Polyphenols in Parkinson's Disease: A Systematic Review of In Vivo Studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder. However, therapeutic options treating only its symptoms are very disappointing. Therefore there is an ongoing search for compounds capable of tackling the multi-dimensional features of PD. Recently natural polyphenols have gained great interest as potential therapeutic agents. Herein, we have attempted to summarize results obtained in different animal models demonstrating their neuroprotective effects. The in vivo findings presented below are supported by human subject data and reports regarding the ability of polyphenols to cross the blood-brain barrier. The beneficial effects of polyphenols are demonstrated by the results of behavioral examinations, mainly related to motor and cognitive capabilities, histopathological and immunohistochemical examination concerning the protection of dopaminergic neurons, analyses of dopamine and the concentration of its metabolites, as well as mechanistic studies regarding the modulation of oxidative stress, neuroinflammation, cellular iron management, proteinopathy, and additionally the regulation of signaling pathways. Importantly, data about brain distribution of the metabolic derivatives of the reviewed polyphenols are crucial for the justification of their nutritional intake in neuroprotective intervention, as well as for the identification of potential targets for a novel therapeutic approach to Parkinson's disease.

Neuroprotective Effects of Pomegranate Juice against Parkinson's Disease and Presence of Ellagitannins-Derived Metabolite-Urolithin A-In the Brain

Pomegranate juice is a rich source of ellagitannins (ETs) believed to contribute to a wide range of pomegranate's health benefits. While a lot of experimental studies have been devoted to Alzheimer disease and hypoxic-ischemic brain injury, our knowledge of pomegranate's effects against Parkinson's disease (PD) is very limited. It is suggested that its neuroprotective effects are mediated by ETs-derived metabolites-urolithins. In this study, we examined the capability of pomegranate juice for protection against PD in a rat model of parkinsonism induced by rotenone. To evaluate its efficiency, assessment of postural instability, visualization of neurodegeneration, determination of oxidative damage to lipids and α-synuclein level, as well as markers of antioxidant defense status, inflammation, and apoptosis, were performed in the midbrain. We also check the presence of plausible active pomegranate ETs-derived metabolite, urolithin A, in the plasma and brain. Our results indicated that pomegranate juice treatment provided neuroprotection as evidenced by the postural stability improvement, enhancement of neuronal survival, its protection against oxidative damage and α-synuclein aggregation, the increase in mitochondrial aldehyde dehydrogenase activity, and maintenance of antiapoptotic Bcl-xL protein at the control level. In addition, we have provided evidence for the distribution of urolithin A to the brain.

Protective effect of red beetroot against carbon tetrachloride- and N-nitrosodiethylamine-induced oxidative stress in rats

The aim of the study was to investigate the potential protective effect of beetroot juice in a model of oxidative stress induced by N-nitrosodiethylamine (NDEA) and carbon tetrachloride (CCl(4)). Male Wistar rats were treated with beetroot juice per os, 8 mL/kg/day for 28 days, and a single i.p. dose of the xenobiotics: 150 mg/kg NDEA or 2 mL/kg CCl(4). Simultaneously, two groups of rats not pretreated with juice were given only each of the xenobiotics. The level of microsomal lipid peroxidation in the liver, expressed as TBARS concentration, was increased several fold in rats administered only NDEA or CCl(4). TBARS were decreased by 38% only in rats pretreated with beetroot juice before the administration of CCl(4). In animals pretreated with juice and receiving NDEA, a further increase in TBARS occurred. All of the investigated antioxidant enzymes were inhibited by the administration of either toxicant alone by 26%-77% as compared to controls. Pretreatment with juice caused a partial recovery in the activity of glutathione peroxidase and glutathione reductase, by 35% and 66%, respectively. Superoxide dismutase activity was increased about 3-fold in animals pretreated with juice. Both xenobiotics caused a rise in plasma protein carbonyls, which were reduced by 30% in rats pretreated with juice and then injected with NDEA. Similarly, DNA damage in blood leukocytes caused by either toxicant was slightly diminished, by 20%, in the rats treated with juice before NDEA administration. It could be concluded that pretreatment with beetroot juice can counteract, to some extent, xenobiotic-induced oxidative stress in rats.

