Flavonoids and bioflavonoids what they are and why take them
Flavonoids or bioflavonoids are natural compounds widely present in the plant world. They represent a large class of phenolic compounds widespread in the plant world. They are secondary metabolites produced by plants. Flavonoids are a vast class of phenolic compounds that includes more than 6,000 different molecules. They are able to exert various biological activities that are very useful for the body. Hence the importance for health recognized to these compounds. Among the properties of flavonoids, the most interesting is the antioxidant action, the protective action on the microcirculation, the estrogen-like action and the anti-inflammatory action. In the field of medical-pharmaceutical research, the potential anticancer properties and the preventive/beneficial role that these compounds would be able to exert in the presence of diseases of different origin and nature are mainly (but not exclusively) investigated. 
Types and classification of bioflavonoids from a chemical point of view
At the moment well over 6,000 molecules belonging to the large group of flavonoids are known. The classification of so many compounds involves the division into different groups and subgroups containing molecules different in structure and activity. They are divided according to the position on the C ring to which the B ring is attached and according to the degree of unsaturation and oxidation of the C ring. Depending on the carbon of the C ring to which the B ring is attached, it is possible to distinguish:
- Flavonoids or bioflavonoids in which the B ring is bound on carbon number 2 of the C ring (the chemical structure is the one listed in the figure above).
- Isoflavonoids, in which the B ring is bonded to carbon number 3 of the C ring (position 3).
- Neoflavonoids, in which the B ring is bound to carbon number 4 of the C ring (position 4).
Isoflavonoids and Neoflavonoids – Basic Skeleton of Chemical Structure
Furthermore, depending on the degree of unsaturation and oxidation of the C ring and depending on the different substitutions on all rings, it is possible to distinguish different subgroups:
- Flavonoids or bioflavonoids in which the B ring is bound at position 2 can be further divided into:
- Flavones (apigenin and luteolin);
- Flavonols (quercetin, rutin and kaempferol);
- Flavanones (naringerin and hesperetin);
- Flavanols, better known as catechins or as flavan-3-ols;
- Flavans;
- Anthocyanins (cyanidin), well known because they are responsible for the pigmentation of some plants, flowers and fruits of purple-blue color (blueberry, red grapes, blackcurrants, etc.);
- Chalcones (arbutin). Unlike all the other subgroups, chalcones do not have in the skeleton of their structure the three rings mentioned in the chapter above because the C ring is missing. For this reason, they are also referred to as "open-chain flavonoids".
- Isoflavonoids, on the other hand, can be further divided into:
- Isoflavones (genistein and daidzein); Very well known are, for example, soy isoflavones;
- Isoflavonols;
- Isoflavans;
- Isoflavanols;
- Isoflavanones.
The role in plants
Flavonoids or bioflavonoids are secondary plant metabolites. Inside the plant, they carry out numerous and important actions:
- give color to plants, flowers and fruits
- protect plants from UV rays
- are involved in the symbiotic synthesis of nitrogen
- can act as chemical messengers and cell cycle regulators
- protect plants from certain microorganisms that are pathogenic to them
- are involved in frost and drought resistance processes
In addition to the numerous activities carried out by flavonoids within the plant, they have been and still are the subject of numerous studies also for the activities exerted on human health.
Biological activity of flavonoids or bioflavonoids in humans
From the numerous studies conducted on this wide variety of compounds, it has emerged that flavonoids are able to exert different beneficial actions on the human body. More in detail, among the main biological activities ascribed to flavonoids we find:
- antioxidant and radical-scavenger properties (literally free radical scavengers)
- anti-inflammatory properties
- protective and strengthening properties against capillaries and microcirculation
- properties similar to those of estrogens naturally produced by the body
- Hepatoprotective properties
- Antimicrobial properties
- Antiulcer properties
- antiallergic properties
In which foods are they found?
Flavonoids are extremely common compounds in the plant world and are found in fruits and vegetables, but also in seeds, leaves, rhizomes, roots and bark of numerous plants, as well as in some types of drinks derived from them (such as tea and red wine). Each type of flavonoid can be more or less present within the different types of plants or their derivatives:
- Isoflavones are present especially in soybeans and legumes, but also in various medicinal plants;
- Flavones are contained in vegetables such as celery and red peppers and in the peel of citrus fruits, but are also found in other vegetables, such as mint, ginkgo biloba and parsley;
- Flavonols, on the other hand, are found in fruits and vegetables such as apples, grapes, tomatoes, lettuce, cabbage and onion, but are also present in beverages such as tea, fruit juices and red wine;
- Flavanones are found in citrus fruits;
- Flavanols or catechins are found within fruits such as peaches, pears, bananas, apples, blueberries and within cocoa;
- Anthocyanins are found in particular in fruits such as cranberries, red grapes, raspberries, strawberries, blackcurrants, blackberries, etc. but are also available in cocoa;
- Chalcones are found in significant quantities in tomatoes, strawberries, bearberries and pears, but also in wheat.
- Flavonoids are also contained in propolis, a beekeeping product with interesting antibacterial, anti-inflammatory, healing and immunostimulating properties.
In the plant cell, flavonoids tend to concentrate mainly in vacuoles (where they are present as glycosides) and plastids. These compounds are ubiquitous in the plant world but present at different concentrations that vary, even a lot, both between one plant and another, and within the same plant that can present parts in which bioflavonoids are more concentrated and parts in which there is a lower concentration. 
Bibliography and sources
Dietary flavonoid intake and weight maintenance: three prospective cohorts of 124 086 US men and women followed for up to 24 years, British Medical Journal Flavonoids intake and risk of type 2 diabetes mellitus, Medicine Dietary flavonoid intake and cardiovascular risk: a population-based cohort study, Journal of Translational Medicine Efficacy of flavonoids in the management of high blood pressure, Nutrition Reviews flavonoids, chemistry, biochemistry and applications by Ø. M. Andersen (University of Bergen) and K. R. Markham (Industrial Research Ltd.). CRC Press/Taylor & Francis, Boca Raton. 2006. XIV + 1237 pp. 7 × 101/4 in. $249.95. ISBN 0-8493-2021-6, American Chemical Society CAUTION The information contained in this site is presented for informational purposes only, in no case can it constitute the formulation of a diagnosis or the prescription of a treatment, and is not intended and must not in any way replace the direct doctor-patient relationship or specialist visit. It is recommended to always seek the advice of your doctor and / or specialists regarding any indication reported. If you have any doubts or questions about the use of a supplement or medication you should contact your doctor. Read the Disclaimer.