Malvidin's Effects on Rat Pial Microvascular Permeability Changes Due to Hypoperfusion and Reperfusion Injury

Food Anthocyanins: Malvidin and Its Glycosides as Promising Antioxidant and Anti-Inflammatory Agents with Potential Health Benefits

Anthocyanins are flavonoid compounds that are abundantly present in fruits and vegetables. These compounds contribute to the color of these foods and offer various health benefits to consumers due to their biological properties. There are more than 1000 types of anthocyanins in nature, all derived from 27 anthocyanidin aglycones that have different glycosylations and acylations. Malvidin is one of the most well-known anthocyanidins. Several studies, including those conducted on cell lines, animals, and humans, have suggested that malvidin and its glycosides possess anti-carcinogenic, diabetes-control, cardiovascular-disease-prevention, and brain-function-improvement properties. These health benefits are primarily attributed to their antioxidant and anti-inflammatory effects, which are influenced by the molecular mechanisms related to the expression and modulation of critical genes. In this article, we review the available information on the biological activity of malvidin and its glycosides concerning their health-promoting effects.

Effects of physical exercise associated with a diet enriched with natural antioxidants on cerebral hypoperfusion and reperfusion injury in spontaneously hypertensive rats

Oxidative stress is implicated in the pathogenesis of arterial hypertension. The reduction in the bioavailability of nitric oxide (NO) causes endothelial dysfunction, altering the functions of cerebral blood vessels. Physical exercise and intake of antioxidants improve the redox state, increasing the vascular NO production and/or the decrease in NO scavenging by reactive oxygen species (ROS). The present study was aimed at assessing the effects of physical exercise associated with a diet enriched with antioxidants from the Annurca apple in preventing the microvascular damage due to cerebral hypoperfusion and reperfusion injury in spontaneously hypertensive rats (SHRs). The rat pial microcirculation was investigated by intravital fluorescence microscopy through a parietal closed cranial window. As expected, SHRs subjected to physical exercise or an antioxidants-enriched diet showed a reduction of microvascular permeability, ROS formation, and leukocyte adhesion to venular walls, with a major effect of the antioxidants-enriched diet, when compared to untreated SHRs. Moreover, capillary perfusion was preserved by both treatments in comparison with untreated SHRs. Unexpectedly, the combined treatments did not induce higher effects than the single treatment. In conclusion, our results support the efficacy of physical activity or antioxidant supplement in reducing the microvascular alterations due to hypertension and ascribe to an antioxidants-enriched diet effective microvascular protection in SHRs.

Effects of a catechins-enriched diet associated with moderate physical exercise in the prevention of hypertension in spontaneously hypertensive rats

Hypertension represents the main risk factor for the onset of cardiovascular diseases. Pharmacological treatments to control hypertension have been associated with new treatments involving physical activity and/or the intake of natural components (nutraceuticals). We here report the effects produced by a combination of a natural component (catechins) and a moderate exercise program on the development of hypertension in spontaneous hypertensive rats compared with those of each individual treatment. Arterial blood pressure and heart rate were measured with a non-invasive method in 28 rats randomly assigned to four groups: rats subjected to moderate physical exercise; rats with a catechins-enriched diet; rats subjected to moderate physical exercise combined with a catechins-enriched diet; control, untreated-rats left to age. All treatments were applied for 6 weeks. The statistical analysis revealed that the three treatments significantly reduced the weekly increase in arterial blood pressure observed in control rats (SBP, P < 0.0001; DBP, P = 0.005). However, the reduction of arterial blood pressure induced by combined treatments was not higher than that induced by the single treatment, but more prolonged. All treatments showed strong antioxidative properties. Our data show that physical activity and a diet enriched with catechins individually have an important hypotensive effect, while the association did not produce a higher hypotensive effect than the single treatment, even if it was able to decrease blood pressure for a longer time. These findings have important implications for developing a protocol to apply in novel hypertension prevention procedures.

