Evaluation of the safety and toxicity of the oligomerized polyphenol Oligonol

Treatment with autophagic inhibitors enhances oligonol‑induced apoptotic effects in nasopharyngeal carcinoma cells

Although the combination of chemotherapy and radiotherapy has increased the survival rate of patients with nasopharyngeal carcinoma (NPC), certain patients do not respond well to the treatment and have a poor prognosis. Therefore, novel therapeutic drugs and strategies to improve prognosis of patients with NPC are required. As certain plant extracts can suppress the viability of cancer cells, the present study investigated whether oligonol, a polyphenolic compound primarily found in lychee fruit, exerts anticancer activities in NPC cells. MTT, ELISA and immunoblotting were performed to investigate cell survival, cytokeratin-18 fragment release, and the expression of apoptosis and autophagy markers, respectively. Oligonol decreased the viability of NPC-TW01 and NPC/HK1NPC cell lines. Oligonol increased the protein expression of several apoptosis markers, including cleaved caspase-8 and -3, cleaved PARP and cytokeratin 18 fragment. Moreover, it also increased expression of autophagy markers Beclin 1 and LC3-II, as well as LC3-II/LC3-I ratio in both NPC cell lines. Furthermore, treatment with autophagy inhibitors 3-methyladenine or LY294002 significantly increased oligonol-induced viability inhibition in NPC-TW01 cells. Combined treatment of oligonol + LY294002 reduced LC3-II expression and the LC3II/LC3I ratio while increasing cleaved caspase-8 and -3, cleaved PARP and cytokeratin 18 fragment expression in NPC-TW01 cells. These findings indicated autophagy inhibitors could enhance viability inhibition and apoptotic effects induced by oligonol in NPC cells.

Oligonol enhances brain cognitive function in high-fat diet-fed mice

Oligonol, a low-molecular-weight polyphenol derived from lychee fruit, is well recognized for its antioxidant properties, blood glucose regulation, and fat mass reduction capability. However, its effect on the central nervous system remains unclear. Here, we investigated the effects of oligonol on brain in a high-fat diet (HFD) fed mouse model, and SH-SY5Y neuronal cells and primary cultured cortical neuron under insulin resistance conditions. HFD mice were orally administered oligonol (20 mg/kg) daily, and SH-SY5Y cells and primary cortical neurons were pretreated with 500 ng/mL oligonol under in vitro insulin resistance conditions. Our findings revealed that oligonol administration reduced blood glucose levels and improved spatial memory function in HFD mice. In vitro data demonstrated that oligonol protected neuronal cells and enhanced neural structure against insulin resistance. We confirmed RNA sequencing in the oligonol-pretreated insulin-resistant SH-SY5Y neuronal cells. Our RNA-sequencing data indicated that oligonol contributes to metabolic signaling and neurite outgrowth. In conclusion, our study provides insights into therapeutic potential of oligonol with respect to preventing neuronal cell damage and improving neural structure and cognitive function in HFD mice.

Oligomeric Proanthocyanidins: An Updated Review of Their Natural Sources, Synthesis, and Potentials

Oligomeric Proanthocyanidins (OPCs), as a class of compounds widely found in plants, are particularly abundant in grapes and blueberries. It is a polymer comprising many different monomers, such as catechins and epicatechins. The monomers are usually linked to each other by two types of links, A-linkages (C-O-C) and B-linkages (C-C), to form the polymers. Numerous studies have shown that compared to high polymeric procyanidins, OPCs exhibit antioxidant properties due to the presence of multiple hydroxyl groups. This review describes the molecular structure and natural source of OPCs, their general synthesis pathway in plants, their antioxidant capacity, and potential applications, especially the anti-inflammatory, anti-aging, cardiovascular disease prevention, and antineoplastic functions. Currently, OPCs have attracted much attention, being non-toxic and natural antioxidants of plant origin that scavenge free radicals from the human body. This review would provide some references for further research on the biological functions of OPCs and their application in various fields.

Litchi-Derived Polyphenol Alleviates Liver Steatosis and Gut Dysbiosis in Patients with Non-Alcoholic Fatty Liver Disease: A Randomized Double-Blinded, Placebo-Controlled Study

Preclinical data suggest the role of litchi extract in alleviating non-alcoholic fatty liver disease (NAFLD) by modulating gut microbiota. We aimed at investigating whether oligonol, a litchi-derived polyphenol, could improve liver steatosis and gut dysbiosis in patients with NAFLD. Adults with grade ≥2 steatosis, defined by an MRI proton density fat fraction (MRI-PDFF) of ≥11%, were randomly assigned to receive either oligonol or placebo for 24 weeks. The alteration in the MRI-PDFF and gut microbiota composition assessed by 16S ribosomal RNA sequencing were examined. There were 38 patients enrolled (n = 19 in each group). A significant reduction in the MRI-PDFF between week 0 and week 24 was observed in the oligonol group, while there was a non-significant decrease in the placebo group. A significant improvement in alpha-diversity was demonstrated in both of the groups. The oligonol-induced microbiota changes were characterized by reduced abundance of pathogenic bacteria, including Dorea, Romboutsia, Erysipelotrichaceae UCG-003 and Agathobacter, as well as increased abundance of short-chain fatty acids (SCFAs)-producing bacteria, such as Akkermansia, Lachnospira, Dialister and Faecalibacterium. In summary, this study is the first to provide evidence that supports that oligonol improves steatosis through the modulation of gut bacterial composition. Our results also support the beneficial and complementary role of oligonol in treating NAFLD.

Omnifarious fruit polyphenols: an omnipotent strategy to prevent and intervene diabetes and related complication?

Diabetes mellitus is a metabolic syndrome which cannot be cured. Recently, considerable interest has been focused on food ingredients to prevent and intervene in complications of diabetes. Polyphenolic compounds are one of the bioactive phytochemical constituents with various biological activities, which have drawn increasing interest in human health. Fruits are part of the polyphenol sources in daily food consumption. Fruit-derived polyphenols possess the anti-diabetic activity that has already been proved either from in vitro studies or in vivo studies. The mechanisms of fruit polyphenols in treating diabetes and related complications are under discussion. This is a comprehensive review on polyphenols from the edible parts of fruits, including those from citrus, berries, apples, cherries, mangoes, mangosteens, pomegranates, and other fruits regarding their potential benefits in preventing and treating diabetes mellitus. The signal pathways of characteristic polyphenols derived from fruits in reducing high blood glucose and intervening hyperglycemia-induced diabetic complications were summarized.

Effects of oligonol on the submandibular gland in ovariectomized rats

The aim of this study was to observe the effects of oligonol on submandibular gland dysfunction in ovariectomized rats. We randomly divided female Sprague-Dawley rats into sham-operated, ovariectomized, and oligonol-treated ovariectomized groups. Oligonol was intraperitoneally administered at 30 mg/kg daily for six weeks. Lipogenesis increased after the ovariectomy while fatty acid oxidation increased and intracellular triglyceride levels decreased in response to oligonol treatment. Submandibular gland fibrosis characterized by collagen type I accumulation was observed in the ovariectomized group. However, oligonol markedly reduced fibrosis to a level comparable to that observed in the sham group. Aquaporin 1 and glucose transporter 4 were downregulated in the ovariectomized group. Nevertheless, both factors were significantly upregulated by oligonol treatment. However, aquaporin 5 was significantly downregulated in the oligonol treatment group. Our findings indicate that oligonol protects against damage in postmenopausal rat salivary glands.

