Do efficacy and toxicity vary among different NK-1RA-based triple regimens for prevention of CINV? What is the optimal dose of dexamethasone?Journal of the National Cancer Institute (Source: Medscape Today Headlines)
MedWorm Message: Have you tried our new medical search engine? More powerful than before. Log on with your social media account. 100% free.
After completing tamoxifen or chemotherapy, how long does risk reduction for contralateral breast cancer last?Breast Cancer Research (Source: Medscape Today Headlines)
from ! Medicine by Alexandros G. Sfakianakis via alwin on Inoreader http://ift.tt/2sXOc7Y
via IFTTT
American teens may be becoming more conservative about sex. According to a new Centers for Disease Control and Prevention report reflecting data from 2011 to 2015, about 42 percent of girls and about 44 percent of boys ages 15-19 reported that they'd had sex. Both numbers continue a gradual decades-long decline: In 1988, 51 percent […]Related:Their daughter died of a 'brain-eating amoeba.' A year later, they are suing for $1 million.More U.S. counties are finding mosquitoes that can spread ZikaU2's The Edge talks up food as an anti-cancer weapon (Source: Washington Post: To Your Health)
from ! Medicine by Alexandros G. Sfakianakis via alwin on Inoreader http://ift.tt/2rFiyIq
via IFTTT
| Broader Benefit of CRT in Head and Neck Cancer? MedPage Today ... the National Cancer Database for the years 2004 to 2012. They searched for patients with newly diagnosed stage III-IVB squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx, treated with definitive surgery and adjuvant RT ... |
The risk of developing breast cancer in women who carry BRCA1 or BRCA2 mutations increases with the number of relatives who have a breast cancer diagnosis, a large prospective cohort study published...
The risk of developing breast cancer in women who carry BRCA1 or BRCA2 mutations increases with the number of relatives who have a breast cancer diagnosis, a large prospective cohort study published...
Interventions combining diet with physical activity and behavioural change can have a small, short term effect in reducing weight among children and adolescents who are overweight or obese, report...
Interventions combining diet with physical activity and behavioural change can have a small, short term effect in reducing weight among children and adolescents who are overweight or obese, report...
Flavonoids (or bioflavonoids) (from the Latin word flavus meaning yellow, their color in nature) are a class ofplant and fungus secondary metabolites.
Chemically, flavonoids have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and heterocyclic ring (C). This carbon structure can be abbreviated C6-C3-C6. According to the IUPACnomenclature,[1][2] they can be classified into:
The three flavonoid classes above are all ketone-containing compounds, and as such, are anthoxanthins (flavonesand flavonols). This class was the first to be termed bioflavonoids. The terms flavonoid and bioflavonoid have also been more loosely used to describe non-ketone polyhydroxy polyphenol compounds which are more specifically termed flavanoids. The three cycle or heterocycles in the flavonoid backbone are generally called ring A, B and C. Ring A usually shows a phloroglucinol substitution pattern.
Flavonoids are widely distributed in plants, fulfilling many functions. Flavonoids are the most important plant pigments for flower coloration, producing yellow or red/blue pigmentation in petals designed to attract pollinator animals. In higher plants, flavonoids are involved in UV filtration, symbiotic nitrogen fixation and floral pigmentation. They may also act as chemical messengers, physiological regulators, and cell cycle inhibitors. Flavonoids secreted by the root of their host plant help Rhizobia in the infection stage of their symbiotic relationship with legumes like peas, beans, clover, and soy. Rhizobia living in soil are able to sense the flavonoids and this triggers the secretion of Nod factors, which in turn are recognized by the host plant and can lead to root hair deformation and several cellular responses such as ion fluxes and the formation of a root nodule. In addition, some flavonoids have inhibitory activity against organisms that cause plant diseases, e.g. Fusarium oxysporum.[3]
Over 5000 naturally occurring flavonoids have been characterized from various plants. They have been classified according to their chemical structure, and are usually subdivided into the following subgroups (for further reading see[4]):
Anthoxanthins are divided into two groups:[5]
| Group | Skeleton | Examples | |||
|---|---|---|---|---|---|
| Description | Functional groups | Structural formula | |||
| 3-hydroxyl | 2,3-dihydro | ||||
| Flavone | 2-phenylchromen-4-one | ✗ | ✗ |  | Luteolin, Apigenin, Tangeritin |
| Flavonol or 3-hydroxyflavone | 3-hydroxy-2-phenylchromen-4-one | ✓ | ✗ |  | Quercetin, Kaempferol, Myricetin, Fisetin, Galangin,Isorhamnetin, Pachypodol, Rhamnazin,Pyranoflavonols, Furanoflavonols, |
| Group | Skeleton | Examples | |||
|---|---|---|---|---|---|
| Description | Functional groups | Structural formula | |||
| 3-hydroxyl | 2,3-dihydro | ||||
| Flavanone | 2,3-dihydro-2-phenylchromen-4-one | ✗ | ✓ |  | Hesperetin, Naringenin, Eriodictyol,Homoeriodictyol |
| Group | Skeleton | Examples | |||
|---|---|---|---|---|---|
| Description | Functional groups | Structural formula | |||
| 3-hydroxyl | 2,3-dihydro | ||||
| Flavanonol or 3-Hydroxyflavanone or 2,3-dihydroflavonol | 3-hydroxy-2,3-dihydro-2-phenylchromen-4-one | ✓ | ✓ |  | Taxifolin (orDihydroquercetin),Dihydrokaempferol |
Include flavan-3-ols (flavanols), flavan-4-ols and flavan-3,4-diols.
