Absorption and DNA protective effects of flavonoid glycosides from an onion meal

Summary Background. It is widely believed that antioxidant micronutrients obtained from fruit and vegetables afford significant protection against cancer and heart disease, as well as ageing. Flavonoids are potential antioxidants found in food such as onions; information on their effectiveness in vivo is so far lacking. Aims. To determine uptake as well as in vivo antioxidant effects of flavonoids from foods. Methods. Six healthy non-obese normocholesterolaemic female volunteers in the age range 20–44 years participated in a randomised two-phase crossover supplementation trial to compare the antioxidant effects associated with (a) a meal of fried onions and (b) a meal of fried onions and fresh cherry tomatoes. Plasma flavonoids, lymphocyte DNA damage, plasma ascorbic acid, tocopherols and carotenoids, urinary malondialdehyde and 8-hydroxy-2’-deoxyguanosine were determined to assess flavonoid absorption and antioxidant efficacy. Results. Flavonoid glucosides (quercetin-3-glucoside and isorhamnetin-4-glucoside) were significantly elevated in plasma following ingestion of the onion meal and the increases were associated with an increased resistance of lymphocyte DNA to DNA strand breakage. A significant decrease in the level of urinary 8-hydroxy-2’-deoxyguanosine was evident at 4 h following ingestion of the onion meal. After the combined tomato and onion meal, only quercetin was detected in plasma. Endogenous base oxidation was decreased but resistance to strand breakage was unchanged. There was no significant change in the excretion of urinary malondialdehyde following either meal. Conclusion. Both meals – onions, and onions together with tomatoes – led to transient decreases in biomarkers of oxidative stress, although the particular biomarkers affected differ. It is possible that the differences in patterns of response reflect the different uptakes of flavonoids but the underlying mechanism is not understood. Received: 1 April 2000, Accepted: 1 August 2000     

In vitro receptor screening of pure constituents of St. John's wort reveals novel interactions with a number of GPCRs

RATIONALE: Hypericum perforatum L. (St. John's wort; SJW) is one of the leading psychotherapeutic phytomedicines and great effort has been devoted to clarifying its mechanism of action. OBJECTIVE: We have undertaken a comprehensive analysis of several pure compounds isolated from the crude extract to gain further insight into the molecular actions of various substituents of SJW. METHODS: We characterized the in vitro pharmacology of the naphthodianthrones hypericin and pseudohypericin, the phloroglucinol derivative hyperforin, and several flavonoids at 42 biogenic amine receptors and transporters using the resources of the National Institute of Mental Health Psychoactive Drug Screening Program. RESULTS: The biflavonoid amentoflavone significantly inhibited binding at serotonin (5-HT(1D), 5-HT(2C)), D(3)-dopamine, delta-opiate, and benzodiazepine receptors. The naphthodianthrone hypericin had significant activity at D(3)- and D(4)-dopamine receptors and beta-adrenergic receptors. With the exception of the D(1)-dopamine receptor, the phloroglucinol derivative hyperforin was less active than other SJW constituents tested on all screened receptors. CONCLUSION: Our present in vitro data clearly show that several pure substances in SJW are potential CNS psychoactive agents and may contribute to the antidepressant efficacy of the plant in a complex manner. Our data also reveal novel and heretofore unexpected interactions of pure compounds in SJW at a number of GPCRs, transporters, and ion channels. We hypothesize that additive or synergistic actions of different single compounds may be responsible for the antidepressant efficacy of SJW. These results and this general approach may impact our understanding of phytomedicines in general and H. perforatum specifically.     

Stability and antioxidant activity of polyphenols in extracts of Myrtus communis L. berries used for the preparation of myrtle liqueur

Flavonoids and anthocyanins in berry extracts from Myrtus communis, prepared by following a typical Sardinia myrtle liqueur recipe, were identified by HPLC coupled with Electrospray Mass Spectrometry and quantified by HPLC coupled with Ultraviolet/Visible Detection in order to evaluate the stability of the extracts during 1 year of storage. Antioxidant activity was measured by using TEAC assay, and the free-radical scavenging activity was monitored during time of the stability evaluation.Anthocyanins have found to be the most instable compounds, but a considerable instability was observed also for flavonoids, suggesting the use of extracts not over 3 months from their preparation. The myrtle extract showed interesting free-adical scavenging activity. Antioxidant activity was preserved in 3 months.     