Oligonol, a Low-molecular Weight Polyphenol Extracted from Lychee Fruit, Modulates Cholesterol Metabolism in Rats within a Short Period

There is growing research interest in the hypocholesterolemic effect of various food components such as polyphenols. In this study, we examined the effects of oligonol-a low-molecular weight polyphenol extracted from lychee fruit-on cholesterol metabolism in rats under short-term administration. Administration of oligonol for 3 days significantly increased cecum weight and decreased cecal n-butyric acid concentrations in rats. Oligonol also significantly lowered the levels of hepatic cholesterol and increased the levels of total neutral steroids excreted in the feces. It also increased fecal β-muricholic acid significantly, whereas the levels of total acidic steroids remained unchanged. Gene expression of hepatic CYP7A1 (cytochrome P450 family 7 subfamily A member 1) significantly increased following the administration of oligonol. This increase could be ascribed to changes in the expression of farnesoid X receptor, small heterodimer partner, and fibroblast growth factor 15 in ileum. Our data suggest that oligonol induces hypocholesterolemic effects through the inhibition of biliary cholesterol absorption from the intestine and the upregulation of cholesterol catabolism in rats even following short-term administration. Therefore, oligonol may be an important food component for reducing cholesterol level.

Effects of a Standardized Oligomerized-Polyphenol from Litchi chinensis Fruit Extract and Mixed Plant Extract Supplementation on Peripheral Circulation and Cold Sensitivity

Certain individuals tend to suffer from a cold sensation-particularly in the lower extremities-despite most people not suffering from the same sensation. In Japan, this phenomenon is called "hie-sho" and reduces quality of life for several people, particularly women. A previous study has shown that a standardized oligomerized-polyphenol from Litchi chinensis fruit extract (OPLFE) reportedly causes a significant increase in body surface temperature. The present study aimed to investigate whether supplementation with OPLFE affected peripheral circulation and cold sensitivity. This randomized, double-blind, placebo-controlled trial was performed including 25 participants (age, 45.0±10.4 y; 3 males and 22 females) who were assigned to consume OPLFE, mixed plant extract with OPLFE, or placebo capsules for 14 d. Participants were instructed to relax for 60 min in a temperature-controlled room prior to obtaining measurements. Changes in skin temperature and peripheral blood flow of the middle finger were assessed immediately before and 1, 5, 10, 20, and 30 min after immersion in cold water (10ºC). Participants' height, weight, skin temperature, and blood flow in peripheral tissue were measured; furthermore, their "hie-sho" was measured using the Visual Analog Scale (VAS). Skin temperature and blood flow in peripheral tissue increased in the OPLFE and mixed plant extract with OPLFE groups on day 14 compared with those on day 1. In addition, cold sensitivity in these two groups significantly improved between day 1 and day 14. These findings suggest that OPLFE improves "hie-sho" by increasing peripheral blood flow and skin temperature.

Nutrient components, health benefits, and safety of litchi (Litchi chinensis Sonn.): A review

Litchi (Litchi chinensis Sonn.) is a tropical to subtropical fruit that is widely cultivated in more than 20 countries worldwide. It is normally consumed as fresh or processed and has become one of the most popular fruits because it has a delicious flavor, attractive color, and high nutritive value. Whole litchi fruits have been used not only as a food source but also for medicinal purposes. As a traditional Chinese medicine, litchi has been used for centuries to treat stomach ulcers, diabetes, cough, diarrhea, and dyspepsia, as well as to kill intestinal worms. Both in vitro and in vivo studies have indicated that whole litchi fruits exhibit antioxidant, hypoglycemic, hepatoprotective, hypolipidemic, and antiobesity activities and show anticancer, antiatherosclerotic, hypotensive, neuroprotective, and immunomodulatory activities. The health benefits of litchi have been attributed to its wide range of nutritional components, among which polysaccharides and polyphenols have been proven to possess various beneficial properties. The diversity and composition of litchi polysaccharides and polyphenols have vital influences on their biological activities. In addition, consuming fresh litchi and its products could lead to some adverse reactions for some people such as pruritus, urticaria, swelling of the lips, swelling of the throat, dyspnea, or diarrhea. These safety problems are probably caused by the soluble protein in litchi that could cause anaphylactic and inflammatory reactions. To achieve reasonable applications of litchi in the food, medical and cosmetics industries, this review focuses on recent findings related to the nutrient components, health benefits, and safety of litchi.

Flavanol-rich lychee fruit extract substantially reduces progressive cognitive and molecular deficits in a triple-transgenic animal model of Alzheimer disease

Effective treatment to prevent or arrest the advance of Alzheimer disease (AD) has yet to be discovered. We investigated whether Oligonol^R, an FDA-approved flavanol-rich extract prepared from lychee fruit and green tea, exerted beneficial effects relevant to AD in a triple transgenic male mouse model of AD (3×Tg-AD). At 9 months of age, untreated 3×Tg-AD mice vs. wild-type (WT) controls displayed cognitive deficits in behavioral assays and, at 12 months, elevated levels of hippocampal amyloid beta-protein (Aβ), amyloid precursor protein (APP), tau phosphorylation, and pro-inflammatory cytokines. 3×Tg-AD mice given Oligonol showed fewer cognitive deficits and attenuated pathological indices at 12 months. Oligonol treatment of 3×Tg-AD mice modulated expression of some critical brain proteins that involve multiple pathways relevant to mitochondrial dysfunction, proteasomal failure, endoplasmic reticulum (ER) stress and synaptic impairment. Together, these results demonstrate that continuous Oligonol treatment attenuates AD-like pathology and cognitive impairment of 3×Tg-AD mice and set the stage for clinical trials of this flavanol-rich plant extract in patients with early AD.

Positive and negative effects of polyphenol incorporation in baked foods

Polyphenols are hot research topics worldwide owing to their physiological and pharmaceutical activities. Polyphenols and polyphenol-enriched by-products have been widely used in bakery foods because of their neutraceutical properties. This review summarizes the classification, biosynthesis, main source and analysis of polyphenols and intensively discusses the effects of their incorporation in baked foods. The positive effects of polyphenol incorporation include elevation of antioxidant activity of baked foods, scavenging of food-borne toxins produced during thermal processing and decreasing postprandial serum glucose level. Meanwhile, polyphenol incorporation negatively influences colour, texture and flavour of baked foods and bioavailability of the added polyphenols. Most polyphenols are thermally sensitive and reactive. Thus far, few studies have investigated on neoformed compounds from the reaction of polyphenols or their oxidised products (quinones) with other food components. Before launching polyphenol-incorporated bakery foods in the market, future work should focus on full toxicological evaluation of newly derived compounds from polyphenols.

