Antioxidant activity of various teas against free radicals and LDL oxidation

Bioactive Compounds Formulated in Phytosomes Administered as Complementary Therapy for Metabolic Disorders

Metabolic disorders (MDs), including dyslipidemia, non-alcoholic fatty liver disease, diabetes mellitus, obesity and cardiovascular diseases are a significant threat to human health, despite the many therapies developed for their treatment. Different classes of bioactive compounds, such as polyphenols, flavonoids, alkaloids, and triterpenes have shown therapeutic potential in ameliorating various disorders. Most of these compounds present low bioavailability when administered orally, being rapidly metabolized in the digestive tract and liver which makes their metabolites less effective. Moreover, some of the bioactive compounds cannot fully exert their beneficial properties due to the low solubility and complex chemical structure which impede the passive diffusion through the intestinal cell membranes. To overcome these limitations, an innovative delivery system of phytosomes was developed. This review aims to highlight the scientific evidence proving the enhanced therapeutic benefits of the bioactive compounds formulated in phytosomes compared to the free compounds. The existing knowledge concerning the phytosomes' preparation, their characterization and bioavailability as well as the commercially available phytosomes with therapeutic potential to alleviate MDs are concisely depicted. This review brings arguments to encourage the use of phytosome formulation to diminish risk factors inducing MDs, or to treat the already installed diseases as complementary therapy to allopathic medication.

Natural compounds as safe therapeutic options for ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology. Several conventional treatments for UC such as corticosteroids, immunosuppressive agents, tumor necrosis factor antagonist, integrin blockers, and interleukin antagonist, and salicylates are available but are associated with the various limitations and side-effects. None of the above treatments helps to achieve the ultimate goal of the therapy, i.e., maintenance of remission in the long-term. Natural remedies for the treatment of UC show comparatively less side effects as compared to conventional approaches, and affordable. The current review presents details on the role of herbal drugs in the treatment and cure of UC. Google, PubMed, Web of Science, and Scopus portals have been searched for potentially relevant literature to get the latest developments and updated information related to use of natural drugs in the treatment of UC. Natural products have been used over centuries to treat UC. Some of the essential herbal constituents exhibiting antiulcerogenic activity include gymnemic acid (Gymnema sylvestre), shagoal (Zingiber officinale), catechin (Camellia sinensis), curcumin (Curcuma longa), arctigenin (Arctium lappa), and boswellic acid (Boswellia serrata). Although many plant-derived products have been recommended for UC, further research to understand the exact molecular mechanism is still warranted to establish their usefulness clinically.

Fructooligosaccharides Increase in Plasma Concentration of (-)-Epigallocatechin-3-Gallate in Rats

(-)-Epigallocatechin-3-gallate (EGCG) undergoes auto-oxidation at physiological pH and therefore may be poorly absorbed in the intestine. Fructooligosaccharides (FOS), comprising a group of 1-kestose, nystose, and 1^F-β fructofuranosyl-nystose, are fermentable by gut bacteria and converted mainly into lactate. This study was conducted to determine whether dietary FOS may help to increase the plasma concentration of EGCG in rats by preventing it from auto-oxidation. Rats consumed an assigned diet, either a 0.3% (w/w) EGCG diet or an EGCG diet with additional 1, 3, or 5% (w/w) FOS, for 2 weeks. The results showed that the plasma concentration of EGCG was 0.21 ± 0.05 μM for the EGCG alone group, and it was significantly higher at 0.65 ± 0.12 μM for the EGCG plus 5% FOS group. Treatments with FOS resulted in a dose-dependent increase in the cecal level of lactate and brought the cecal pH down, with an accompanying alteration in the abundance of Lactobacillus and Collinsella. Because EGCG concentrations in the cecal digesta of rats fed the FOS-containing diet maintained comparatively high levels, FOS likely contributed to the protection of EGCG from auto-oxidation. In conclusion, FOS reduced the pH of the lumen of the intestine, kept EGCG intact to a certain degree, and consequently allowed EGCG to be taken into the blood circulation from the intestine.

Medicinal plants used by 'root doctors', local traditional healers in Bié province, Angola

ETHNOPHARMACOLOGICAL RELEVANCE

This study is one of the first post-civil war efforts to document traditional botanical knowledge in Bié province, central Angola, in a first step to bring more studies on the use of medicinal plant resources in this area so as to bring new insights into Angolan bio-cultural diversity.

AIM OF THE STUDY

Examine the variety of plant species used for medical purposes, as well as characterize their social and cultural values. Also, it is aimed to compare their uses in the studied region with those in Sub-Saharan Africa and report new ethnomedicinal uses.

