3. COUMARINS
Coumarin (2H-chromen-2-
one) is a fragrant organic
chemical compound in
the benzopyrone chemical
class, which is a colorless
crystalline substance in
its standard state It is found
naturally in many plants
Families : umbelliferae,
rutaceae, leguminaceae,etc
Carribean word : coumarou
5. 2.Furocoumarins are formed in result of
furan ring and coumarin condensation in
6,7 positions (psoralen-derivatives) or 7,8
(angelicin-derivatives). Substitutes may
occur within any of these rings
psoralen angelicin
6. 3. Pyranocoumarins are result of condensation of
coumarin with 2’2’-dimethylpyrane in positions 5,6
(dimethylxantyletin); 6,7 or 7,8 (visnadine) and may
have substitutes in any of rings.
2’2’dimethylxantyletin visnadin
7. 4. Benzocoumarins containing benzyl ring
condensed with coumarin in 3,4
positions occur Anacardiaceae and Rosaceae. Hy
droxyderivative of 3,4-benzocoumarin is a
structural component of ellagic acid.
3,4-benzocoumarin-hydroxy-derivative
10. BIOLOGICAL SOURCE
Dried ripe fruits of
psoralea corylifolia
Family :Leguminosae
Content of the fruit:
◦ Psoralen
◦ Isopsoralen
It is present up to 3-4 %
in the fruit
14. CONSTITUTION
Structure of psoralen is deduced by using
its degradation reaction
It exhibits normal reactions of lactone of
coumarin such as ring opening by alkali to
give coumarinic acid or coumaric acid
derivatives
potassium permanganate causes oxidation
of furan ring
other oxidation produce furan 2,3-
dicarboxylic acid
15. ISOLATION
Dried fruits of Psoralea
corylifolea
Coarse
powder
To remove
essential oils
&resinous matter
present on outer
coat
Defatted with petroleum ether
Dried the
marc
16. Extracted with methanol
Methanolic extract (psoralen +other
coumarins +flavanoids)
Concentrate & dry
Chromatographed on silica gel
plate
Chloroform
as eluent
Psoralen in first few
fraction
Crystallised from
ethanol or solvent
ether
Concentrate to yield
psoralen
17. IDENTIFICATION TESTS
1mg of psoralen in 5ml of ethanol+3 parts
of propylene glycol+43 parts of water
Blue fluoresence
1mg psoralen in 2ml ethanol+2 drops of
0.1M NaOH Emits yellow
flourescence
Uv
light
Uv
light
18. 1mg of Psoralen
in1ml of
methanol
Spotted on
silicagel-G plates
Plates are eluted in
benzene:chloroform
(98:2)
Dried plates
observed under
UV light
Psoralen shows blue fluracent
spot with Rf value 0.25
19. USES
In PUVA treatment for skin disease
◦ Psoriasis
◦ eczema
◦ vitiligo
Recommended in the treatment of
alopecia
Psoralen is a mutagen & is used in
molecular biology research
Tannin activator in sun screens
20. SYNTHESIS
O OH
2,3-dihydrobenzofuran
CO, HCl
CuCl ,AlCl 3 O OH
O
H
(CH3CO) 2O CH3COONa
O O O
Pd
2+
O O O
psoralen
Guttermann Koch reacion
Perkin Condensation
dehydrogenation
7-hydroxy derivative of
21. O OOH
Umbellliferone
OPPCH3
CH3
attack of DMAPP
CH3
OH O O
CH3
O2
NADPH
OO O
Demethylsuberosin
Marmesin
O2
NADPH
OO O
OO O
OCH 3
O
O
O
Psoralen
Angelicin
O2
NADPH
BIOSYNTHESIS
22.
23. Xanthotoxin or Methoxsalen is extracted
from Ammi majus, a plant of the family
Umbelliferae. It modifies the way skin
cells receive the UV radiation.
AMMI MAJUS - Bishops flower, Queen
Anne’s Lace
Also known as Bishopsweed, Bishop’s
weed, Bullwort, Greater ammi, Lady’s
lace, Laceflowe
24. Introduction contd…
A tall plant originating in
the Nile River Valley
which has large, rounded,
10-15 cm flower heads
made up of hundreds of
tiny, snow-white florets.
It is cultivated in North
India also.
The Seed of the plant
contains Xanthotoxin
25. Chemistry
Chemically, methoxsalen belongs to a
class of organic natural molecules known as
furanocoumarins. They consist of coumarin
annulated with furan. Xanthotoxin is 8-
methoxy psoralen or 8-methoxy 3’,2’-6,7
furocoumarin.
28. Extraction and Purification
The pulverised coarse powder of the seed is used
for extraction with n-hexane.
Extraction is effected in 2-3 hrs and 3-4 washings
are done.
All the washings are combined and the solvent is
distilled off. The separated solid is dried and de
alkylated using HCl and methanol.
29. Extraction and Purification contd…
The de alkylated material contains
Xanthotoxol and Xanthotoxin
The de alkylated material is refluxed with
benzene for 2 hrs and cooled to room
temp. Xanthotoxol is separated
Xanthotoxin is crystallised from the
filtrate at 10-150C.
34. Synthesis contd…
The activation of dimethylallyl pyrophosphate
(DMAPP), produced via the mevalonate pathway, to
form a carbo-cation via the cleavage of the
diphosphates.
Once activated, the enzyme umbelliferone 6-
prenyltransferase catalyzes a C-alkylation between
DMAPP and umbelliferone at the activated position
ortho to the phenol, yielding demethylsuberosin. This
is then followed by a hydroxylation catalyzed by the
enzyme marmesin synthase to yield marmesin.
Another hydroxylation is catalyzed by psoralen
synthase to yield psoralen. A third hydroxylation by the
enzyme psoralen 8-monooxygenase yields xanthotoxol
which is followed by a methylation via the enzyme
xanthotoxol O-methyltransferase and S-adenosyl
35. BIOLOGICALACTIONS
Photosensitisation effect: when irradiated to
long wave length UV radiation
Killing bacteria: upon irradiation
Formation of mutants: Mutagenic effect is seen
in E Coli and Sarcina lutea
Inactivation of tumour cells
Inactivation of viruses
36. Properties and Uses
Used to treat psoriasis, eczema, vitiligo, and
some cutaneous Lymphomas in conjunction
with exposing the skin to sunlight.
Tonic, carminative and diuretic
Relaxes smooth muscles
Useful in kidney calculi and for angina pectoris
In formulations of sun-tan lotions
To increase the tolerance of sunlight
37. REFERNCES
Pharmacognosy and pharmacobiotechnology
by Ashutoshkar, revised expanded 2nd edition
Plant biosynthesis by Dr.S.S.Khadabadi
,S.L.Deore ,B.A.Baviskar
Pharmacognosy &phytochemistry by
Vinod.D.Rangari ,volume 2
