A wild blueberry-enriched diet (Vaccinium angustifolium) improves vascular tone in the adult spontaneously hypertensive rat

The effect of a wild blueberry-enriched diet on vasoconstriction and vasorelaxation was examined in the adult, 20-week-old spontaneously hypertensive rat (SHR) after 8 weeks of a control (C) or an 8% wild blueberry (WB) diet. Nitric oxide (NO)- and cyclooxygenase (COX)-mediated aortic responses were examined ex vivo with the agonists L-phenylephrine (Phe) and acetylcholine (Ach), in the absence or presence of the NO synthase (NOS) inhibitor L-NG-monomethyl arginine (L-NMMA) or the COX inhibitor mefenamic acid (MFA). The vasoconstriction elicited by Phe was reduced in the WB group, attributed to the NO pathway, favoring a lower vascular tone under basal conditions. Acetylcholine-induced vasorelaxation in the WB group was possibly mediated through the COX, but not the NO pathway. These findings document the potential of wild blueberries to modify major pathways of vasomotor control and improve the vascular tone in the adult SHR with endothelial dysfunction.     

Triterpenic compounds from "orujo" olive oil elicit vasorelaxation in aorta from spontaneously hypertensive rats

There is currently a considerable amount of interest in the benefits of certain dietary elements, and in particular of olive oil, in endothelial function and thus in hypertension. "Orujo" or pomace olive oil is obtained from the residues of the olive by a novel centrifugation process, and it is a good dietary source of triterpenic compounds such as oleanolic and maslinic acid, erythrodiol, and uvaol. Until now, there was no information available regarding the properties of these triterpenoids on the vasculature of hypertensive animals. However, in this in vitro study, we have analyzed the vasorelaxation induced by these triterpenoids in isolated aorta from spontaneously hypertensive rats (SHR). The triterpenoids tested induced concentration-dependent vasorelaxation, mostly involving nitric oxide (NO). Indeed, the responses were attenuated by removal of the endothelium or following pretreatment with the NO synthase inhibitor L-NAME. Furthermore, the differences that were observed in the potency of relaxation, the selectivity, and the dependence on the endothelium were attributed to structural features of the triterpenoids. In conclusion, triterpenic components in pomace olive oil induce vasorelaxation of the aorta from SHR, and this effect generally involves endothelial NO.     

Synthesis of (-)-[4-3H]epigallocatechin gallate and its metabolic fate in rats after intravenous administration

Because a great deal of attention has been focused on the metabolism of (-)-epigallocatechin gallate (EGCg), quantitative analysis of this compound is required. For this purpose we developed a method of chemical synthesis of [4-(3)H]EGCg. Synthesized [4-(3)H]EGCg showed 99.5% radiochemical purity and a specific activity of 13 Ci/mmol. To clarify the excretion route of EGCg, the radioactivity levels of bile and urine were quantified after intravenous administration of [4-(3)H]EGCg to bile-duct-cannulated rats. Results showed that the radioactivity of the bile sample excreted within 48 h accounted for 77.0% of the dose, whereas only 2.0% of the dose was recovered in the urine. The excretion ratio of bile to urine was calculated to be about 97:3. These results clearly showed that bile was the major excretion route of EGCg. Time-course analysis of the radioactivity in blood was also performed to estimate the pharmacokinetic parameters following intravenous administration of [4-(3)H]EGCg. In addition, EGCg metabolites excreted in the bile within 4 h after the intravenous dose of [4-(3)H]EGCg were analyzed by HPLC. The results showed that 4',4"-di-O-methyl-EGCg was present in the conjugated form and made up about 14.7% of the administered radioactivity.     

Effects of the food additive sulfite on nitrite-dependent nitric oxide production under conditions simulating the mixture of saliva and gastric juice

