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Flavonoids
Which foods contain flavonoids
Flavonoids are polyphenolic compounds present in vegetables, fruits, berries and beverages such as tea, red wine and fruit juices, having similar effects as antioxidants. Especially green vegetables, onions, apples, berries and tea are rich sources of flavonoids. Actually, ‘flavonoids’ form a group of many different compounds of which more than 5000 have been currently characterised. Flavonoids can be classified into several subclasses according to their chemical structure.
The health effects of flavonoids have been intensively investigated for the last ten years. It has been proposed that flavonoids may protect against damage in blood vessels, thus decreasing the risk of cardiovascular diseases. In addition, they may have a role in cancer prevention and enhancement of the immune system of the body. More information about the potential health effects of flavonoids can be found on this website.
Currently there are no recommendations on the intake of flavonoids, like there is for example for vitamins and minerals. More research is needed for creating the recommendations. At the moment it is suggested to eat vegetables, fruit and berries plentifully to ensure your flavonoid intake and optimal health!
Studies of structure-activity relationship on plant polyphenol-induced suppression of human liver cancer cells.
Loa J, Chow P, Zhang K. Cancer Chemother Pharmacol. 2008 Sep 3. [Epub ahead of print]
Department of Experimental Surgery, Singapore General Hospital, BLK 9, Level 3, Outram Road, Singapore, 169608, Singapore.
PURPOSE: To study anticancer activities of 68 plant polyphenols with different backbone structures and various substitutions and to analyze the structure-activity relationships.
METHODS: Antiproliferative activity of 68 plant polyphenols on human liver cancer cells were screened by the 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide method. Structure-activity relationships were analyzed by comparison of their activities with selected structures. Cell cycle progression was assayed by flow cytometry analysis and apoptosis was analyzed by DNA fragment assay.
RESULTS: Based on their backbone structures, 68 polyphenols were sub-classed to flavonoids (chalcones, flavanones, flavones and isoflavones), chromones and coumarins. The order of their potency to suppress the human liver cancer cells is chalcones > flavones > chromones > isoflavones > flavanones > coumarins. Chalcones comprise the most potent group with IC(50) values ranging from 21.69 to 197 microM. Top nine most potent chalcones in the group have hydroxylation at 2'-carbon position in B-ring. Flavones ranked second in their potencies. Quercetin, 4-hydroxyflavone and luteolin are three hydroxyflavones with highest potencies in this group. Their IC(50) values are 30.81, 39.29 and 71.17 microM, respectively.
Chromones, isoflavones, flavanones and coumarins showed much lower potencies when compared to the first two groups with IC(50) ranges of 61 to >400, 131 to >400, 138 to >400 and 360.85 to >400 microM, respectively. In mechanistic studies, the most potent chalcone, 2,2'-dihydroxychalcone could induce G2/M arrest and then apoptosis of the cancer cells.
CONCLUSIONS: An analysis of structure-activity relationship showed that following structures are required for their inhibitory potencies on human liver cancer cells: (1) of the six sub-classes of the polyphenols tested, the unique backbone structure of chalcones with a open C-ring; (2) within the chalcone group, hydroxyl substitution at 2'-carbon of B-ring; (3) hydroxyl substitution at 3'-carbon in B-ring of flavones. However, some other structures were found to decrease their potencies: e.g. substitutions by sugar moieties in flavones. These data are valuable for design and modification of new polyphenols, which could be potential antiproliferative agents of cancer cells.
Role of flavonoids as antioxidants in human organism
MiPol Merkur Lekarski. 2008 Jun;24(144):556-60.
ller E, Malinowska K, Gałecka E, Mrowicka M, Kedziora J.
III Szpital Miejski w Lodzi, Oddział i Poradnia Rehabilitacji. betty.miller@interia.pl
The increasing interest in flavonoids means higher demand for the complex and synthetic knowledge about those substances. The following study is an overview of the contemporary knowledge about the mentioned substances, and hopefully it will magnify this topic.
Flavonoids are the ingredients of many nutrition substances and a vital diet element. They are also a group of many medicines with different influence on live organisms. At the moment, there are over hundreds of bio-flavonoids identified. The phenol compounds are used as natural drugs in the cases of various sicknesses of blood, breathing, food, and urinary circuit, and in dermatology as well. The existence of these compounds in the diet, especially maintenance of their proper consumption level, is a very important element in the prevention of many diseases, such as atherosclerosis.
The intensity of experimental studies on flavonoids in the last decade (mainly studies on cell cultures) showed varied attributes of these compounds. The results give hope for the use of flavonoids in prevention and neoplasmatic treatment. Phenol compounds as antioxidants may affect in many different aspects: direct reaction with free radicals, scavenging free radicals, growing dismutation of free radicals to the compounds with much lower reactiveness, chelatation of pro-oxidant metals (mainly iron), delaying or strengthening many enzymes. What is more, they can strengthen the functionality of other antioxidants, such as vitamins resolving in fat, and low-molecular substances resolving in water. The wide spectrum of the functions of flavonoids and their synthetic derivatives gives hope for the research of new chemical compounds (drugs) with exploratory characteristics.
Studies:
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