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All about flavonoids

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  1. 1. Name: Randive Pragati Mangesh Department: Agricultural Biotechnology Class: Jr.Msc Reg No: 0025 Course Title: Basic Biochemistry Course No: Biochem-501 Topic: Flavonoids
  3. 3. CONTENTS  Introduction  Structure of Flavonoids  Classification and Chemistry of Flavonoids  Sources of Flavonoids  Biosynthetic Pathway of Flavonoids  Role of Flavonoids in Plants  Beneficial effects associated with consumption of Flavonoids  Antioxidant activity of Flavonoids  Role of antioxidants on human health  Mode of action of Flavonoids  Dosage
  4. 4.  Flavonoids are a group of plant polyphenolic secondary metabolites showing a common three ring structure (Wiley J. & Sons, Inc., Publication, 2010).  Widely distributed in different amounts, according to the plant species, organ, developmental stage and growth conditions.  The Flavonoids have aroused considerable interest recently because of their potential beneficial effects on human health as well as their role in plant metabolism.  They have been reported to have antiviral, antitumor, anti- allergic, anti-platelet, anti-inflammatory and antioxidant activities.  Introduction
  5. 5.  Their basic structure is a skeleton of diphenylpropane, namely, two benzene rings (ring A and B, see figure) linked by a three carbon chain that forms a closed pyran ring (heterocyclic ring containing oxygen,the C ring) with benzenic A ring.  Therefore, their structure is also referred to as C6-C3-C6. In most cases, B ring is attached to position 2 of C ring, but it can also bind in position 3 or 4; this, together with the structural features of the ring B and the patterns of glycosylation and hydroxylation of the three rings, makes the flavonoids one of the larger and more diversified groups of phytochemicals.  Structure of Flavonoids
  6. 6. Flavonoids are classified in 6 major subgroups depending on the carbon of the C ring on which B ring is attached, and the degree of unsaturation and oxidation of the C ring.  Classification and Chemistry of Flavonoids. B ring is linked in position 3 of the ring C- isoflavones. B ring is linked in position 4, Neoflavonoids. B ring is linked in position 2 , flavones, flavonols, flavanones, flavanols,catechin, and anthocyanidin. open C ring – Chalcone Wiley J. & Sons, Inc., Publication, 2010)
  7. 7. SOURCES OF FLAVONOIDS Chalcones FlavoneFlavanone Flavonol Anthocyanins Isoflavonoids
  8. 8. Classification of Flavonoids Class: Flavone Structure:  Subclasses: Apigenin Luteolin Tangeritin Diosmetin Sources: Celery, Parsley, Red Pepper, Ginkgo biloba.
  9. 9. Class: Flavonol Structure:  Subclasses: Kaempferol Rutin Myrecetin Quercetin Morin Sources: Yellow Onions, scallions, broccoli, Apple, berries.
  10. 10. Class: Flavanone Structure:  Subclasses: Naringin Naringenin Hesperitin Eriodictiyol Sources: Oranges, Lemons, Grapes
  11. 11. Class: Anthocyanin Structure:  Subclasses: Cyanidin Malvidin Pelargonidin Peonidin Delphinidin Sources: Blue-berries, plum, brinjal, grapes
  12. 12. Class: Isoflavonoids Structure:  Subclasses: Genistin Daidzin Glyceitin Sources: Soyabean, soy foods, legumes
  13. 13. Class: Chalcone Structure:  Subclasses: Phloretin Arbutin Chalchonaringenin Sources: Tomatoes, pears, strawberry, wheat products
  14. 14.  Biosynthetic Pathway of Flavonoids in plants
  15. 15. Phenylpropanoids, act as key chemical modulators of plant communication with insects and microbes, either as attractants or repellants , or as phytoalexins against pathogens and herbivores. Induce root nodulation when excreted by symbiotic nitrogen-fixing rhizhobia (Mandal et al;2010).  Role Of Flavonoids In Plant Defense Derivatives of the initial phenylpropanoid scaffold play vital roles in plant structural integrity, protection against UV radiation and phytopathogens, internal regulation of plant cell physiology and signaling. (Koes et al 1994, Shirley, 1996) Some flavonoids provide stress protection, for example act as scavengers of free radicals such as reactive oxygen species (ROS), as well as metal chelating agents that generate ROS. (Mol et al., 1998; Winkel-Shirley, 2002; Bradshaw and Schemske, 2003)
  16. 16.  Beneficial effects associated with consumption of Flavonoids Reduced risk of cardiovascular diseases. Reduction in Blood Pressure due to its vasodilatory effect. Delays or prevents the onset of diseases caused by free radicals Best antioxidant Anti-inflammatory activity Improvement of endothelial functions Inhibits LDL oxidation by free radicals Inhibits platelet Aggregation Antiviral Antibacterial
  17. 17.  Antioxidant activity of Flavonoids Antioxidants are compounds that protect cells against the damaging effects of Reactive Oxygen Species(ROS), such as singlet oxygen, superoxide, peroxyl radicals and peroxy nitrite. The antioxidative activity of flavonoids is connected with the structure of the molecule: the presence of conjugated double bonds and the occurrence of functional groups in the rings. An imbalance between antioxidants and ROS results in oxidative stress, leading to cellular damage. Flavonoids reduce the production of and quench reactive oxygen species (ROS) through: -Suppression of singlet oxygen; -Inhibition of enzymes that generate ROS (cyclooxygenase, lipoxygenase, monooxygenase, xanthine oxidase); -Chelating ions of transition metals, which may catalyze ROS production; -Quenching cascades of free-radical reactions in lipid peroxidation; -“Re-cycling” of other antioxidants. Due to their low redox potential, they can reduce strong free radicals such as superoxides, alkyl radicals, hydroxyl radicals.
