Inhibition of Glial Activation and Subsequent Reduction in White Matter Damage through Supplementation with a Combined Extract of Wheat Bran, Citrus Peel, and Jujube in a Rat Model of Vascular Dementia.

Vascular dementia (VaD) is the second most common type of dementia after Alzheimer's disease. In our previous studies, we showed that wheat bran extract (WBE) reduced white matter damage in a rat VaD model and improved memory in a human clinical trial. However, starch gelatinization made the large-scale preparation of WBE difficult. To simplify the manufacturing process and increase efficacy, we attempted to find a decoction containing an optimum ratio of wheat bran, sliced citrus peel, and sliced jujube (WCJ). To find an optimal ratio, the cell survival of C6 (rat glioma) cultured under hypoxic conditions (1% O2) was measured, and apoptosis was assessed. To confirm the efficacies of the optimized WCJ for VaD, pupillary light reflex, white matter damage, and the activation of astrocytes and microglia were assessed in a rat model of bilateral common carotid artery occlusion (BCCAO) causing chronic hypoperfusion. Using a combination of both searching the literature and cell survival experiments, we chose 6:2:1 as the optimal ratio of wheat bran to sliced citrus peel to sliced jujube to prepare WCJ. We showed that phytic acid contained only in wheat bran can be used as an indicator component for the quality control of WCJ. We observed in vitro that the WCJ treatment improved cell survival by reducing apoptosis through an increase in the Bcl-2/Bax ratio. In the BCCAO experiments, the WCJ-supplemented diet prevented astrocytic and microglial activation, mitigated myelin damage in the corpus callosum and optic tract, and, consequently, improved pupillary light reflex at dosages over 100 mg/kg/day. The results suggest that the consumption of WCJ can prevent VaD by reducing white matter damage, and WCJ can be developed as a safe, herbal medicine to prevent VaD.

Intake of psyllium seed husk reduces white matter damage in a rat model of chronic cerebral hypoperfusion.

Vascular dementia (VaD) develops through a pre-VaD step during which blood vessels narrow due to atherosclerosis attributed to risk factors, including hyperlipidemia. This is followed by a VaD progression step during which inadequate blood supply results in white matter damage and consequent cognitive impairment. Furthermore, administration of arabinoxylan attenuated white matter damage in a rat model of VaD. Thus, we hypothesized that consumption of psyllium seed husk (PSH), containing a high level of arabinoxylan (~60%), could inhibit the VaD progression step. To test this hypothesis, rats were supplemented with PSH at various dosages for 33 days in a model of bilateral common carotid artery occlusion. PSH supplementation decreased astrocytic and microglial activation in the optic tract (opt) and, consequently, attenuated white matter damage in the opt. Attenuation of white matter damage resulted in improvement of pupillary light reflex, an indicator reflecting intactness of the opt. In addition, PSH treatment improved survival of glial cells cultured under hypoxic and glucose-deprived conditions by inhibiting both apoptosis and autophagy. These findings indicate that PSH consumption can inhibit the VaD progression step through a decrease of white matter damage. Therefore, these results support our hypothesis that PSH consumption prevents VaD due to the high arabinoxylan content in the rat model. PSH consumption has already been shown to reduce risk factors, thereby inhibiting the pre-VaD step. Consequently, PSH consumption can contribute to the prevention of VaD by inhibiting both the pre-VaD and VaD progression steps. In conclusion, our rat study suggests that PSH might be a candidate to explore its use in clinical studies to reduce VaD.

Xyloglucan intake attenuates myocardial injury by inhibiting apoptosis and improving energy metabolism in a rat model of myocardial infarction.

The development of coronary heart disease can be divided into preocclusion and postocclusion steps. We previously showed that cell wall polysaccharides consisting of a high content of arabinose and/or xylose, such as apple pectin, protected against myocardial injury by inhibiting postocclusion steps. We hypothesized that xyloglucan, another apple cell wall polysaccharide that consists of a high content of xylose, might also show myocardial protection. To test the hypothesis, rats were supplemented with either tamarind xyloglucan (TXG) (1, 10, and 100 mg/kg per day) or cotton cellulose (CCL) (100mg/kg per day) for 3 days. Then, rats underwent 30 minutes of ischemia followed by 3 hours of reperfusion. Supplementation with TXG at a dosage greater than 10mg/kg per day significantly reduced the infarct size (IS), whereas supplementation with CCL at 100mg/kg per day did not reduce IS. TXG supplementation up-regulated the expression of myoglobin and fatty acid-binding protein, both of which are known to be involved in apoptosis and ATP generation. Indeed, TXG supplementation inhibited apoptosis through decrease in p38 and JNK phosphorylation, increase in Bcl-2/Bax ratio, inhibition in the conversion of procaspase-3 to cleaved caspase-3, and decrease in the generation of DNA nicks. From these results, we demonstrated that xyloglucan in apple can protect against myocardial injury by inhibiting apoptosis and improving energy metabolism. Therefore, apple xyloglucan and pectin contribute to the known beneficial effects of apple in reducing the risk of coronary heart disease by blocking postocclusion steps through apoptosis inhibition. In addition, this study demonstrates the feasibility of developing TXG as a cardioprotectant.