MATERIALS AND METHODS

We documented traditional medicinal plant knowledge among professional herbalists in two areas in Bié province through participatory observation, semi-structured interviews and transect walks. Ethnobotanical information was quantified based on Use Reports to (1) rate traditional knowledge; and (2) determine most useful taxa.

RESULTS

In total, 10 traditional healers shared information on their knowledge. A total of 87 plant species distributed among 57 genera and 36 botanical families were documented with Fabaceae being the best-represented family with 18 species, followed by Phyllanthaceae (6), Apocynaceae (5), Asteraceae (5), Rubiaceae (5), Lamiaceae (4), and Ochnaceae (3). Most medicinal plants are usually gathered at a distance from human settlements because of the belief in the higher efficacy of 'wild' plants shared by all herbalists. Roots are the most common plant part used (79%), explaining why the consulted herbalists call themselves 'root doctors'.

CONCLUSIONS

The culturally most important medicinal species identified in this study, i.e. Securidaca longepedunculata, Garcinia huillensis, Annona stenophylla, Afzelia quanzensis and Strychnos cocculoides, were previously reported for the same use in neighbouring countries and elsewhere in Africa. Our study also indicates that there are several locally valuable species that have not yet been studied for their medical potential, to name a few: Alvesia rosmarinifolia, Diplorhynchus condylocarpon, Eriosema affine, Paropsia brazzaeana, Rhus squalida, Sclerocroton cornutus or Xylopia tomentosa. Moreover, the ethnomedicinal use of 26 species was reported for the first time to sub-Saharan Africa.

CLASSIFICATION

Ethnopharmacological field studies.

Dietary habits, lipoprotein metabolism and cardiovascular disease: From individual foods to dietary patterns

Cardiovascular disease (CVD) remains the first cause of mortality in Western countries. Among cardiometabolic risk factors, dyslipidemia, and especially high low-density lipoprotein cholesterol (LDL-C) concentrations, have been extensively linked to the development and progression of atherosclerosis and to CVD events. Recent evidence has shown that the prevention of unhealthy dietary habits and sedentarism is crucial in the management of dyslipidemia. In this sense, a number of scientific societies recommend the adherence to certain healthy dietary patterns (DPs), such as the Mediterranean diet (MedDiet), the Dietary Approaches to Stop Hypertension (DASH), the Portfolio diet, the Vegetarian diet, the Nordic diet and low-carbohydrate diets, as well as increased physical activity between others. This nutritional and lifestyle advice could be adopted by government bodies and implemented in different health programs as a reliable way of providing health-care professionals with efficient tools to manage cardiometabolic risk factors and thus, prevent CVD. In this narrative review, we will discuss recent data about the effects of nutrition on dyslipidemia, mainly focusing on high LDL-C concentrations and other lipid particles related to atherogenic dyslipidemia such as triglycerides (TG) and non-high density lipoprotein cholesterol (non-HDL-C), that are related to CVD. On the other hand, we also comment on other cardiometabolic risk factors such as type 2 diabetes mellitus (T2DM), high blood pressure (HBP), inflammation and endothelial dysfunction. This review includes food groups as well as different healthy DPs.

Effects of Acute Dietary Polyphenols and Post-Meal Physical Activity on Postprandial Metabolism in Adults with Features of the Metabolic Syndrome

Approximately 22% of U.S. adults and 25% of adults globally have metabolic syndrome (MetS). Key features, such as dysglycemia and dyslipidemia, predict type 2 diabetes, cardiovascular disease, premature disability, and death. Acute supplementation of dietary polyphenols and post-meal physical activity hold promise in improving postprandial dysmetabolism. To our knowledge, no published review has described the effects of either intervention on postprandial glucose, insulin, lipids, and markers of oxidative damage and inflammation in adults with features of MetS. Thus, we conducted this review of controlled clinical trials that provided dietary polyphenols from oils, fruits, teas, and legumes during a dietary challenge, or implemented walking, cycling, and stair climbing and descending after a dietary challenge. Clinical trials were identified using ClinicalTrials.gov, PubMed, and Google Scholar and were published between 2000 and 2019. Dietary polyphenols from extra virgin olive oil, grapes, blackcurrants, strawberries, black tea, and black beans improved postprandial glucose, insulin, and markers of oxidative damage and inflammation, but results were not consistent among clinical trials. Freeze-dried strawberry powder distinctly improved postprandial insulin and markers of oxidative damage and inflammation. Post-meal physical activity attenuated postprandial glucose, but effects on postprandial lipids and markers of oxidative damage and inflammation were inconclusive. Consuming dietary polyphenols with a meal and completing physical activity after a meal may mitigate postprandial dysmetabolism in adults with features of MetS.

