A novel biosynthesis of irregular sesquiterpene artemone in artemisia pallens

Tetrahedron Printed in

Letters,Vol.27,No.48,pp Great Britain

OF

A NOVEL SESQUITERPENE

IRREGULAR

A.

AKHILA,

Central

ABSTRACT

-

IPP

and

(I)

units and

join

"H

plant

the

this to

a

to

geraniol

artemone shift

R.

S.

THAKUR Plants

to

these

Such

chief

the

join

in

various

does

not

compounds from

whereas

the

two

biosynthesise

units of

that

isolated

[6]

as

fashion

rearrangement

[4-51.

,

(DMAPP)

times

(VII),

II

to

to kown

Artemisia

davanone

(VI) in

isoprene terpenoids

"H

bonds

seem are

constituent

& T"

fashion

and

organic

be

formed

as

irregular

pallens, is

another

is

by

an

sesqui-

essential

the

now

and

to

FPP

of

IV

at

biosynthesis, to

to of

oil

of

give

C-2' the

the

sesquiterpenes to

shift

to

[lo]. to

two

desired

5885

which

further

(Scheme

C-3" V is

metabolise D-methyls product

1).

It

nerolidylpyrophosphate

sesquiterpenoids

cyclic

would

(III)

farnesylpyrophosphate

produce

isomerises

interconversion)

oxidation

C-5

I

and

acyclic

C-5"

- linalool

of

precursor that

many

from

geranylpyrophosphate

molecule

traditional

-0PP

(VII)

give

another

established

case

Tail"

compound

linkage

metabolise

cyclisation

must

rise

with

(FPP,IV), well

AND

PALLENS

[7,8].

with

to

and

present

condenses

(V)

to

Several

fission

T"

condenses

is

"Head

sesquiterpene

terpene this

a

Artemone

irregular

SHARMA

ARTEMISIA

Institute of Medicinal and Aromatic Lucknow India 226 016

[l-3].

&

terpenoids.

I

in

gives

usual

K.

dimethylallylpyrophosphate

the

then

groups

P.

BIOSYNTHESIS ARTEMONE IN

0040-4039/86 $3.00 + .OO Perqamon Journals Ltd.

A novel condensation between two isoprene units, isopentenylpyrophosphate and dimethylvinylcarbinylpyro(IPP) phosphate (DMVCPP) is being reported here for the first time within the plant system to produce artemone, an iregular sesquiterpene.

steroids

and

5885-5888,1986

to

give

expected VI.

In

from

C-3

(Scheme

1).

[9]. V

In

( analogy to

the of

undergo case

of

V

VI

or

5886

Y3 s’

3’ ’

2,

2”

0

5

f .-

3"

4

4"

3 I

151'

2

VI

I:

Scheme

In

Possible biosynthetic pathway to Vl and VT1 from C-5 units. The numbering system follows that of the mevalonic acid. The C-l of the decarboxylation and form,ltion of IPP, MVA being lost during DMAPP and DMVCPP.

order

shifted of

A.

set

to to

find C-5

pallens

of

out

or

some

were

fed

degraded product c-5 of MVA which

has

from

VI

of

V

in

VII.

However

in

the

precursor

on

when

two

terminal

The

results

during 2

and

C-2"

some

suggested

to

of

other for

to

ratios

and

cyclisationand

1)

ratio

in

:

; 2

14C

suggest

XII

it

and

VII

C-3

1)

can

(3H

one

oxidation

C-5

place,

of

the

the

twigs

separate

is

the

in

fact

methyls

have

!>rcn

lost

the

same

7s

as

?tI. I,a t e r from

the

C-5)]. only to

one

VT

and

Scheme

1

C-2'

of

from

have

1'11 and

VII

: 1)

; 2

VI

in

two

would

: 14C

that

from H

C-3 Had

or

suggesting no loss of 3 ob\iousl>tl atoms, four

oxidation

well

V

1)

suggest

3

of

taken

that

(actually

and

that

:

lost

unaffected

this

has

C-3

[5-3H2, 2-14c]-NVA 14 C) in VT and

degradation. 3 the two H at

C-5

('Table

be

:

('H

at

during

cyclisation

suggests

carbon

and

[C-5"

Exp.2

seem This

biogenesis. to

(3H

degraded

from

pathway

to

isotope

(MVA)

course

biogenetic

lost

shifted

gem-methyls

[2-'H2,2-14C]

(Exp.l,Table

methylenes

the

two

isotope

been

the

was

it

other

(XII)

or

the

with

The

experiments.

