 1.8-fold compared with diabetic EPCs, respectively; all P < 0.05). At the molecular level, the phosphorylation levels of AMP-activated protein kinase (AMPK) Thr 172 and endothelial nitric oxide synthase (eNOS) Ser1177 were higher in EPCs derived from the C3G-treated diabetic mice compared with those in nondiabetic mice. Furthermore, compared with nondiabetic controls, diabetic apoE−/− mice had a 3.5-fold increase in the aortic lesion area, which was lowered by 45% in C3G-fed diabetic mice. This study extends our current knowledge that C3G improves the impairment of EPC function, enhances endothelial repair, and thus limits accelerated atherogenesis caused by diabetes. Our findings emphasize the potential utility of anthocyanin in the prevention and treatment of diabetic vascular complications.

Cyanidin-3-O-β-glucoside, a typical anthocyanin, exhibits antilipolytic effects in 3T3-L1 adipocytes during hyperglycemia: Involvement of FoxO1-mediated transcription of adipose triglyceride lipase

Elevated concentrations of circulating free fatty acids (FFAs) have been demonstrated to potentially link obesity, insulin resistance and type 2 diabetes. Inhibition of lipolysis reduces FFAs availability and improves insulin sensitivity. Anthocyanins from different plant foods were shown to improve hyperlipidemia and insulin resistance in vivo. In this study, cyanidin-3-O-β-glucoside (C3G), a typical anthocyanin was selected to examine its in vitro effects on high-glucose-induced lipolysis in cultured 3T3-L1 adipocytes. Incubation with C3G efficiently inhibited FFAs and glycerol release from the adipocytes during hyperglycemia in a dose- and time-dependent manner. C3G treatment also increased the activity of AMP-activated protein kinase, decreased the activity of glutamine:fructose 6-phosphate aminotransferase, reduced cellular UDP-N-acetylglucosamine production, thereby suppressing the hexosamine biosynthetic pathway. In addition, C3G attenuated high-glucose-promoted O-glycosylation of transcription factor FoxO1, resulting in decreased expression of adipose triglyceride lipase (ATGL). Our findings reveal a novel mechanism by which anthocyanin regulates FoxO1-mediated transcription of ATGL and thus inhibits adipocyte lipolysis, suggesting its potential therapeutic application in diabetes-associated hyperlipidemia.

Cyanidin-3-O-β-glucoside induces oxysterol efflux from endothelial cells: Role of liver X receptor alpha

ObjectivesOxidized sterols are toxic to endothelial cells and play a central role in promoting atherogenesis. In this study, we evaluated the impact of anthocyanin, a class of flavonoid compounds, on oxysterol efflux from endothelial cells and the underlying mechanism. Methods and resultsThe human aortic ECs (HAECs) were incubated with anthocyanin cyanidin-3-O-β-glucoside (C3G) for different times. C3G treatment upregulates ABCG1 and ABCA1 expression in a dose-dependent manner in HAECs. Moreover, C3G promotes the efflux of cholesterol mainly 7-ketocholesterol (7-KC) from HAECs in an ABCG1-dependent manner. As a result, C3G abrogated the 7-KC-mediated increase of reactive oxygen species (ROS) and apoptosis in HAECs. Furthermore, C3G treatment reverses the inhibition of endothelial nitric oxide synthase (eNOS) activity by 7-KC, leading to the preservation of nitric oxide (NO) bioavailability. The induction of ABCG1 and its mediated 7-KC efflux from HAECs by C3G resulted from liver X receptor α (LXRα) activation, which was confirmed by its blockage of ABCG1 expression after pharmacological or small interfering RNA inhibition of LXRα. ConclusionsThese data uncover a novel mechanism by which C3G ameliorates oxysterol-induced oxidative damage on endothelial cells.

Cyanidin-3-O-β-Glucoside and Protocatechuic Acid Exert Insulin-Like Effects by Upregulating PPARγ Activity in Human Omental Adipocytes

OBJECTIVEInsulin resistance (IR) represents an independent risk factor for metabolic, cardiovascular, and neoplastic disorders. Preventing/attenuating IR is a major objective to be reached to preserve population health. Because many insulin-sensitizing drugs have shown unwanted side effects, active harmless compounds are sought after. Dietary anthocyanins have been demonstrated to ameliorate hyperglycemia and insulin sensitivity. This study aimed at investigating whether cyanidin-3-O-β-glucoside (C3G) and its metabolite protocatechuic acid (PCA) might have a role in glucose transport activation in human omental adipocytes and 3T3-L1 cells.RESEARCH DESIGN AND METHODSIn cells treated with 50 µmol/L C3G and 100 µmol/L PCA, [3H]-2-deoxyglucose uptake, GLUT4 translocation by immunoblotting, adiponectin secretion, and peroxisome proliferator–activated receptor-γ (PPARγ) activation by enzyme-linked immunosorbent assay kits were evaluated. Parallel experiments were carried out in murine adipocyte 3T3-L1. To define the role of PPARγ in modulating polyphenol effects, small interfering RNA technique and PPARγ antagonist were used to inhibit transcription factor activity.RESULTSC3G and PCA increased adipocyte glucose uptake (P < 0.05) and GLUT4 membrane translocation (P < 0.01). Significant increases (P < 0.05) in nuclear PPARγ activity, as well as in adiponectin and GLUT4 expressions (P < 0.01), were also shown. It is interesting that PPARγ inhibition counteracted the polyphenol-induced adiponectin and GLUT4 upregulations, suggesting a direct involvement of PPARγ in this process.CONCLUSIONSOur study provides evidence that C3G and PCA might exert insulin-like activities by PPARγ activation, evidencing a causal relationship between this transcription factor and adiponectin and GLUT4 upregulation. Dietary polyphenols could be included in the preventive/therapeutic armory against pathological conditions associated with IR.