Comprehensive Review on Phytochemicals, Pharmacological and Clinical Potentials of Gymnema sylvestre

Gymnema sylvestre is a plant included in Apocynaceae family and is located in many regions of Asia, Africa and Australia. This plant is widely used as a traditional therapy for different purposes. Even now it is being used as a dietary supplement due to its numerous therapeutic uses. It is known to have blood glucose lowering potential and, thus, is widely used in traditional and Ayurvedic systems of medicine. It renders glucose lowering activity due to the presence of phytochemicals, such as gurmarin, gymnemic acid as well as gymnemasaponins. Gymnema sylvestre is also known to have anti-oxidant, antibiotic, anti-inflammatory, antiviral, gastro and hepatoprotective, anticancer and lipid-lowering activities. This review discusses in details on different pharmacological and clinical potentials of Gymnema sylvestre and its chemical constituents associated with its therapeutic potentials.

A novel Gymnema sylvestre extract protects pancreatic beta-cells from cytokine-induced apoptosis

Inflammatory cytokines such as interleukin-1β, TNF-α, and interferon-γ are known to be involved in mediating β-cells death in diabetes mellitus (DM). Thus, protecting from β-cells death in patients with DM may be a useful target in alleviating symptoms of hyperglycemia. Traditional plant-based remedies have been used to treat DM for many centuries and may play a role in protecting β-cell from death. An example of these remedies is Gymnema sylvestre (GS) extract. In this study, we investigated the effect of this plant extract on β-cells apoptosis. Om Santal Adivasi (OSA®) maintained cell membrane integrity in MIN6 cells and mouse islets. Om Santal Adivasi significantly protected MIN6 cells and mouse islets from cytokine-induced apoptosis. In the presence of cytokines, OSA® significantly reduced the expression and activity of caspase-3. The antiapoptotic effect of OSA® as shown by microarray analysis is largely mediated by activating pathways involved in cell survival (mainly casein kinase II pathway) and the free radical scavenger system (specifically superoxide dismutase and catalase). This study indicates that the GS isolate OSA® protects against cytokine-induced apoptosis of β-cells by increasing the expression of cell survival pathways and free radical scavenger system.

Protective effect of tea against lead and cadmium-induced oxidative stress-a review

Exposure to Cd and Pb reduces the activity of antioxidant enzymes, which points to a decrease in the antioxidant potential of the body as a result of supplying factors which enhance cellular oxidation processes. Man is exposed to the effects of toxic metals because they are present in the environment, including in food. Since no effective ways to reduce the concentrations of Cd an Pb in food exist, studies are undertaken to develop methods of reducing their toxic effect on the body through chelating these metals using nutrients (which reduces their absorption by tissues) or increasing the oxidative capacity of the body (which decreases the possibility of inducing oxidative damage to internal organs). Studies performed on laboratory animals have shown that the use of tea infusions fulfil both functions.

Elicitation of gymnemic acid production in cell suspension cultures of Gymnema sylvestre R.Br. through endophytic fungi

The enhancement of plant secondary metabolite production in cell suspension cultures through biotic or abiotic elicitation has become a potential biotechnological approach for commercialization or large-scale production of bioactive compounds. Gymnema sylvestre R.Br. is an important medicinal plant, rich in a group of oleanane triterpenoid saponins called gymnemic acid, well known for its anti-diabetic activity. Two endophytic fungal strains were isolated from the leaves of G. sylvestre and identified as Polyancora globosa and Xylaria sp. based on the PCR amplification and internal transcribed spacer (ITS 1-5.8S-ITS 2) sequencing of 18S rRNA gene. The process of elicitation of cell suspension cultures of G. sylvestre with dried powder of fungal mycelia (DPFM) and extracellular culture filtrate (ECF) of endophytic fungi consistently enhanced the accumulation of gymnemic acid and the DPFM was proved to be an effective elicitor when compared to the ECF. The DPFM elicited the gymnemic acid content in the range of 2.57–10.45-fold, while the ECF elicited the gymnemic acid content in the range of 2.39–7.8-fold. P. globosa, a novel and a rare endophytic fungal strain, has shown a great influence on the production of gymnemic acid. Cell suspension cultures elicited with DPFM of P. globosa produced higher amount of gymnemic acid content (124.23 mg/g dried cell weight) compared to the cultures elicited with DPFM of Xylaria sp. (102.24 mg/g DCW). But the cultures treated with consortium of DPFM of both fungi showed great influence on the production of gymnemic acid (139.98 mg/g DCW) than the cultures treated with DPFM alone. Similarly, cultures treated with consortium of ECF of both fungi produced more gymnemic acid content (94.86 mg/g DCW) compared with cultures treated with ECF of Xylaria sp. (77.93 mg/g DCW) and ECF of P. globosa (78.65 mg/g DCW) alone.

