Sesqui- and diterpenoids from the panamanian liverwort Bryopteris filicina

Pergrmon

0031-9422J94)E0276-X

Phyrorhmiwry. Vol 37. No 2 pp. 433-439. 1994 Copynghc Q 1994 Ekncr Sama Ltd Bnlpin All liphI. -cd 0031 9422/94 57.00+00

mntedI”Gral

SESQUI-

AND

DITERPENOIDS FROM THE PANAMANIAN BRYOPTERIS FlLfCINA

LIVERWORT

FUMIHIRO NAGASHIMA,HIROMI IZUMO, SHIGERUTAKAOKA,MOTOO TORI and YOSHINORI ASAKAWA Faculty of Phannaceutlcal

Sciences, Tokushima

Bunri University,

Yamashiro-cho,

Tokushima

770, Japan

(Receiced 7 February 1994)

Key Word Index--Bryoprerisfilicina; Lejuneaceae; Hepaticae; bryopterins A-D, fusicogigantepoxide; isomarchantin C; norpinguisane-; pin&sane-; guaiane-; germacrane-; aromadendrane-; lepidozanetype sesquiterpenoids; fusicoccane-type diterpenoid; bisbibenzyl; chemosystematics.

Abstract-Four new pinguisane-type sesquiterpenoids, bryopterins A-D, were isolated from the Panamanian liverwort Bryopteris filicina along with some previously known sesqui- and diterpenoids and the marchantin-type bisbibenzyl, isomarchantin C and their structures determined by extensive NMR techniques and chemical degradation. The stereochemistry of fusicogigantepoxide was determined by X-ray crystallographic analysis. Bryopterisfilicina is chemically similar to Ptychantus species.

INTRODUCTION We are continuing to investigate the chemical constituents of the liverworts [l-3]. Previously we have reported on the structural determination of new terpenoids and aromatic compounds of liverworts collected in Japan, Europe, South America and New Zealand [ 11. We have now investigated the chemical constituents of the Panamanian liverwort Bryopterisfilicino. Here, we report on the isolation and characterization of four new pinguisane-type sesquiterpenoids (l-4) and the stereostructure

Q% ’

of the previously known fusicoccane-type fusicogigantepoxide (10).

diterpenoid,

RESULTSAND DISCUSSION The ether extract of B. jilicina was chromatographed on silica gel. Sephadex LH-20 and prep. HPLC to give four new pinguisane-type sesquiterpenoids, named bryopterins A (l), B (2), C (3) and D (4), together with the previously known sesquiterpenoids, norpinguisone methyl ester (5) [4]. 4,6-guaiadiene (6) [S, 63, l(lO),Sgermacradien-4.1 I -dial (7) [7], (4S+,SS*,6R l,7R *)l(lO)E-lepidozen-S-01 (8) [S]. ent-spathulenol (9) [8,9], a fusiccocane diterpenoid, fusicogigantepoxide (10) [lo], the cyclic bisbibenzyl isomarchantin C (11) [ll], and stigmasterol. The IH and lJCNMR spectra of 10 were completely identical with those of the known fusicogigantepoxide. isolated from the Malaysian liverwort Pleurozia giganteo

0

I

MI

.

12 R’.H,.

R’=OAc

17 R’.O

R’.OH

18 R’.O.

R’.OAc

22 :I

13 R’.R=OAc.

Fly-H

15 R’.l?.R’.H 19 R’.R’.OAc.

16 R’.R’.H

:I

R’.R’=OH

20 R’.R’;R’.OAc.

R’.H

1;

H :I 11

AZ-OH

433

434

F. NAGASHIMA er al.

[IO].

However,

determined. ray

its relative stereochemistry

As 10 was obtained

crystallographic

ORTEP

drawing

fusicogigantepoxide of

6 173.5 s). Moreover, the presence

spectrum

The

data are of

(C,D,)

(Table

2) showed

ring. The

(I 725 cm

‘;

test for 1 indi-

‘H NMR

contained

I6 carbons

bon, four

carbons

(Table

3); an exomethylenic

of an z$-disubstituted

carbons. Compound sesquiterpenoid,

spectra showed

group

the positive Ehrlich

of the furan

(65.07,

car-

furan.

two

methyls, three methylenes. a methine and two quaternary

to be 10.

(analyt. 260.1416) was determined

the presence of an ester carbonyl ca!eJ

protons

spectrum

out.

1 showed m/z 260 [M] + and its molecu-

The IR and 13C NMR

exomethylene

(66.30, 7.02 each d, J = 2.0 Hz). The “C NMR

carried

has been determined

by HRMS.

