Flavonoids are plant secondary metabolites that are classified based on their chemical structure. They are abundant in many plant families and occur as both free compounds and glycosides. Key classes include flavonols, flavones, flavanones, isoflavones, and anthocyanidins. Flavonoids have a variety of biological effects and are found in several plants that are used medicinally such as orange peel, garcinia, soybean, liquorice, cranberry, and buckwheat.

1. FLAVONOIDS

2. CONTENT
• Introduction
• Classification
• Chemical test
• Occurrence
• Orange peel – Flavonol, Flavanone
• Garcinia
• Soybean - Isoflavones
• Liquorice
• Cranberry
• Buckwheat

3. INTRODUCTION
• Flavonoids are regarded as C6-C3-C6 compounds (15
carbon skeleton) in which C6 moiety is benzene ring,
• The variation in the state of oxidation of the
connecting C3 moiety determines the property and
class of such compounds.
• Occurs in plants as Glycoside in which one or more of
the phenolic hydroxyl groups are combined with
sugar residue.
• The –OH groups are found in positions 5 and 7 in
ring A, while in ring B commonly carries –OH or
alkoxyl groups.
• Flavonoids consists of aromatic ring A, condensed to
heterocyclic ring C attached to second aromatic ring

4. INTRODUCTION
• They are formed from 3 acetate units and a phenyl
propane unit.
• They are classified according to the state of
oxygenation of the C3 unit, i.e. C-2-,3,4.
• They have been used extensively as chemotaxonomic
marker and are abundant in the Polygonaceae,
Rutaceae, Leguminosae, Umbelliferae and
Compositae family
• They occur both in free state and as glycosides; most
are o-glycoside but a considerable number of
flavonoid C-glycoside are known. Dimeric
compounds with, e.g. 5’-8-carbon-carbon linkage are
also known (bioflavonoids)

6. OCCURRENCE IN NATURE
Type Compound Nature Occurrence
Flavone Luteolin Tetrahydroxy
5,7,3’,4’
Wild carrot
Flavonol Quercetin Pentahydroxy
3,5,7,3’,4’
Rutin
(Rhamnoglucoside
)
Kaempferol Tetrahydroxy
3,5,7,4’
Senna
Flavonone Liquiritigenin Dihydroxy 7,4’ Liquorice
Chalcone Unstable isomers
of flavonones
Family rutaceae
and Liquorice
Xanthone Gentisin 1,7-Dihyroxy-3-
methoxy
Gentiana &
Swertia spp.
Iso flavones Soyabeans
Bi flavones Garcinia

8. CLASSIFICATION
• Classified in to Anthocyanins & Anthoxanthins
• Anthocyanins are glycosides of anthocyanidins, which
are water soluble plant pigment and responsible for
various colors such as purple, blue and red to fruits,
flowers and leaves.
• Anthoxanthins are white or yellowish or colorless
compounds and includes flavonols, flavanols,
isoflavones and flavanones
• General pharmacologic activity includes cardiac
stimulant, diuretic and antioxidants to lipids

9. • Sugar free pigments are called as Anthocyanidins.
• Natural Anthocyanidines are classified into 3 groups:
Pelargonidin, Cyanidin and Delphinidin
• Factors like pH, complex forming metal, tannins
affect the colors of the anthocyanins.

10. CHEMICAL TEST
1. Shinoda test: drug solution + Mg turning + conc.
HCl drop wise, pink scarlet, crimson red or
occasionally green to blue color appears in few
minutes
2. Alkaline reagent test: drug solution + NaOH,
intense yellow color is formed which turns to
colorless on addition of few drops of dil. Acid
3. Zinc HCl test: drug solution + zinc dust + conc. HCl,
red color after few minutes

11. • Rutin: occurs as a yellow crystalline powder.
• Soluble in alkali but only slightly soluble in water
• On hydrolysis yield Quercetin, rhamnose and glucose
• Hesperidin:
• On hydrolysis yield hesperetin (or methyl eridictyol),
rhamnose and glucose
• It decrease capillary fragility ad are therefore
employed in cases of hypertension and radiation
injuries.

12. 1. ORANGE PEEL
(HESPERIDIN)
• Source: peels of Citrus aurantium
• Family: Rutaceae
• Constituent: Flavonoid (Hesperidin)
• Colorless needle like crystals, closely related to
Vitamin P (Citrin), readily soluble in hot water,
sparingly soluble in alcohol and cold water and
practically insoluble in ether, benzene and
chloroform
• Use: prevention and management of capillary fragility
so used in hypertension, CVS disorders,

14. 2. GARCINIA
(BI0FLAVONOIDS)
• Dried de-seeded fruits of Garcinia cambogia
• Family: Guttiferae
• GS: Western Ghat, Nilgiri, Srilanka
• Constituent: Biflavonoids, Hydroxy citric acid
• Use: Flavonoids reported to lower the lipid levels so
used in obesity and hypercholestermia
• The content of bioflavonoids in the plant, which may
increase the level of peripheral testosterone, which
can stimulate erythropoiesis in humans hence

15. 3. SOYBEAN (ISOFLAVONES)
• Source: dried seeds of Glycine max
• Family: Leguminosae
• Constituents: Isoflavones
• Use: Soy flavonoids (isoflavones) can also reduce
blood cholesterol and can help to prevent osteoporis.
Soy flavonoids are also used to ease menopausal
symptoms.
• CVS, Mental and Women’s health, cancer prevention

17. 4. LIQUORICE
(BIOFLAVONOIDS)
• Syn: Mulethi, Jethimadh
• Source: dried roots and stolons of Glycyrrhiza
glabara
• Family: Leguminosae
• Constituents: Glycyrrhizoflavone, Isocoflavonol,
Licochalcone
• Use: Liver protective, Bioflavonoids have been shown
in recent years to have a wide range of biological
activities, including cardiovascular, antioxidant, anti-
inflammatory, anti-allergic, detoxicant and
antimicrobial, etc.

18. 5. CRANBERRY (QUERCETIN)
• Source: berries of Vaccinium macrocarpon
• Family: Ericaceae
• GS: Canada, US
• Constituents: Proanthocyanidins, flavonols and
anthocyanins, Quercetin
• Use: Reduction in urinary tract infection,
Atherosclerosis, CVS disorders, Ovarian cancer

20. 6. BUCK WHEAT (RUTIN)
• Source: powder of dried food grains of Fagopyrum
esculentum
• Family: Polygonaceae
• GS: food crop in US, Russia, Japan
• Constituents: 12% protein, 2% fat, mainly RUTIN
• Rutin is microcrystalline greenish yellow tasteless
powder, soluble in methanol-isopropyl alcohol-
pyridine-alkali hydroxides
• Use: capillary bleeding along with increased capillary
fragility so used in retinal haemorrhage