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FLAVONOIDS. Dr Khaled Abo EL-Sooud Prof. of Veterinary Pharmacology Faculty of Vet. Med. Cairo University. Flavonoids ( bioflavonoids ). Definition: They are secondary metabolites that eliciting pharmacological or toxicological effects in man and animals.
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FLAVONOIDS Dr Khaled Abo EL-Sooud Prof. of Veterinary Pharmacology Faculty of Vet. Med. Cairo University
Flavonoids (bioflavonoids) Definition:They are secondary metabolites that eliciting pharmacological or toxicological effects in man and animals. Flavonoids represent the most common and widely distributed group of plant phenolics and are abundant in foods; quercetin and rutin are the flavonoids most abundantly consumed
Flavonoids (bioflavonoids) Flavonoids are the largest group of naturally occurring phenolic compounds, which occurs in different plant parts in Free form or combined with other secondary metabolites as tannins and glycosides
Chemically, flavonoids are polyphenolics have the general structure consists of two phenyl rings (A and B) and heterocyclic ring (C). This carbon structure can be abbreviated C6-C3-C6. B A
Classification Flavonoids can be divided into 6 major subclasses: Flavones, Flavonols, Flavanones, Flavanols (cathechins and proanthocyanidins), Anthocyanins, Isoflavones.
Flavonols, Quercetin, Kaempferol Cherry tomatoes, Onions, Tea and Broccoli
Flavanones, Hesperetin, Naringenin Citrus fruits
Flavanols (cathechins and proanthocyanidins), Chocolates and Beans
Anthocyanins, Cyanidin, Delphinidin 2-phenylchromenylium) ion skeleton Red cabbages
Isoflavones 3-phenylchromen-4-one skeleton Genistein, Daidzein, Glycitein Soya, Peas
Parsley is a source of flavones. Blueberries are a source of dietary anthocyanidins. Parsley is a source of flavones A variety of flavonoids are found in citrus fruits, including grapefruit.
Antioxidant All compounds contain phenol-groups involved in an effect as general antioxidant. The antioxidant activity is due to their ability to reduce free radical formation and to scavenge free radicals. Both the absorbed flavonoids and their metabolites may display an in vivo antioxidant activity,
Mechanisms of antioxidant action can include (1) Suppression of ROS formation either by inhibition of enzymes or by chelating trace elements involved in free radical generation; (2) Scavenging ROS; and (3) Up-regulation or protection of antioxidant defenses.
Mechanisms of antioxidant action Flavonoids inhibit the enzymes involved in ROS generation • microsomal monooxygenase, • glutathione S-transferase, • mitochondrial succinoxidase, • NADH oxidase.
Anti-inflammatory Flavonoids inhibit the pro-inflammatory activity of enzymes involved in free radical production, such as cyclooxygenase (COX), lipoxygenase or inducible nitric oxide synthase, and to modify intracellular signaling pathways in immune cells, or in brain cells after a stroke
Anti-Cancer Clinical studies investigating the relationship between flavonoid consumption and cancer prevention/development for most types of cancer. Dietary flavonoid intake is associated with reduced gastric carcinoma risk in women,and reduced aero-digestive tract cancer risk in smokers.
Treatment of Cardiovascular diseases They inhibit coagulation, thrombus formation or platelet aggregation reduce risk of atherosclerosis They reduce arterial blood pressure and risk of hypertension
Antibacterial • Flavonoids have been shown to have • direct antibacterial activity, • (b) synergistic activity with antibiotics, • (c) the ability to suppress bacterial virulence factors in numerous in vitro and a limited number of in vivo studies
Antiallergic Flavonoids are powerful inhibitors of allergic inflammation (histamine release) , other anti-allergic compounds, humanized anti-IgE antibody and cytokine (Interleukin (IL)-4, IL-5 and IL-13) by basophils and so prevent allergic condition. Allergic diseases including asthma, pollen diseases and atopic dermatitis
Antithrombus Platelets are associated with the development of different thrombotic disorders, including atherosclerosis, arterial thrombosis and stroke, deep venous thrombosis and pulmonary embolism; therefore, platelets are the target of a number of anti-thrombotic strategies Flavonoids Prevent the adhesion of blood platelets to prevent thrombi and attenuated mobilization of intracellular free Ca2+ so reduction of the risk of cardiovascular disease.
Tests for detection HCl Test: To the sample, added 5 ml of 95% ethanol and few drops of concentrated HCl. Immediate development of a red colour indicates the presence of flavonoids. .
Tests for detection Lead Acetate Test: To the small quantity of alcoholic extract, lead acetate solution was added. Formation of yellow precipitate indicated the presence of flavonoid.
Tests for detection Ferric chloride Test: To the small quantity of alcoholic extract, ferric chloride solution was added. Formation of deep blue or black colour indicated the presence of flavonoid.
Tests for detection Sodium Hydroxide Test: On addition of an increasing amount of sodium hydroxide To the small quantity of alcoholic extract, the sample containing flavonoids indicated yellow to orange coloration, this decolorized after addition of acid.
Tests for detection Ammonia Test: On addition of an increasing amount of Ammonia To the small quantity of alcoholic extract, the sample containing flavonoids showed deep yellow coloration, this decolorized after addition of acid.
Thin Layer Chromatography (TLC) TLC using two Solvent systems First system: Chloroform-methanol(95:5v/v). - Second system: Ethyl acetate- methanol-water (60:5:4 v/v/v). Notes the color of spot under UV light(brown). Use AlCl3 as a reagent and notes the change in spot color under UV light (yellow). Calculate Rf for flavonoid spot in two systems.