Larch Arabinogalactan Attenuates Myocardial Injury by Inhibiting Apoptotic Cascades in a Rat Model of Ischemia-Reperfusion.

We reported previously that supplementation with apple pectin, a dietary fiber, reduced myocardial injury in a rat model of ischemia-reperfusion. In this study, we further investigated an arabinogalactan, one of the constituent polysaccharides of pectin, to determine which domains comprising pectin were responsible for the protection. In a rat model of 30-min ischemia followed by 3-h reperfusion, supplementation with larch arabinogalactan (LAG) over 50 mg/kg/day significantly reduced infarct size. Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and immunoblot analyses showed that intake of LAG blocked the steps involved in apoptotic cascades through downregulation of gelsolin gene expression at the protein (Gelsolin) level, inhibition of p38 phosphorylation in mitogen-activated protein kinase (MAPK) pathways, decreased bax/bcl-2 ratio at the protein (Bax/Bcl-2) level, which was correlated with the ratio at the mRNA level, inhibition of the conversion of Procaspase protein to Caspase-3 protein, and consequently a decrease in apoptotic cells. In addition, the intake of LAG reduced the hif1-α gene expression at the protein (HIF1-α) level. These findings suggest that arabinogalactan is an active component of pectin for reducing myocardial injury by inhibiting apoptosis in postocclusion steps, possibly indicating that arabinogalactan can be developed as a cardioprotectant to prevent myocardial injury.

Plant-based foods containing cell wall polysaccharides rich in specific active monosaccharides protect against myocardial injury in rat myocardial infarction models.

Many cohort studies have shown that consumption of diets containing a higher composition of foods derived from plants reduces mortality from coronary heart disease (CHD). Here, we examined the active components of a plant-based diet and the underlying mechanisms that reduce the risk of CHD using three rat models and a quantitative proteomics approach. In a short-term myocardial infarction (MI) model, intake of wheat extract (WE), the representative cardioprotectant identified by screening approximately 4,000 samples, reduced myocardial injury by inhibiting apoptosis, enhancing ATP production, and maintaining protein homeostasis. In long-term post-MI models, this myocardial protection resulted in ameliorating adverse left-ventricular remodelling, which is a predictor of heart failure. Among the wheat components, arabinose and xylose were identified as active components responsible for the observed efficacy of WE, which was administered via ingestion and tail-vein injections. Finally, the food components of plant-based diets that contained cell wall polysaccharides rich in arabinose, xylose, and possibly fucose were found to confer protection against myocardial injury. These results show for the first time that specific monosaccharides found in the cell wall polysaccharides in plant-based diets can act as active ingredients that reduce CHD by inhibiting postocclusion steps, including MI and heart failure.

Intake of hot water-extracted apple protects against myocardial injury by inhibiting apoptosis in an ischemia/reperfusion rat model.

Intakes of apple and its products are shown to reduce the risk of coronary heart disease by delaying occlusion of coronary arteries. In our previous study, we showed that apple pectin protected against myocardial injury by prohibiting apoptotic cascades in a rat model of ischemia/reperfusion. Thus, we hypothesized that water-extracted apple, into which apple pectin was released from the cell wall, might exhibit the same efficacy as apple pectin. To test this hypothesis, we fed rats either cold water- (400 mg kg(-1) d(-1)) or hot water-extracted apples (HWEA; 40, 100, and 400 mg kg(-1) d(-1)). Three days later, the rats were subjected to myocardial injuries by ligating the left anterior descending coronary artery (30 minutes), and subsequently, the heart (3 hours) reperfused by releasing the ligation. Only the rats that were supplemented with HWEA (400 mg kg(-1) d(-1)) showed significant reductions in infarct size, which was 28.5% smaller than that of the control group. This infarct size reduction could be partly attributed to the prevention of steps leading to apoptosis. These steps are manifested by a higher Bcl-2/Bax ratio, lower procaspase-3 conversion to caspase-3, and inhibition of DNA nick generation, which reflects the extent of apoptosis. The findings indicate that HWEA supplementation reduces myocardial injury by inhibiting apoptosis under ischemia/reperfusion conditions. In conclusion, this study suggests that apple intake, specifically boiled apple, might reduce the risk of coronary heart disease by inhibiting postocclusion steps, such as myocardial injury after artery occlusion, as well as preocclusion steps, such as atherosclerotic plaque formation.