Green tea catechins prevent low-density lipoprotein oxidation via their accumulation in low-density lipoprotein particles in humans

Green tea is rich in polyphenols, including catechins which have antioxidant activities and are considered to have beneficial effects on cardiovascular health. In the present study, we investigated the effects of green tea catechins on low-density lipoprotein (LDL) oxidation in vitro and in human studies to test the hypothesis that catechins are incorporated into LDL particles and exert antioxidant properties. In a randomized, placebo-controlled, double-blind, crossover trial, 19 healthy men ingested green tea extract (GTE) in the form of capsules at a dose of 1 g total catechin, of which most (>99%) was the gallated type. At 1 hour after ingestion, marked increases of the plasma concentrations of (-)-epigallocatechin gallate and (-)-epicatechin gallate were observed. Accordingly, the plasma total antioxidant capacity was increased, and the LDL oxidizability was significantly reduced by the ingestion of GTE. We found that gallated catechins were incorporated into LDL particles in nonconjugated forms after the incubation of GTE with plasma in vitro. Moreover, the catechin-incorporated LDL was highly resistant to radical-induced oxidation in vitro. An additional human study with 5 healthy women confirmed that GTE intake sufficiently increased the concentration of gallated catechins, mainly in nonconjugated forms in LDL particles, and reduced the oxidizability of LDL. In conclusion, green tea catechins are rapidly incorporated into LDL particles and play a role in reducing LDL oxidation in humans, which suggests that taking green tea catechins is effective in reducing atherosclerosis risk associated with oxidative stress.

Correlation between catechin content and NF-κB inhibition by infusions of green and black tea

This study investigates whether infusions of green and black tea inhibit the NF-κB driven transcription in human epithelial gastric AGS cells. Water extracts were prepared from different brands of green and black tea available on the Italian market. Teas with or without caffeine were studied. An industrially prepared freeze-dried water extract of green tea was also tested. Catechin and caffeine contents were measured by HPLC analysis. The decrease in phenol and catechin content three months after the expiry date was also investigated. The NF-κB driven transcription and the free radical scavenger activity were inhibited, and this effect was related to catechin levels. The potency of epigallocatechin 3-gallate in inhibiting NF-κB driven transcription is so great that tea extracts low in epigallocatechin 3-gallate are still highly active. In one decaffeinated sample of green tea, the phenol and catechin content was very low, probably as a consequence of caffeine removal. The decrease in catechin levels after 3 months did not reduce the inhibition of NF-κB driven transcription by tea infusions. This is the first paper reporting the inhibitory effect of NF-κB of commercial green and black infusions at the gastric level, evaluating their stability as well.

Pleiotropic preventive effects of dietary polyphenols in cardiovascular diseases

Polyphenols are common constituents of the diet, and research on their health benefits has developed quickly over the past few years. Our purpose is to review recent findings highlighting daily dietary polyphenol intake and the diverse function of polyphenols and their possible relationships to cardiovascular disease (CVD). Several cohort studies have reported an inverse relationship between the daily consumption of polyphenols and CVD risk. Many studies showed that beverages could be a large source of polyphenols. Our previous findings provide that Japanese people intake polyphenols mainly from beverages, especially coffee and green tea (in descending order of polyphenol content). Many kinds of polyphenols act as an antioxidant against low-density lipoprotein oxidation, which is known to promote atherosclerosis. Recent accumulating evidence suggests that dietary polyphenols could exert their cardioprotective actions through their potential to improve metabolic disorder and vascular inflammation. These findings raise the possibility that polyphenols have a wide variety of roles in the intestine, liver and vascular tissue. In addition to identifying mechanisms of polyphenol bioactivity by basic research, much more epidemiological and clinical evidence linking reduced cardiovascular risk with dietary polyphenols intake are needed.