Cyanidin-3-O-β-glucoside with the aid of its metabolite protocatechuic acid, reduces monocyte infiltration in apolipoprotein E-deficient mice

Polyphenols, including anthocyanins, from various plant foods are effective in reducing the severity of atherosclerosis in animal and human studies. Due to the poor understanding of the bioavailability of anthocyanins, the potential antiatherogenic mechanisms underlying the action remain largely unknown. Herein, we found that oral gavage of cyanidin-3-O-β-glucoside (Cy-3-G) could be transformed into protocatechuic acid (PCA), and the plasma maximal levels of Cy-3-G were 3.7-fold lower than that of PCA in the apolipoprotein E (ApoE)-deficient mice. Subsequently, we observed that PCA treatment has a higher capacity than Cy-3-G treatment in decreasing CC chemokine receptor 2 (CCR2) expression in the mouse peripheral blood monocytes (PBMs), along with reducing the mouse PBMs chemokine toward CC ligand-2 (CCL2) in a Boyden chamber. Interesting, in the ApoE-deficient mouse model, orally gavaged with Cy-3-G has a higher ability than gavaged with PCA to reduce CCR2 expression in PBMs. PBMs deprived from the Cy-3-G-treated ApoE-deficient mice have a lower ability than those from PCA-treated animals to migrate toward CCL2. Furthermore, as compared with the PCA group, Cy-3-G treatment more efficiently reduced thioglycollate-induced macrophage infiltration into the abdominal cavity. Thus, we suggest that Cy-3-G may reduce the monocyte infiltration in mice via down-regulation of CCR2 expression in monocytes, at least in part, with the aid of its metabolite PCA. These above data imply that the anti-monocyte/macrophage infiltration property of Cy-3-G and its metabolite PCA may be an important antiatherogenic mechanism for anthocyanins.

Neuroprotective Effect of Anthocyanin on Experimental Traumatic Spinal Cord Injury

We investigated the neuroprotective effect of anthocyanin, oxygen radical scavenger extracted from raspberries, after traumatic spinal cord injury (SCI) in rats. THE ANIMALS WERE DIVIDED INTO TWO GROUPS : the vehicle-treated group (control group, n=20) received an oral administration of normal saline via stomach intubation immediately after SCI, and the anthocyanin-treated group (AT group, n=20) received 400 mg/kg of cyanidin 3-O-β-glucoside (C3G) in the same way. We compared the neurological functions, superoxide expressions and lesion volumes in two groups. At 14 days after SCI, the AT group showed significant improvement of the BBB score by 16.7±3.4%, platform hang by 40.0±9.1% and hind foot bar grab by 30.8±8.4% (p<0.05 in all outcomes). The degree of superoxide expression, represented by the ratio of red fluorescence intensity, was significantly lower in the AT group (0.98±0.38) than the control group (1.34±0.24) (p<0.05). The lesion volume in lesion periphery was 32.1±2.4 µL in the control and 24.5±2.3 µL in the AT group, respectively (p<0.05), and the motor neuron cell number of the anterior horn in lesion periphery was 8.3±5.1 cells/HPF in the control and 13.4±6.3 cells/HPF in the AT group, respectively (p<0.05). Anthocyanin seemed to reduce lesion volume and neuronal loss by its antioxidant effect and these resulted in improved functional recovery.

Cyanidin-3- O-β-glucoside inhibits iNOS and COX-2 expression by inducing liver X receptor alpha activation in THP-1 macrophages

Anthocyanins belong to a large and widespread group of water-soluble phytochemicals and exhibit potent antioxidative and anti-inflammatory properties; however, the molecular mechanisms of these biochemical actions mediated by anthocyanins remain unclear. In this study, our data show that pretreatment of THP-1 macrophages with Cyanidin-3- O-β-glucoside (C3G) for 12 h can enhance the expression and transcriptional activities of the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) and liver X receptor α (LXRα). Furthermore, pretreatment of these cells with C3G for 12 h causes dose-dependent inhibition of lipopolysaccharide (LPS)-induced nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the mRNA and protein levels together with a decrease in nitric oxide (NO) and prostaglandin E 2 (PGE 2) production. Consequently, addition of geranylgeranyl pyrophosphate ammonium salt (GGPP), an LXRα antagonist, significantly downregulates the inhibitory effect of C3G on LPS-induced iNOS and COX-2 expression in THP-1 macrophages, whereas the PPARγ antagonist GW9662 has no effect. Further investigation revealed that LXRα might interfere with LPS-induced iNOS and COX-2 expression by suppressing the functional activation of nuclear factor-κB (NF-κB), not – as was previously proposed – by reducing NF-κB nuclear translocation. Taken together, these results indicate that LXRα activation has an essential role in the anti-inflammatory property of C3G. Moreover, they provide new insight into the molecular basis for the anti-inflammatory property of anthocyanins.