The food additive sulfite is mixed with saliva, which contains nitrite, in the oral cavity, and the mixture is mixed with gastric juice in the stomach. In the stomach, salivary nitrite can be transformed to nitric oxide (NO). In this study, the effects of sulfite on nitrite-dependent NO production were investigated using acidified saliva (pH 2.6) and acidic buffer solutions (pH 2.0). Sulfite enhanced NO production in acidified saliva and acidic buffer solutions, and the enhancement increased with the increase in sulfite concentration from 0 to 0.1 mM, whereas suppressed NO production and the suppression increased as the concentration was increased over 0.2 mM. The enhancement was due to the increase in reaction rate between nitrous acid and nitrososulfonate (ONSO(3)(-)) that was formed by the reaction of nitrous acid with hydrogen sulfite, and the suppression was due to the increase in hydrogen sulfite-dependent consumption rate of ONSO(3)(-). A salivary component SCN(-) (1 mM) enhanced and suppressed NO production induced by 1 mM nitrite when sulfite concentrations were lower and higher than 1 mM, respectively. ONSO(3)(-) formed from hydrogen sulfite and nitrosyl thiocyanate (ONSCN), which was produced by the reaction of nitrous acid with SCN(-), seemed to contribute to the enhancement and suppression. NO production induced by nitrite/ascorbic acid systems was suppressed by sulfite, and the suppressive effects were decreased by SCN(-), whereas sulfite-induced suppression of NO production in nitrite/rutin systems was increased by SCN(-). During reactions of nitrite with sulfite in the presence and absence of SCN(-), oxygen was taken up. The oxygen uptake is discussed to be due to autoxidation of NO and radical chain reactions initiated by hydrogen sulfite radicals. The results of the present study suggest that sulfite can enhance and suppress nitrite-dependent NO production. It is discussed that radicals including hydrogen sulfite radicals can be formed through the reactions of nitrite and sulfite in the stomach.     

一氧化氮对NaCl胁迫下苜蓿种子萌发的影响

以甘农4号、阿尔冈金2个品种苜蓿为材料,用一氧化氮(NO)供体硝普钠、NO 清除剂c-PTIO、一氧化氮合酶抑制剂N-硝基-L-精氨酸甲脂、硝酸还原酶抑制剂钨酸钾及硝普钠类似物亚铁氰化钠(不产生NO)处理苜蓿种子,研究NO对盐胁迫下苜蓿种子萌发的生理效应。结果表明,盐胁迫显著抑制了2个苜蓿品种的发芽率、胚芽和胚根长及幼苗干重(P<0.05),降低种子萌发过程中α、β-淀粉酶、蛋白水解酶活性,抑制淀粉水解和可溶性糖积累(P<0.05);盐胁迫下添加外源NO则使2个品种苜蓿α、β-淀粉酶、蛋白水解酶活性、种子发芽率显著提高(P<0.05),淀粉含量降低,可溶性糖含量升高、胚芽和胚根长及幼苗干重显著增加(P<0.05);NO 供体SNP 的类似物亚铁氰化钠对盐胁迫下苜蓿种子萌发的各项指标无明显影响;施用NO 清除剂c-PTIO、硝酸还原酶抑制剂钨酸钾和一氧化氮合酶抑制剂N-硝基-L-精氨酸甲脂具有降低苜蓿种子萌发的效应(P<0.05)。因此,盐胁迫抑制苜蓿种子的萌发,而添加外源NO是缓解这种抑制作用的有效途径,内源NO也可能参与盐胁迫下苜蓿种子萌发的调节,且通过NOS和NR途径产生的NO在缓解盐胁迫抑制苜蓿种子萌发中可能起关键作用。     

Polyphenol-induced inhibition of the response of na(+)/glucose cotransporter expressed in Xenopus oocytes

To study the effects of polyphenols on the Na(+)/glucose cotransporter (SGLT1) response, SGLT1 was expressed in Xenopus oocytes by injecting cRNA synthesized from the cloned cDNA of the small intestine cotransporter of rats, and the electrical response elicited by glucose or galactose was measured by a voltage clamping method. Most phenol derivatives had no effect on the response. However, the polyphenols (+)-catechin, (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg), which are components of green tea, caused an inhibition of the response, which was almost independent of glucose concentration. The inhibition constants were estimated to be 2.3 mM for (+)-catechin and 0.45 mM for both ECg and EGCg, assuming the noncompetitive inhibition mechanism. Saponin prepared from tea seeds also inhibited the response significantly. Tannic acid and aqueous extracts of teas induced nonspecific electrical responses in both cRNA-injected and noninjected oocytes at lower concentrations than those that caused an inhibition of the SGLT1 response when their dose-dependent effects were examined. These results are possibly helpful in the development of a dietary supplement for diabetic patients.     

Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.     

Malachite green influence on calcium (45Ca2+) absorption by sorghum root tips

Malachite green (MG) [N‐[4‐[[4‐dimethylamino)phenyl] phenyl‐methylene]‐2,5‐cyclohexadien‐l‐yl idene] ‐N‐methyl‐methanarninium chloride] (0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 mM) was evaluated for influence on calcium (⁴⁵Ca²⁺) absorption by 1‐cm root‐tips of sorghum [Sorghum bicolor (L.) Moench. cv GP‐10, SC283, SC574, and Funk G522DR]. Calcium (⁴⁵Ca²⁺) absorption was significantly decreased in all four cultivars at 0.1 mM. LD₅₀’s were Funk G522DR (0.15 mM), GP10 (0.25 mM), SC283 (0.30 mM), and SC574 (0.31 mM).     

