Prenylated coumarates from Artemisia xanthochroa

Short Reports alcohol) m/z 677 [M +Na]+ (+NaI), 693 [M +K]+ (+KI); EIMS m/z (rel. int.): 654 [M]’ (< 1), 547 (4) [XylGlc (OAc),]+, 428 (13), 259 (65) [Xyl (OAc),] +, 199 (30), 157 (45), 139 (69), 91 (100) [Ph-CHz]+; ‘HNMR (CDCl,): 6 1.99,2.00,2.02,2.03,2.05 ( x 2). 2 hexaacetate, FABMS (m-nitrobenzyl alcohol) m/z 691 [M+Na]+ (+NaI), 707 [M+KJ+ (+KI); EIMS m/z (rel. int.): 668 [[Ml + (< 1), 547 (6) [XylGlc (OAc),] +, 331 (30), 259 (100) CXyl(GAc),l+> 199 (29), 157 (41), 139 (42), 105 (79) [PhCH,CH,l +; ‘HNMR (CDCI,): 61.89, 1.96,1.98,2.01,2.04,2.05. 3 hexaacetate, FABMS (m-nitrobenzyl alcohol) m/z 669 [M +Na]+ (+NaI), 685 [M+K]+ (+KI); EIMS m/z (rel. int.): 646 [M]’ (2), 547 (7) [XylGlc (OAc),] +, 259 (100) [Xyl(OAc),]+, 199 (40), 157 (47), 139 (42), 83 (14) [MeCH,CH=CH(CH,),]+; ‘H NMR (CDCI,): 61.99, 2.02, 2.03, 2.04, 2.05 (x2). Analysis of the sugar portion. Ca 2 mg of each sample was treated with 5% HCl gas in dry MeOH at 95” for 3 hr. The reaction mixt. was neutralized by the addition of A&O, and then filtered. After the solvent had been removed, several drops of a TMS-imidazole solution was added, followed by standing at 65” for 15 min. The reaction mixt. was partitioned between Hz0 (1 ml) and n-hexane (1 ml x 2). The hexane layer was coned and subjected to GC analysis. Column: 1.5% OV-1 (2 mm x 2 m); temp: 170” (isothermal); N,: 40 ml min-i; R,: Xyl, 5.52 and 6.00 min, Glc, 14.77 and 16.44 min; 1:Xyl, 5.52 and 6.02 min, Glc, 14.84 and 16.44 min; 2: Xyl, 5.53 and 6.01 min, Glc, 14.78 and 16.45 min; 3 Xyl, 5.53 and 6.01 min, Glc, 14.81 and 16.48 min. authors wish to thank Dr Y. Takeda of The University of Tokushima for the elemental analyses. Acknowledgement-The

Phytochemistry, Vol. 29, No. 11, pp. 3683-3685, Printed in Great Britain.

3683 REFERENCES

1. Otsuka, H., Yamauchi, T. and Yamasaki, K (1989) Phytochemistry 28, 3197. 2. Nakamoto, K., Otsuka, H. and Yamasaki, K. (1988) Phytochemistry 27, 1856. 3. Aquino, R., D’Agostino, M., de Simone, F. and Pizza, C. (1988) Phytochemistry 27, 1827. 4. Miyase, T., Ueno, A., Takizawa, N., Kobayashi, H. and

Karasawa, H. (1987) Chem. Pharm. Bull. 35, 1109. 5. Kasai, R., Suzuo, M., Asakawa, J. and Tanaka, 0. (1977) Tetrahedron Letters 175. 6. Bonner, T. G., Bourne, E. J. and McNally, S. (1962) J. Chem.

Sot. 761. 7. Miyase, T., Ueno, A., Takizawa, N., Kobayashi, H. and Oguchi, H. (1987) Chem. Pharm. Bull. 35, 3713. 8. Okamura, N., Yagi, A. and Nishioka, I. (1981) Chem. Pharm. Bull. 29, 3507. 9. Bisset, N. G., Choudhury, A. K. and Houghton, P. J. (1989) Phytochemistry 28, 1553. 10. Nonaka, G.-L, Nishimura, H. and Nishioka, I. (1982) Chem. Pharm. Bull. 30, 2061.

