flavonoids

• Flavonoids

  Water soluble polyphenolic molecules containing 15 carbon atoms, belonging to the polyphenol family
• Flavonoids

  • Can be visualized as two benzene rings joined together with a short three carbon chain, with one carbon of the short chain connected to a carbon of one of the benzene rings, either directly or through an oxygen bridge, forming a third middle ring which can be five or six-membered
  • Consist of 6 major subgroups: chalcone, flavone, flavonol, flavanone, anthocyanins and iso-flavonoids
  • Together with carotenes, are responsible for the coloring of fruits, vegetables and herbs
• Distribution of flavonoids

  • Found in most plant material
  • Most important dietary sources are fruits, tea and soybean
  • Green and black tea contains about 25% percent flavonoids
  • Other important sources are apple (quercetin), citrus fruits (rutin and hesperidin)
• Properties of flavonoids

  • Have antioxidant activity
  • Have many health promoting effects including anti-allergic, anti-cancer, antioxidant, anti-inflammatory and anti-viral
  • Quercetin is known for its ability to relieve hay fever, eczema, sinusitis and asthma
  • Prevent the oxidation of low-density lipoprotein thereby reducing the risk for the development of atherosclerosis
  • Contribute significantly to the total antioxidant activity of food components, with daily intake varying between 50 to 500 mg
• Sources of flavonoids


  • Red wine (quercetin and rutin)
  • Tea (many health benefits including reducing oxidation of low-density lipoprotein, lowering blood cholesterol and triglycerides)
  • Soy (isoflavones can reduce blood cholesterol and help prevent osteoporosis, also used to ease menopausal symptoms)
• The high intake of red wine (and flavonoids) by the French might explain why they suffer less from coronary heart disease then other Europeans, although their consumption of cholesterol rich foods is higher (French paradox)
• Many studies have confirmed that one or two glasses of red wine daily can protect against heart disease
• Biological roles of flavonoids

  • Most important pigments for flower coloration producing yellow or red/blue pigmentation in petals, to attract pollinator animals
  • Protect plants from attacks by microbes and insects
  • Widely distributed in plants fulfilling many functions
  • Relatively low toxicity compared to other active plant compounds (for instance alkaloids)
  • Many animals, including humans, ingest significant quantities in their diet
  • Referred to as "nature's biological response modifiers" because of their ability to modify the body's reaction to allergens, viruses, and carcinogens
  • Show anti-allergic, anti-inflammatory, anti-microbial and anti-cancer activity