Identification of active compounds from Aurantii Immatri Pericarpium attenuating brain injury in a rat model of ischemia-reperfusion.

Ischemic stroke is caused by brain injury due to prolonged ischemia by occlusion of cerebral arteries. In this study, we isolated active compounds from an ethanol extract of Aurantii Immatri Pericarpium (HY5356). We first showed by DNA fragmentation assay that HY5356 improved human hepatocellular carcinoma cells (HepG2) under hypoxic conditions by inhibiting apoptosis. When HY5356 was fractionated with dichloromethane (MC), ethyl acetate (EA) and n-butanol (BU), the MC fraction improved cell viability at the lowest concentration (100 µg/ml). Intraperitoneal injection of HY5356 (200 mg/kg) or the MC fraction (200 mg/kg) to rats prior to occlusion attenuated brain injury significantly in a rat model of ischemia-reperfusion. Adopting cell viability under hypoxic conditions as an activity screening system, we isolated nobiletin and tangeretin as active compounds. The results suggest that intake of Aurantii Immatri Pericarpium containing nobiletin and tangeretin as active compounds might be beneficial for preventing ischemic stroke.

Water extract of Triticum aestivum L. and its components demonstrate protective effect in a model of vascular dementia.

Although vascular dementia is the second leading cause of dementia and often underdiagnosed, there are no drugs yet approved for the treatment of vascular dementia. In this study, it is demonstrated that water extract of Triticum aestivum L. (TALE) and some of its components have protective effects against vascular dementia-induced damage by preserving the myelin sheath and inhibiting astrocytic activation. The memory test used a vascular dementia model utilizing bilateral ligation of the carotid arteries of rats. TALE, some of its components, such as starch, total dietary fiber (TDF), arabinoxylan, beta-glucan, and degraded products of arabinoxylan, such as arabinose and xylose, were administered to the animals from day 8 to day 14, following the surgery. Twenty-one days after the surgery, the water maze test was performed for 5 days, and the time taken to find the platform during training trials (mean escape latency) was measured. The mean escape latency was decreased consistently in the TALE-, starch-, TDF-, arabinoxylan-, and arabinose-treated groups, compared with that in the vascular dementia group. To measure brain damage, Luxol fast blue staining and immunohistochemistry of myelin basic protein (MBP) were performed to observe myelin sheath in the white matter, and immunohistochemistry of glial fibrillary acidic protein (GFAP) was performed to observe the astrocytic reaction. Vascular dementia reduced the MBP level and increased the GFAP level. Arabinose effectively inhibited the MBP and GFAP change, whereas arabinoxylan inhibited the GFAP change only. These results suggest that TALE and some of its components can be used as a medicinal material for the development of neuroprotective agents against vascular dementia.

Neuroprotective effects of Triticum aestivum L. against beta-amyloid-induced cell death and memory impairments.

beta-Amyloid (A beta) is a key component of senile plaques, neuropathological hallmarks of Alzheimer's disease (AD) and has been reported to induce cell death via oxidative stress. This study investigated the protective effects of Triticum aestivum L. (TAL) on A beta-induced apoptosis in SH-SY5Y cells and cognitive dysfunctions in Sprague-Dawley (SD) rats. Cells treated with A beta exhibited decreased viability and apoptotic features, such as DNA fragmentation, alterations in mitochondria and an increased Bax/Bcl-2 ratio, which were attenuated by TAL extract (TALE) pretreatment. To elucidate the neuroprotective mechanisms of TALE, the study examined A beta-induced oxidative stress and cellular defense. TALE pretreatment suppressed A beta-increased intracellular accumulation of reactive oxygen species (ROS) via up-regulation of glutathione, an essential endogenous antioxidant. To further verify the effect of TALE on memory impairments, A beta or scopolamine was injected in SD rats and a water maze task conducted as a spatial memory test. A beta or scopolamine treatment increased the time taken to find the platform during training trials, which was decreased by TALE pretreatment. Furthermore, one of the active components of TALE, total dietary fiber also effectively inhibited A beta-induced cytotoxicity and scopolamine-caused memory deficits. These results suggest that TALE may have preventive and/or therapeutic potential in the management of AD.