Preventive effect of oligonol on nitric oxide and reactive oxygen species production through regulation of nuclear factor kappa B signaling pathway in RAW 264.7 macrophage cells against sodium nitroprusside

Oligonol attenuated SNP-induced oxidative stress and inflammatory responsesviaregulation of the NF-κB signalling pathway in RAW 264.7 macrophage cells.

Supplementation with Oligonol, Prevents Weight Gain and Improves Lipid Profile in Overweight and Obese Saudi Females

Background:

Obesity is a global health problem, increasing susceptibility to Type 2 Diabetes (T2DM) and Cardiovascular Disease (CVD). Varieties of products have been proposed for treatment with varying degrees of success. Recent studies, suggested Oligonol; an optimized phenolic product mixture from Lychee Fruit Polyphenols (LFP); as such treatment in Japanese population.

Objectives:

We aimed to investigate the effect of oligonol on weight, insulin resistance by (HOMA-IR), lipids profile, leptin, Adiponectin, and resistin in healthy overweight and obese Saudi females.

Subjects and Methods:

60 Saudi healthy overweight and obese females were enrolled in a double blind case/control study to take either Oligonol or placebo for 12 weeks without dietary or lifestyle re-strictions. Weight, height, Waist Circumference (WC), hip circumference (HC), and blood pressure were measured, and fasting blood samples of participants were taken before, and at the end of study. Total cholesterol, HDL-cholesterol, triglycerides, glucose, insulin, leptin, adiponectin, and resistin were meas-ured. LDL- cholesterol, HOMA-IR were calculated by equation.

Results:

47 subjects completed the study, 25 in placebo group, and 22 in Oligonol group. No ill effects were noted in any participant. Oligonol reduced means of serum triglycerides (P=0.008), and resistin (P=0.045) significantly. In addition, no weight gain was noted in oligonol group, unlike placebo group which exhibited significant increase in mean weight (P= 0.036), WC (P=0.027), HC (P= 0.047), and leptin (P <0.001).

Conclusion:

Oligonol could be suggested as future hypolipidemic and weight controlling agent for overweight and obese Saudi females.

Proanthocyanidins against Oxidative Stress: From Molecular Mechanisms to Clinical Applications

Proanthocyanidins (PCs) are naturally occurring polyphenolic compounds abundant in many vegetables, plant skins (rind/bark), seeds, flowers, fruits, and nuts. Numerous in vitro and in vivo studies have demonstrated myriad effects potentially beneficial to human health, such as antioxidation, anti-inflammation, immunomodulation, DNA repair, and antitumor activity. Accumulation of prooxidants such as reactive oxygen species (ROS) exceeding cellular antioxidant capacity results in oxidative stress (OS), which can damage macromolecules (DNA, lipids, and proteins), organelles (membranes and mitochondria), and whole tissues. OS is implicated in the pathogenesis and exacerbation of many cardiovascular, neurodegenerative, dermatological, and metabolic diseases, both through direct molecular damage and secondary activation of stress-associated signaling pathways. PCs are promising natural agents to safely prevent acute damage and control chronic diseases at relatively low cost. In this review, we summarize the molecules and signaling pathways involved in OS and the corresponding therapeutic mechanisms of PCs.

Oligonol promotes glucose uptake by modulating the insulin signaling pathway in insulin-resistant HepG2 cells via inhibiting protein tyrosine phosphatase 1B

Insulin resistance and protein tyrosine phosphatase 1B (PTP1B) overexpression are strongly associated with type 2 diabetes mellitus (T2DM), which is characterized by defects in insulin signaling and glucose intolerance. In a previous study, we demonstrated oligonol inhibits PTP1B and α-glucosidase related to T2DM. In this study, we examined the molecular mechanisms underlying the anti-diabetic effects of oligonol in insulin-resistant HepG2 cells. Glucose uptake was assessed using a fluorescent glucose tracer, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose, and the signaling pathway was investigated by western blotting. Oligonol significantly increased insulin-provoked glucose uptake and decreased PTP1B expression, followed by modulation of ERK phosphorylation. In addition, oligonol activated insulin receptor substrate 1 by reducing phosphorylation at serine 307 and increasing that at tyrosine 895, and enhanced the phosphorylations of Akt and phosphatidylinositol 3-kinase. Interestingly, it also reduced the expression of two key enzymes of gluconeogenesis (glucose 6-phosphatase and phosphoenolpyruvate carboxykinase), attenuated oxidative stress by scavenging/inhibiting peroxynitrite, and reactive oxygen species (ROS) generation, and augmented the expression of nuclear factor kappa B. These findings suggest oligonol improved the insulin sensitivity of insulin-resistant HepG2 cells by attenuating the insulin signaling blockade and modulating glucose uptake and production. Furthermore, oligonol attenuated ROS-related inflammation and prevented oxidative damage in our in vitro model of type 2 diabetes. These result indicate oligonol has promising potential as a treatment for T2DM.

Impact of Maturity of Malay Cherry (Lepisanthes alata) Leaves on the Inhibitory Activity of Starch Hydrolases

Aqueous extracts of young (7-day-old) Malay cherry (Lepisanthes alata) leaves were incorporated into wheat and rice flours to evaluate their inhibitory activities against α-amylase and α-glucosidase. HPLC-ESI/MS² results showed that the active components in young leaves were proanthocyanidins with lower mean degrees of polymerisation (≤10). The IC₅₀ of the aqueous extracts of young leaves were 2.50 ± 0.03 and 12.91 ± 0.29 µg/mL, against α-amylase and α-glucosidase, which make them less active compared to the mature leaves. In contrast, total proanthocyanidins in aqueous extracts decreased as the leaves matured, indicating that the compounds in the mature leaves have much higher activity. However, there was no significant difference in the digestibility of wheat noodles incorporated with the aqueous extracts from either young or mature leaves. Interestingly, with regard to rice noodles, their digestibility was mostly reduced by incorporating aqueous extracts of young leaves compared to using mature leaves.

A new class of hepatitis B and D virus entry inhibitors, proanthocyanidin and its analogs, that directly act on the viral large surface proteins

Introduction of direct-acting antivirals against hepatitis C virus (HCV) has provided a revolutionary improvement in the treatment outcome. In contrast to HCV, however, the strategy for developing new antiviral agents against hepatitis B virus (HBV), especially viral-targeting compounds, is limited because HBV requires only four viral genes for its efficient replication/infection. Here, we identify an oligomeric flavonoid, proanthocyanidin (PAC) and its analogs, which inhibit HBV entry into host cells by targeting the HBV large surface protein (LHBs). Through cell-based chemical screening, PAC was identified to inhibit HBV infection with little cytotoxic effect. PAC prevented the attachment of the preS1 region in the LHBs to its cellular receptor, sodium taurocholate cotransporting polypeptide (NTCP). PAC was shown to target HBV particles and impair their infectivity, whereas it did not affect the NTCP-mediated bile acid transport activity. Chemical biological techniques demonstrated that PAC directly interacted with the region essential for receptor binding in the preS1 region in the LHBs protein. Importantly, PAC had a pan-genotypic anti-HBV activity and was also effective against a clinically relevant nucleoside analog-resistant HBV isolate. We further showed that PAC augmented the ability of a nucleoside analog, tenofovir, to interrupt HBV spread over time in primary human hepatocytes by cotreatment. Moreover, derivative analysis could identify small molecules that demonstrated more-potent anti-HBV activity over PAC.