  18. 18. Oxidative stress has been linked to cancer, aging, atherosclerosis, ischemic injury, inflammation and neurodegenerative diseases(Parkinson’s and Alzheimer’s). Flavonoids may help provide protection against these diseases by contributing along with antioxidant vitamins and enzymes, to the total antioxidant defense system of the human body. Antioxidant flavonoids- -Quercetin (a flavonol in vegetables, fruit skins, onions) -Xanthohumol ( a prenylated chalcone in hops and beer) -Isoxanthohumol ( a prenylated flavanone in hops and beer) Among all the flavonoids, Quercetin is the most abundant dietary flavonol, and is potent antioxidant because it has all the right structural features for free radical scavenging activity.
  19. 19.  Role of antioxidants on human health Support kidney function Improve reproductive function Maintain good dental health  Improve nervous system functioning Have anti-aging effect Protect liver Support immune system and improve defense power of the body Reduce obesity Maintain healthy vision Offer protection against digestive disorders Support respiratory system
  20. 20.  Mode of action of Flavonoids Flavonoids as antioxidants The flavones and catechins seem to be the most poerful flavonoids for protecting the body against ROS. Flavonoids are oxidized by radicals , resulting in a more stable, less reactive radical. Because of high reactivity of hydroxyl group of the flavonoids, radicals are made inactive. Anti-ulcer effect Quercetin seems to play very important role in the prevention and treatment of peptic ulcer. It acts by promoting mucous secretion, thereby serves as gastroprotective agent, also quercetin has been shown to inhibit the growth of helicobactor pylori bacterium in in-vito studies. Anti-atherosclrotic effect Atherosclerosis is referredto as hardening of arteries.An elevated plasma of low density lipoprotein (LDL) concentration is a primary risk factor for the development of atherosclerosis and coronory artery disease. Flavonoids seem to suppress LDL oxidation and inflammatory progression in the artery wall.
  21. 21. Anti-inflammatory effect Cyclooxygenase (COX) is an enzyme that plays an important role as inflammatory mediator and is involved in the release of arachidonic acid, which is a precursor for biosynthesis of ecosanoids like prostaglandins and prostacyclin. The release of arachidonic acid can be considered as the starting point for general inflammatory response. Flavonoids like quercetin are shown to inhibit the COX pathway.This inhibition reduces the release of arachidonic acid. Hepatoprotective activity Many flavonoids have also been found to posses hepato-protective activity.e.g. silimarin,apigenin,naringenin,quercetin. The result of several clinical investigations showed the efficacy and safety of flavonids in the treatment of hepato-bilary dysfunction and digestive complaints such as sensation of fullness, loss of appetite, nausea and abdominal pain.
  22. 22.  Dosage Flavonoid intake depends upon the consumtion of fruits, vegetables and certain beverages, such as red wine, tea and beer. The high consumption of tea and wine may be most influential on total flavonoid intake in certain groups of people. This intake is high as compared to the average daily intake of other diatery antioxidants like: -Vitamin C(70 mg) -Vitamin E( 110 mg) -Carotenoids (23 mg)
  23. 23. (de la Rosa L.A., Alvarez-Parrilla E., Gonzàlez-Aguilar G.A. Fruit and vegetable phytochemicals: chemistry, nutritional value, and stability. 1th Edition. Wiley J. & Sons, Inc., Publication, 2010). B.Winkel-Shirley,Flavonoid biosynthesis. A colorful model for genetics, biochemistry, cell biology, and biotechnology, Plant Physiology 126 (2001) 485-493. Winkel-Shirley, B. (2006). “The biosynthesis of flavonoids,” in The Science of Flavonoids,edE.Grotewold (New York, NY: Springer),71–95. References
  24. 24. Thank You