Potential of the ellagic acid-derived gut microbiota metabolite - Urolithin A in gastrointestinal protection

Urolithin A (UA) is a metabolic compound generated during the biotransformation of ellagitannins by the intestinal bacteria. The physiologically relevant micromolar concentrations of UA, achieved in the plasma and gastrointestinal tract (GI) after consumption of its dietary precursors, have been revealed to offer GI protection. The health benefit has been demonstrated to be principally related to anticancer and anti-inflammatory effects. UA has been shown to possess the capability to regulate multiple tumor and inflammatory signaling pathways and to modulate enzyme activity, including those involved in carcinogen biotransformation and antioxidant defense. The purpose of this review is to gather evidence from both in vitro and in vivo studies showing the potential of UA in GI protection alongside suggested mechanisms by which UA can protect against cancer and inflammatory diseases of the digestive tract. The data presented herein, covering both studies on the pure compound and in vivo generated UA form its natural precursor, support the potential of this metabolite in treatment interventions against GI ailments.

What is the Evidence That Parkinson's Disease is a Prion Disorder, Which Originates in the Gut?

Parkinson's disease (PD) is a neurodegenerative disorder resulting from degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). PD is characterized by motor dysfunctions as well as gastrointestinal symptoms and mental impairment. The pathological hallmark of PD is an accumulation of misfolded α-synuclein aggregates within the brain. The etiology of PD and related synucleinopathy is poorly understood, but recently, the hypothesis that α-synuclein pathology spreads in a prion-like fashion originating in the gut has gained much scientific attention. A crucial clue was the appearance of constipation before the onset of motor symptoms, gut dysbiosis and synucleinopathy in PD patients. Another line of evidence, demonstrating accumulation of α-synuclein within the peripheral autonomic nervous system (PANS), including the enteric nervous system (ENS), and the dorsal motor nucleus of the vagus (DMV) support the concept that α-synuclein can spread from the ENS to the brain by the vagus nerve. The decreased risk of PD following truncal vagotomy supports this. The convincing evidence of the prion-like behavior of α-synuclein came from postmortem observations that pathological α-synuclein inclusions appeared in healthy grafted neurons. In this review, we summarize the available data from human subjects' research and animal experiments, which seem to be the most suggestive for explaining the hypotheses.

Using Graphene-Based Biosensors to Detect Dopamine for Efficient Parkinson's Disease Diagnostics

Parkinson's disease (PD) is a neurodegenerative disease in which the neurotransmitter dopamine (DA) depletes due to the progressive loss of nigrostriatal neurons. Therefore, DA measurement might be a useful diagnostic tool for targeting the early stages of PD, as well as helping to optimize DA replacement therapy. Moreover, DA sensing appears to be a useful analytical tool in complex biological systems in PD studies. To support the feasibility of this concept, this mini-review explores the currently developed graphene-based biosensors dedicated to DA detection. We discuss various graphene modifications designed for high-performance DA sensing electrodes alongside their analytical performances and interference studies, which we listed based on their limit of detection in biological samples. Moreover, graphene-based biosensors for optical DA detection are also presented herein. Regarding clinical relevance, we explored the development trends of graphene-based electrochemical sensing of DA as they relate to point-of-care testing suitable for the site-of-location diagnostics needed for personalized PD management. In this field, the biosensors are developed into smartphone-connected systems for intelligent disease management. However, we highlighted that the focus should be on the clinical utility rather than analytical and technical performance.