CONCLUSION

PAC and its analogs represent a new class of anti-HBV agents that directly target the preS1 region of the HBV large surface protein. These agents could contribute to the development of a potent, well-tolerated, and broadly active inhibitor of HBV infection. (Hepatology 2017;65:1104-1116).

Grape Seed Extract Attenuates Hepatitis C Virus Replication and Virus-Induced Inflammation

Hepatitis C virus (HCV) infection is a causative factor leading to hepatocellular carcinoma due to chronic inflammation and cirrhosis. The aim of the study was first to explore the effects of grape seed extract (GSE) in HCV replication, and then to study mechanisms. The results indicated that a GSE treatment showed significant anti-HCV activity and suppressed HCV-elevated cyclooxygenase-2 (COX-2) expression. In contrast, exogenous COX-2 expression gradually attenuated antiviral effects of GSE, suggesting that GSE inhibited HCV replication by suppressing an aberrant COX-2 expression caused by HCV, which was correlated with the inactivation of IKK-regulated NF-κB and MAPK/ERK/JNK signaling pathways. In addition, GSE also attenuated HCV-induced inflammatory cytokine gene expression. Notably, a combined administration of GSE with interferon or other FDA-approved antiviral drugs revealed a synergistic anti-HCV effect. Collectively, these findings demonstrate the possibility of developing GSE as a dietary supplement to treat patients with a chronic HCV infection.

Defining Conditions for Optimal Inhibition of Food Intake in Rats by a Grape-Seed Derived Proanthocyanidin Extract

Food intake depends on homeostatic and non-homeostatic factors. In order to use grape seed proanthocyanidins (GSPE) as food intake limiting agents, it is important to define the key characteristics of their bioactivity within this complex function. We treated rats with acute and chronic treatments of GSPE at different doses to identify the importance of eating patterns and GSPE dose and the mechanistic aspects of GSPE. GSPE-induced food intake inhibition must be reproduced under non-stressful conditions and with a stable and synchronized feeding pattern. A minimum dose of around 350 mg GSPE/kg body weight (BW) is needed. GSPE components act by activating the Glucagon-like peptide-1 (GLP-1) receptor because their effect is blocked by Exendin 9-39. GSPE in turn acts on the hypothalamic center of food intake control probably because of increased GLP-1 production in the intestine. To conclude, GSPE inhibits food intake through GLP-1 signaling, but it needs to be dosed under optimal conditions to exert this effect.

Grape seed powder improves renal failure of chronic kidney disease patients

Chronic kidney disease (CKD) is a syndrome characterized by progressive and irreversible deterioration of renal function linked to slow destruction of renal parenchyma, eventually terminating in death when sufficient number of nephrons are damaged. Oxidative stress is commonly observed in CKD patients resulting from an imbalance between overproduction of reactive oxygen species (ROS) and impairment of defence mechanisms. Grape seed extract (GSE) is a polyphenolic mixture exhibiting antioxidant and anti-inflammatory properties. We conducted an interventional pilot study of supplementation with GSE capsules (GSE group, n = 23) or placebo (control group, n = 10) on CKD patients. Blood and urine samples were collected at baseline and after a six-month-long supplementation period to determine some renal function biomarkers, as well as antioxidant, anti-inflammatory and haematological parameters. GSE improved glomerular filtration rate (GFR) and proteinuria, increased the anti-oxidant status as assessed by high plasma catalase and superoxide dismutase and also lowered lipoperoxidation and carbonylation. GSE ameliorated inflammation by decreasing CRP, triglyceridemia and counteracted anemia and thrombocytopenia. Supplementation with 2 g GSE/day for six months improved some kidney function parameters of CKD patients and this beneficial effect of GSE seems to be mediated at least partly by its antioxidant and anti-inflammatory properties.

Oligonol, a lychee fruit-derived low-molecular form of polyphenol mixture, suppresses inflammatory cytokine production from human monocytes

Monocytes produce high levels of inflammatory cytokines including IL-6 and TNF-α that are involved in autoimmunity, inflammatory diseases, cardiovascular disease and obesity. Therapies targeting IL-6 and TNF-α have been utilized in treating chronic inflammatory diseases. Oligonol is a lychee fruit-derived low-molecular form of polyphenol mixture, typically catechin-type monomers and oligomers of proanthocyanidins, which are produced by an oligomerization process. Although previous studies reported anti-inflammatory properties of Oligonol, it is unknown whether and how Oligonol suppresses IL-6 and TNF-α production in human monocytes. The results of our study demonstrate that Oligonol (25μg/ml) decreases the production of IL-6 and TNF-α from human primary monocytes as measured by flow cytometry and ELISA. Such an anti-cytokine effect was likely mediated by the suppression of NF-κB activation without inducing cell death. Our findings raise the possibility of exploring the benefits of Oligonol in controlling inflammatory conditions, especially those associated with monocytes, in humans.

Oligonol promotes anti-aging pathways via modulation of SIRT1-AMPK-Autophagy Pathway

BACKGROUND/OBJECTIVES

Oligonol, mainly found in lychee fruit, is an antioxidant polyphenolic compound which has been shown to have anti-inflammatory and anti-cancer properties. The detailed mechanisms by which oligonol may act as an anti-aging molecule have not been determined.

MATERIALS/METHODS

In this study, we evaluated the ability of oligonol to modulate sirtuin (SIRT) expression in human lung epithelial (A549) cells. Oligonol was added to A549 cells and reactive oxygen species production, mitochondrial superoxide formation, and p21 protein levels were measured. Signaling pathways activated upon oligonol treatment were also determined by western blotting. Furthermore, the anti-aging effect of oligonol was evaluated ex vivo in mouse splenocytes and in vivo in Caenorhabditis elegans.

RESULTS

Oligonol specifically induced the expression of SIRT1, whose activity is linked to gene expression, metabolic control, and healthy aging. In response to influenza virus infection of A549 cells, oligonol treatment significantly up-regulated SIRT1 expression and down-regulated viral hemagglutinin expression. Oligonol treatment also resulted in the activation of autophagy pathways and the phosphorylation of AMP-activated protein kinase (AMPK). Furthermore, oligonol-treated spleen lymphocytes from old mice showed increased cell proliferation, and mRNA levels of SIRT1 in the lungs of old mice were significantly lower than those in the lungs of young mice. Additionally, in vivo lethality assay revealed that oligonol extended the lifespan of C. elegans infected with lethal Vibrio cholerae.

CONCLUSIONS

These data demonstrated that oligonol may act as an anti-aging molecule by modulating SIRT1/autophagy/AMPK pathways.

Low-molecular-weight polyphenols protect kidney damage through suppressing NF-κB and modulating mitochondrial biogenesis in diabetic db/db mice

We examined the protective effects of oligonol, a low-molecular-weight polyphenol derived from lychee fruit and green tea, on kidney damage in diabeticdb/dbmice.

