Flavonoids are a group of plant secondary metabolites called phenolics. They contain an aromatic ring structure with one or more hydroxyl groups attached. There are over 3000 known flavonoids found throughout plants. Flavonoids may function as antioxidants, pigments, and have potential health benefits for humans. Common tests used to identify flavonoids include the Shinoda test and ferric chloride test.

1. FLAVONOIDS

2.  Phenolics
 Group of secondary plant products or compounds
 Composed of a hydroxyl group attached to an aromatic
ring
 A broad range of compounds - found in all components
of plants: leaves, flowers, fruit etc
 Function of most compounds is unknown
 Comprised of many groups: Flavonoids, Tannins,
Lignin etc. All very chemically diverse!

3.  Water soluble pigment
 Most widely studied group of
phenolics: over 3000 described
 Seem to have major health
benefits for humans - red
wine and cholesterol
 Variety of important functions
in plants
Flavonoids

4. Flavonoids were originally referred to as Vitamin P,
likely due to the effect they had on the permeability
of vascular capillaries, but this term is rarely used
now .
The flavonoids are polyphenolic compounds
possessing 15 carbon atoms; two benzene rings
joined by a linear three carbon chain.

5. C6 - C3 - C6 system
 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.

6. Classification
 Flavonoid: derived from 2-phenylchromen-4-one
(2-phenyl-1,4-benzopyrone)
 Isoflavonoids: derived from 3-phenylchromen-4-
one (3-phenyl-1,4-benzopyrone)
 Neoflavonoids: derived from 4-phenylcoumarine
(4-phenyl-1,2-benzopyrone)

7. Localization Potential by Family
 Fabaceae (one branch), Cannabaceae, Lilliaceae,
Pinaceae = 45% cytoplasm
 Rosaceae = 60% cytoplasm
 Fabaceae (other branch) and Pteridophytes = 34%
mitochondrial matrix

8. Chemical Tests
1. Shinoda test:
To alcoholic solution of extract add few
magnesium turnings, ad concentrated HCL
dropwise, magenta colour indicates presence
of flavanoids.
2. Ferric chloride test: to the alcoholic
solution, add few drops of neutral ferric
chloride, green colour is produced.

9. Uses
 Antioxidants,
 Colouring agents
 Flavonoids have been found to possess a number
of biological activities. Silymarin which is a
flavonolignan from seeds of milk thistle is
Antihepatotoxic.

10. Role of Flavonoids
 Wedelolactone from Eclipta alba, known as Maka
in Ayurveda is retmarkably active against cirrhosis
of liver. Baicalin from scutellaria baicalensis is
active against HIV. Genistein from Glycin max is
found to be antitumour, as it induces mammalian
topoisomerase II dependent DNA clevage.
 Flavonoids shows anti-inflammatory activities.
They are also found to possess antiviral against
poliovirus. Flavonoids also exert antibacterial
activity against various pathogenic bacteria.

11. Phenylpropanoids
 Phenylpropanoids represent a large conglomerate of
naturally occurring phenolic compounds essentially
derived from the aromatic amino acids
Phenylalanine and Tyrosine or incertain specific
instances the intermediates obtained from shikimic
acid biosynthetic pathway. In other words, these
compounds comprise of a phenylring to which is
attached a 3-C-side chain and may also contain one
or more C6-C-3 residues.

12. Phenylpropanoids
 The unique combination of phenyl-propane side
chain (i.e. 3-C-atom) evidently represent in
'phenylpropanoids' are absolutely devoid of nitrogen
atom, which is observed to be in contradiction to
such other vital class of natural products, namely:
alkaloids, cyanogenetic glycosides and
glucosinolates. The phenylpropanoids are distinctly
phenolic character by virtue of the presence of one or
several hydroxyl groups attached to the aromatic
ring (C6H6), they are more often as known as 'Plant
phenolics'.

13. Phenylpropanoids
 The phenylpropanoids may be classified on the basis
of their basic chemical moieties as enumerated
below:
 Hydroxycinnamic acid
 Phenylpropenes
 Coumarins
 Biphenylproanoid derivatives
 High molecular weight phenylpropanoids

14. LIGNANS
 Lignans, the plant products with low molecular weight that
are accomplished by the oxidative coupling of para-
hydroxyphenylpropene unit wherein the two units may be
linked by an oxygen bridge.

 The monomeric precursor units are namely : cinnamic acid,
cinnamyl alcohol, propenylbenzene and alkylbenzene.
However, the terminology lignan or more precisely Haworth

 Lignan is generally applied to such cornpounds that are
derived by coupling acid and/or alcohol exclusively; whereas,
the compounds which are derived by coupling propenyl
and/or allyl derivatives are known as Neolignans.