(63.24).

was

I. Thus. the stereostructure

C,,H,,OJ

group

furan ring

analysis

lar formula

methoxyl

5. I9 s), and two protons of an z, /I-disubstituted

of 10 and the crystallographic

shown in Fig. I and Table The EIMS

has not been

as a single crystal. an X-

(C,D,)

the presence of a tertiary

methyl (6 I. 17). a secondary methyl (60.77 d, J = 6.8 Hz). a

1 appeared

to be a pinguisane-type

because the above spectral data were

similar to those of norpinguisone ‘H-‘H

COSY

and HMQC

units (Fig. 2). Correlation

of each unit was further indi-

cated by analysis of the HMBC methyl proton (H-13) quaternary

methyl ester (5) [4]. The

spectra led to three partial spectrum. The secondary

in unit A was correlated

with the

carbon (C-8). The tertiary methyl proton (H-

14) was correlated with the methylene carbon (C-3) in unit A, a quaternary Table Chemical

I. Summary

of crystallographic

formula

data for 10

Volume of unit cell z value Densities: D,,,,

unit A werecorrelated l4), a quaternary

C,,H,,O,

Molecular weight Crystal system Space group Crystal size Umt-cell chmcnslons

carbon (C-4) in unit C and two quatern-

ary carbons (C-8 and 9). The methylene protons (H-3) in with the tertiary methyl carbon (C-

carbon (C-4) in unit C and two quatern-

304 Monoclinrc

ary carbons (C-8 and 9). The methylene

P,, ( i+ 4) 0.30 x 0.20 x 0.10 mm’ a = 9.854 (2) A h L I 5.020 (3) A c=6.238 (I) A j?= 103.51 (1). 897.7 (3) A’

unit A, two oletinicquaternary

unit B were correlated D. two quaternary

carbon (C-12).

2

carbons (C-8 and 9). and a carbonyl

Moreover.

the exomethylene

carbon

carbon (C-5) in unit D and a

(C-9).

The above spectral

that 1 was a pinguisane-type

1.12 gem-’

with a methoxycarbonyl

protons (H-

with the olefinic quaternary

carbon (C-4). a quaternary confirmed

in

carbons (C-5 and 6) in unit

15) in unit C were correlated quaternary

protons (H-7) in

with the methine carbon (C-l)

evidence

sesquiterpenoid

at C- 12 and an exomethylene

Mac science MXCIB

Radiation

CuKz

difference

Total

1762

acetate 12 derived from 1. NOES

-lI
(i) H-13 and H-12, (ii) H-13 and H-7a. (iii) H-14 and H-

Diffractometer

u.sed

relleclions measured

Rellccrlon (hkl) limits

(i=

1.54178)

-17
reflections

1548

Internal

consistency: Rint

0.04

Least squares rctinement method

Full matrix

Absorption

correction

F(OO0) Linear absorption Reflections

Data reduction Maximum

coefficient

used in L.S. cut-off

sin (O);i

experiment

12. (iv) H-14 and H-7/I ively. From

13CNMR

showed

those of 1, except methoxy

0.00

This assumption

0.583

long range I%-‘H

O.CNIOO

“C-‘H

carbonyl

COSY

15) of two methine

(analyt. ‘H

for

the presence of an additional

in place of the exomethylene was supported COSY

by ‘H--‘H,

experiments.

spectrum (Table

was correlated

This methine proton

1.0000 0.0608

ated with a methylene

R,

0.0583

carbon (C-5) of a furan ring. The other carbonyl

Max shift/e.s.d.

1.4393

(C-12) was correlated

Average shift/e.s.d.

0.2173

above spectral data indicated

Goodness of fit Fourier map type Sim weighting Fourier map grid Maximum peak in final Fourier map Mimmum peak in final Fourier map

0.32483E +02

type sesquiterpenoid

with a methoxy

F,-F,

and

The

OFF

determined

0.333 A 0.16 e A - 3 (0.608 0.887 0.908) -0.29eA-’ (0.574 0.975 0.854)

H-15.

(iv) H-13

13. NOES (ii) H-14

and H-12,

a

(C-3) and a quaternary carbon

with methylene protons (H-7). The that 2 was a pinguisane-

relative

by difference NOE

the diacetate and

carbon

with

was correl-

Eta coefficient

15. respectively.

and

The long range

4) indicated that one(C-

carbons

(H-4).

at C-4.