Effectiveness of plant-derived proanthocyanidins on demineralization on enamel and dentin under artificial cariogenic challenge

Dental caries is considered a disease of high prevalence and a constant problem in public health. Proanthocyanidins (PAs) are substances that have been the target of recent studies aiming to control or treat caries.

Oligonol suppresses lipid accumulation and improves insulin resistance in a palmitate-induced in HepG2 hepatocytes as a cellular steatosis model

Background

Oligonol is a low molecular weight form of polyphenol polymers derived from lychee fruits. Several studies suggest that Oligonol has an anti-obesity effect. Since obesity is tightly associated with insulin resistance, we investigated a possible remission effect of Oligonol on lipid accumulation and insulin resistance in human hepatic HepG2 cells.

Methods

HepG2 cells were treated with palmitate for 24 h to induce cellular hepatic steatosis and insulin resistance. The cells were then treated with Oligonol at subtoxic concentrations and examined for lipid metabolism, cytokine production, and insulin signaling using quantitative RT-PCR and western blot analysis.

Results

Oligonol treatment reversed the palmitate-induced intracellular lipid accumulation, down regulated the expression of lipogenic genes, and up-regulated genes for fatty acid degradation. Oligonol restored insulin sensitivity, as was determined by the phosphorylation states of IRS-1. Oligonol also inhibited STAT3-SOCS3 signaling and increased AMPK phosphorylation in HepG2 cells.

Conclusion

Oligonol treatment improved palmitate-induced cellular steatosis and insulin resistance in HepG2 cells with concomitant reduction of inflammatory cytokines and decrease in STAT3-SOCS3 and AMPK-mTOR pathways. Oligonol may have beneficial effects in lipid metabolism and insulin resistance in the liver.

Therapeutic Effects of Oligonol, Acupuncture, and Quantum Light Therapy in Chronic Nonbacterial Prostatitis

This research aimed to compare anti-inflammatory effects of oligonol, acupuncture, and quantum light therapy in rat models of estrogen-induced prostatitis. Adult male Wistar albino rats were grouped as follows: Group I, control (n = 10); Group II, chronic prostatitis (n = 10); Group III, oligonol (n = 10); Group IV, acupuncture (n = 10); Group V, quantum (n = 10); Group VI, oligonol plus quantum (n = 10); Group VII, acupuncture plus oligonol (n = 10); Group VIII, quantum plus acupuncture (n = 10); and Group IX, acupuncture plus quantum plus oligonol (n = 10). Chronic prostatitis (CP) was induced by the administration of 17-beta-estradiol (E2) and dihydrotestosterone (DHT). Oligonol was given for 6 weeks at a dose of 60 mg/day. Acupuncture needles were inserted at CV 3/4 and bilaterally B 32/35 points with 1-hour manual stimulation. Quantum therapy was administered in 5-minute sessions three times weekly for 6 weeks. Lateral lobes of prostates were dissected for histopathologic evaluation. Although all of the treatment modalities tested in this study showed anti-inflammatory effects in the treatment of CP in male rats, a synergistic effect was observed for oligonol plus quantum light combination. Monotherapy with oligonol showed a superior anti-inflammatory efficacy as compared to quantum light and acupuncture monotherapies.

Analgesic effects of oligonol, acupuncture and quantum light therapy on chronic nonbacterial prostatitis

Background:

Chronic Nonbacterial Prostatitis (CNBP) is a condition that frequently causes long-term pain and a significant decrease in the quality of life.

Objectives:

The present study aimed to examine the analgesic effects of oligonol, acupuncture, quantum light therapy and their combinations on estrogen-induced CNBP in rats.

Materials and Methods:

This experimental study was conducted in Edirne, Turkey, using a simple randomized allocation. A total of 90 adult male Wistar rats were randomized into 9 groups of 10 rats each: Group I, control; Group II, CNBP, Group III, oligonol only, Group IV, acupuncture only; Group V, quantum only; Group VI, oligonol + quantum; Group VII, acupuncture + oligonol; Group VIII, quantum + acupuncture; Group IX, acupuncture + quantum + oligonol. Oligonol treatment was given at a dose of 60 mg/day for 6 weeks. Conceptual vessels (CV) 3 and 4, and bilaterally urinary bladder (Bl) 32 and 34 points were targeted with 1-hour acupuncture stimulation. The quantum light therapy was applied in 5-minute sessions for 6 weeks (3-times/a week). For pain measurements, mechanical pressure was applied to a point 2 cm distal to the root of the tail to elicit pain and consequent parameters (peak force, latency time of response and total length of measurement) were assessed.

Results:

Analgesic effects were observed with all treatment regimens; however, the most prominent median analgesic effect was shown in the quantum light therapy in combination with acupuncture for estrogen-induced CNBP (PF1 = 663.9, PF2 = 403.4) (P = 0.012). Furthermore, we observed that monotherapy with quantum light showed a better analgesic efficacy as compared to oligonol and acupuncture monotherapies (PF1 = 1044.6, PF2 = 661.2) (P = 0.018, P = 0.008, P = 0.018; respectively).

Conclusions:

All treatment modalities showed a significant analgesic effect on CNBP in rats, being most prominent with the quantum light therapy.

Oligonol supplementation modulates plasma volume and osmolality and sweating after heat load in humans

Oligonol is a low-molecular-weight polyphenol that possesses antioxidant and anti-inflammatory properties. This study investigated the effects of Oligonol supplementation on sweating response, plasma volume (PV), and osmolality (Osm) after heat load in human volunteers. We conducted a placebo-controlled crossover trial. Participants took a daily dose of 200 mg Oligonol or placebo for 1 week. After a 2-week washout period, the subjects were switched to the other study arm. As a heat load, half-body immersion into hot water (42°C±0.5°C for 30 min) was performed in an automated climate chamber. Tympanic and mean body temperature (Tty, mTb) and whole-body sweat loss volume (WBSLV) were measured. Changes in PV, Osm, and serum levels of aldosterone and sodium were analyzed. Oligonol intake attenuated increases in Tty, mTb, and WBSLV after heat load compared with the placebo (P<.01, P<.05, and P<.01, respectively). In addition, serum aldosterone was maintained at a relatively low degree and serum sodium was maintained at a relatively high degree with Oligonol compared to the placebo (P<.01 and P<.05, respectively). However, PV decreased and Osm increased significantly with Oligonol compared to the placebo (P<.05 and P<.05, respectively). This study demonstrates that Oligonol supplementation for 1 week can attenuate elevation of body temperature and excessive sweating under heat load in healthy humans, but interpretation of the results requires caution due to the potent diuretic effect of Oligonol.