15. LIGNANS
 Biological source: Lignans occur widely and have
been obtained from roots, heart wood, foliage, fruit
and resinous exudates of plants. They represent the
dimer stage intermediate between the monomeric
propylphenol units and lignin.The alpha lignin has
been found in the roots and rhirhizomes of
podophyllum hexandrum Royle belonging to family
Berberidaceae.

16. Preparation of LIGNANS
 Generally, the lignans are formed by the reduction of
ferulic acid to coniferyl alcohol as its first and
foremost step; and subsequently via the
oxidative dimerization of the coniferyl alcohol units
and the establishment of linkage through the B-
carbon atom of the C-3 side chain.

17. Characteristic features
 Lignans are typically found as single enantiomeric
forms i.e., either as d- or l- isomers. These also occur
as their rccemic products i.e., 'dl-forms. It has been
observed that the lignans vary to a large extent with
regard to their respective oxidation levels, degree of
substitution and the structural complexicity.
 Examples : Podophyllum

18. Podophyllum
 Synonym: Indian Podophyllum, Podophyllum radix.
 Biological source : It consists of the dried rhizome
and root of Podophyllum hexandrum Royle
(Podopyllum emodi),
 American podophyllum consists of dried rhizomes
and roots of P peltatum. family- Berberidaceae
 Geographical source: It is grow in forest of the
Himalaya from Kashmir, Tibet, Afghanistan.

19. Collection
 The plant is perennial herb found at 2000 metres
height. The drug is collected both from wild and
cultivated plants, Rhizomes of plants older than two
years are collected in autumn. Rhizomes ate dug out
and washed well with water.
 They ate dried at first in the sun and then by placing
on wire nets 3 ft. Above the ground with fire below.

20. Macroscopic character
 Drug contains either rhizomes or roots or both.
Internodes of the rhizomes are very short and developed
vety little, So the rhizomes appear knotty and tortuous
having the length of 3 to 8 cm and thickness of 1 to 2 cm.
 Rhizomes are sub cylindrical in shape, with irregular
nodes tortuous and dorsiventrally flattened. Upper
surface of rhizome possesses 3 to 4 circular depressed
stem-scars. On lateral surface buds or bud scars and on
the under surface numerous strong roots or root-scars
are seen. Roots are 10 cm long, 3mm thick, longitudinally
wrinkled, nearly straight, curved or tortuous.

21. Macroscopic character
 Roots detach easily and are therefore found separate
in the drug. Rhizomes are earthy brown in colour
with short, horny and starchy fractures. It has slight,
characteristic odour and bitter taste.

22. Microscopic character
 The rhizome is covered externally by about six layers
of tabular, thin walled, polygonal cork cells the
ground tissue consist of a stout-walled cellulosic
parenchyma with simple pits and containing starch
grains which are usually two to four, rarely upto
twenty compound, the individual grain being
 usually 2 to 7 microns and rarely upto 35 microns in
diameter, so that generally they are smaller than
those of P. peltatum.

23. Microscopic character
 Cluster crystals of calcium oxalate occurs in
parenchyma and mostly measure about 20 to 30
microns, sometimes being larger, but never over 60
microns-another distinction from P. peltatum.
 On the inner side of the vascular bundles there are
perimedullary groups of short and contorted
sclereids; the elements of xylem vessels also are often
rather short and irregular in shape.

24. Microscopic character
 The roots have a slightly papillose epiblema with
strongly thickened outer and anticlinal walls; the
cortex is wide and the cells contain starch similar to
that of rhizome, but calcium oxalate is absent; both
exodermis and endodermis are suberised and have
wavy longitudinal walls; the stele is four to nine --
arch and there is usually a pith composed largely of
central group of pitted sclereids.

25. Chemical constituents
 It contains Podophyllin resin is known as
podophyllotoxin. α and ß peltatins are present only
in the American podophyllum. It also contains
Quercetin kaempferol, asiragalin, essential oil.
Podophyllin is a lignin compound. Etoposide (4-
methylepipodophyllotoxin ethylidene. glucoside) is
semi-synthetically processed and used in testicular
and lung cancer.

26. Uses
 It is slow purgative, Podophyllum has antimitotic
action and is used in cancer. It is also used in the
treatment of veneral and other warts.