Protective effect of yellow tea extract on N-nitrosodiethylamine-induced liver carcinogenesis

Context Yellow tea containing the same catechins as other types of tea but in different proportions has been suggested to possess potent anticancer activities. Objective This study investigates the chemopreventive effect of yellow tea aqueous extract against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis in rats by employing histological and biochemical methods. Materials and methods Wistar rats were divided randomly into four groups: control (I), yellow tea (II), NDEA (III), and yellow tea + NDEA (IV). Groups II and IV were exposed via a diet to yellow tea extract in a concentration of 10 g/kg feed; groups III and IV received 0.01% NDEA in drinking water. The experiment lasted for 13 weeks. Results Daily intake of yellow tea in an average dose of 800 mg/kg b.w. alleviated the carcinogenic effect of NDEA as evidenced by reversed histopathological changes towards normal hepatocellular architecture and decreased lipid peroxidation, protein carbonyl formation, and DNA degradation by 64%, 37% and 15%, respectively, as compared with values obtained in NDEA alone-treated rats. Treatment with yellow tea extract caused protection of superoxide dismutase (SOD) and catalase (CAT); their activity was recovered by 47% and 12%, respectively, as compared with the NDEA-treated rats. Moreover, the extract normalized the NDEA-induced activity of paraoxonase 1 (PON1) and glutathione peroxidase (GPx), while a further increase in the level of reduced glutathione (GSH) was noticed. Conclusions On the basis of these findings, it can be concluded that treatment with yellow tea partially protected the livers of rats from NDEA-induced hepatocarcinogenesis and that its antioxidant activity contributed to this effect.

Spray-Dried Potato Juice as a Potential Functional Food Component with Gastrointestinal Protective Effects

BACKGROUND

Peptic ulcer disease, including its complications and functional dyspepsia, are prevalent gastrointestinal diseases, etiopathogenesis of which is associated with mucosal inflammation. Research into new therapeutics capable of preventing or curing gastrointestinal mucosal damage has been steadily developing over past decades. This study was undertaken to evaluate whether a spray-dried preparation of potato juice is applicable for treating and preventing gastrointestinal mucosal damage.

METHODS

We assessed potential protective effects of spray-dried potato juice (SDPJ) against gut inflammation in the co-culture Caco-2/RAW264.7 system, as well as a gastroprotective activity in a rat model of gastric ulceration.

RESULTS

The obtained results indicated that SDPJ down-regulates lipopolysaccharide (LPS)-induced mRNA expression and protein production of proinflammatory cytokines IL-6 and TNF-α in the co-culture model. Moreover, SDPJ provided dose-dependent protection against LPS-induced disruption of intestinal barrier integrity. In rats, five-day pretreatment with SDPJ in doses of 200 mg/kg and 500 mg/kg suppressed HCl/ethanol-induced TNF-α expression in gastric mucosa by 52% and 35%, respectively. In addition, the pretreatment with the lower dose of SDPJ reduced the incidence of ulcers (by 34%) expressed as ulcer index.

CONCLUSION

The spray-dried potato juice appears to be an attractive candidate for ameliorating inflammation-related diseases of the gastrointestinal tract.

Protective effect of chokeberry on chemical-induced oxidative stress in rat

Male Wistar rats were treated with chokeberry juice per os, 10 mL/kg/day, for 28 days and a single intraperitoneal (i.p.) dose of N-nitrosodiethylamine (NDEA), 150 mg/kg, or carbon tetrachloride (CCl(4)), 2 ml/kg. The level of hepatic microsomal lipid peroxidation, expressed as thiobarbituric acid reactive substances (TBARS), was increased in animals dosed with NDEA and CCl(4). Juice pretreatment resulted in a significant decrease in TBARS by 53% and 92%, respectively. In rats administered juice alone, 50% decrease in TBARS was noted. The activities of all antioxidant enzymes were decreased in the liver of rats administered either toxicant by 29%-52% as compared to controls. Juice pretreatment resulted in an increase in the activity of catalase, glutathione peroxidase and glutathione reductase by 117%, 56% and 44%, respectively, only in rats challenged with NDEA. Although no response of plasma protein carbonyls to both toxicants was observed, the pretreatment with juice caused a 55% decrease of this parameter in CCl(4)-dosed rats. DNA damage in blood leukocytes induced by either toxicant was slightly reduced, by 24%, in the rats pretreated with juice and administered NDEA. The results of the study showed that pretreatment with chokeberry juice confers some protection against chemical-induced oxidative stress.