一氧化氮对小鼠卵母细胞自发成熟的影响及作用机制

为研究一氧化氮（NO）供体硝普钠（nitroprusside sodium，SNP）对小鼠卵母细胞体外自发成熟的作用，并进一步探讨NO影响卵母细胞体外自发成熟的可能机制，我们采用了体外细胞培养方法和放射免疫分析法（RIA）。细胞培养研究结果显示，NO供体SNP（1mM）能够延迟卵丘卵母细胞复合体(cumulus-oocyte complexes, COCs) 自发成熟过程中GVBD的发生，抑制PB1的释放。放射免疫分析（RIA）实验结果表明，1mM SNP能够显著的升高COCs内cGMP的水平，而可溶性鸟苷酸环化酶（sGC）抑制剂ODQ（10μM）能够消除SNP对cGMP水平升高的促进作用。同时10μM ODQ还能够逆转SNP对卵母细胞自发成熟的抑制作用，而PKG抑制剂KT5823（1μM）却不能够逆转SNP对COCs自发成熟的抑制作用。以上结果说明NO是通过激活sGC，提高细胞内cGMP水平来发挥其作用的，但cGMP下游的PKG信号通路并不参与NO调控的COCs自发成熟过程。     

基于两种计算模型的油松与元宝枫根系固土效能分析

[目的]定量分析北方常见植物(油松、元宝枫)根系对提高土壤抗剪能力的作用,为更好地评价植物根系固土效能提供理论基础。[方法]选取不同根系面积比(RAR)的油松(Pinus tabulaeformis)根土复合体、元宝枫(Acer truncatum)根土复合体及素土分别进行了不同垂直压力下的直剪试验,得出了油松根土复合体、元宝枫根土复合体及素土的抗剪强度增量。并通过根系的拉伸试验测定了植物根系的抗拉强度,同时使用Wu的根土复合体模型和Pollen的纤维束模型对抗剪强度增量进行模拟并与实际测定的抗剪强度增量进行对比分析。[结果](1)根系主要通过增强土壤的黏聚力来增强土壤的抗剪切强度;(2)植物根系抗拉强度、拔出强度与根系直径都符合幂函数关系,抗拉强度和拔出强度大小存在阈值,根系大于2mm时,根系拔出强度小于根系抗拉强度,小于2mm时则反之;(3)Wu的根土复合体模型高估植物根系固土效果值平均为26.81%,而纤维束模型对根系提高土壤抗剪强度则平均高估9.82%。[结论]相对于Wu模型,纤维束模型对土壤的固土效果的计算更为准确。     

A tea catechin suppresses the expression of the high-affinity IgE receptor Fc epsilon RI in human basophilic KU812 cells

Human basophilic KU812 cells express the high-affinity IgE receptor Fc epsilon RI, which plays a central role in the IgE-mediated allergic response. The effect of several major tea catechins, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate (EGCg), on the cell surface expression of Fc epsilon RI in KU812 cells was studied. Flow cytometric analysis showed that only EGCg was able to decrease the cell surface expression of Fc epsilon RI after a 24 h treatment in a dose-dependent manner. Moreover, immunoblot analysis revealed that the total cellular expression of the Fc epsilon RI alpha chain decreased upon treatment with EGCg. Fc epsilon RI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. KU812 cells treated with EGCg expressed lower levels of Fc epsilon RI alpha and gamma mRNA than nontreated cells. These results suggest that EGCg has an ability to down-regulate Fc epsilon RI expression, and this suppressive effect may be due to the down-regulation of Fc epsilon RI alpha and gamma mRNA levels.     

Dynamic behavior of tea catechins interacting with lipid membranes as determined by NMR spectroscopy

Interaction between tea catechins, such as epicatechin gallate (ECg) and epigallocatechin gallate (EGCg), and isotropic bicelle model lipid membranes was investigated by solution NMR techniques. (1)H NMR measurements provided signals from the B-ring and the galloyl moiety in ECg and EGCg that were obviously shifted, and whose proton T1 relaxation times were shortened upon interaction of the catechins with the bicelles. These results indicate that the B-ring and the galloyl moiety play an important role in this interaction. Nuclear Overhauser effect spectrometry experiments demonstrated that the B-ring and the galloyl moiety are located near the gamma-H in the phospholipid trimethylammonium group. On the basis of these findings, we propose that ECg and EGCg interact with the surface of lipid membranes via the choline moiety.     