Asperuloside stimulates metabolic function in rats across several organs under high-fat diet conditions, acting like the major ingredient of Eucommia leaves with anti-obesity activity

Eucommia leaves (Eucommia ulmoides Oliver) contain chlorogenic acid (a caffeic acid derivative) and geniposidic acid and asperuloside (ASP), iridoid glucosides used in beverages. We used a metabolic syndrome rat model, produced by feeding a 35 % high-fat diet (HFD), to examine potential anti-obesity and anti-metabolic syndrome effects and mechanisms of chronic administration of ASP. These effects were compared with Eucommia leaf extract (ELE), the positive control, which exhibits anti-obesity effects. A total of six rats were studied for 3 months in five groups. ASP suppressed body weight, visceral fat weight, food intake and circulating levels of glucose, insulin and lipids, and increased the plasma adiponectin level in rats on a HFD. These effects are similar to those of ELE, except for the influence on the plasma glucose level. RT-PCR studies showed that ASP (like ELE with known anti-obesity effects) diminished isocitrate dehydrogenase 3α, NADH dehydrogenase flavoprotein 1 (Comp I) mRNA and fatty acid synthase levels (white adipose tissue), increased carnitine palmitoyltransferase 1α and acyl-CoA dehydrogenase, very-long-chain mRNA levels (liver), and increased Glut4, citrate synthase, isocitrate dehydrogenase 3α, succinyl CoA synthase, peroxisomal 3-ketoacyl-CoA thiolase, dihydrolipoamide succinyl transferase and succinate dehydrogenase mRNA levels (skeletal muscle) under HFD conditions. Interestingly, ASP administration resulted in significantly increased mRNA levels of uncoupling protein 1 (UCP1) in the brown adipose tissue of HFD-fed rats; ELE did not affect the expression of UCP1. The increased expression of UCP1 may be negated by many ingredients other than ASP in the ELE. These findings suggest that chronic administration of ASP stimulates anti-obesity and anti-metabolic syndrome activity in HFD-fed rats across several organs, similar to ELE administration; thus, ASP may be an important ingredient of ELE.

The Memory-Ameliorating Effects of Artemisia princeps var. orientalis Against Cholinergic Dysfunction in Mice

Artemisia princeps var. orientalis (Compositae) is widely distributed in China, Japan and Korea and is known to have anti-inflammatory and anti-oxidative activities. The ethyl acetate fraction of ethanolic extract of A. princeps var. orientalis (AEA) was found to inhibit acetylcholinesterase activity in a dose-dependent manner in vitro (IC50 value: 541.4 ± 67.5 μg/ml). Therefore, we investigated the effects of AEA on scopolamine-induced learning and memory impairment using the passive avoidance, the Y-maze, and the Morris water maze tasks in mice. AEA (100 or 200 mg/kg, p.o.) significantly ameliorated scopolamine-induced cognitive impairments in the passive avoidance and Y-maze tasks (p < 0.05). In the Morris water maze task, AEA (200 mg/kg, p.o.) significantly shortened escape latencies in training trials and increased both swimming time spent in the target zone and probe crossing numbers during the probe trial as compared with scopolamine-treated mice (p < 0.05). Additionally, the ameliorating effect of AEA on scopolamine-induced memory impairment was antagonized by a subeffective dose of MK-801. These results suggest that AEA could be an effective treatment against cholinergic dysfunction and its effect is mediated by the enhancement of the cholinergic neurotransmitter system via NMDA receptor signaling or acetylcholinesterase inhibition.

The protective effects of green tea polyphenols: lipid profile, inflammation, and antioxidant capacity in rats fed an atherogenic diet and dextran sodium sulfate

Acute and chronic inflammation and dyslipidemia play a critical role in the development of various diseases, including cardiovascular disease. Green tea polyphenols possess potent antioxidative and anti-inflammatory properties that contribute to the beneficial effects on heart health. The present study was carried out to determine if administration of a green tea extract (Polyphenon(®) E [PPE]; Mitsui Norin Co., Ltd., Tokyo, Japan) at 0.2% in the diet reduces cardiovascular risk factors, including dyslipidemia, inflammation, adiposity, and oxidative stress, in rats fed an atherogenic (high fat, cholesterol, and sugar) diet with dextran sodium sulfate (DSS) in drinking water. DSS treatment increased serum total cholesterol, low-density lipoprotein (LDL)-cholesterol, C-reactive proteins (CRP), and markers of liver toxicity and decreased high-density lipoprotein (HDL)-cholesterol significantly. Adding PPE to the atherogenic diet (PPE-diet) was associated with lower total cholesterol and LDL-cholesterol (P<.001) and increased HDL-cholesterol (P=.001). In addition, the PPE-diet was associated with decreased serum CRP concentration (P=.023) and increased total antioxidant capacity (P=.016) and catalase (P=.001) and glutathione peroxidase (P=.050) activities. The PPE-diet significantly lowered epididymal fat pad weight (P=.009). Feeding the PPE-diet also ameliorated some of the DSS-induced lipid, inflammatory, and oxidative symptoms. In summary, green tea supplementation decreased several cardiovascular risk factors, including body composition, dyslipidemia, inflammatory status, and antioxidant capacity, in rats fed an atherogenic diet. This study supports green tea as an effective dietary component for sustaining cardiovascular health.