Inhibition of Adipogenesis by Oligonol through Akt-mTOR Inhibition in 3T3-L1 Adipocytes

Polyphenols have recently become an important focus of study in obesity research. Oligonol is an oligomerized polyphenol, typically comprised of catechin-type polyphenols from a variety of fruits, which has been found to exhibit better bioavailability and bioreactivity than natural polyphenol compounds. Here, we demonstrated that Oligonol inhibits 3T3-L1 adipocyte differentiation by reducing adipogenic gene expression. During adipogenesis, Oligonol downregulated the mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding proteins α (C/EBPα), and δ (C/EBPδ) in a dose-dependent manner and the expression of genes involved in lipid biosynthesis. The antiadipogenic effect of Oligonol appears to originate from its ability to inhibit the Akt and mammalian target of rapamycin (mTOR) signaling pathway by diminishing the phosphorylation of ribosomal protein S6 kinase (p70S6K), a downstream target of mTOR and forkhead box protein O1 (Foxo1). These results suggest that Oligonol may be a potent regulator of obesity by repressing major adipogenic genes through inhibition of the Akt signaling pathway, which induces the inhibition of lipid accumulation, ultimately inhibiting adipogenesis.

Beneficial effect of Oligonol supplementation on sweating response under heat stress in humans

Oligonol is a low-molecular weight polyphenol that possesses antioxidant and anti-inflammatory properties. However, nothing is known regarding the impact of Oligonol on sudomotor activity. This study investigated the effects of Oligonol supplementation on sudomotor activity during heat load in humans. Initially, we conducted a placebo-controlled, cross-over trial where participants took a daily dose of Oligonol 200 mg or placebo for one week. After a 2 week washout period, the subjects were switched to the other study arm. As a heat load, half-body immersion into hot water (42 ± 0.5 °C for 30 min) was performed in an automated climate chamber. Tympanic and skin temperatures were measured. Sudomotor activity, including onset time, sweat rate (SR) and volume (SV), active sweat gland density (ASGD), and sweat gland output (SGO), was tested in four or eight areas of skin. When compared with placebo, Oligonol attenuated increases in tympanic and skin temperatures after the heat load. There was an increasing trend in local sweat onset time, but there was a decrease in local SR, SV, ASGD, and SGO for Oligonol compared to placebo. The mean ASGD was significantly higher in the Oligonol group than in the placebo group for 10, 20, and 30 min. This study demonstrates that Oligonol appears to be worthy of consideration as a natural supplement to support more economical use of body fluids against heat stress.

Oligonol, a low-molecular-weight polyphenol derived from lychee fruit, attenuates diabetes-induced renal damage through the advanced glycation end product-related pathway in db/db mice

This study was conducted to examine whether oligonol, a low-molecular-weight polyphenol derived from lychee fruit, has an ameliorative effect on diabetes-induced alterations, such as advanced glycation end product (AGE) formation or apoptosis in the kidneys of db/db mice with type 2 diabetes. Oligonol [10 or 20 mg/(kg body weight · d), orally] was administered every day for 8 wk to prediabetic db/db mice, and its effect was compared with vehicle-treated db/db and normal control mice (m/m). The administration of oligonol decreased the elevated renal glucose concentrations and reactive oxygen species in db/db mice (P < 0.05). The increased serum urea nitrogen and creatinine concentrations, which reflect renal dysfunction in db/db mice, were substantially lowered by oligonol. Oligonol reduced renal protein expression of NAD(P)H oxidase subunits (p22 phagocytic oxidase and NAD(P)H oxidase-4), AGEs (except for pentosidine), and c-Jun N-terminal kinase B-targeting proinflammatory tumor necrosis factor-α (P < 0.05). Oligonol improved the expressions of antiapoptotic [B-cell lymphoma protein 2 (Bcl-2) and survivin] and proapoptotic [Bcl-2-associated X protein, cytochrome c, and caspase-3] proteins in the kidneys of db/db mice (P < 0.05). In conclusion, these results provide important evidence that oligonol exhibits a pleiotropic effect on AGE formation and apoptosis-related variables, representing renoprotective effects against the development of diabetic complications in db/db mice with type 2 diabetes.

Oligonol supplementation affects leukocyte and immune cell counts after heat loading in humans

Oligonol is a low-molecular-weight form of polyphenol and has antioxidant and anti-inflammatory activity, making it a potential promoter of immunity. This study investigates the effects of oligonol supplementation on leukocyte and immune cell counts after heat loading in 19 healthy male volunteers. The participants took a daily dose of 200 mg oligonol or a placebo for 1 week. After a 2-week washout period, the subjects were switched to the other study arm. After each supplement, half-body immersion into hot water was made, and blood was collected. Then, complete and differential blood counts were performed. Flow cytometry was used to enumerate and phenotype lymphocyte subsets. Serum concentrations of interleukin (IL)-1β and IL-6 in blood samples were analyzed. Lymphocyte subpopulation variables included counts of total T cells, B cells, and natural killer (NK) cells. Oligonol intake attenuated elevations in IL-1β (an 11.1-fold change vs. a 13.9-fold change immediately after heating; a 12.0-fold change vs. a 12.6-fold change 1h after heating) and IL-6 (an 8.6-fold change vs. a 9.9-fold change immediately after heating; a 9.1-fold change vs. a 10.5-fold change 1h after heating) immediately and 1 h after heating in comparison to those in the placebo group. Oligonol supplementation led to significantly higher numbers of leukocytes (a 30.0% change vs. a 21.5% change immediately after heating; a 13.5% change vs. a 3.5% change 1h after heating) and lymphocytes (a 47.3% change vs. a 39.3% change immediately after heating; a 19.08% change vs. a 2.1% change 1h after heating) relative to those in the placebo group. Oligonol intake led to larger increases in T cells, B cells, and NK cells at rest (p < 0.05, p < 0.05, and p < 0.001, respectively) and immediately after heating (p < 0.001) in comparison to those in the placebo group. In addition, levels of T cells (p < 0.001) and B cells (p < 0.001) were significantly higher 1 h after heating in comparison to those in the placebo group. These results demonstrate that supplementation with oligonol for 1 week may enhance the immune function under heat and suggest a potential useful adjunct to chemotherapy in malignant diseases.

Oligonol improves memory and cognition under an amyloid β(25-35)-induced Alzheimer's mouse model

Alzheimer's disease is an age-dependent progressive neurodegenerative disorder that results in impairments of memory and cognitive function. It is hypothesized that oligonol has ameliorative effects on memory impairment and reduced cognitive functions in mice with Alzheimer's disease induced by amyloid β(25-35) (Aβ(25-35)) injection. The protective effect of an oligonol against Aβ(25-35)-induced memory impairment was investigated in an in vivo Alzheimer's mouse model. The aggregation of Aβ25-35 was induced by incubation at 37°C for 3 days before injection into mice brains (5 nmol/mouse), and then oligonol was orally administered at 100 and 200 mg/kg of body weight for 2 weeks. Memory and cognition were observed in T-maze, object recognition, and Morris water maze tests. The group injected with Aβ(25-35) showed impairments in both recognition and memory. However, novel object recognition and new route awareness abilities were dose dependently improved by the oral administration of oligonol. In addition, the results of the Morris water maze test indicated that oligonol exerted protective activity against cognitive impairment induced by Aβ(25-35). Furthermore, nitric oxide formation and lipid peroxidation were significantly elevated by Aβ(25-35), whereas oligonol treatment significantly decreased nitric oxide formation and lipid peroxidation in the brain, liver, and kidneys. The present results suggest that oligonol improves Aβ(25-35)-induced memory deficit and cognition impairment.