27. TEA
 Synonym : Camelia thea.
 Biological source : It contains the prepared leaves and leaf buds of
Thea sinensis Linne, family Theaceae.
 Geographical source :
 Large areas of land are put under cultivation of tea in India, Sri
Lanka, China, Indonesia and Japan. It is available as black tea from
India and Sri Lanka and green tea from China and Japan.
 Black tea is obtained by fermenting the heap of fresh tea leaves and
further drying with artificial heat. Green tea is obtained by putting
tea leaves in copper pans and then drying by artificial heat.

28. Cultivation and collection
 It is prepared by exposing the freshly collected leaves
to the air until most of the moisture is removed.
Then they are roasted and stirred continuously until
leaves become moist and flaccid. Then they are
passed to rolling table and rolled into balls and
subjected to a pressure which removes the moisture.
Then the leaves are shaken out on the copper pans
and roasted again till the leaves assume dull green
colour. The leaves are than winnowed, screened and
graded into various varieties.

29. Macroscopic character
 It is a small evergreen shrub when cultivated reaches
to the height of 1.0-1.5 metres, while wild growing
plants reach upto 6.0 metres. Plant is much
branched and bears grey bark. Leaves are dark green,
lanceolate or elliptical, blunt at apex, base is tapering
margin shortly serrate. Young leaves are hairy while
matured leaves are glabrous. Flowers are solitary or
in groups of 2 or 3 in the leaf axils and drooping
having characteristics odour and bitter taste.

30. Microscopic character
 The transverse section of a tea leaf through the midrib
shows the prominent hump below and has broad ridge
above. The upper and lower epidermis are made up of
polygonal cells with wavy anticlinal walls. The lower
epidermal layer shows presence of numerous stomata.
 The thick walled conical trichomes are also present lower
epidermis. Two layer of palisade parenchyma are present
beneath the upper epidermis of lamina and is discontinued
in midrib region.
 Spongy parenchyma follows palisade in lamina. The central
midrib region consist of the arc of xylem above and phloem
below. Cluster crystals of calcium oxalate are found
throughout.

31. Chemical constituents
 Tea leaves are considered as a rich source of caffeine
(1-3%). It is extracted from tea dust and tea leaf
waste or sweepings. It also contains theobromine
and theophylline in minor quantities. The colour of
tea leaves is due to gallotannic acid (15%) The
agreeable odour is due to presence of a yellow
volatile oil. Tea leaves also contain an enzymatic
mixture called thease.

32. Uses
 CNS stimulant in the form of beverage and also as
diuretic.

33. RUTA
 Synonym : Rue, Garden rue.
 Biological source : It consists of fresh and dried
leaves of Ruta graveolens L., Family Rutaceae.
 Geographical source : Ruta graveolens L. is
indigenous of Southeastern Europe but is widely
naturalized in Southern Europe and cultivated
worldwide.

34. Cultivation and collection
 It is a perennial shrub with smooth erect stems,
leaves are green colored compound leaves with lobed
obovate leaflets, flowers are found in terminal
umbels with four spoon-shaped yellow shining non-
fringed petals. Fruit is a capsule containing many
seeds.

35. Macroscopic character
 The leaves of Ruta graveolens are bluish green
colored when fresh and turn to yellowish brown
when dried; leaves alternate, entire and fern like
compound with deeply lobed obovate leaflets, gland
dotted with dark spots; unipinnate to tripinnate.

 Leaflets are linear to oval or oblong; 7.5 to 20 cm
long and 2-3cm broad; leaves become fragile on
drying and mostly found as powdery in the bulk
sample. The odor is strongly aromatic and tastes
slightly bitter.

36. Microscopic character
 TS of petiole of Ruta graveolens is circular in outline
With outer epidermis followed by single layered
hypodermis. The outer cortex consists of 3 to 4 layers of
chlorenchyma cells with few volatile oil cells distributed
randomly. The middle cortex is formed of 4 to 5 layers of
collenchymas cells some of which contains prismatic
crystals and rosette crystals. The inner cortex is made up
of few parenchyma cells and a ring of 5-co-joint,
collateral vascular bundles at the center.
 A discontinuous pericycle layer surrounds the vascular
ring which is followed by a group of phloem cells, and
xylem facing towards pith. The pith is formed of
parenchyma cells.

37. Chemical Constituents
 The Ruta leaves contains rutin, quercetin,
rutacridone, gravacridondiol and the essential oil
contains monoterpenes, like limonene, a-pinene and
cineole.

38. Uses
 In Chinese medicine ruta is considered as intestinal
antispasmodic, sedative, uterine stimulant, cold and
fever.
 In Poland, it is used as an aphrodisiac and choleretic.
The herb is used medicinally as a bitter, an aromatic
stimulant, ecbolic and in suppression of the menses.

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