Eucommia ulmoides Oliv. antagonizes H2O2-induced rat osteoblastic MC3T3-E1 apoptosis by inhibiting expressions of caspases 3, 6, 7, and 9

Eucommia ulmoides Oliv. (EuO), also known as Duzhong, native to China, has been reported to have antioxidative function, but its cellular mechanism is not fully examined yet. We investigated inhibitory effects of EuO leaf ethanol extracts on H(2)O(2)-induced apoptosis in rat osteoblastic MC3T3-E1 cells and underlying mechanisms. Locally-grown Duzhong leaves were extracted with ethanol. MC3T3-E1 cells were treated with EuO (6.25, 12.5, 25, 50, and 100 µg/ml) for 24 h, and then H(2)O(2) (800 µmol/L) for an additional 24 h. Cell survival rate, percentage of apoptosis, and expressions of caspases 3, 6, 7, and 9 were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, microscopic analysis, Western blotting, and reverse transcription polymerase chain reaction (RT-PCR). The final EuO leaf ethanol extract powder was detected to contain caffeotannic acid at 58 mg/g and geniposide at 3.45 mg/g by high performance liquid chromatography (HPLC). EuO remarkably restrained cell oxidative damage and increased cell survival rate in a dose-dependent manner: 0 µg/ml, 0.21; 6.25 µg/ml, 0. 28; 12.5 µg/ml, 0.31; 25 µg/ml, 0.48; 50 µg/ml, 0.54; and 100 µg/ml, 0.66 (P<0.05), with the half-effective concentration being around 25 µg/ml. MTT results were confirmed by microscopic analysis. Western blotting and RT-PCR analyses showed that the expressions of caspases 3, 6, 7, and 9 were significantly decreased in the EuO-treated cells compared with the control (EuO- and H(2)O(2)-free) (P<0.05), with the half-effective concentration of EuO ranging from 12.5 to 25 µg/ml. We conclude that the ethanol-extracted EuO leaf extracts promoted the growth of MC3T3-E1 cells, and suppressed the H(2)O(2)-induced apoptosis in a rat MC3T3-E1 osteogenic cell model, likely due to the inhibition of caspases' activities. The results indicate that EuO is a potent antioxidant, which may contribute to its many cellular protective functions, including the promotion of bone growth.

Sweet potato (Ipomoea batatas L.) leaves suppressed oxidation of low density lipoprotein (LDL) in vitro and in human subjects

Sweet potato (Ipomoea batatas L.) leaves are consumed as vegetables around the world, especially in Southeast Asia. The aim of this study was to investigate the inhibitory effect of sweet potato leaves on low-density lipoprotein oxidation in vitro and in human subjects. We compared the antioxidant activity of 8 kinds of sweet potato leaves. Every sweet potato leaf had high radical scavenging activity and prolonged a lag time for starting low-density lipoprotein oxidation in vitro. We found that sweet potato leaves contained abundant polyphenol compounds and the radical scavenging activity and prolongation rate of lag time were highly correlated with total polyphenol content. We also confirmed that thiobarbituric acid reactive substances production was increased in endothelial cell-mediated low-density lipoprotein oxidation, which was decreased by treatment with sweet potato leaves. We further measured the low-density lipoprotein oxidizability in 13 healthy volunteers after their intake of 18 g of “Suioh”, raw sweet potato leaves. “Suioh” prolonged a lag time for starting low-density lipoprotein oxidation and decreased low-density lipoprotein mobility. These results suggest that sweet potato leaves have antioxidant activity leading to the suppression of low-density lipoprotein oxidation.