马蔺地下部分的化学成分

目的:研究鸢尾科鸢尾属植物马蔺(Iris lactea Pall.var.chinensis(Fisch.)koidz.)地下部分的化学成分.方法:采用70%乙醇提取,硅胶柱层析分离及重结晶等方法分离其化学成分,通过波谱及化学方法进行结构鉴定.结果:分离并鉴定了10个化合物,分别为:5-羟基-7-甲氧基黄酮(tectochrysin,Ⅰ)、5,2'-二羟基-6,7-亚甲二氧基二氢黄酮(5,2'-dihydroxy-6,7-methylenedioxyflavanone,Ⅱ)、5,7-二羟基-6,2'-二甲氧基异黄酮(5,7-dihydroxy-6,2'-dimethoxyisoflavone,Ⅲ)、4',5-二羟基-6,7-二甲氧基异黄酮(4',5-dihydroxy-6,7-dimethoxyisoflavone,Ⅳ)、4',5,7-三羟基-6-甲氧基异黄酮(tectorigenin)(4',5,7-trihydroxy-6-methoxyisoflavone,Ⅴ)、5,3'-二羟基2'-甲氧基-6,7-亚甲二氧基异黄酮(5,3'-dihydroxy-2'-methoxy-6,7-methylenedioxyisoflavone,Ⅵ)、5,2'-二羟基-6,7-亚甲二氧基异黄酮(5,2'-dihydroxy-6,7-methylenedioxyisoflavone,Ⅶ)、irisoid D(Ⅷ)、irisoid A(Ⅸ)和十七烷酸(heptadecanoic acid,X).结论:这些化合物均为在该植物中首次分得,其中化合物Ⅵ为本属植物中首次发现.     

Development of a database of critically evaluated flavonoids data: application of USDA's data quality evaluation system

The USDA Special Interest Database for flavonoid content of selected foods contains 26 most abundant compounds within 5 predominant subclasses of flavonoids–flavonols, flavones, flavanones, flavan-3-ols, and anthocyanidins. All the data were evaluated for 5 quality evaluation categories (sampling plan, sample handling, analytical method, analytical quality control and number of samples), using the data quality evaluation system developed by the USDA scientists. Confidence Codes (A–through D) were then assigned to every value. The database contains acceptable values for 225 selected foods. Only 97 sources out of approximately 475 collected included acceptable analytical data. The overall quality of data was good with 64% of the observations receiving A or B confidence codes; the flavan-3-ols subclass received better ratings than other subclasses. While this is the first comprehensive database for flavonoids in foods, the majority of data came from Europe and countries other than the US. Due to the observed variability in the values it will be important to have data for US foods. The evaluation of data quality helps set priorities and further identifies the foods to be analyzed as well as areas to improve data quality. Furthermore, release of data quality confidence codes with data provides necessary information to investigators to assess the impact of flavonoid intake on risk of various chronic diseases.     

黄精根茎及须根中相关成分的分析

目的：黄精根茎与须根相关成分分析。方法：薄层层析法检测。结果：南京地区典精中含有多糖，几乎不含黄酮、蒽醌类化合物。结论：根茎与须根成分基本相同。     

Studies on the Chemical Constituents of Epimedium koreanum Nakai and Epimedium wanshanense,S.Z.He et Guo

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Modulation of MPP<Superscript>+</Superscript> uptake by tea and some of its components in Caco-2 cells

The entry of most xeno/endobiotics into the organism is limited by their intestinal absorption. The interference of certain foods with the therapeutic efficacy of drugs or with chemical toxicity is becoming evident and growing attention is being given to these subjects. The aim of this work was to study the effect of green tea (GT) and black tea (BT), as well as some of their components, on the transport of organic cation molecules. For this purpose, ³H-MPP⁺ (radiolabeled 1-methyl-4-phenylpyridinium) was used as a model organic cation and Caco-2 cells were used as an intestinal epithelial model. Our results showed that both GT and BT significantly increased ³H-MPP⁺ absorption in these cells. Additionally, we studied the effect of epigallocatechin-3-gallate (EGCG), myricetin, caffeine, and theophylline. Whereas EGCG (2 mM) increased, myricetin (50 μM) and caffeine (1 mM) decreased, and theophylline (1 mM) had no effect on the uptake of ³H-MPP⁺ into Caco-2 cells. When GT was supplemented with caffeine or theophylline, we observed a partial loss of its effect. When BT was supplemented with EGCG, its ability to increase ³H-MPP⁺ uptake was much more pronounced than that observed with BT alone. In conclusion, this study showed that GT and BT might interfere with the absorption of the model organic cation MPP⁺ by the intestinal epithelium. Since important compounds are organic cations, the consequences of this interference may have an impact on human health. Although this constitutes only preliminary work and further studies are needed, tea should be included in the growing list of foodstuffs that have the potential to be involved in food–drug interactions.     