11. Takei, S., Sakato, Y., Oono, M. and Kuroiwa, Y. (1938) Nippon Nougeikagaku Kaishi 14, 709. 12. Nagumo, S., Kawai, K.-I., Nagase, H., Inoue, T. and Nagai, M. (1984) Yakugaku Zasshi 104, 1223.

13. Miyase, T., Ueno, A., Takizawa, N., Kobayashi, H. and Oguchi, H. (1988) Chem. Pharm. Bull. 36,2475.

1990 0

0031-9422/90 $3.00+0.00 1990 Pergamon Press plc

PRENYLATED COUMARATES FROM ARTEMISIA XANTHOCHROA J. JAKUPOVIC,R.X.

TAN,* F. BOHLMANN,Z.J.JIA* and S. HUNECKt

Institute for Organic Chemistry, Technical University of Berlin, D-1000 Berlin 12, F.R.G.; *Department of Chemistry, Lanzhou University, Lanzhou 730000, P.R. China; TInstitute of Plant Biochemistry, Academy of Science, Halle, G.D.R. (Received in reoised form 22 March 1990)

Key Word Index-Artemisia xanthochroa; Compositae; acetylenic compounds; prenylated coumarates; sesquiter penes; aromatic compounds.

Abstract-Artemisia

sesquiterpenes

xanthochroa from Mongolia contains several known acetylenic, aromatic compounds and as well as seven new prenylated coumarates. Structures were elucidated by highfield NMR techniques.

INTRODUCTION From the large genus Artemisa (Compositae, tribe Anthemideae) many species have already been studied chem-

ically. Most widespread are sesquiterpene lactones [l] and acetylenes [2]. In continuation of our investigation of Mongolian Artemisia species [3J we now have re-examined A. xanthochroa Krasel. [3] from a different locality.

RESULTSANDDISCUSSION Aerial parts of A. xanthochroa

afforded,

in addition

to

widespread compounds (Experimental), the acetylenic compounds l-5 [2], the epimeric endoperoxides 6 and 7 [4] and the methyl coumarate derivatives g-14. The ‘H NMR spectrum of 8 (Table 1) was close to that of the corresponding acid [S], with only small shift differences

3684

Short Reports

Table 1. ‘H NMR spectral data of compounds S-14 and 8Ac (400 MHg CDCI,, d-values) H

8

8Ac

9

10

11

12

13%

14t

Multiplicity

1.25 6.96 7.22 7.56 6.23

7.38 7.06 7.40 7.65 6.38

1.17 6.67 7.14 7.48 6.14

1.25 6.74 7.22 7.5-l 6.22

7.29 6.82 7.32 1.65 6.29

7.90 6.75 7.40 6.80 5.80

3.35

3.25

3.34

3.46

2

5.33

5.41

5.49

5.57

5.39

4

4.17

4.66

3.89

4.00

4.33

5’ OMe

1.75 3.75

1.81

1.65

1.75

1.80 br d

3.81

3.66 3.83 ~ --

3.75

3.79

7.32 6.68 7.24 1.56 6.21 2.95 3.20 4.70 3.61 3.67 0.92 3.73

d d dd d d

3.36

7.33 6.71 7.25 7.59 6.23 3.01 dd

2.29

.--

2.33 2.07

OAc

5.66

1.80 3.72

3.24 dd 4.94 ddd 3.60 dd 3.68 dd 0.95 d 3.75

dd dd ddd dd dd d

br d br t hr s hr s

--

*H-3’ 1.95 dtq. tH-3’ 2.01 dtq. J [Hz]: 2,6=2; 5,6=8; ?,8= 16; 1’,2’=8; compound 11: 2’,5’= 1; compound 12: ?,8= 13; compound 13: l’,,l;= 16; 1;,2’=9.5; l&2=8; 2’,3’=5; 3’,4; =?; 3’,4;=5.5; 3’,5’=?.5; 4;,4;= 11; compound 14: l’,,l;= 16; 1’,2’=2’;3’=9; 3’,4; =6; 3’,4; = 5.5; 3’,5’= 7; 4;,4; = 11.5.

