Guaianolides from Centaurea musimomum

Phymhemirtry.

Vol. 45, No. 7. pp. 1449-1451, 1997 ,c, 1997 Elsevm Saence Ltd A,, nghts reserved Prmted I” Great Rntam 0031-9422197 517.00+0.00

PII: SOO31-9422(%)00813-8

GUAIANOLIDES

FROM CENTAUREA

MUSIMOMUM

KAMEL MEDJROUBI,* FADILA BENAyAcH&*t SAMIR BENAYACHE,* SALAH AKKAL,* NADRA KHALFALLAH* and PAUL ACLINOU$ *Unit& de Recherche de Chimie, Laboratoire de Phytochimie I, Universite de Constantine, 25000 Constantine. Algeria; $Facult& des Sciences, Laboratoire de Photochimie, Universitt de Reims, France (Received in revisedform 14 October 1996)

Key Word Index-Centaurea

musimomum; Compositae;

sesquiterpene

lactones;

guaianolides.

new guaianolides have been isolated from the aerial parts of Centaurea musimomum, 3oxo-4a-acetoxy-15-hydroxy-laH, SctH, 6pH, 7aH, 1 lbH-guai-10(14)-ene-6,12-olide and 3-oxo-4a-hydroxy15-hydroxy-1 cwH, SaH, 6/3H, 7aH, 11BH-guai-10( 14)-ene-6,12-olide. The structures of the compounds were elucidated by NMR spectroscopy. 0 1997 Elsevier Science Ltd. All rights reserved

Abstract-Two

INTRODUCTION In continuation of our study on Centaurea species found in Algeria [l&3], we isolated two new guaianolides from the methanol extract of the aerial parts of Centaurea musimomum collected in the region of Constantine (Algeria).

RESULTS AND

DISCUSSION

The chloroform soluble part of the methanol extract from the aerial parts of Centaurea musimomum yielded two new guaianolides 1 and 2. The IR spectra of these two compounds exhibited bands indicative of hydroxyl(3410 cm-‘), lactone carbonyl (1770 cm-‘), cyclopentanone (1730 cm-‘) and C==C double bond. In addition to the absorptions characterising these functions, the IR spectrum of 1 exhibited acetate bands (1720 and 1240 cm- ‘). The UV spectra of both compounds exhibited end absorption at A,,,,, = 214 nm. The 13C NMR spectrum of 1 (Table 1) confirmed the presence of three carbonyl groups by exhibiting three carbonyl signals at S 219 (ketone), 176 (lactone) and 170 (ester). The chemical shift value of the lactonic carbonyl signal showed that the C-l l/C-13 bond was saturated. Furthermore, a DEPT experiment showed two methyl, five methylene, and five methyne carbons and confirmed the presence of five quaternary carbons. These results, in addition to those obtained by EIMS and CIMS (NH,) which, respectively, showed a [Ml- ion at m/z 322 and a [M + NH,]+ ion at m/z 340, led to the formula C,,H,,O,. The presence

tAuthor to whom correspondence

should be addressed

R 1

AC

2

H

of fragments at m/z 262 (EIMS) and 263 (CIMS) suggested a C, ester side chain. The ‘H NMR spectral data (Table 2) indicated that the side chain was an acetoxy group (6 2.09) which was assigned to C-4. The spectrum also showed an AB system (6 4.15, and 4.32, J = 11.7 Hz) which was attributed to CH2- 15, carrying a hydroxyl group while a doublet at 6 1.24 (J = 6.84 Hz) could be attributed to a methyl group on C-l 1. Assuming the usual /?orientation for the side chain at C-7, this methyl must be G(because of the value of J, ,,,3. (10 Hz) and, therefore, H-6 must be fi (J6,, = 10.3 Hz) [4-51. The quartet of doublets at 6 1.44, (J = 12.7,4.9) was attributed to H-8,, because of the chemical shift which is in good 1449

Guaianolides from C. musimomum 323 [MH]+ (7.13), 305 [MH - H,O]+ (0.8), 263 [MH CH,CO,H]+ (0.8); [a];’ + 124125” (CHCl,; c 0.1). 3-Oxo-4cc-hydroxy-15-hydroxy-laH, 5aH, 6bH, ~xH, 1 l/?H-guai-10(14)-ene-6,12-ofide 2. Crystals, mp (154155”); UV 2::” nm: 214; IR vkz cm-‘: 3400 (OH), 1770 (y-lactone), 1730 (cyclopentanone), 1640 (C=C). EIMS 70 eV, m/z (rel. int.): 280 [Ml+ (2), 262 [M-H,O]+ (1.5) 252 [M-CO]+ (8.44), 250 [M - CH,O]+ (42.22), 249 [M - CH,OH]+ (4.89), 107 (29.33) 105 (37.33), 91 (35.11), 81 (43.1 lo), 69 (37.33), 55 (44.89), 43 (34.67), 41 (100); CISM(NH,), m/z (rel. int.): 298 [MNH,]+ (100) 281 [MH]+ (9.05); [a];‘+ 145 (CHCl,; c 0.04).

Acknowledgements-We ersite de Constantine), Rennes l), Mr H. Bailla, de Reims) for the NMR (Universite de Paris-Sud,

thank Dr Teniou, A. (UnivDr D. Giee (Universiie de Mr B. Menhour (Universite spectra and MS M. Wanat Orsay), for the mass spectra.

3.

4. 5. 6. 7. 8. 9.

10. 11. 12.

REFERENCES

Massiot, G., Morfaux, A. M., Le Men-Olivier, L., Bouquant, J., Madaci, A., Mahamoud, A., Chopova, M. and Aclinou, P., Phytochemistry, 1986, 25, 258. Benayache, F., Benayache, S., Medjroubi, K.,

13.

14. 15.

1451

Massiot, G., Aclinou, P., Drozdz, B. and Nowak, G., Phytochemistry, 1992, 12,4359. Akkal, S., Benayache, F., Benayache, S. and Jay, M., Biochemical Systematics and Ecology, in press. Fernandez, I., Garcia, B., Grancha, F. J. and Pedro, J. R., Phytochemistry, 1987, 26, 2403. Appendino, G., Gariboldi, P. and Belliardo, F., Phytochemistry, 1986, 25, 2163. Gonzalez, A. G., Bermejo, J. and Rodriguez, R. M., An. Quim. 1972,68, 333. Bohlmann, F. and Le Van, N., Phytochemistry, 1977, 37, 487. Halim, A. F., Zaghloul, A. M. and Bohlmann, F., Phytochemistry, 1980, 19, 2767. Das, S., Baruah, R. N., Sharma, R. P., Baruah, J. N., Kulanthaivel, P. and Herz, W., Phytochemistry, 1983, 22, 1989. Bruno, M., Diaz, J. G. and Herz, W., Phytochemistry, 1991 30,4165. Kisiel, W., Phytochemistry, 1992, 31, 328. Kisiel, W., Jakupovic, J. and Huneck, S., Phytochemistry, 1994, 35, 269. Gonzalez, A. G., Bermejo, J., Amaro, J. M., Massanet, G. M., Galindo, A. and Cabrera, I., Cunadian Journal of Chemistry, 1978,56, 49 1. ijksuz, S. and Topcu, G., Phytochemistry, 1994, 37,487. Drozdi, B. and Piotrowski, J., Polish Journal of Pharmacology and Pharmacy, 1973,25,91.