“C-‘H

Residuals. R Residuals

and

spectra (Tables 2 and 3) resembled

carbonyl

proton

spectra of 2, C,,Hz20s

I; ~3~173.6. 173.9 s). The

(CDCI,)

19.424 cm _ ’

Extinction

of bryop-

the presence of two ester carbonyl

(I726 cm

1489

261

and (v) H-14 and H-15, respect-

The IR and ‘3C NMR groups

34191

on the mono-

were observed between

these spectral data. the structure

306.1469).

369

L. S. parameters

performed

by a

terin A was established to be 1.

empirical

L. S. matrix elements coefficient

NOE

was determined

at

C-4. The relative stereochemistry

carbonyl

at C-12

stereochemistry

was

experiments performed on

were observed between (i) H-14 and

H-78,

(v) H-12

(iii) H-14

and

H-12,

and H-7/? and (vi) H-13

and H-7a. In order to obtain the known deoxopinguisone (15) [I23

from 13, 13 was reduced by LiAIH,

to afford a

diol which was treated with p-toluenesulphonyl

chloride

Terpenoids

Fig.

I. ORTEP

Table

I 2 3 4 7 IO II I3 I4 I5 OMe

of Bryopterisfilicina

drawing

of fusimgigantepoxide

435

(10).

spectral data of l-4

2. ‘H NMR

1 (CA)*

1 (CDCI,)

2 (CDCI, 1

3 (CDCI,

2.03 m I.61 m 1.92 m 2.27 ddd, J = 12.9. 9.0, 2.2 2.48ddd. J=l2.9, 11.5, 7.6

2.00 m ISOm 1.88 m 2.27 2H. m

l.%m l&m 1.71-1.88 1.71-1.88

2.96d. 3.45 d, 6.30 d. 7.02 d, 0.77 d. I.17 s 5.07 s 5.19s 3.24 s

2.85 d. 3.31 d, 6.44 d, 7.26 s 0.89 d, 1.10s 5.12 s 5.19 s 3.72 s

2.01-2.17 m IhO-l.70m 2.01-2.17 m 2.01-2.17 m 2.32 m 3.54 br s 2.75 d, J = 18. I 3.26 dd, J = 18.1. 2.9 6.14d. J=20 7.29 d, J = 2.0 0.91 d, J=6.3 0.90 s

2.73 3.51 6.33 7.27 0.96 0.97

3.71 s 3.76 s

3.71 s 3.73 s

J=l8.1 J = 18.1 J = 2.0 J = 2.0 J = 6.8

J = 18.1 J= 18.1 J = 2.0 J = 6.8

d, d, d. s d, s

)

4 (C,D,) 1.87 like q

m 2H. m

J = 16.9 J= 16.9 J = 2.0 J = 7. I

2.44 d, J = 18.8 3.56 d, J = 18.8 2.72 3.56 6.53 6.77 0.7 I 0.93

d, J = 18.8 d, J = 18.8 s s d. J = 6.8 s

3.06 s

*Measured at 600 MHz J values in Hz.

in pyridine, followed by LiAIH, to furnish 14, in place of deoxopinguisonc (15). From the above spectral evidence, the structure of bryopterin B was determined to be 2. The molecular formula of 3 was indicated to be C,,Hz20b (analyt. 322.1392) by HRMS. The 13CNMR and IR spectra showed the presence of a tertiary hydroxyl and two ester carbonyls (3503 cm- ‘; 6c78.4~) (1723 cm- ’ ; 6cl73.9, 175.8 each s) groups. The ‘H and 13C NMR (Tables 2 and 3) spectra were similar to those of 2. except for the presence of a carbon bearing a hydroxyl group. In the ‘H NMR spectrum of 3 the signal for the methine proton at H-4 in 2 was absent, indicating

that 3 might be a pinguisane-type sesquiterpenoid with a hydroxyl group at C-4 and two methoxy carbonyls at C12 and 15. This assumption was further supported by the ‘H-‘H, “C-‘H COSY and HMBC spectra (Table 4). In order to confirm the structure of 3, we attempted to derive the known 16 [4] from 3. Reduction of 3 with LiAIH, gave a mixture of the reduced compounds, which was oxidized by sodium periodate to give the monoalcohol 17. Treatment of 17 with acetic anhydride-pyridine gave the monoactate 18 which was reduced by LiAIH, to a mixture. The *H NMR signals of the mixture were partly identical to those of 16 [4]. The stereochemistry of the

436

F. Table

39.2 29.1 36.0 146.1 116.X 149.2 25. I 61.8 51.4 107.2 142.2 173.5 15.5 25.2 106.4 50.8

*Measured

3. “C NMR spectral 2

3

38.8 29.4 35.8 145.7 116.2 148.8 24.6 61.7 51.1 106.8 141.9 174.2 15.4 25.2 106.3 51 3

38.8 29.4 35.5 48.7 Ill.4 148.2 24.0 62.6 48.4 110.5 141.2 173.9 15.3

45.0 31.3 36.1 78.4 116.3 150.9 21.9 61.1 55.3 108.9 141.2 173.9 15.1 21.0 175.x 51.1 52.5

18.5 173.6 51.4 51.8

4. Long range correlarions

2 ‘W

3 4 7 13 14

1. 2. 3, 5, I. 5, I. 2 3. 4.

unit

t

d

4, 6. 6. 8 8.