being observed. Acetylation gave the diacetate 8Ac. The ‘HNMR spectra of 9 and 10 (Table 1) clearly indicated that the corresponding 4-O-methyl ether and 4-O-acetate of 8 were present. In the case of 9 the configuration of the double bond was determined by NOED which gave a clear effect between H-4’ and H-2’. The ‘HNMR spectrum of 11 (Table 1) differed from that of 8 characteristi-

3 4

tally in the chemical shifts of H-2’, H-4’ and H-5’ indicating that compound 11 was the Z’Z-isomer of 8. The ‘HNMR spectrum of 12 (Table 1) differed from that of 8 even though their molecular formulae were identical. Comparison of data with those of related 7Zcoumarates clearly showed that 12 was the 7Z-isomer of 8. The ‘H NMR spectra of 13 and 14 (Table 1) were also different from that of 8 and also from that of 12; again, their molecular formulae were identical with that of 8. However, the ‘HNMR data of the side chain protons showed that the double bond was absent and that an oxygen ring had to be proposed. Spin decoupling gave a clear sequence which required a dihydrobenzofuran moiety with a hydroxyisopropyl group at C-2’. Comparison of the data with those of related dihydrobenzofurans [6] allowed the assignment of the structure and the stereochemistry as a hydrogen bond between the ether oxygen and the hydroxy group leads to a fixed situation. Accordingly, the configuration at C-3’ followed from the different couplings J,., 3,. Compound 13 we have named xanthochroa coumarate. While the acetylenes l-5 are common in Artemisia [2] prenylated coumarates are rare. So far they have been isolated only from two species [3, 71. Surprisingly, the previous study of A. xanthorhroa gave several guaianolides [3] which could not be detected from this new COzMe collection.

E

z 6

la,40

7

ll3.48

OH 5

EXPERIMENTAL

8

9

10

11

12

R’

H

Me

AC

H

H

R' R"

H OH

H OH

H OH

OH H

H OH 72

13

14

3'aH 3'BH

Air-dried aerial parts (450 g, collected in the desert at DzaraCholaj, 104” lO’E, 44” 3O’i\l, omnii-Gov-Aimak, Vost. Gobi, in June 1988, voucher 450/88, deposited in the Herbarium of Dr Knapp, Halle, G.D.R.) were extracted with MeOH-Et,Opetrol (1: 1: 1) and the extract obtained sepd as reported previously [8]. CC frs were combined to 5. The first one gave by TLC (Et,O-petrol, 1: 9) 26 mg curcumene, 23 mg 1,24 mg 7 and