| Skeleton | Name |
|---|---|
 | Flavan-3-ol (flavanol) |
 | Flavan-4-ol |
 | Flavan-3,4-diol (leucoanthocyanidin) |
Flavonoids (specifically flavanoids such as the catechins) are "the most common group of polyphenoliccompounds in the human diet and are found ubiquitously in plants".[6] Flavonols, the original bioflavonoids such as quercetin, are also found ubiquitously, but in lesser quantities. The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plant compounds (for instance alkaloids) mean that many animals, including humans, ingest significant quantities in their diet. Foods with a high flavonoid content include parsley,[7] onions,[7] blueberries and other berries,[7] black tea,[7] green tea and oolong tea,[7] bananas, all citrus fruits, Ginkgo biloba, red wine, sea-buckthorns, anddark chocolate (with a cocoa content of 70% or greater). Further information on dietary sources of flavonoids can be obtained from the US Department of Agriculture flavonoid database.[7]
Parsley, both fresh and dried, contains flavones.[7]
Blueberries are a dietary source of anthocyanidins.[7][8]
Black tea is a rich source of dietary flavan-3-ols.[7]
The citrus flavonoids include hesperidin (a glycoside of the flavanone hesperetin), quercitrin, rutin (twoglycosides of the flavonol quercetin), and the flavone tangeritin.
Flavonoids exist naturally in cocoa, but because they can be bitter, they are often removed from chocolate, even dark chocolate.[9] Although flavonoids are present in milk chocolate, milk may interfere with their absorption;[10][11] however this conclusion has been questioned.[12]
Peanut (red) skin contains significant polyphenol content, including flavonoids.[13][14]
| Food source | Flavones | Flavonols | Flavanones |
|---|---|---|---|
| Red onion | 0 | 4 - 100 | 0 |
| Parsley, fresh | 24 - 634 | 8 - 10 | 0 |
| Thyme, fresh | 56 | 0 | 0 |
| Lemon juice, fresh | 0 | 0 - 2 | 2 - 175 |
Food composition data for flavonoids were provided by the USDA database on flavonoids.[7] In the United States NHANES survey, mean flavonoid intake was 190 mg/d in adults, with flavan-3-ols as the main contributor.[17] In the European Union, based on data from EFSA, mean flavonoid intake was 140 mg/d, although there were considerable differences between individual countries.[16]
The main type of flavonoids consumed in the EU and USA were flavan-3-ols, mainly from tea, while intake of other flavonoids was considerably lower.[16][17]
Though there is ongoing research into the potential health benefits of individual flavonoids, neither theFood and Drug Administration (FDA) nor the European Food Safety Authority (EFSA) has approved any health claim for flavonoids or approved any flavonoids as pharmaceutical drugs.[18][19][20] Moreover, several companies have been cautioned by the FDA over misleading health claims.[21][22][23][24]
Flavonoids have been shown to have a wide range of biological and pharmacological activities in in vitrostudies. Examples include anti-allergic,[25] anti-inflammatory,[25][26] antioxidant,[26] anti-microbial(antibacterial,[27][28] antifungal,[29][30] and antiviral[29][30]), anti-cancer,[26][31] and anti-diarrheal activities.[32]Flavonoids have also been shown to inhibit topoisomerase enzymes[33][34] and to induce DNA mutations in the mixed-lineage leukemia (MLL) gene in in vitro studies.[35] However, in most of the above cases no follow up in vivo or clinical research has been performed, leaving it impossible to say if these activities have any beneficial or detrimental effect on human health. Biological and pharmacological activities which have been investigated in greater depth are described below.