Malvidin protects against lipopolysaccharide-induced acute liver injury in mice via regulating Nrf2 and NLRP3 pathways and suppressing apoptosis and autophagy

Sepsis-related acute liver injury (ALI) is a fatal disease associated with many complications. Recent studies indicate that malvidin, an active flavonoid, has multiple bioactivities including anti-oxidant and anti-inflammation. However, the protective roles of malvidin against LPS-induced ALI are unknown. The purpose of this research is to explore whether malvidin has biological activities on LPS-induced ALI in mice and the underlying mechanisms. Male C57 mice were injected intraperitoneally with malvidin for five days and the mice were euthanized 6 hours after LPS (10 mg/kg body weight) intraperitoneal injection. Multiple methods of H&E staining, biochemical kits, qRT-PCR assay, western blotting analysis, TUNEL and transmission electron microscope (TEM) were used. Results showed that decreased ALT, AST levels and alleviated histopathological damage of liver tissue were observed in malvidin pretreatment group in mice. Then, malvidin prevented LPS-induced reduction of antioxidant enzyme activities such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) via up-regulating nuclear factor E2-related factor2 (Nrf2) pathway. In addition, in malvidin pretreatment groups, mRNA levels of pro-inflammatory cytokines (TNF-α，IL-1β, IL-6) and protein levels of NOD-like receptor protein 3 (NLRP3) inflammasome in the liver were significantly down-regulated. We also found that the malvidin could reduce the expression of apoptosis key protein and TUNEL-labeled apoptotic hepatocytes. Furthermore, malvidin inhibited the protein expression of ATG5, p62 and the ratio of LC3-II/LC3-I. In conclusion, our study firstly suggests that malvidin is a potentially protective agent against LPS-induced ALI through up-regulating Nrf2 signaling pathway, suppressing NLRP3 inflammasome and inhibiting apoptosis and autophagy.

The Pomace Extract Taurisolo Protects Rat Brain From Ischemia-Reperfusion Injury

Taurisolo^® is a pomace extract from Aglianico Grapes, a wine cultivar native to Campania (Southern Italy). It exhibits a very high polyphenolic content and, consumed as a nutraceutical, is effective in reducing the level of Trimethylamine N-oxide (TMAO), a cardiovascular disease risk factor marker. We here show the effects of Taurisolo^® on rat brain microvascular alterations induced by a diminution in cerebral blood flow (CBFD) for 30 min, due to bilateral common carotid artery occlusion, and subsequent blood flow restoration (CBFR) for 60 min. The rat pial microcirculation was investigated by intravital fluorescence microscopy through a parietal closed window implanted into the skull bone. The rat pial arterioles were classified according to Strahler’s ordering scheme, from smaller penetrating arterioles up to the larger ones. Western blotting analysis and mass spectrometry (MS)-based metabolomics were used to investigate the expression of endothelial nitric oxide synthase (eNOS) or the presence of peroxidized cardiolipin and several inflammatory mediators, respectively. Radical Oxygen Species (ROS) formation and neuronal loss were assessed. In rats CBFD and CBFR caused a decrease in arteriolar diameter, increase in fluorescent leakage and in adhesion of leukocytes to venular walls, reduction in the length of perfused capillaries and increment of ROS formation with large infarct size. Taurisolo^®, intravenously or orally administered, induced pial arteriolar dilation (up to >30% of baseline), prevented fluorescent leakage, adhesion of leukocytes, ROS formation, while facilitated capillary perfusion and significantly reduced infarct size. These effects were accompanied by an increase in eNOS expression. Mass-spectrometry metabolomics analysis detected a marked decrease in the amount of peroxidized cardiolipin and pronounced reduction in pro-inflammatory prostaglandins and thromboxane Txb2. Altogether, these results extend the nutraceutical potential of Taurisolo^® and suggest their eligibility for preventing brain damage due to ischemia-reperfusion injury.

Dietary Anthocyanins and Stroke: A Review of Pharmacokinetic and Pharmacodynamic Studies

Cerebrovascular accidents are currently the second major cause of death and the third leading cause of disability in the world, according to the World Health Organization (WHO), which has provided protocols for stroke prevention. Although there is a multitude of studies on the health benefits associated with anthocyanin (ACN) consumption, there is no a rigorous systematization of the data linking dietary ACN with stroke prevention. This review is intended to present data from epidemiological, in vitro, in vivo, and clinical studies dealing with the stroke related to ACN-rich diets or ACN supplements, along with possible mechanisms of action revealed by pharmacokinetic studies, including ACN passage through the blood-brain barrier (BBB).

