Title: Flavonoids
1By - Jaspreet Rekhi www.rhombnet.com
www.ppt.rhombnet.com
2 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.
3Tests for flavonoids
- 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.
4The Most Important Classes of Flavonoids and their Biological Significance The Most Important Classes of Flavonoids and their Biological Significance The Most Important Classes of Flavonoids and their Biological Significance
class number of known members biological significance (so far as known)
anthocyanin(s) 250 red and blue pigments
chalcons 60 yellow pigments
aurones 20 yellow pigments
flavones 350 cream-coloured pigments of flowers
flavonols 350 feeding repellents (?) in leaves
dihydrochalcons 10 some taste bitter
proanthocyanidins 50 astringent substances
catechins 40 some have propertieslike those of tannins
isoflavonoids 15 oestrogen effect, toxic for fungi
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
5Core 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
6Flavonoids there example
- Flavone- Luteolin, Apigenin, Tangeritin
- Flavonol- Quercetin, Kaempferol, Myricetin,
- Fisetin, Isorhamnetin,
- Pachypodol, Rhamnazin
- Flavanone- Hesperetin, Naringenin,
- Eriodictyol,
Homoeriodictyol - Flavanonol- Taxifolin, Dihydrokaempferol
7 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.
8- 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.
9ISOLATION OF FLAVONOIDS
Ground plant material
- Maceration (3 times)
- Purification with Chloroform (3 times)
-
-
- Dropwise addition of 10 NACL solution
- and centrifugation
-
Aqueous layer
Aqueous layer
Flavonoids in supernant liquid
Precipitate of tannins
Partioning with ethyl acetate
Flavonoid obtained by evaporation of
ethylacetate layer
10Flavonoids
- 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
11- Many flavonoid containing plants are
- Diuretic.
- Antispasmodic.
- Diaphoretic.
- Increase tensile strength of capillary walls.
- Free radical scavengers.
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By - Jaspreet Rekhi www.rhombnet.com
www.ppt.rhombnet.com