This review summarizes the current knowledge of condensed tannins (proanthocyanidins), their chemical structure, classification and biological effects. These compounds are widely distributed in higher plants and are an important part of the human diet. Recent interest in these substances has been stimulated by their potential health benefits, which are believed to arise mainly from their antioxidant activity. The mechanisms of their antioxidation action, like free radical scavenging activity, chelation of transition metals and inhibition of prooxidative enzymes and lipid peroxidation are discussed. Health prevention properties like anticarcinogenic, cardiovascular system preventing and antiinflammatory effects of proanthocyanidins are also presented. Their health benefit is promising, but additional research on the mechanism of action and metabolic fate after consumption of proanthocyanidins is required.
Plants and their secondary metabolites, including flavonoids, exhibit a wide range of biological effects. Consequently, natural substances are receiving an increased attention in medicinal research. Owing to these facts, in vitro antiplatelet activity of ethanol summary extract and four flavonoids from Leuzea carthamoides was determined in human platelet-rich plasma. Arachidonic acid (AA), adenosine diphosphate (ADP), collagen (COL), and thrombin were used as agonists of platelet aggregation. The summary extract showed a significant inhibition of the aggregation induced by COL and ADP. Of the tested flavonoids, eriodictyol (1) and patuletin (2) influenced COL- and AA-induced aggregation. Their IC(50) values are presented. Flavonoid glycosides eriodictyol-7-beta-glucopyranoside (3) and 6-hydroxykaempferol-7-O-(6''-O-acetyl-beta-D[small cap]-glucopyranoside) (4) were found to be weak antiplatelet agents. These results confirmed the fact that glucosylation decreases the antiplatelet activity. Quantitative composition of tested flavonoids in L. carthamoides extract was also determined. Though two of the tested flavonoids inhibited platelet aggregation, further evaluation of L. carthamoides, in order to discover other antiplatelet active compounds and possible adverse health effects, is needed.
- MeSH
- adenosindifosfát metabolismus MeSH
- agregace trombocytů účinky léků MeSH
- chromony farmakologie MeSH
- financování organizované MeSH
- flavanony farmakologie MeSH
- flavonoidy farmakologie izolace a purifikace MeSH
- inhibitory agregace trombocytů farmakologie izolace a purifikace MeSH
- kempferoly farmakologie MeSH
- kolagen metabolismus MeSH
- kyselina arachidonová metabolismus MeSH
- Leuzea chemie MeSH
- lidé MeSH
- listy rostlin MeSH
- techniky in vitro MeSH
- thrombin metabolismus MeSH
- trombocyty metabolismus účinky léků MeSH
- vyšetření funkce trombocytů MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC(50) parameter. 29 extracts exhibited IC(50) value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC(50) = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4',5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3', 4'- tetrahydroxyflavanone (eriodictyol) (2), 3',4',5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-beta-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6''-O-acetyl-beta-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.
- MeSH
- antioxidancia farmakologie chemie MeSH
- Asteraceae chemie MeSH
- bifenylové sloučeniny MeSH
- biologické přípravky farmakologie chemie MeSH
- chromany (dihydrobenzopyrany) chemie izolace a purifikace MeSH
- financování organizované MeSH
- hydraziny MeSH
- Leuzea chemie MeSH
- molekulární struktura MeSH
- pikráty MeSH
- preklinické hodnocení léčiv MeSH
- quercetin chemie izolace a purifikace MeSH
- Rhodophyta chemie MeSH
- rostlinné extrakty farmakologie chemie izolace a purifikace MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Geografické názvy
- Evropa MeSH
