Isolation of saikogenin F, another genuine sapogenin from bupleurum falcatum L.

Tetrahedron Letters No.41, pp. 5045-5048, 1966. Pergmon Press Ltd. Printed in tireatBritain.

ISOLATION

OF

SAIKOGENIN FROM

Research

ANOTHER

BUPLEURUM

Tokuo Shionogi

F,

FALCATUM

Kubota

Laboratory,

GENUINE

and

Shionogi

Hiroshi

8 Co.,

SAPOGENIN

L.

Hinoh

Ltd.,

Fukushimo-ku,

Osaka,

Japan

(Received 1 August 1966) Previously, from was

the

root

first

Aimi

isolating

cation

wish

saponin

(2)

(3)

and

in our

from

lb afford&

Prof.

B (II),

the

present

isolation

fi

that (i-4).

saikoside Their

D (IV)

(4)

of another

lb and

both

saikosides

la gave amended

5045

named

the

saikogenin were

in

C (Ill) saikogenin A (I).

to be equivalent named

by Shibato

II fraction la and

(3,4).

lb showed

of a hetemonnular

indicated

results

II*

saikoside

saikogenin

it was

succeeded

to saikogenin seem

the

(2) that

of which

longispinogenin.

sapogenin,

shows

obtained

to saikogenins

from

lb fraction

isolation

independently

which la,

soponin

ond

corresponding

fractions,

lb,

crude

A (I),

mp chomcteristic

lo and

the

corresponding

that

described

soikosides

Shihoto

saikogenin

the

and

authors

obtained

and 260 only

C (III)

saikosides

reported

have

both

main

of

saikogenins

sapogenin

has been

previously

hydrolysis

sapogenin

mobility,

E (V)

et al. of

(2),

of three

at 242,251

Shibata

afforded

to describe

determination,

hydrolysis

acid

L.

a genuine

consists

have

absorption

that

to be a genuine

bikogenin

Although acid

Shibota

is shown

et al. UV

et al.

of chromatographic

(2).

However,

l

and

(1)

falcotum

by Shibato

now

crude

Shibata strong

Bupleurum

We

in order

et al.

described

E (V),

which

The

have

saikogenin

B (II).

F (VI),

to,

of

reported

Recently,

and

we

strong

diene.

absorption

A (I) was

and

obtained

in a private A (I),

but

traced

by us.

that

from

communisaikoside

No.41

HO R

I III

\ d

CHIOH OH

II

R = CHzOH R = CH3

the la fraction exhibits only a very weak absorption at those region in comparison with that at 205 mu. The lo fraction

is subjected to the reaction sequence, which was successful for the

isolation of saikogenin E (V) (4). sodium m&ape&dote

The product which is obtained by oxidation

followed by treatment with ethanolic

with

KOH is shown to be much

more polar than saikogenin A (I) on thin layer chromatography.

Its analytical

value,

C&HssOp, indicates that the product still has a hexose in addition to the expected aglyco.ne through partial saponin is

not elucidated

degradation

of the saponin.

Although the structure of the

vet, the above results suggest that, in the saponin, a sugar

No.41

5047

molecule

linked to an aglycone

sugar molecules. vicinal

has no vicinal

glycol owing to linkages with additional

The remaining sugar molecule

in the product should now have a

glycol through release from the linkages with the adjoining sugar molecules and

should be cleft with periodate. periodate,

The intermediate

which is consumed as expected.

boiling ethonolic

is again treated with sodium meta-

Treatment of the oxidation

product with

KOH gives saikogenin F (VI), w h’ICh on recrystallization

form is obtained OS plates combined with chloroform, C3cHg04*‘/2CHCl3, 273”,

[a j,

+95.7’

(+107.8”

on calculation

m.p.

Scikogenin

F (VI) on the UV spec-

trum shows no absorption except at 205 mu and its IR spectrum (Nujol)

exhibits a broad

hydroxyl absorption, and sharp bands at 977, 904 and 884 cm-’ indicative linkage

+109.6’,

respectively,

shows signals at T 9.17-8.88 of ocetoxy groups), 6.80

AB quartet, at CD;

AB quartet,

J=7.5

singlet),

groups; two quartets), A”;

of VI affords the triacetote,

C&H5407,

m.p.

which displays no hydroxyl band in the IR spectrum.

MC, in CDCI,)

CHzOAc

of an oxide

and ot 763 and 754 cm-’ due to CHCI,.

Mild acetylation

bridge;

265-

The combined chloroform

as CHCI,-free).

is not lost by heating in vacua at 100’ for 5 hrs.

from chlom-

(6 Me), 7.98

and 6.01

[a],

Its NMR spectrum (60

ond 7.94

(1 Me and 2 Me,

(CH, at Ca being involved in the ether

cps, with small split in the former signal), 6.22

(CH, of

5.22

and 4.55

(1H each at C3 and Cl, bearing the acetaxy

and 4.56

and 4.12

(2H of the two-substituted

double bond at

J=lO cps, with smal I splits in each of the signals).

Since saikogenin F (VI) on heating with H$O, saikogenin

205~208.5’,

in aqueous ethanol readily affords

A (I), the former (VI) is shown to be the genuine sapogenin corresponding

to the latter (I), which has been obtained as a major sapogenin of this plant (1,2). From the above-mentioned lished as 1@:28-epaxyolean-1

results, the structure of saikagenin l-one-3@,16#,23+iol

(VI),

F has now been estab-

in connection with the

5008

No.41

structure of saikogenin A (I) and with the correlation

(4) between saikogenins C (III)

and E (V). On the other hand, the saikoside lb fraction exhibits a strong UV absorption due to the conjugated diene, as already mentioned, and even on treatment with the same procedure which yielded soikogenin F (VI) affords saikogenin it is supposed that saikogenin

be so unstable, owing to its axial

alkali

From these facts,

D (IV) itself exists as a genuine sapogenin in the plant,

but it should be noted that on imaginative

during extraction

D (IV).

from the plant.

genuine sopogenin corresponding to IV may

hydroxy group at C16, that it might be transformed The fact that the repeoted treotments of the periodate-

sequence are required for isolation of saikogenins F (VI) and D (IV) suggests that

the saikosider lo and lb may contain the same type of a sugar moiety branched at sugar molecules linked to the aglycones.

Acknowledgement: The authors are grateful to Dr. K. Takeda, Director of this Laboratory, for his interest and encouragement during this work.

REFERENCES

1.

T. Kubota, F. Tonami and H. Hinoh,

2.

5. Shibata,

3.

N.

4.

T. Kubota and H. Hinoh,

Tetrahedron Letters

I. Kitagawa and H. Fujimato,

Aimi and 5. Shibata,

701 (1966).

Tetrahedron Letten

Tetrahedron Letters, in press (1966). Tetrahedron Letters,

in press (1966).

3733 (1965).