Physiological studies on salinity and nitrogen interaction in alfalfa plants: III. nitrate reductase activity

Nitrate reductase activity (NRA) was determined to investigate the effect of salinity and nitrogen (N) interactions on alfalfa [Medicago sativa (L) cv. Gilboa] during its vegetative growth. Increasing levels of sodium chloride (NaCl) (0, 30, 65, and 100 mM) decreased NRA in both plant parts, i.e., root and leaf, however to a lesser extent in leaves. The inclusion of Neither as nitrate (NO₃) or ammonium (NH₄) (0, 3, and 6 mM) to the nutrient medium resulted in a substantial enhancement of NR activity in salinized and non‐salinized plants as well.     

Metabolic fate of (-)-[4-(3)H]epigallocatechin gallate in rats after oral administration

After oral administration of [4-(3)H]EGCg to rats, the radioactivity in blood, major tissues, urine, and feces was measured over time. The radioactivity in blood and most tissues remained low for 4 h postdose, began to increase after 8 h, peaked at 24 h, and then decreased. Major urinary excretion of radioactivity occurred in the 8-24 h period, and the cumulative radioactivity excreted by 72 h was 32.1% of the dose. The radioactivity in the feces was 35.2% of the dose within 72 h postdose. In the case of rats pretreated with antibiotics (antibiotic-pretreated rats), the radioactivity levels of the blood and urine were definitely lower than those in rats not pretreated with antibiotics (normal rats). The radioactivity recovered in the antibiotic-pretreated rat urine was estimated to be only (1)/(100) of that in the normal rat urine. These results clearly demonstrated that the radioactivity detected in the blood and urine of normal rats mostly originated from degradation products of EGCg produced by intestinal bacteria. Furthermore, a main metabolite in the normal rats was purified and identified as 5-(5'-hydroxyphenyl)-gamma-valerolactone 3'-O-beta-glucuronide (M-2). In feces of the normal rats, EGC (40.8% of the fecal radioactivity) and 5-(3',5'-dihydroxyphenyl)-gamma-valerolactone (M-1, 16.8%) were detected. These results suggested that M-1 was absorbed in the body after degradation of EGCg by intestinal bacteria, yielding M-1 with EGC as an intermediate. Furthermore, M-2 was thought to be formed from M-1 in the intestinal mucosa and/or liver, then to enter the systemic circulation, and finally to be excreted in the urine. Taking into account all of the above findings, a possible metabolic route of EGCg orally administered to rats is proposed.     

Identification of the strong vasorelaxing substance scirpusin B, a dimer of piceatannol, from passion fruit (Passiflora edulis) seeds

Piceatannol is present in passion fruit (Passiflora edulis) seeds in high amounts. In this study, we isolated the second major polyphenolic compound of passion fruit seeds and identified it as scirpusin B, which is a dimer of piceatannol. We investigated the antioxidant activities and vasorelaxing effects of these polyphenols. Their antioxidant effects were measured using an in vitro 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and their vasorelaxant effects were determined ex vivo in rat thoracic aorta. Both polyphenolic compounds exhibited potent antioxidant activities and significant vasorelaxant effects in endothelium-intact aortas. More specifically, scirpusin B exerted a greater antioxidant activity and vasorelaxant effect compared with that of piceatannol. Additionally, the vasorelaxation effects of the compounds were induced via the NO derived from the endothelium. This study provides the possibility that polyphenols in passion fruit seeds are effective against cardiovascular diseases (CVDs).     

NO-AMPK通路对牛肉宰后成熟过程中蛋白特性与肉品质的影响

为研究宰后NO-AMPK通路对牛肉蛋白特性及肉品质的影响,以一氧化氮合成酶(NOS)抑制剂L-NAME、一磷酸腺苷活化蛋白激酶(AMPK)抑制剂Compound C处理的牛臀股四头肌为研究对象,生理盐水处理作为对照,将肉样与处理液在4℃条件下1:1(g:mL)混合浸泡12 h后,在成熟0、6、12、24、48、72、120 h测定肉样的蛋白功能特性、保水性、嫩度以及肌肉组织结构等相关指标。结果显示,L-NAME组中一氧化氮NO含量在6~72 h显著低于对照组(P<0.05);3组中AMPK活性先增大后减小,L-NAME组和Compound C组中AMPK活性在6 h分别比对照组降低14.78%和26.75%;L-NAME组中总蛋白溶解性在6、24 h低于Compound C组,高于对照组(P<0.05),表面疏水性在12、48 h显著低于对照组(P<0.05)并高于Compound C组;L-NAME组中剪切力仅在48 h显著高于对照组并低于Compound C组(P<0.05);对照组中肉样蒸煮损失最大,Compound C组中肉样蒸煮损失最小。以上结果表明,牛肉宰后成熟过程中,NO能够通过AMPK通路改善牛肉嫩度,但对其保水性产生了不利影响。本研究结果可为牛肉宰后能量代谢及肉品质控制相关研究提供一定的理论基础。     