Potential role of flavonoids in the prevention of intestinal neoplasia: a review of their mode of action and their clinical perspectives

Intestinal neoplasia (adenomas and carcinomas) can possibly be prevented by a diet rich in vegetables and fruits, treatment with aspirin and other nonsteroidal antiinflammatory drugs, and early colonoscopic removal of adenomas. Ballast, fiber, and secondary plant products could play a major role in colon cancer prevention. Recently there has been much experimental work in vitro and in vivo about flavonoids as inducers of bioprevention. Flavonoids are secondary plant products with a wide variety of beneficial biological properties, and they possess anticarcinogenic, antimutagenic, and antioxidative modes of actions. Flavonoids are the main components of a healthy diet containing fruits and vegetables and are concentrated especially in tea, apples, and onions. We will focus this review on flavonoids which are derived from tea products such as proanthocyanidins (green tea) and flavons (camomille tea). Oral supplementation with bioflavonoids derived from tea could be used in humans to prevent growth of intestinal neoplasia such as adenomatous polyps of the colon. Flavonoids are a large group of natural compounds of which only a few have been used in animal models, cell cultures, and enzyme studies to inhibit mutagenic and carcinogenic events. Their clinical mode of action was evaluated by epidemiological studies, but no intervention studies in humans have been performed so far. In vitro flavonoids can bind electrophils, inactivate oxygen radicals, prevent lipid peroxidation, and inhibit DNA oxidation. In cell cultures they increase the rate of apoptosis, inhibit cell proliferation, and angiogenesis. In vivo they can induce the activities of protective enzymes (conjugating enzymes such as glutathione transferases and glucuronosyl transferases) of the intestine and the liver. In models of intestinal polyposis, flavonoids suppress polyp formation. Some epidemiological studies show a protective effect of flavonoids contained in fruits, vegetables, and tea.Flavonoid mixtures of tea origin supplied as nutritional supplements could be studied as a new way of bioprevention of intestinal neoplasia (colon adenomas and cancer). Therefore, a controlled, randomized clinical study should be performed to evaluate the efficacy of flavonoids.     

Antimycobacterial activity and cytotoxicity of flavonoids from the flowers of<Emphasis Type="Italic">Chromolaena odorata</Emphasis>

From the flowers of Chromolaena odorata (Eupatorium odoratum) four flavanones, isosakuranetin (5,7-dihydroxy-4'-methoxyflavanone) (1), persicogenin (5,3'-dihydroxy-7,4'-dimethoxyflavanone) (2), 5,6,7,4'-tetramethoxyflavanone (3) and 4'-hydroxy-5,6,7-trimethoxyflavanone (4), two chalcones, 2'-hydroxy-4,4',5',6'-tetramethoxychalcone (5) and 4,2'-dihydroxy-4',5',6'-trimethoxychalcone (6), and two flavones, acacetin (5,7-dihydroxy-4'-methoxyflavone) (7) and luteolin (5,7,3',4'-tetrahydroxyflavone) (8) were isolated and identified. Compound 1 exhibited moderate antimycobacterial activity against Mycobacterium tuberculosis with the MIC value of 174.8 microM, whereas compounds 4, 7, and 8 exhibited weak activity with the MIC values of 606.0, 704.2 and 699.3 microM respectively. Compound 7 showed moderate cytotoxicity against human small cell lung cancer (NCI-H187) cells with the MIC value of 24.6 microM, whereas compound 8 exhibited moderate toxicity against NCI-H187 cells and week toxicity against human breast cancer (BC) cells with the MIC values of 19.2 and 38.4 microM respectively.