A triterpene from the bark of Tamarix aphylla

Phytochemistry, Vol.31,No. 11,pp. 40314032,1992 Printedin Great Britain.

A TRITERPENE

003l-9422/92$5.00+ 0.00 0 1992Pergamon Press Ltd

FROM THE BARK OF TAMARIX

I. MERFORT,*

J. BUDDRUS,~ M. A. M. NAWWAR~

APHYLLA

and J. LAMBERT?

Institut fiir Pharmazeutische Biologie, Heinrich-Heine-Universitlt Diisseldorf, Geb. 26.23, Universitiitsstrasse 1, 4000 Diisseldorf, Germany; TInstitut fur Spektrochemie, Bunsen-Kirchhoff Strasse 11, 4600 Dortmund 1, Germany; SNational Research Centre, Dokki, Cairo, Egypt (Received in revisedform aphylla;

Key Word Index--Tamarix cadiol.

Tamaricaceae;

9 Mmch 1992)

bark; triterpenes;

o-friedoolean-l4en-3u,28-diol;

myri-

Abstract-The bark of Tamarix aphylla contains the new triterpene D-friedoolean-14-en-3a,28-diol (isomyricadiol), its 38 isomer (myricadiol) and its 3-ketone. The structure of isomyricadiol was established by comparing its “C NMR data with those of its 38 isomer and 3-epibetulinic aldehyde. The published *‘C NMR spectrum of myricadiol has been partly reassigned via a standard and an inverse H,C-COSY experiment.

INTRODUCTION

In previous papers, the phenolic constituents of Tam&x aphyh L., a wild plant in Egypt, were investigated [l-4]. Here we describe the isolation and characterization of a new triterpene (1) together with myricadiol(2) [S] and 28hydroxy-D-friedoolean-14-en-3-one (3) [S] from a chloroform extract of T. upkyllu bark.

performed partly by comparison, and partly by standard and inverse C,H-COSY experiments. Comparison of the 13CNMR data of 2 and 1 showed that some published data of myricadiol had to be reassigned (see Table 1). Triterpenes with a /I-hydroxyl group at C-3 are more common than those with an a-hydroxylic group [7]. The ketone 3 might be considered as an intermediate compound between these isomers.

RESULTSANDDISCUSSIONS

EXPERIMENTAL

Compound 1, on FAB mass spectrometry, gave a [M +H]+ peak at m/z 443 equivalent to CJOH5,,02+H+. The structure of 1 was established by comparing the 13CNMR spectrum with those of 2 (myricadiol) [5] and 3-epibetulinic aldehyde (4) (see Table 1) [6]. The c+ position of the hydroxyl group at C-3 was confirmed by the small 3J a,” coupling (2.7 Hz) of the equatorial proton at C-3. The assignment of the 13C NMR signals of 1 was

PIant matehal. Samples of Tamurix aphylla bark were collected during April 1987, from a lO-year-old tree, growing wild near

Table l.‘“CNMR spectral data of compounds 1, 2 and 3-epibetulinic aldehyde

(4)* C

1 2 3 4 5 6 I 8 9 10 11 12 13 14 15 16 17 18 19 20

R 1 B-H,

a-OH

2 a-H,

&OH

30 *Author to whom correspondence should be addressed. 4031

1t 32.6 r 25.0 t 76.2 d 37.5 se 48.8 P 18.7 t 41.2 t$ 40.3 s 49.2 db 37.3 z 17.3 t 32.2 t* 38.0 s’ 159.3 s 115.5 d 30.8 t$ 39.2 s 44.7 d$ 35.8 t$ 28.6 s

2 CSI 37.8 28.0 78.2 41.4 56.0 19.2 4m 39.3 z+ 37.8 17.9 33.3 38.2 158.7 116.8 31.4 38.3 45.6$ 36.3$ 28.8

4 VI 33.6 25.9

76.4 37.5 49.9 18.4 34.4 41.0 50.5 37.3 20.8 25.6 38.7 42.6 29.5 28.8 59.3 48.0 47.5 149.8