Attenuation of KBrO3-induced renal and hepatic toxicity by cloudy apple juice in rat

The aim of the study was to evaluate a protective effect of apple juice on KBrO3-induced oxidative stress in rats. Male Wistar rats were administered apple juice per os, 10 ml/kg b.w. for 28 days. On 27 day of the experiment, some rats were given i.p. a single 125 mg/kg b.w. dose of KBrO3 . Markers of oxidative damage and clinical chemistry parameters were determined. Treatment with apple juice prior to KBrO3 challenge prevented an increase in hepatic and renal microsomal lipid peroxidation by 25 and 44%, respectively, increased the activity of antioxidant enzymes in the liver by 29 - 59% and decreased the plasma content of carbonyl groups by 19%. Aminotransferases activity in plasma was reduced by 19% and 36%, concentrations of plasma bilirubin, cholesterol and creatinine were suppressed by 21%, 16% and 26%, respectively, in rats supplemented with juice before KBrO3 injection. No protective effect of apple juice on nuclear DNA was observed. Supplementation with cloudy apple juice to some extent attenuated oxidative damage induced by KBrO3 in the liver and kidney of rats as evidenced by alterations of certain oxidative stress markers and clinical chemistry parameters.

Cloudy apple juice protects against chemical-induced oxidative stress in rat

BACKGROUND

Apples abundant in phenolic compounds show a variety of biological activities that may contribute to beneficial effects against some chronic diseases.

PURPOSE

The aim of our study was to assess the protective effect of cloudy apple juice against chemical-induced oxidative stress in rats.

METHODS

Male Wistar rats were treated with apple juice per os, 10 mL/kg/day for 28 days and with a single dose of N-nitrosodiethylamine (NDEA), 150 mg/kg or carbon tetrachloride (CCl(4)), 2 mL/kg, 24 h before killing. Two groups of rats not pretreated with juice were administered each of the xenobiotics alone.

RESULTS

Microsomal lipid peroxidation in the liver was decreased in rats pretreated with juice by 52-87% when compared to animals given NDEA or CCl(4) alone. Pretreatment with juice protected antioxidant enzymes: catalase, glutathione peroxidase and glutathione reductase but not superoxide dismutase. Their activity was recovered by 49-173% when compared to that in rats given either toxicant alone. The plasma activity of paraoxonase 1 was reduced by both toxicants and was increased by 23% in the apple/CCl(4) group. A rise in plasma protein carbonyls caused by the xenobiotics was reduced by 20% only in apple/NDEA-treated rats. Also, in this group of animals, a 9% decrease in DNA damage in blood leukocytes was observed.

CONCLUSION

Phytochemicals in commonly consumed apple juice may protect some macromolecules against oxidative insult induced by xenobiotics.

Protective Effect of Morus alba Leaf Extract on N-Nitrosodiethylamine-induced Hepatocarcinogenesis in Rats

BACKGROUND/AIM

The leaves of white mulberry (Morus alba L.) contain various polyphenolic compounds possessing strong antioxidant activity and anticancer potential. This study was designed to investigate the chemopreventive effect of aqueous extract of mulberry leaves against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis.

MATERIALS AND METHODS

Wistar rats were divided into four groups: control, mulberry extract-treated, NDEA-treated, and mulberry extract plus NDEA-treated. Mulberry extract was given in the diet (1,000 mg/kg b.w./day); NDEA was given in drinking water.

RESULTS

Mulberry extract reduced the incidence of hepatocellular carcinoma, dysplastic nodules, lipid peroxidation, protein carbonyl formation, and DNA degradation. Treatment with mulberry leaf extract along with NDEA challenge did not affect the activity of antioxidant enzymes and glutathione content.

CONCLUSION

Treatment with mulberry leaf extract partially protected the livers of rats from NDEA-induced hepatocarcinogenesis and a direct antioxidant mechanism appears to contribute to its anticarcinogenic activity.

