BOROVNICA PROTIV DIJABETESA
…i poremećaja metabolizma, oboljenja krvnožinog sustava, pretilnosti, bolesti jetre...[1] Ljubičasta boja pigmenata borovnice sadrži anthocyanins /v. flavonoidi/ i antioksidanse![2]
Nešto manje flavonoida sadrže brusnica, malina i kupina![3]
Opširnije:
Anthocyanin pigments are responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers. They have long been the subject of investigation by botanists and plant physiologists because of their roles as pollination attractants and phytoprotective agents. They have also been very useful in taxonomic studies. Even Linus Pauling was interested in related compounds called anthocyanidins—he discussed their chemical structure to illustrate the use of resonance in understanding structural problems in a 1939 paper. Food scientists and horticulturists continue to study these compounds because of their obvious importance to the color quality of fresh and processed fruits and vegetables. Our laboratory first started studying these compounds because of color degradation of strawberry preserves, fruit juice concentrates, and wine. Subsequent projects were designed to determine their utility as natural food colorants and to authenticate fruit juice.
Today, interest in anthocyanin pigments has intensified because of their possible health benefits as dietary antioxidants. Over 300 structurally distinct anthocyanins have been identified in nature. Anthocyanins are one class of flavonoid compounds, which are widely distributed plant polyphenols. Flavonols, flavan-3-ols, flavones, flavanones, and flavanonols are additional classes of flavonoids that differ in their oxidation state from the anthocyanins. Solutions of these compounds are colorless or pale yellow. Other phenolic compounds that comprise part of our diet include phenolic acids and their esters, such as chlorogenic acid and polymeric tannins. At least 5,000 naturally occurring polyphenolics have been identified, including over 2,000 flavonoids. The term polyphenolics is increasingly being used to describe phenolic-based compounds having similar solubility properties that are analyzed by high-performance liquid chromatography. The polyphenolic profile of fruit juices is likely to include flavonols, free and esterified phenolic acids, and procyanidins. Polyphenolics contribute to food and beverage color by serving as substrates for an enzyme to produce brown pigments. The procyanidins and condensed tannins provide astringency and bitterness in tea and wine.
There is considerable anecdotal and epidemiological evidence that dietary anthocyanin pigments and polyphenolics may have preventive and therapeutic roles in a number of human diseases. Through the much publicized “French paradox”, the public has become aware that certain populations of red-wine drinkers in France and Italy have much lower rates of coronary heart disease (CHD) than their North American and Northern European counterparts. It is widely accepted that red wine phenolics contribute at least partly to this beneficial effect. A number of studies have shown that mortality from CHD is inversely correlated with intake of flavonoids in the diet. Flavonoids may also help prevent strokes. While some flavonoids have been shown to inhibit tumor development, some experts have concluded that compounds other than flavonoids must be responsible for the anticancer effects of dietary fruits and vegetables.
The anthocyanin pigments of Bilberries (Vaccinium myrtillus) have long been used for improving visual acuity and treating circulatory disorders. There is experimental evidence that certain anthocyanins and flavonoids have anti-inflammatory properties, and there are reports that orally administered anthocyanins are beneficial for treating diabetes and ulcers and may have antiviral and antimicrobial activities. The chemical basis for these desirable properties of flavonoids is believed to be related to their antioxidant capacity—their ability to scavenge and trap free radicals that damage biomolecules. Some people believe that eventually we will have a recommended minimum daily requirement for these dietary antioxidants. Much remains to be learned, however, before that occurs. The antioxidant content of many foodstuffs is unknown, making accurate estimates for human consumption of flavonoids and the correlation with disease difficult. Our knowledge of the anthocyanin and polyphenolic composition of many fruits, vegetables and cereals is incomplete, and little is known about the effects of processing and cooking on these substances. It is also uncertain how much of the particular flavonoids are absorbed into the bloodstream and get to various cells.
A pilot project grant from the Linus Pauling Institute permitted us to investigate the antioxidant properties of dietary phenolics. Our lab supplied Dr. Vadim Ivanov of LPI with purified samples of sinapyl derivatives of glutathione that Ling Wen, Ph.D. candidate in Food Science, had identified in pineapple juice. These novel compounds have not been previously found in nature and are present as major compounds in pineapple juice. Their antioxidant capacity, as measured by photo-chemiluminescence methodology, was from 1-4 times greater than Trolox, which is a chemical analog of vitamin E. This initial work has led to several collaborative projects with LPI in which we are investigating the antioxidant capacities of various fruits and vegetables. [4]
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[1] A University of Maine
[2] ScienceDaily (Apr. 20, 2009)
[3] http://en.wikipedia.org/wiki/Anthocyanin
[4] http://lpi.oregonstate.edu/ss01/anthocyanin.html
Karlo Šoštarić
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