C-3

whether

be

explained

of

NPP

(V)

the

during VT

by to

from V lost 3 'I'he H at C-

'Fi is VII.

VI

or

the or

VT1

X-group VII

course has

of

shlfted

mechanism

(Scheme

3).

5887

gb c2

OPP

II

5"

IX

\

I

Scheme VII

2:

subjected

was

and

exchange alpha of The be

to

base

Biosynthetic to

isotope

suggesting ratios

biosynthesised

(Scheme VIII

2)

-f IX

+

the

I

-t x

that

DMVCPP

produced authors

interest thanks

he to

DMAPP

viva

are

thankful

has

shown

CSIR,

New

VII

and

plant

Delhi

+

to during for

DMVCPP

proceeds

Dr. the

via

the to

actively

DMVCPP taken

course

of

the

this

assistance.

in

carbons

the

presence

(VII)

condenses

following

the in

at

‘H20-

VII.

knowledge within

using

tracer

artemone

(VIII)

Husain, of

blanks

of

that

part

IPP

exchanged

C-3'

authors

Akhtar

financial

at

suggest if

To

isomerised has

present

was

and

by

exchange

tracer

XII

{DMVCPP

checked

allow

of

system

VII).

from (as

to

to 50% 3 H was

biosynthesis -9 XI has

in

40

VI,

the

artemone

' H-NMR)

that

in in

and

report

The

by

group.

to

conditions

known

monitored

carbonyl [ll]

scheme

OPP

only

IPP(I)

sequence. this

is

plant

terpene

Director work

can

with

+

first

system

and

biosynthesis. CIMAP

and

(I

the

one

for of

us

keen PKS

'T:!BLE1

: Tsotopc ratio in Davanone (VI) and Artemone (V1T) obtained .S.yallens after being

fed with douh!y

labeLled mevalunic

Ir;im acid.

____ isotope ratio

Precursor

Exp.

?L Incorporation

‘3.

Isotope ratio ( tl : Davanone

‘%)

,Arremonc Ocg. f'roduct

YVt\ Q&3I1.,,2-~4C] 2 : I 0 . (15 4.91 : 3 4.88 : I! 4,?0 : 3 i ________________________________________________--_______-___--_-~---_----------~---2.

REFERENCES 1i.

2. 3. 4. 3. 6. 7. 8. 9. 10. 11. 12.

13.

0. WALLAC, Ann. Chem. (1887) 239, 1. I,. RlJZTCKA, A. ESCHENMOSER and H. IIEUSSER; Experientja (1953) 9, 357. R. CROTEAU and >l. A. JOHNSON; Biology and chemistry of Plant 'I'richomes (1'1841, 133. Edited by Eloy Kodrignez, Patrick I,. ffealp and Indira Xehta. G. R. WALLER, C. pi. FROST and D. BURLESON; Phytochemistr-g (1968) 7, 217. (1375) i')?. .J . SHAW, T. NOBLE and W. W. EPSTEIN; J. Chem. Sot. Chem. Cs P. NAEGRLI, J, KLIMES and D. WEHER: Tett. Lett. (1070) 57, %):!I. G. SIMPA and R. VANDER WAT,; Rec. Trav. Chem. Pay-Bas (1068) 87. A. F. THOMAS and G. PITTON; Iielv. Chim. Acta (1971) 54 , 1890. (1980) 36, 1109. D. E. CANE: Tetrahedron D. V. RAYTHORPE and B. V. CHARLWOOD; Chemistry of Terpencs and 'i‘erpcnoids (1972) 337. Edited bv A. A. Newmann. Academic Press, London. A. AKtl1L.Aand-D. V. RANTHORPE; Phytochemistry (1980) 19, I69i. Another hypothetical biogenetic route to artemnne (VTI), and this r~ould alsu give the same isotope rat?<) in VI1 (as shown in 'Table 1). 'Thrs route does not pathrv,a:y sum
(Received

in

UK

22

September

1986)