Effect of 3-O-octanoyl-(+)-catechin on the responses of GABA(A) receptors and Na+/glucose cotransporters expressed in xenopus oocytes and on the oocyte membrane potential

Recently, 3-O-octanoyl-(+)-catechin (OC) was synthesized from (+)-catechin (C) by incorporation of an octanoyl chain into C in the light of (-)-epicatechin gallate (ECg) and (-)-epigallocatechin gallate (EGCg), which are the major polyphenols found in green tea and have strong physiological activities. OC was found to inhibit the response of ionotropic gamma-aminobutyric acid (GABA) receptors (GABA(A) receptors) and Na+/glucose cotransporters expressed in Xenopus oocytes in a noncompetitive manner more strongly than does C. OC also induced a nonspecific membrane current and decreased the membrane potential of the oocyte, and thus death of the oocyte occurred even at lower concentrations than that induced by C or EGCg. Although EGCg produced H2O2 in aqueous solution, OC did not. This newly synthesized catechin derivative OC possibly binds to the lipid membrane more strongly than does C, Ecg, or EGCg and as a result perturbs the membrane structure.     

Determinants of Summer Nitrate Concentration in a Set of Adirondack Lakes,New York

Following reductions in the emission and deposition of sulfur compounds in the past decade, atmospheric deposition of nitrogen has become a focus of concern. Identification of watershed characteristics that mediate the effect of atmospheric nitrogen deposition can help evaluate the sensitivity of lakes to chronic and episodic nitrogen addition. Twenty four lakes in the southwestern portion of the Adirondack Park, New York, U.S.A., were classified into three N classes by cluster analysis of lakewater NO3- N concentration [N] during the summers of 1994–1996. The lake-N classes were best characterized as having (1) low [N] throughout the summer, (2) high [N] in early- but low [N] in late-summer, and (3) high [N] throughout the summer. The three lake-N classes were reconstructed perfectly by canonical discriminant analysis based mainly on lake average depth (AD), and lakewater concentrations of chlorophyll a [Chla] and SO4-S [S] in mid-summer. Increases in AD and [S], but decrease in [Chla] corresponded with a transition from low- to high-N classes.     

From field to health: a simple way to increase the nutraceutical content of grape as shown by NO-dependent vascular relaxation

Polyphenolic grapevine components involved in plant resistance against pathogens possess various pharmacological properties that include nitric oxide (NO)-dependent vasodilation and anti-inflammatory and free radical scavenging activities, which may explain the protective effect of moderate red wine consumption against cardiovascular disease. The aim of this work was (a) to verify the possibility that preharvest treatments of grapevine with a plant activator, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), could lead to an enriched nutraceutical potential of wine and (b) to characterize the profile of metabolites responsible for pharmacological activity. Plant spraying at the end of veraison, with a water suspension of BTH (0.3 mM), led to increased whole anthocyanin content as confirmed by HPLC comparative analysis. Extracts from berry skins of BTH-treated grapevines caused NO-dependent vasorelaxation, with a concentration-response curve that was significantly shifted to the left of the control non-BTH-treated curve. Moreover, 1:1000 dilutions of berry extracts from BTH-treated plants significantly increased basal production of guanosine 3',5'-cyclic monophosphate (cGMP) in human vascular endothelial cells when compared to the corresponding extracts of untreated plants. These results show that BTH treatment increases anthocyanin content of grape extracts, as well as their ability to induce NO-mediated vasoprotection. No increase of anthocyanin content was observed in the wine extracts from BTH-treated vines. It is concluded that BTH treatment could be exploited to increase the nutraceutical potential of grapes.     

Inhibition of Df-protease associated with allergic diseases by polyphenol.

It was reported that Df-protease from house dust mite (Dermatophagoides farinae) catalyzes the activation of the kallikrein-kinin system in human plasma and is closely associated with mite-induced allergy. Therefore, to prevent the release of kinin by Df-protease, the inhibitory activity of polyphenols including catechins and flavonols was tested in vitro and in vivo. Among them, myricetin and epigallocatechin gallate (EGCg) effectively inhibited the amidase activity of Df-protease with K(i) values of 1 x 10(-)(8) and 6 x 10(-)(4) M, respectively. The kinin release in human plasma was extensively inhibited by the addition of EGCg in comparison with myricetin. Enhancement of vascular permeability in guinea pigs caused by Df-protease was markedly suppressed by EGCg.