Acylated triterpene glycoside from roots of Dipsacus asper

Phpxhemam_ Val 2’) Na I, pp 3% 374,199o Prmted I” Grcdt Bntnm

ACYLATED

TRITERPENE

ISAO KOLNO,

Faculty

,

AKIKO

of Pharmaceutlcdl

GLYCOSIDE ASPER TXBOI,

MIHO

Sciences, Nagdsakt

FROM

NANRI

Umverslty,

and

ROOTS

NOBUSUKE

Bunkyomachl

003 1 9423 ‘90 $3 QO+ 0 00 1989 Pergnmon Preca plc

OF DIPSACUS

KAWAIW

1-14 Nagdsakl

852. Japan

(Rrc e,t ed 28 April 1989)

Abstract--An acylated trtterpene glycostde was isolated from the roots of Dtpsacu, asper together wrth the known trtterpene gfycostde. akebta saponm D, and the known rrtdord glycosrdes, swerostde. loganm and cantfeyostde The structure of the acylated compound was eluctdated as the 4’-O-acetate of akebta saponm D by spectroscoptc methods _____ -~

IYTRODUCTION

revealed to be 3-0-r-L-arabmopyranosyl hederagenm 2%@~-D-glucopyranosyl (l +h)-/3-D-gfucopyranoside, a compound prevtously isolated from ALebra 9urnuta, and named akebta saponm D [7] The r3C NMR spectrum of 2 was almost supertmposable on that of 1 As the FARMS showed the molecular ton at m/z 993 [M + Na]’ and the ‘H and r3C NMR spectra showed the presence of an acetyl group, It was apparent that compound 2 was a mono acetylated dertvatrve of 1 On selecttve cleavage, compound 2 gave compound 6 Compartson of the ’ 'C NMR data of compound 2 wtth those of compound 1 estabhshed that the acetyl group IS located at the C-4’ hydroxy group of Arabmose (Table 1) A stmrlar compound to 2, the 2’-0-acylated dertvatrve of akebta saponm D was Isolated from the roots of Pcltrrnra sc&osac~0l1r (Valertanaceae) [g]

D~psacus usper

Wall IS distributed m Chma and Its dried roots are used m Chinese medtcme for the treatment of fractures. Although a number of studies on the constituents of Dipsacus spectes have been reported [l-5], there are no reports on the constttuent of D asper We now report on the rsolatton of the 4’-O-acetate of akebta saponm D from the roots of this plant along with akebta saponm D and three known lrtdotd glycostdes RESCLTS Compounds

1-5

were

AND DISCUSSION isolated

from

the

roots

of D

Compound 4 was tdenttfied as the secologanm swerostde by FABMS (m/z 359 [M + H] ‘)> rH-‘H 2D COSY and the r3C NMR, while compound 5 was shown to be the rrtdotd glycosrde, loganm, by FABMS and ‘H and 13CNMR [6] Both compounds were tdenttfied as their acetates Compound 3 gave a molecular ton at nrjz 769 [M + Na]1 The connecrtvmes of the loganm and the secorrtdotd units were revealed by ‘H-‘H 2D COSY Thus, compound 3 was considered to be the bts-trtdord glycosrde, cantleyostde The r3C NMR data of this compound were identical wrth those of cantleyosrde cited m ref [Z] Compound 1 was shown to be a trtterpene trrglycoside by r3C NMR spectroscopy On actd hydrolyses, 1 afforded hederagenm, glucose and arabmose Hederagenm was confirmed by duect comparison wtth an authentic sample On selective alkahnc hydrolyses, 1 gave hederagenm monoglycostde (6) mdtcatmg that 1 1s a btsdesmostdtc saponm and the 28-carboxyhc group 15 estertfied by a dtglycostde This was supported by the carbon signal at 695.7 (C-I”) Because 6 was shown to be hederagenm 3-0arabmostde by acid hydrolyses. and 1 showed the molecular ton at m,‘z 95 1 [M + Na] + on FABMS, 1 should have 2 mol of glucose m the estertfied sugar part In the 13C NMR spectrum, the hydroxymethyl carbon signal (C-6”. 869 4) of the sugar moiety was observed along wtth that of the termmal glucose The configurattons at C-i of each glycostde were determined by esttmatmg the d value of each anomertc proton stgnal Thus. compound 1 was asper

Mp uncorr [air, MeOH ‘H (400 MHz) and r3CNMR (100 MHz) pyrtdtne wdh TMS as mt rtan&rd CC &~a gel (Kreselgel 60) TLC OX mm precoated \rlrca gel (bOF,,,, Merck) Spots were detected by UV hght (254 nm~ and sprdylng 20Y0 H,SO, followed by hedtmg