8. 9 9. 15 8. 9. 12 9

A

tertiary

hydroxyl

51.6

51.63

117.4

of 2-4 4 ‘H

“C

1 2 3 7 13

7, 8, 12. 13 1. 3. 13 24.8.9. 14 I. 5. 6. 8. 9. I2 I. 2. 8

I 3 7 IO II

2. 2, I. 6. 5.

I4

3. 4. 8. 9

I3 I4

1. 2. 8 3, 4. 8. 9

C=CH2

group

162.4 24.5 59.9 s2.5 107.5 144.0 172.0 9.3 20.6

39.87 29.53 33.27 197.32 116.75 163 21 25.14 61.83 58.46 107.09 144.44 173.16 15.58 20.64

“C

unit E

unit D

Fig. 2. Partial

50.3 210.8 45.4 193.9

‘H

tCH2*

unit c

5 [41

3

CH3

&H-CH*-CH2*

4 (C,D,)

at 150 MHz.

Table

‘H

data of 1-S

I

I (C,D,)’ I 2 3 4 5 6 7 8 9 IO II I2 13 14 15 OMe

NAGASHIMA rr al.

structures

of I.

of 3 was revealed

by a difference

NOE experiment performed on the diacetate 19. NOES were observed between (i) H-13 and H-12, (ii) H-14 and H-15 and (iii) H-14 and H-78. These results confirmed that the tertiary hydroxyl group at C-4 possesed zconfiguration. Thus, the structure of bryopterin C was 3. Compound 4, C,,H,,O, (analyt. 276.0990). showed the presence of carbonyl and ester carbonyl groups (1748. 1730 cm-‘). and an z. /I-disubstituted furan ring (positive

3. 4. 5. II 6.

7. I(. 12, 13 9. 14 6. 8. 9. 12 IO

Ehrlich test; bH6.53, 6.77 each s). The 13C NMR (C,D,) spectrum (Table 3) showed 15 carbons: three methyl, two methylene, a methine, two quaternary carbons, an a,/?disubstituted furan ring and two carbonyl carbons (6 193.9. 2 10.8 s) and an ester carbonyl carbon (6 172.0s). The ‘H NMR spectrum (Table 2) was similar lo that of norpinguisone methyl ester (5) [4]. The HMBC spectrum (Table 4) indicated that the methine proton (H-l) was correlated with a secondary methyl (C-13). two methylene carbons (C-3 and 7) and a quaternary carbon (C-8). as well as with an ester carbonyl carbon (C-12) and a carbonyl carbon (C-2). The methylene protons (H-3) were correlated with a tertiary methyl (C-14). a quaternary carbon (C-9) and two carbonyl carbons (C-2 and 4). In addition, the tertiary methyl proton (H-14) was correlated with a methylene carbon (C-3). two quaternary carbons (C-8 and 9) and a carbonyl carbon (C-4). The above data established that 4 was a norpinguisane-type sesquiterpenoid with a methoxy carbonyl at C-12 and two ketone groups at C-2 and 4, respectively. This was confirmed by the following chemical reaction. Treatment of 4 with LiAIH, followed by acetic anhydride-pyridine

Tefpcnoids of Bryoprerisjlkina

10. Asakawa, Y.. Lin, X., Tori, M. and Kondo. K. (1990) Phytuchemistry 29. 2597. 11. Asakawa, Y., Tori, M., Takikawa, K.. Krishnamurthy, H. G. and Kar, S. K. (1987) Phytochemistry 26, 1811. 12. Asakawa, Y. and Aratani, T. (1976) Bull. Sot. Chim. Fr. 1469.

PHY 37:2-K

439

13. Hashimoto, T., Tori, M., Taira, Z. and Asakawa, Y. (1985) Phytochemistry 26. 6473. 14. Tori, M., Nagai, T., Asakawa, Y., Huncck, S. and Ogawa, K. (1993) Phytochemistry 34, 181.