Vintha M. Thadhani1, Syed G. Musharraf2, Afshan
Begum2, M. Iqbal Choudhary2 & Veranja
Karunaratne3
1Institute
of Chemistry, Colombo, Sri Lanka; 2ICCBS,
University of Karachi, Pakistan,3University of
Peradeniya, Sri Lanka
Symbiotic association of fungus &
algae
Worldwide distribution
Able to grow under extreme
conditions
About 20,000 lichen species
identified .
Still many lichen rich areas
remain unexplored
Total number may well be close
to 100,000.
Occurs exclusively in these symbiotic organisms
Even with the advances of analytical methods,
there is comparatively less isolation of new
lichen metabolites may be due to the limited
biosynthetic pathways.
Approximately only 1050
lichen metabolites have been
isolated to date.
We have already reported various biological
activities of lichen compounds including,
– antioxidant,
– α-glucosidase inhibitory,
– urease inhibitory,
– antimicrobial,
– cytotoxicity etc
Zeorin isolated in 3.4% yield
from Cladonia sp.
Subjected to various bioassays
Patent obtained for αglucosidase inhibitory
activity.
Biotransformation through
Cumingharella elegans
Yielded 1,3-diacylglycerol &
diacylperoxide.
1-(5-dodecenoyl), 3-(5-decanoyl)glycerol
5-decenoic acid-1,1-diacylperoxide
R
7
6
1
4
4
2
3
OH
1
7
5
(A)
1'
4'
O
1
2'
3'
OR
7
C O 2R
6
RO
4
2
3
R
C arb o x yl i c ac id
5'
6
es t eri fi cat io n
5
C O2 R
OR
2
+
O
R
3
CO 2 H HO
5
RO
7'
6'
R
OH
D ep si d e
B e nz yl es t er
(B )
S m i le s rear ran ge m en t
R
R
7
6
P d (O A c) 2 /T F A
5
1
4
RO
2
3
5'
O
7'
6'
C O 2H
1'
4'
Di p h en yl et h er
C O2 R
2'
3'
OR
CH3 O
CH3 O
CH3 O
OH
O
HO
CH3 O
O
OH
HO
OH
O
A tran o rin
CHO
OH
CH3 O
CH3 O
HO
O
OH
CH3
OH
L ecarno ric acid
O
OH
OH
E ry thrin
C H 2O H
OH
CH3
R
R
O
R
R
6'
R
O
5'
O
O
O
R
O
1'
K 2CO 3
O
OH
6
5
R /H O
O
1
4
2
3
4'
2'
3'
OH
DM SO
R/ HO
O
-
OH
Sm ile s rea rra ngem ent
para de pside
R
R
O
O
R /H O
O
R
-
O
D iphenyl ether
O
OH
C O 2R
C O 2H
HO
C O 2H
N aO H /M eO H
C O 2C H 3
R eflux
OH
O
CH3
CH3
CH3
CH3
HO
D ip h en y l eth er 1
OH
O
D ip h en yl eth er 2
R = -C H 2 C H (O H )C H (O H )C H 2 O H
P d(O A c) 2
T F A /A cetic acid
CH3
CH3
OH
OH
C O 2H
COOCH3
HO
O
H y p o s tre p s ilic a c id
OH
H 3C
O
D ib e n zo fu ra n
CH3
HO
CH3
CH3
C O 2H
C O 2R
1) N aO H /M eO H
O
CH3
CH3
OH
D ip h en yl eth er 1
C O 2C H 3
5
C O 2C H 3
5'
2) K 2 C O 3 /M eI
HO
3
OH
O
3'
D ip h en yl eth er 2
R = -C H 2 C H (O H )C H (O H )C H 2 O H
3-3'
OCH3
3-5'
OCH3
OCH3
C O 2C H 3
H 3C
O
CH3
C O 2C H 3
D ib en zo fu ran 1
CH3
C O 2C H 3
H 3C
O
OCH3
C O 2C H 3
D ib en zo fu ran 2
OCH3
CH3
OCH3
CH3
C O 2C H 3
H 3C
O
OCH3
C O 2H
H 3C
C O 2H
O
OCH3
C O 2C H 3
S ch izo p eltic a cid
OH
Iso -sch izop eltic a cid
CH3
OH
CH3
C O 2H
C O 2C H 3
B
H 3C
O
C O 2H
P a n n a ric a cid
OH
H 3C
O
C O 2H
9 -M eth y lp a n n a ra te
OH
This study reveals the possibility of conversion
of major lichen specific secondary metabolites
into new compounds through
biotransformation and semi-synthesis.