Structure-antioxidant activity relationships of flavonoids and phenolic acids

http://www.dietcan.net/docs/Polifenoles%20en%20alimentos%20y%20biodisponibilidad.pdf

Polyphenols: food sources and bioavailability

Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.

The Effects of Plant Flavonoids on Mammalian Cells:Implications for Inflammation, Heart Disease, and Cancer

admission. This proportion could already be greater in some parts of the country and may increase if referrals of cases of self-poisoning increase faster than the facilities for their assessment and management. The provision of social work and psychiatric expertise in casualty departments may be one means of preventing unnecessary medical admissions without risk to the patients. Dr Blake's and Dr Bramble's figures do not demonstrate, however, that any advantage would attach to medical teams taking over assessment from psychiatrists except that, by implication, assessments would be completed sooner by staff working on the ward full time. What the figures actually suggest is that if assessment of overdoses were left to house doctors there would be an increase in admissions to psychiatric units (by 19°U), outpatients (by 5O°'), and referrals to social services (by 140o). So for house doctors to assess overdoses would provide no economy for the psychiatric or social services. The study does not tell us what the consequences would have been for the six patients who the psychiatrists would have admitted but to whom the house doctors would have offered outpatient appointments. E J SALTER

Vitamin D deficiency.

Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study.

Objective: To determine whether flavonoid intake explains differences in mortality rates from chronic diseases between populations. Design: Cross-cultural correlation study. Setting/Participants: Sixteen cohorts of the Seven Countries Study in whom flavonoid intake at baseline around 1960 was estimated by flavonoid analysis of equivalent food composites that represented the average diet in the cohorts. Main Outcome Measures: Mortality from coronary heart disease, cancer (various sites), and all causes in the 16 cohorts after 25 years of follow-up. Results: Average intake of antioxidant flavonoids was inversely associated with mortality from coronary heart disease and explained about 25% of the variance in coronary heart disease rates in the 16 cohorts. In multivariate analysis, intake of saturated fat (73%;P=.0001), flavonoid intake (8%;P=.01), and percentage of smokers per cohort (9%;P=.03) explained together, independent of intake of alcohol and antioxidant vitamins, 90% of the variance in coronary heart disease rates. Flavonoid intake was not independently associated with mortality from other causes. Conclusions: Average flavonoid intake may partly contribute to differences in coronary heart disease mortality across populations, but it does not seem to be an important determinant of cancer mortality. (Arch Intern Med. 1995;155:381-386)

https://jamanetwork.com/journals/intemed/articlepdf/620075/archinte_155_4_006.pdf

Flavonoid intake and long-term risk of coronary heart disease and cancer in the seven countries study.

Polyphenols and disease risk in epidemiologic studies

The content of the potentially anticarcinogenic flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin of 28 vegetables and 9 fruits was determined by RP-HPLC with UVdetection. Fresh foods were purchased in a supermarket, a grocery, and a street market and combined to composites. Processed foods were purchased additionally. Sampling was carried out in spring, summer, winter, and spring of the following year

Content of potentially anticarcinogenic flavonoids of 28 vegetables and 9 fruits commonly consumed in the Netherlands

Flavonoids are strong antioxidants that occur naturally in foods and can inhibit carcinogenesis in rodents. Accurate data on population-wide intakes of flavonoids are not available. Here, using data of the Dutch National Food Consumption Survey 1987-1988, we report the intake of the potentially anticarcinogenic flavonoids quercetin, kaempferol, myricetin, apigenin, and luteolin among 4,112 adults. The flavonoid content of vegetables, fruits, and beverages was determined by high-performance liquid chromatography. In all subjects, average intake of all flavonoids combined was 23 mg/day. The most important flavonoid was the flavonol quercetin (mean intake 16 mg/day). The most important sources of flavonoids were tea (48% of total intake), onions (29%), and apples (7%). Flavonoid intake did not vary between seasons; it was not correlated with total energy intake (r = 0.001), and it was only weakly correlated with the intake of vitamin A (retinol equivalents, r = 0.14), dietary fiber (r = 0.21), and vitamin C (r = 0.26). Our use of new analytic technology suggests that in the past flavonoid intake has been overestimated fivefold. However, on a milligram-per-day basis, the intake of the antioxidant flavonoids still exceeded that of the antioxidants beta-carotene and vitamin E. Thus flavonoids represent an important source of antioxidants in the human diet.

/pdf/intake-of-potentially-anticarcinogenic-flavonoids-and-their-4hwfoi2wxu.pdf

Peter C. H. Hollman

Papers

Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study.

Flavonoid intake and long-term risk of coronary heart disease and cancer in the seven countries study.

Polyphenols and disease risk in epidemiologic studies

Content of potentially anticarcinogenic flavonoids of 28 vegetables and 9 fruits commonly consumed in the Netherlands

Intake of potentially anticarcinogenic flavonoids and their determinants in adults in the Netherlands