Research at the Linus Pauling Institute and the European Food Safety Authority shows that flavonoids are poorly absorbed in the human body (less than 5%), with most of what is absorbed being quickly metabolized and excreted.[20][36][37] These findings suggest that flavonoids have negligible systemic antioxidant activity, and that the increase in antioxidant capacity of blood seen after consumption of flavonoid-rich foods is not caused directly by flavonoids, but is due to production of uric acid resulting from flavonoid depolymerizationand excretion.[38]
Inflammation has been implicated as a possible origin of numerous local and systemic diseases, such ascancer,[39] cardiovascular disorders,[40] diabetes mellitus,[41] and celiac disease.[42]
Preliminary studies indicate that flavonoids may affect anti-inflammatory mechanisms via their ability to inhibit reactive oxygen or nitrogen compounds.[43] Flavonoids have also been proposed to inhibit the pro-inflammatory activity of enzymes involved in free radical production, such as cyclooxygenase, lipoxygenaseor inducible nitric oxide synthase,[43][44] and to modify intracellular signaling pathways in immune cells,[43] or in brain cells after a stroke.[45]
Procyanidins, a class of flavonoids, have been shown in preliminary research to have anti-inflammatory mechanisms including modulation of thearachidonic acid pathway, inhibition of gene transcription, expression and activity of inflammatory enzymes, as well as secretion of anti-inflammatory mediators.[46]
Clinical studies investigating the relationship between flavonoid consumption and cancer prevention/development are conflicting for most types of cancer, probably because most studies are retrospective in design and use a small sample size.[47] Two apparent exceptions are gastric carcinomaand smoking-related cancers. Dietary flavonoid intake is associated with reduced gastric carcinoma risk in women,[48] and reduced aerodigestive tract cancer risk in smokers.[49]
Among the most intensively studied of general human disorders possibly affected by dietary flavonoids, preliminary cardiovascular diseaseresearch has revealed the following mechanisms under investigation in patients or normal subjects:[50][51][52][53][54]
Listed on the clinical trial registry of the US National Institutes of Health (July 2016) are 48 human studies completed or underway to study the dietary effects of plant flavonoids on cardiovascular diseases.[55]
However, population-based studies have failed to show a strong beneficial effect[56] which might be due to the considerably lower intake in the habitual diet of those investigated.
Flavonoids have been shown to have (a) direct antibacterial activity, (b) synergistic activity with antibiotics, and (c) the ability to suppress bacterialvirulence factors in numerous in vitro and a limited number of in vivo studies.[27][57] Noteworthy among the in vivo studies[58][59][60] is the finding that oral quercetin protects guinea pigs against the Group 1 carcinogen Helicobacter pylori.[60] Researchers from the European Prospective Investigation into Cancer and Nutrition have speculated this may be one reason why dietary flavonoid intake is associated with reduced gastric carcinoma risk in European women.[61] Additional in vivo and clinical research is needed to determine if flavonoids could be used as pharmaceutical drugs for the treatment of bacterial infection, or whether dietary flavonoid intake offers any protection against infection.
Flavonoid synthesis in plants is induced by light color spectrums at both high and low energy radiations. Low energy radiations are accepted byphytochrome, while high energy radiations are accepted by carotenoids, flavins, cryptochromes in addition to phytochromes. Thephotomorphogenic process of phytochome-mediated flavonoid biosynthesis has been observed in Amaranthus, barley, maize, Sorghum and turnip. Red light promotes flavonoid synthesis.[62]
Several recent research articles have demonstrated the efficient production of flavonoid molecules from genetically engineered microorganisms.[63][64][65]
Four pieces of magnesium filings are added to the ethanolic extract followed by few drops of concentrated hydrochloric acid. A pink or red colour indicates the presence of flavonoid.[66] Colours varying from orange to red indicated flavones, red to crimson indicated flavonoids, crimson to magenta indicated flavonones.
Sodium hydroxide testAbout 5 mg of the compound is dissolved in water, warmed and filtered. 10% aqueous sodium hydroxide is added to 2 ml of this solution. This produces a yellow coloration. A change in color from yellow to colorless on addition of dilute hydrochloric acid is an indication for the presence of flavonoids.[67]
p-Dimethylaminocinnamaldehyde testA colorimetric assay based upon the reaction of A-rings with the chromogen p-dimethylaminocinnamaldehyde (DMACA) has been developed for flavanoids in beer that can be compared with the vanillin procedure.[68]
Lamaison and Carnet have designed a test for the determination of the total flavonoid content of a sample (AlCI3 method). After proper mixing of the sample and the reagent, the mixture is incubated for 10 minutes at ambient temperature and the absorbance of the solution is read at 440 nm. Flavonoid content is expressed in mg/g of quercetin.[69]
Immobilized Candida antarctica lipase can be used to catalyze the regioselective acylation of flavonoids.[70]
|chapter=ignored (help) 
.PMID 20087468. doi:10.3390/ijms10114941. . PMID 26010916.doi:10.1371/journal.pone.0128132. . PMID 11160126. doi:10.1172/JCI11914. .PMID 24071942. doi:10.3390/ijms141019434. .PMID 18461976. doi:10.1021/tx8000785. . PMID 24029069. doi:10.1016/j.jnutbio.2013.06.003. .PMID 22606367. doi:10.3390/nu4040243. . PMID 24741667.doi:10.1002/acn3.54. .PMID 24069431. doi:10.1371/journal.pone.0075604. . PMID 23512608. doi:10.1007/s11883-013-0324-x. . PMID 19844590.doi:10.1616/1476-2137.14184. . PMID 12732539. doi:10.1128/AEM.69.5.2699-2706.2003. . PMID 22373191.doi:10.1186/2191-2858-1-14. 