4032

Short Reports Table 1. Continued C

21 22 23 24 25 26 27 28 29 30

It

33.5 t= 27.9 t 28.2 q 22.2 q 15.2 q 29.9 q 26.2 q 65.5 t 21.5 q 33.5 q

2

PI

33.8

28.7 16.5

28.4 14.8 30.1 26.2

64.6 22.0 338 -L

4 C61 30.0 33.2 28.2 22.2 15.9 16.1 14.2 205.6 110.1 19.0

*Underlined numbers are suitable for comparison with 1. tMultiplicities were determined by a DEPT-135” NMR experiment. SAssignments via normal and inverse C,H-COSY. SReassigned (see text). ‘-‘Assignments bearing the same superscript may be interchanged.

Mersa Matrouh, Egypt. Classification was carried out by Dr L. Boulos (Professor of Botany, National Research Centre, Cairo, Egypt). Isolation and identification. The CHCl, extract (80.5 g) from 1 kg of bark material was first separated by CC (silica gel) with an EtOAc -n-hexane mixture (1:l) (system 1). Further CC (silica

gel) using, successively, solvent systems 1 and 2 (CH,Cl,cyclohexane -MeOH, 7:4: 1) gave a fraction containing 1-3. Prep. TLC on silica gel plates using system 2 afforded 1(24 mg), 2 (6 mg) and 3 (14 mg). D-Friedoolean-14-en-3a,28-dioI (1). C,,H,,O,; FAB-MS, m/z (rel. int.): 443 [M+H]+ (2x lo-‘), 425 [M+H-H,O]+ (1.5 x 10e2); EIMS, m/z (rel. int.): 406 [M-2H,O]+ (lo), 269 (15), 189 (78); ‘HNMR (400 MHz, CDCI,; assignments via standard or inverse C,H-COSY are marked with *): 60.55 (lH, dd, J = 13.4, 3.7 Hz, H-18*), 0.85,0.87,0.89.0.91,0.94,0.945, 1.05 (3H each, all s. Me x 7), 1.0 (lH, dd, J=13.4, 3.7 Hz, H-19/?*), 1.4 (lH, t, J =13.4 Hz, H-19a*), 1.06-1.7 (l9H, m), 1.74 (lH, dd, J=15.3, 3.4 Hz, H-16*), 1.9 (lH, tm, J= 15 Hz, H-2/?*), 2.0 (lH, dm, J = 13 Hz, H-78*), 2.08 (lH, dd, J= 15.3, 8.2, H-16*), 3.1. 3.28 (1H each, d, J=ll.l Hz, H,-28*), 3.38 (lH, t, J=2.7 Hz, H-3*). 5.47 (lH, dd, J=8.2, 3.4 Hz, H-15*); 13CNMR (100 MHz, CDCl,fi see Table 1. REFERENCES

Saleh, M. A. M., El-Sissi, H. I. and Nawwar, M. A. M. (1975) Phytochemistry 14, 312. El-Ansari, M. A., Nawwar, M. A. M., El-Sherbieny, A. E. A. and El-Sissi, H. 1. (1976) Phytochemistry 15, 231. Nawwar, M. A. M., El-Sherbieny, A. E. A. and El-Ansari, M. A. (1975) Experientia 31. 1118. Souleman, A. M. A., Barakat, H. H., El-Mousallamy, A. M. D., Marzouk, M. S. A. and Nawwar, M. A. M. (1992)(in press). 5. Sakurai, N., Yaguchi, Y. and Inoue, T. (1987) Phytochemistry 26, 217. 6. Monaco, P. and Previtera, L. (1984) J. Nat. Prod. 47, 673. 7. Dev, S. (1989) Handbook of Terpenoids, Triterpenoids Vol. II. CRC Press, Boca Raton.