Rat Pial Microvascular Changes During Cerebral Blood Flow Decrease and Recovery: Effects of Cyanidin Administration

The reactive oxygen species (ROS) are known to play a major role in many pathophysiological conditions, such as ischemia and reperfusion injury. The present study was aimed to evaluate the in vivo cyanidin (anthocyanin) effects on damages induced by rat pial microvascular hypoperfusion-reperfusion injury by cerebral blood flow decrease (CBFD) and subsequent cerebral blood flow recovery (CBFR). In particular, the main purpose was to detect changes in ROS production after cyanidin administration. Rat pial microvasculature was investigated using fluorescence microscopy through a cranial window (closed); Strahler's method was utilized to define the geometric features of pial vessels. ROS production was investigated in vivo by 2'-7'-dichlorofluorescein-diacetate assay and neuronal damage was measured on isolated brain sections by 2,3,5-triphenyltetrazolium chloride staining. After 30 min of CBFD, induced by bilateral common carotid artery occlusion, and 60 min of CBFR, rats showed decrease of arteriolar diameter and capillary perfusion; furthermore, increase in microvascular leakage and leukocyte adhesion was observed. Conversely, cyanidin administration induced dose-related arteriolar dilation, reduction in microvascular permeability as well as leukocyte adhesion when compared to animals subjected to restriction of cerebral blood flow; moreover, capillary perfusion was protected. ROS generation increase and marked neuronal damage were detected in animals subjected to CBFD and CBFR. On the other hand, cyanidin was able to reduce ROS generation and neuronal damage. In conclusion, cyanidin treatment showed dose-related protective effects on rat pial microcirculation during CBFD and subsequent CBFR, inducing arteriolar dilation by nitric oxide release and inhibiting ROS formation, consequently preserving the blood brain barrier integrity.

Laser Speckle Imaging of Rat Pial Microvasculature during Hypoperfusion-Reperfusion Damage

The present study was aimed to in vivo assess the blood flow oscillatory patterns in rat pial microvessels during 30 min bilateral common carotid artery occlusion (BCCAO) and 60 min reperfusion by laser speckle imaging (LSI). Pial microcirculation was visualized by fluorescence microscopy. The blood flow oscillations of single microvessels were recorded by LSI; spectral analysis was performed by Wavelet transform. Under baseline conditions, arterioles and venules were characterized by blood flow oscillations in the frequency ranges 0.005-0.0095 Hz, 0.0095-0.021 Hz, 0.021-0.052 Hz, 0.052-0.150 Hz and 0.150-0.500 Hz. Arterioles showed oscillations with the highest spectral density when compared with venules. Moreover, the frequency components in the ranges 0.052-0.150 Hz and 0.150-0.500 were predominant in the arteriolar total power spectrum; while, the frequency component in the range 0.150-0.500 Hz showed the highest spectral density in venules. After 30 min BCCAO, the arteriolar spectral density decreased compared to baseline; moreover, the arteriolar frequency component in the range 0.052-0.150 Hz significantly decreased in percent spectral density, while the frequency component in the range 0.150-0.500 Hz significantly increased in percent spectral density. However, an increase in arteriolar spectral density was detected at 60 min reperfusion compared to BCCAO values; consequently, an increase in percent spectral density of the frequency component in the range 0.052-0.150 Hz was observed, while the percent spectral density of the frequency component in the range 0.150-0.500 Hz significantly decreased. The remaining frequency components did not significantly change during hypoperfusion and reperfusion. The changes in blood flow during hypoperfusion/reperfusion caused tissue damage in the cortex and striatum of all animals. In conclusion, our data demonstrate that the frequency component in the range 0.052-0.150 Hz, related to myogenic activity, was significantly impaired by hypoperfusion and reperfusion, affecting cerebral blood flow distribution and causing tissue damage.