Short Reports 17 mg 2. Fr 2 gave by TLC (EtzGpetrol, 1:9, x 2) 15 mg 6 and 21 mg of a mixt of 6 and 7. TLC of fr. 3 (EtzO-petrol, 1:9, x 3) gave 30 mg 3, 17 mg bisabolol, 18 mg nerolidol and 3 mg acetophenone. TLC of fr. 4 (Et,&petrol, 1:4, x 2) gave 19 mg spathulenol, 30 mg p-hydroxyacetophenone, 21 mg 5 and 17 mg 4. The last fr. was sepd again by MP CC into three frs (S/1-5/3). TLC of 5/l (EtzO-petrol, 2: 1, x 2) gave 26 mg umbelliferone and 10 mg sakuranetin while TLC of 5/2 afforded 10 mg sakuranetin and 9 mg isosakuranetin. HPLC of 5/3 (MeOH-HzO, 3:2, RP 8) gave 12 mg hesperitin, 12 mg eriodictyol and two mixts (5/3/l and 5/3/2). TLC of 5/3/l (EtzO-CHCl,-petrol, 2:4: 1) gave 9 mg 9 (R, 0.33), 7 mg 8 (R, 0.3) and a mixt which gave by TLC (CH,Cl,-Et,O-petrol, 2: 1:2, x 4) 4 mg 10 (R, 0.41), 3 mg 11 (R, 0.37) and 2 mg 12 (R, 0.33) and a mixt. TLC (Et,O-MeOH-petrol, 100: 1: 50) of the latter gave 14 mg 13 (R, 0.69) and 12 mg 14 (Rf 0.66). Known compounds were identified by comparing their 4OOMHz ‘HNMR spectra with those of authentic materials. Methyl 3-[4’-hydroxypreny&coumarate (8). Gum, purified as its diacetate SAC, gum. IR ~2: cm-‘: 1740 (OAc, CO,R). MS m/z (rel. int.): 346.142 [M]’ (1.5) (talc. for C19H,,0,: 346.142), 286 [M-HOAc]+ (24), 244 [286-ketene]+ (91), 229 [244 -Me]+ (lCO), 197 [229-MeOH]+ (47). Methyl 3-[4’-hydroxyprenyll-coumarate 4-O-methyl ether (9). Gum. IR vfiz” cm- I.. 3600 (OH), 1710, 1610 (PhC=CCO,R). MS m/z (rel. int.): 244.110 [M- MeOH]+ (71) (talc. for C,sHi60s: 244.110), 229 [24&Me]+ (lOO), 197 [229 - MeOH] + (22). Methyl 3-[4’-hydroxyprenyil-coumarate 4-O-acetate (10). Gum. IR ~2:‘~ cm- i: 3600 (OH), 1710, 1613 (PhC=CCO,R). MS m/z(rel. int.): 262 [M -HOAc]+ (28), 244.110 [262-H,O]+ (85) (talc. for C,,Hi60s: 244.110), 229 [24&Me]+ (100) 197 [229 - MeOH] + (44). Methyl 3-[S-hydroxyprenyll-coumarate Gum. (11).

3685

IR vg: cm-‘: 3400 (OH), 1720, 1610 (PhC=CCO,R). MS m/z (rel. int.): 262.121 [M]’ (15) (talc. for C,,H,,O,: 262.121), 244 [M-H,O]+ (44), 229 [244-Me]+ (lOO), 197 (20). Methyl

3-[4’-hydroxyprenyg-7Z-coumarate

(12).

Gum.

IR vzt:’ cm-‘: 3400 (OH), 1730 (CO,R). MS m/z (rel. int.): 262.121 [M]’ (7) (talc. for C 15H 180 4: 262.121) 244 [M-HzO]+ (73), 229 [244-Me]+ (lOO), 197 (23). Xanthochroa coumarate (13). Gum. IR vz:> cm-‘: 3650,348O (OH), 1735, 1650, 1620 (PhCH=CHCO,R). MS m/z (rel. int.): 262.121 [M]’ (100) (talc. for C,,H,,O,: 262.121), 231 [M -CH,OH] + (48), 229 (45), 199 (21) 171 (32), 73 (93). 3’-epi-Xanthochroa coumarate (14). Gum. IR v$: cm-‘: 3628, 3580 (OH), 1728, 1640, 1613 (PhCH=CHCO,R). MS m/z (rel. int.): 262.121 [M]’ (64) (talc. for CISH1s04: 262.121) 231 [M-CH,OH]+ (22),229(24), 153(100), 135[153-H,O]+ (54).

REFERENCES 1. Seaman, F. C. (1982) Bot. Reo. 48, 217. 2. Bohlmann, F., Burkhardt, T. and Zdero, C. (1973) Naturally Occurring Acetylenes, pp. 427435. Academic Press, London. 3. Huneck, S., Zdero, C. and Bohlmann, F. (1986) Phytochemistry 25, 883. 4. Bohlmann, F., Jakupovic, J. and Zdero, C. (1978) Phytochemistry 17, 2034. 5. Zdero, C., Bohlmann, F., Solomon, J. C., King, R. M. and Robinson, H. (1989) Phytochemistry 28, 531. 6. Omar, A. A., El-Ghazouly, M. G., Bohlmann, F. and Zdero, C. (1983) Lieb. Ann. Chem. 1451.

7. Veda, J. Yokota, T. Takahashi, N., Yoshida, M. and Kato, J. (1986) Agric. Biol. Chem. SO, 3083. 8. Bohlmann, F., Zdero, C., King, R. M. and Robinson, H. (1984) Phytochemistry

23, 1979.