The anti-inflammatory effects of flavanol-rich lychee fruit extract in rat hepatocytes

Flavanol (flavan-3-ol)-rich lychee fruit extract (FRLFE) is a mixture of oligomerized polyphenols primarily derived from lychee fruit and is rich in flavanol monomers, dimers, and trimers. Supplementation with this functional food has been shown to suppress inflammation and tissue damage caused by high-intensity exercise training. However, it is unclear whether FRLFE has in vitro anti-inflammatory effects, such as suppressing the production of the proinflammatory cytokine tumor necrosis factor α (TNF-α) and the proinflammatory mediator nitric oxide (NO), which is synthesized by inducible nitric oxide synthase (iNOS). Here, we analyzed the effects of FRLFE and its constituents on the expression of inflammatory genes in interleukin 1β (IL-1β)-treated rat hepatocytes. FRLFE decreased the mRNA and protein expression of the iNOS gene, leading to the suppression of IL-1β-induced NO production. FRLFE also decreased the levels of the iNOS antisense transcript, which stabilizes iNOS mRNA. By contrast, unprocessed lychee fruit extract, which is rich in flavanol polymers, and flavanol monomers had little effect on NO production. When a construct harboring the iNOS promoter fused to the firefly luciferase gene was used, FRLFE decreased the luciferase activity in the presence of IL-1β, suggesting that FRLFE suppresses the promoter activity of the iNOS gene at the transcriptional level. Electrophoretic mobility shift assays indicated that FRLFE reduced the nuclear transport of a key regulator, nuclear factor κB (NF-κB). Furthermore, FRLFE inhibited the phosphorylation of NF-κB inhibitor α (IκB-α). FRLFE also reduced the mRNA levels of NF-κB target genes encoding cytokines and chemokines, such as TNF-α. Therefore, FRLFE inhibited NF-κB activation and nuclear translocation to suppress the expression of these inflammatory genes. Our results suggest that flavanols may be responsible for the anti-inflammatory and hepatoprotective effects of FRLFE and may be used to treat inflammatory diseases.

Oligonol supplementation attenuates body temperature and the circulating levels of prostaglandin E2 and cyclooxygenase-2 after heat stress in humans

Oligonol, a phenolic production from lychee, has been reported to exhibit anti-oxidative and anti-inflammatory effects. This study investigated the effect of Oligonol supplementation on circulating levels of prostaglandin E2 (PGE2) and cyclooxygenase (COX)-2, as well as body temperature, after heat stress in 17 healthy human male volunteers (age, 21.6±2.1 years). All experiments were performed in an automated climate chamber (26.0°C±0.5°C, relative humidity 60%±3.0%, air velocity less than 1 m/sec) between 2 and 5 p.m. Subjects ingested an Oligonol (100 mg)-containing beverage or placebo beverage before half-body immersion into hot water (42°C±0.5°C for 30 min). Tympanic and skin temperatures were measured and mean body temperatures were calculated. Serum concentrations of PGE2 and COX-2 were analyzed before, immediately after, and 60 min after immersion. Oligonol intake significantly prevented elevation of tympanic (temperature difference: 0.17°C at Post, P<.05; 0.17°C at Re-60, P<.05) and mean body temperatures (temperature difference: 0.18°C at Post, P<.05; 0.15°C at Re-60, P<.05), and lowered concentrations of serum PGE2 (increased by 13.3% vs. 29.6% at Post, P<.05) and COX-2 (increased by 15.6% vs. 21.8% at Post, P<.05), compared to placebo beverage. Our result suggests that Oligonol has the potential to suppress increases in body temperature under heat stress, and this is associated with decreases in serum levels of PGE2 and COX-2.

Oligonol inhibits dextran sulfate sodium-induced colitis and colonic adenoma formation in mice

AIMS

To evaluate the effects of oligonol administration on experimentally induced colitis and colonic adenoma formation.

RESULTS

Oral administration of oligonol protected against mouse colitis induced by dextran sulfate sodium (DSS). Under the same experimental conditions, oligonol administration significantly inhibited the activation of nuclear factor-kappa B and signal transducer and activator of transcription (STAT) 3 and expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and cyclin D1 in the mouse colon. Further, oligonol inhibited azoxymethane-initiated and DSS-promoted adenoma formation in the mouse colon. Oligonol administration also attenuated lipid peroxidation (malondialdehyde) and protein oxidation (4-hydroxy-2-nonenal), thereby preventing oxidative stress-induced apoptosis of colonic epithelial cells. In vitro studies demonstrated that oligonol treatment reduced lipopolysaccharide-induced expression of interleukin (IL)-1β, tumor necrosis factor α, il-6, cox-2, and inos in murine macrophage RAW 264.7 cells. In another study, oligonol upregulated the antioxidant gene expression in the intestinal epithelial CCD841CoN cells and in the mouse colon.

INNOVATION

Oligonol, an innovative formulation of catechin-type oligomers derived from the lychee fruit extract, was tested in this study for the first time to evaluate its effects on experimentally induced colitis and colonic adenoma formation in mice.

CONCLUSION

Oligonol is effective in protecting against DSS-induced mouse colitis and colon carcinogenesis, suggesting that this polyphenol formulation may have a potential for the amelioration of inflammatory bowel disease and related disorders.

Oligomerised lychee fruit-derived polyphenol attenuates cognitive impairment in senescence-accelerated mice and endoplasmic reticulum stress in neuronal cells

Recently, the ability of polyphenols to reduce the risk of dementia and Alzheimer's disease (AD) has attracted a great deal of interest. In the present study, we investigated the attenuating effects of oligomerised lychee fruit-derived polyphenol (OLFP, also called Oligonol) on early cognitive impairment. Male senescence-accelerated mouse prone 8 (SAMP8) mice (4 months old) were given OLFP (100 mg/kg per d) for 2 months, and then conditioned fear memory testing was conducted. Contextual fear memory, which is considered hippocampus-dependent memory, was significantly impaired in SAMP8 mice compared with non-senescence-accelerated mice. OLFP attenuated cognitive impairment in SAMP8 mice. Moreover, the results of real-time PCR analysis that followed DNA array analysis in the hippocampus revealed that, compared with SAMP8 mice, the mRNA expression of Wolfram syndrome 1 (Wfs1) was significantly higher in SAMP8 mice administered with OLFP. Wfs1 reportedly helps to protect against endoplasmic reticulum (ER) stress, which is thought to be one of the causes for AD. The expression of Wfs1 was significantly up-regulated in NG108-15 neuronal cells by the treatment with OLFP, and the up-regulation was inhibited by the treatment of the cells with a c-Jun N-terminal kinase-specific inhibitor rather than with an extracellular signal-regulated kinase inhibitor. Moreover, OLFP significantly attenuated the tunicamycin-induced expression of the ER stress marker BiP (immunoglobulin heavy chain-binding protein) in the cells. These results suggest that OLFP has an attenuating effect on early cognitive impairment in SAMP8 mice, and diminishes ER stress in neuronal cells.