Chronic administration of Eucommia leaf stimulates metabolic function of rats across several organs

Eucommia bark (Eucommia ulmoides Oliver) has been used as an herbal medicine, and more recently, the plant's leaves have been widely used to prepare tea which may have anti-obesity properties. We used a metabolic syndrome-like rat model, produced by feeding a 35 % high-fat diet (HFD), to examine potential anti-obesity and anti-metabolic syndrome effects and mechanisms of chronic administration of Eucommia leaf as an extract or green leaf powder. Eighty rats were studied for 3 months in ten groups. Both forms of Eucommia leaves minimised increases in body weight and visceral fat in a dose-dependent fashion. Increases in plasma levels of TAG and NEFA, and insulin resistance secondary to HFD were lessened by both forms of Eucommia leaf. Concomitantly, an increase in plasma adiponectin levels and suppression of plasma resistin and TNF-α levels were confirmed. Real-time PCR studies showed that both forms of Eucommia leaf enhanced metabolic function across several organs, including diminishing ATP production (white adipose tissue), accelerating β-oxidation (liver) and increasing the use of ketone bodies/glucose (skeletal muscle), all of which may exert anti-obesity effects under HFD conditions. These findings suggest that chronic administration of either form of Eucommia leaves stimulates the metabolic function in rats across several organs. The anti-obesity and anti-metabolic syndrome activity in this rat model may be maintained through secretion and regulation of adipocytokines that depend on the accumulation of visceral fat to improve insulin resistance or hyperlipaemia.

Antioxidant properties of Du-zhong (Eucommia ulmoides Oliv.) extracts and their effects on color stability and lipid oxidation of raw pork patties

The ethanol extracts from leaf, roasted cortex, and seed of Du-zhong ( Eucommia ulmoides Oliv.) were examined for total phenolics content (TPC) and total flavonoids content (TFC). The antioxidant activity of the extracts was evaluated by measuring the radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and lipid peroxidation inhibition capacity in a beta-carotene/linoleic acid system. Du-zhong leaf extract was found to have the highest TPC content (94.46 +/- 1.17 mg of gallic acid equiv/g of solid extract) and TFC content (61.36 +/- 0.59 mg of catechin equiv/g of solid extract). In the above three antioxidant assay systems, Du-zhong leaf extract also exhibited the strongest antioxidant capacities, followed by roasted cortex extract and seed extract. The effects of Du-zhong extracts (leaf, roasted cortex, and seed) on lipid oxidation, meat color, and metmyoglobin (MetMb) formation in raw pork patties were investigated and compared with that of butylated hydroxytoluene (BHT) during refrigerated storage at 4 degrees C for 8 days. The results indicated that the addition of leaf extract at 0.1% (w/w), roasted cortex extract at 0.1% (w/w), and BHT at 0.01% (w/w) decreased day 8 TBARS values by 35, 20, and 37%, respectively. Du-zhong leaf extract at 0.1% (w/w) also exhibited a certain stabilizing effect on meat redness a* value and retarded the formation of MetMb. This study suggests that Du-zhong leaf extract may be a potential source of natural antioxidants.

Anti-inflammatory effects of Artemisia princeps in antigen-stimulated T cells and regulatory T cells

Objectives

The aim was to investigate the anti-inflammatory effects of Artemisia princeps extract on the activity of anti-CD3/CD28-stimulated CD4+CD25- T cells and antigen-expanded regulatory T cells.

Methods

CD4+CD25- T cells were activated with coated anti-CD3 and anti-CD28 and cultured in the presence or absence of various concentrations of A. princeps extract. The cultures were pulsed on Day 6 with [3H]thymidine and, after harvesting the cells, [3H] thymidine incorporation was measured. For analysis of interleukin-2 and interferon-γ secreted from CD4+CD25- T cells, culture supernatants were collected on Days 2 and 6. For the analysis of interleukin-10 secreted from the CD4+CD25- T cells and expanded regulatory T cells, supernatants were collected after 2 and 7 days, respectively. Cytokine levels were determined using an enzyme-linked immunosorbent assay. Potential medicinal components of the A. princeps extract were determined using gas chromatography–mass spectrometry.

Key findings

A. princeps (30 μg/ml) effectively suppressed proliferation of CD4+CD25- T cells that were stimulated with anti-CD3/CD28 without causing cytotoxicity in spleen cells incubated under conditions lacking antigen stimulation. A. princeps inhibited production of the pro-inflammatory cytokines interleukin-2 and interferon-γ in anti-CD3/CD28-stimulated CD4+CD25- T cells. Also, the extract slightly increased production of the anti-inflammatory cytokine interleukin-10 in these cells. In regulatory T cells expanded by anti-CD3/CD28, A. princeps increased production of interleukin-10 and Foxp3.

Conclusions

The results suggest that A. princeps may be useful in the treatment of autoimmune diseases and organ transplantation rejection by inhibiting proliferation of inflammatory T cells, suppressing inflammatory processes in antigen-stimulated CD4+CD25- T cells and increasing activity of expanded regulatory T cells.

