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By : - Jaspreet Rekhi www.rhombnet.com www.ppt.rhombnet.com. Flavonoids.
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By : - Jaspreet Rekhi www.rhombnet.com www.ppt.rhombnet.com
Flavonoids • The flavonoids are polyphenolic compounds possessing 15 carbon atoms; two benzene rings joined by a linear three carbon chain having the carbon skeleton C6 - C3 - C6 and they are the plant pigments and they are having polar in nature and solouble in methanol and water. • Flavonoids constitute one of the most characteristic classes of compounds in higher plants. Many flavonoids are easily recognised as flower pigments in most angiosperm families (flowering plants). • However, their occurence is not restricted to flowers but include all parts of the plant. • They are secondary mettabolite and effective in CNS disorders.
The extracts were dissolved in ethanol, filtered and subjected to following tests. • Shinoda test: The dried extracts were dissolved in 95% ethanol (5ml) and few drops of concentracted hydrochloric acid (HCL) were added. Then the magnesium turnings were put into the solution and observed for appearance of pink color. • Lead acetate solution test: To small quantity of above residue, lead acetate solution was added and observed for appearance of formation of yellow colored precipitates. Tests for flavonoids
Flavonoids • Polyphenolic compounds with 15 C atoms, 2 benzene rings on linear 3 C chain • Over 4,000 flavonoids • Easily recognized as flower pigments in most angiosperm plants but are not always flower pigments • In plants they repair damage and shield from environmental toxins
Core structures and nomenclature • The nomenclature of flavonoids proper is straight-forward with the aromatic ring A condensed to the heterocyclic ring C and the aromatic ring B most often attached at the C2 position. The various substituents are listed first for the A and C ring and - as primed numbers - for the B ring (note that the numbering for the aromatic rings of the open-chained precursor chalcones is reversed). • (Harborne JB, ed. (1988) The Flavonoids. Advances in Research. Chapman & Hall.) • Flavonoids Society For Free Radical Biology and Medicine W. Bors et al. .5
Flavonoids & there example • Flavone:- Luteolin, Apigenin, Tangeritin • Flavonol:- Quercetin, Kaempferol, Myricetin, Fisetin, Isorhamnetin, Pachypodol, Rhamnazin • Flavanone:- Hesperetin, Naringenin, Eriodictyol, Homoeriodictyol • Flavanonol- Taxifolin, Dihydrokaempferol
Other flavonoids • CHALCONE • Chalcone is derived from three acetates and cinnamic acid as shown below. • Anthocyanidin is an extended conjugation made up of the aglycone of the glycoside anthocyanins. Next to chlorophyll, anthocyanins are the most important group of plant pigments visible to the human eye.
The anthocyanodins constitute a large family of differently coloured compounds and occur in countless mixtures in practically all parts of most higher plants. They are of great economic importance as fruit pigments and thus are used to colour fruit juices, wine and some beverages. • The anthocyanidins in Hydrangea, colours it RED in acid soil and BLUE in alkali soil.
Maceration (3 times) Purification with Chloroform (3 times) Dropwise addition of 10% NACL solution and centrifugation ISOLATION OF FLAVONOIDS Ground plant material Aqueous layer Aqueous layer Flavonoids in supernant liquid Precipitate of tannins Partioning with ethyl acetate Flavonoid obtained by evaporation of ethylacetate layer
Flavonoids • Act like antioxidants. How effective they are depends on their molecular structural characteristics • Some flavonoids in hops and beer have been found to have better antioxidant effects than tea or red wine; most flavonoids are found in fruits, vegetables, teas, and other drinks. • Flavonoids have been known to have antiviral, anti-allergic, antiplatelet, anti-inflammatory, antitumor and antioxidant activities
Many flavonoid containing plants are: • Diuretic. • Antispasmodic. • Diaphoretic. • Increase tensile strength of capillary walls. • Free radical scavengers.
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