Safety of oligonol, a highly bioavailable lychee-derived polyphenolic antioxidant, on liver, kidney and heart function in rats

Oligonol (OLG), derived from lychee fruit, is a novel compound produced from the oligomerization of polyphenols. In this study, the acute effect of OLG treatment was investigated on heart, liver and kidney in rats. OLG treatment at two different doses (15 or 30 mg/kg body weight) and two different time points (1 day or 7 days of treatment) demonstrated that no toxic effects were observed on heart, liver and renal functions. Moreover, OLG did not induce any DNA damage or oxidative stress as measured by 8-hydroxy-2'-deoxyguanosine levels in plasma. OLG supplementation increased the phosphorylation of myocardial endothelial nitric oxide (NO) level (p-eNOS) in both the treatment groups. Even the low dose OLG treatment (15mg/kg b.w) demonstrated an increase in p-eNOS/eNOS ratio after normalization of p-eNOS values with eNOS on day 1 (1.5-fold) and day 7 (2.2-fold) groups as compared to control. The above results suggest that OLG treatment increases endothelial NO levels and may play a role in NO-mediated vasodilatory effects without adverse side effects on cardiovascular function. This endothelial NO production may underlie the beneficial effect of OLG in cardiovascular health.

Safety evaluation of Evesse EPC, an apple polyphenol extract rich in flavan-3-ols

The safety of the apple polyphenol extract EvesseEPC, which is rich in flavan-3-ols, particularly epicatechin, was evaluated. Both in a bacterial reverse mutation test and a mouse lymphoma assay, EvesseEPC showed a positive response in vitro. In vivo studies (UDS test in hepatocytes, bone marrow micronucleus test and comet assay in intestinal cells) were all negative and hence Evesse EPC is considered not to have genotoxic properties in vivo. In a 90-day study in rats, EvesseEPC was administered at dietary levels of 0%, 1.25%, 2% and 3.25%. Body weights were decreased in the high-dose group in both sexes without effects on feed or water intake. In the high-dose group, thrombocytes (males) and creatinine (both sexes) were decreased, prothrombin time (males) was increased, and liver, kidneys and spleen weights were increased (males), without histological correlates. Diffuse acinar cell hypertrophy, observed in the parotid salivary glands in all treatment groups, was not considered as adverse and presumably reflected a local, reversible and adaptive response to direct contact with EvesseEPC. The NOAEL for EvesseEPC in rats was 2% in the diet, equivalent to an overall average intake of 1.3 and 1.5 g/kg body weight/day for males and females, respectively.

Oral toxicological studies of black soybean (Glycine max) hull extract: acute studies in rats and mice, and chronic studies in mice

Black soybean (Glycine max) has been used for traditional medicine and food in Asian countries, but safety of its hull has not been studied. We conducted acute and chronic oral toxicity studies. For the acute study, an extract of black soybean hull (BE; 2.5 g/kg body weight) was administered singly by intragastric intubation to Sprague-Dawley rats and C57BL/6 mice. There was no death or significant decrease in body weight in rats and mice, and the oral LD(50) of BE was >2.5 g/kg body weight. In the chronic study, BE was administered at dietary levels of 0% (control), 2.0%, and 5.0% to male and female C57BL/6 mice for 26 weeks. No mortality or toxicologically significant clinical changes were observed through the experimental period. Although body weights, as well as abdominal fat, blood levels of triglyceride and total cholesterol in 5.0% males were significantly lower than that in control and 2.0% groups, these changes were considered not to be adverse. Hematology and histopathological observation revealed no toxicologically significant changes. The no-observed adverse-effect-level of BE was estimated to be 5.0% in the diet (5074.1 mg/kg body weight/day for males and 7617.9 mg/kg body weight/day for females).

The effect of transient proanthocyanidins preconditioning on the cross-linking and mechanical properties of demineralized dentin

Proanthocyanidin-based preconditioners were prepared by adding powdered proanthocyanidins-rich grape seed extract to various solvents at different concentrations. Demineralized dentin specimens were preconditioned for 20, 30, 60 or 120 s, followed by the evaluation of their cross-linking degree, mechanical properties and micromorphology. The cross-linking degree of the demineralized dentin collagen exhibited concentration- and time- dependent increase after preconditioning treatment, irrespective of the preconditioner and the solvent. When treated for the same exposure time, specimens after 15% proanthocyanidins preconditioning resulted in the highest mean ultimate tensile strength compared with all the other groups tested. Five percent glutaraldehyde control group produced the highest cross-linking degree, but the ultimate tensile strength was lower than that of 15% proanthocyanidins group. The field emission scanning electron microscopy confirmed that the demineralized dentin collagen was in a homogeneous and regular arrangement after preconditioning and maintained expanding, regardless of the surface moisture conditions.

Grape seed proanthocyanidin extract inhibits glutamate-induced cell death through inhibition of calcium signals and nitric oxide formation in cultured rat hippocampal neurons

Background

Proanthocyanidin is a polyphenolic bioflavonoid with known antioxidant activity. Some flavonoids have a modulatory effect on [Ca²⁺]_i. Although proanthocyanidin extract from blueberries reportedly affects Ca²⁺ buffering capacity, there are no reports on the effects of proanthocyanidin on glutamate-induced [Ca²⁺]_i or cell death. In the present study, the effects of grape seed proanthocyanidin extract (GSPE) on glutamate-induced excitotoxicity was investigated through calcium signals and nitric oxide (NO) in cultured rat hippocampal neurons.

Results

Pretreatment with GSPE (0.3-10 μg/ml) for 5 min inhibited the [Ca²⁺]_i increase normally induced by treatment with glutamate (100 μM) for 1 min, in a concentration-dependent manner. Pretreatment with GSPE (6 μg/ml) for 5 min significantly decreased the [Ca²⁺]_i increase normally induced by two ionotropic glutamate receptor agonists, N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). GSPE further decreased AMPA-induced response in the presence of 1 μM nimodipine. However, GSPE did not affect the 50 mM K⁺-induced increase in [Ca²⁺]_i. GSPE significantly decreased the metabotropic glutamate receptor agonist (RS)-3,5-Dihydroxyphenylglycine-induced increase in [Ca²⁺]_i, but it did not affect caffeine-induced response. GSPE (0.3-6 μg/ml) significantly inhibited synaptically induced [Ca²⁺]_i spikes by 0.1 mM [Mg²⁺]_o. In addition, pretreatment with GSPE (6 μg/ml) for 5 min inhibited 0.1 mM [Mg²⁺]_o- and glutamate-induced formation of NO. Treatment with GSPE (6 μg/ml) significantly inhibited 0.1 mM [Mg²⁺]_o- and oxygen glucose deprivation-induced neuronal cell death.

Conclusions

All these data suggest that GSPE inhibits 0.1 mM [Mg²⁺]_o- and oxygen glucose deprivation-induced neurotoxicity through inhibition of calcium signals and NO formation in cultured rat hippocampal neurons.