2 338

K = AL

Short Reports Table

1. 13CNMR

C

1 (gemn part)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

38 8 t 26 1 r 82.2 d 43.5 s 47 6 d 18 2 t 32 6 t 400s 4821 370s 23.9 t 1230d 144 2 s 42.2 s 28 3 t 23 4 t 47 1 s 41 7d 462t 307s 340t 32 8 t 64.5 t 136q 162q 176q 26 1 q 1765s 33 1 q 23 7 q

-

data of compounds 2 38 8 t 26.1 t * 822d 43.5 s 476d 182t 326t 40.0 s 48 2 d 370s 23 9 t 1230d 1442s 42.2 s 28 3 t 23 4 t 47 1 s 41 7d 46 2 t 30.7 s 340t 32 8 t 64 5 t 136q 16.2 q 176q 26 1 q 1765s 33.1 q 23 7 q

339

1 and 2(100 MHz, pyndme, C

TMS as mt standard)

1 (sugar part)

2

104 6 d 73 1 d 747d 69 5 d 669t

106 7 d 73 3 d 72 5 d 724d 670t 1708s 21 Iq

95.6 d 739d 78 8 d 71.0 d 77.9 d 694t

957d 73.9 d 78 8 d 71 Od 780d 694t

105 3 d 75.1 d 784d 715d 784d 62 7 t

1053d 752d 78 4 d 716d 7841 627 t

ara 2 3’ 4 5’ c=o Meglc (inner) I, 1 2” 3” 4” 5” 6” ale (terminal)

ii”

2”’ 3”’ 4”’ 5”’ 6”’

Plant material. The chipped dried roots of D asper were obtained from the local market Isolatm The roots of D asper were extracted with Me&O-H,0 (1.1) (3 1), and the combined extracts evapd rn uacuo The residue was partitioned between n-BuOH and H,O The n-BuOH soluble part was passed through an Amberhte XAD-2 column elutmg with H,O, H,O-MeOH (1: l), and MeOH, successively. Repeated chromatographlc separation of the MeOH eluate on silica gel (CHCl,-MeOH-H,O 80.20 1) afforded compounds 1 (760 mg), 2 (28 mg), 3 (87 mg) and 4 (22 mg), respectively The H,O-MeOH (1 1) eluate was evapd, then subJected to CC on slhca gel (CHCI,-MeOH-H,O 80 : 20 1) re+atedly to yield compound 5 (73 mg) Usual acetylation of 4 and 5 afforded then acetates The NMR spectral data of 3 and 5 were identical with those of cantleyoslde and logamn, respectively, cited m the hterature Akebla saponrn D (1) Colourless needles, mp 234-235” (decamp.); [a];’ + 14”(MeOH, c 0 2); FABMS m/z 951 [M +Na]+, IR Y::: cm- 1 3350(OH), 1750 and 1725 (COOR) Acid hydrolysis of l(1 i0 mg) with 2 M HCl m 50% MeOH gave hederagemn and the sugars arabmose and glucose (Identified by Avlcel TLC) Selective cleavage of 1 (30mg) with 2% KOH m 50% EtOH, afforded 6, which was hydrolysed with 2 M HCl The acid hydrolysate of 6 contained hederagemn and arabmose Compound 2 White amorphous powder, [a];* + 15” (MeOH, c 0 1); FABMS m/z 993 [M+Na]+ compound 2 (10mg) was refluxed with 2% KOH m 50% EtOH (5 ml) for 1 hr and

reactlon mixture evapd m uacuo to gwe a residue, which showed on TLC one spot identical with compound 6 ‘HNMR (pyndme):6196(3H,s,AcO),318(1H,dd,~=12,5,H-18),541(1H,t, 5=3, H-12), 495 (lH, d, 5=73, ara H-l), 501 (lH, d, 5=77, mner glc H-l), 6.23 (lH, d, .I=8 1, term glc H-l) (These assignments were aided by ‘H-‘H and 13G1H 2D COSY) Acknowledgement-We thank Dr R Hlguchl (Kyushu Umverslty) for the kmd aft of an authentic sample of hederagenm REFERENCES

1 Endo, T ,Suzuki, H and Taguchl, H. (1976) Yakugaku Zasshl 96,246 2 Jensen, S R, Lyse-Peterson, S E and Nielsen, B J (1979) Phytochemlstry 18, 273 3. KOCSIS, A., Pal, Z, Podanyl, B, Szabo, L. and Tetenyl, B (1984) Int Symp. Chem Nat Prod, 14th, Poznan 4 KOCSIS, A, Podanyl, B , Szabo, L and Tetenyl, P (1987) Int Conf Chem. Blotech Btol Act Nat. Prod, 4th Budapest 5 Podany], B, Reid, R. S, Kocsls, A. and Szabo, L. (1989) J Nat. Prod 52, 135 6 Chaudhun, R K , Afifi-Yazar, F U , Stlcher, 0 and Wmkler, T (1980) Tetrahedron 36, 2317 7. Hlguchl, R. and Kawasaki, T (1972) Chem Phurm Bull 20, 2143. 8 Chow, J S and Woo, W S (1987) Planta Med. 62