Coffee and Tea Consumption and Risk of Stroke Subtypes in Male Smokers

Background and Purpose— Coffee and tea consumption could potentially reduce the risk of stroke because these beverages have antioxidant properties, and coffee may improve insulin sensitivity. We examined the associations of coffee and tea consumption with risk of stroke subtypes.

Methods— We used prospective data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a cohort study of 26 556 male Finnish smokers aged 50 to 69 years without a history of stroke at baseline. Coffee and tea consumption was assessed at baseline using a validated food-frequency questionnaire. During a mean follow-up of 13.6 years, from 1985 through December 2004, 2702 cerebral infarctions, 383 intracerebral hemorrhages, and 196 subarachnoid hemorrhages were ascertained from national registries.

Results— After adjustment for age and cardiovascular risk factors, both consumption of coffee and tea was statistically significantly inversely associated with the risk of cerebral infarction but not intracerebral or subarachnoid hemorrhage. The multivariate relative risk of cerebral infarction for men in the highest category of coffee consumption (≥8 cups/d) was 0.77 (95% CI, 0.66 to 0.90; P for trend <0.001) compared with those in the lowest category (<2 cups/d). The corresponding relative risk comparing men in the highest category of tea consumption (≥2 cups/d) with those in the lowest category (nondrinkers) was 0.79 (95% CI, 0.68 to 0.92; P for trend=0.002).

Conclusions— These results suggest that high consumption of coffee and tea may reduce the risk of cerebral infarction among men, independent of known cardiovascular risk factors.

Glutamate-induced retinal lipid and protein damage: the protective effects of catechin

Glutamate toxicity has been implicated in various retinal diseases. Green tea leaf extract catechin has protective effects against cellular toxicity. This study investigated the effects of catechin on the glutamate-treated retina. Porcine retinal homogenates were incubated with glutamate (20 nmol) at 37 degrees C for 60 min. Catechin was co-incubated with the glutamate-treated retina in the same condition. The malondialdehyde (MDA) levels were determined as an index of lipid peroxidation (LPO). Differential protein expressions were derived from two-dimensional gel electrophoresis. Mass spectrometry was conducted to identify the proteins. Glutamate increased the retinal MDA (p<0.0001) and catechin reversed the effect (p<0.0001). There were significant changes in seven proteins after the glutamate treatment (p<0.05), namely, heterogeneous ribonucleoprotein, thioredoxin peroxidase, 5-hydroxytryptamine receptor, pyruvate dehydrogenase, ARHA protein, peroxiredoxin 6 and proteasome. Catechin significantly reversed the changes in thioredoxin peroxidase, 5-hydroxytryptamine receptor, peroxiredoxin 6 and pyruvate dehydrogenase (p<0.05). Our study shows that (a) retinal glutamate toxicity is mediated by LPO and protein modification, and (b) catechin ameliorates the toxicity.

Antiatherogenicity of extra virgin olive oil and its enrichment with green tea polyphenols in the atherosclerotic apolipoprotein-E-deficient mice: enhanced macrophage cholesterol efflux

The antiatherogenic properties of extra virgin olive oil (EVOO) enriched with green tea polyphenols (GTPPs; hereafter called EVOO-GTPP), in comparison to EVOO, were studied in the atherosclerotic apolipoprotein-E-deficient (E0) mice. E0 mice (eight mice in each group) consumed EVOO or EVOO-GTPP (7 microl/mouse/day, for 2 months) by gavage feeding. The placebo group received only water. At the end of the study, blood samples, peritoneal macrophages and aortas were collected. Consumption of EVOO or EVOO-GTPP resulted in a minimal increase in serum total and high-density lipoprotein (HDL) cholesterol levels (by 12%) and in serum paraoxonase 1 activity (by 6% and 10%). EVOO-GTPP (but not EVOO) decreased the susceptibility of the mouse serum to AAPH-induced lipid peroxidation (by 18%), as compared to the placebo-treated mice. The major effect of both EVOO and EVOO-GTPP consumption was on HDL-mediated macrophage cholesterol efflux. Consumption of EVOO stimulated cholesterol efflux rate from mouse peritoneal macrophages (MPMs) by 42%, while EVOO-GTPP increased it by as much as 139%, as compared to MPMs from placebo-treated mice. Finally, the atherosclerotic lesion size of mice was significantly reduced by 11% or 20%, after consumption of EVOO or EVOO-GTPP, respectively. We thus conclude that EVOO possesses beneficial antiatherogenic effects, and its enrichment with GTPPs further improved these effects, leading to the attenuation of atherosclerosis development.