Evaluation of Safety and Antioxidant Activity of Yellow Tea (Camellia sinensis) Extract for Application in Food

The article presents an evaluation of the safety of yellow tea (Camellia sinensis) extract consumption and its antioxidant activity in an animal model. Wistar rats were exposed through diet to 2, 6, and 10 g yellow tea extract/kg feed for 90 days. No signs of toxicity and no differences in mean body weight gain in the treated and control rats were recorded throughout the experiment. No statistically significant differences in hematology findings and clinical chemistry parameters were observed between controls and treated groups. Microscopic examination of tissue sections revealed no pathology attributable to yellow tea extract intake. Lipid peroxidation level in the liver was slightly increased in medium-dose males and high-dose females and decreased in two female groups receiving 2 and 6 g/kg of the extract tested. Content of carbonyl groups in protein, as well as the basal level of DNA damage, was not changed. In a majority of rats, the activity of antioxidant enzymes was increased except superoxide dismutase in high-dose groups, glutathione peroxidase in high-dose females, glutathione reductase in low- and mid-dose groups, and glutathione S-transferase in mid-dose females and high-dose males. It could be concluded that rats tolerated well dietary treatment with yellow tea extract up to 0.8 g/kg b.w./day for 90 days. Results showed that yellow tea extract at the doses tested did not demonstrate adverse effects and improved the antioxidant status in the liver of rats.

Pomegranate Juice Ameliorates Dopamine Release and Behavioral Deficits in a Rat Model of Parkinson's Disease

Pomegranate juice (PJ) is a rich source of ellagitannins (ETs), precursors of colonic metabolite urolithin A, which are believed to contribute to pomegranate's neuroprotective effect. While many experimental studies involving PJ's role in Alzheimer's disease and hypoxic-ischemic brain injury have been conducted, our knowledge of pomegranate's effects against Parkinson's disease (PD) is very limited. Previously, we have reported that PJ treatment improved postural stability, which correlated well with enhancement of neuronal survival, protection against oxidative damage, and α-synuclein aggregation. Since olfactory and motor deficits are typical symptoms of PD, in this study, we aimed to investigate the capability of PJ to protect against olfactory, motoric, and neurochemical alterations. To evaluate its efficiency, Wistar rats were given a combined treatment with ROT (1.3 mg/kg b.w./day, s.c.) and PJ (500 mg/kg/day, p.o.) for 35 days. After this, we assessed the olfactory discrimination index (DI) and vertical and horizontal activities as well as levels of dopamine and its main metabolite 3,4-Dihydroxyphenylacetic acid (DOPAC) in the dissected midbrain of animals. Our findings provide the first evidence that PJ treatment protects against ROT-induced DA depletion in the midbrain, which correlates well with improved olfactory function and vertical activity as well as with the presence of urolithin A in the brain.

Evaluation of Safety of Iron-Fortified Soybean Sprouts, a Potential Component of Functional Food, in Rat

Ferritin-iron is currently considered as one of the most promising iron forms to prevent iron deficiency anaemia. We found that the cultivation of soybean seeds in a solution of ferrous sulfate results in material with extremely high iron content - 560.6 mg Fe/100 g of dry matter, while ferritin iron content was 420.5 mg/100 g dry matter. To assess the potential adverse effects of a preparation containing such a high concentration of iron, male and female Wistar rats were exposed via diet to 10, 30, 60 g soybean sprouts powder/kg feed for 90 days. There were no differences in final body weight and mean food consumption between controls and rats administered sprouts. No statistically significant differences in haematology and clinical chemistry parameters were found between controls and treated rats. Microscopic examination of 22 tissues did not reveal any pathology due to soybean sprouts intake. Long term administration of the test material did not cause oxidative damage to DNA and protein in the liver as evidenced by the unchanged basal levels of DNA damage as well as carbonyl groups content. Lipid peroxidation was slightly increased only in females. The activity of several antioxidant enzymes: superoxide dismutase, glutathione peroxidase and glutathione S-transferase was increased, which substantially enhanced the antioxidant status in the liver from the rats treated with soybean sprouts. Hence, the material tested can be recommended as a component of food supplements for individuals with iron deficiency anaemia and inflammatory bowel diseases.