271
Joumul ofNatnrd P&s Vol. 54, No. 1, pp. 271-272,Jun-Feb 1991
EREMOPHILANES FROM SENECZO DESFONTAZNEZ hiMED A. h i M E D
Departmnt ofChi~m, Fanrlty ofSCimrr, El-Mink U n i m i t y , El-Mink, Egypt h s ~ ~ ~ n . - F o eremophilanes u r have been isolated from the aerial parrs ofSmacio desfmtainci, including a new one, 1l-hydroxyeremophil-q7),9(10>dien-8-one[4]. The structures were established by high field nrnr spectroscopy
The genus Senecio is rich in eremophilanes, furoeremophilanes, and pyrrolizidines, as well as other classes of natural products (1-4), and several compounds have been reported from Senecio desfontainei Druce (= S. coronop$oliolius Desf.) (Compositae) (5-7). Reinvestigation of this species afforded a new eremophilane 4, in addition to three previously reported compounds 1-3. The 'H-nmr data of 4 differed from those of 1-3; the downfield chemical shift of H-12 and H-13 at 6 1.46 and their presence as a singlet indicated that C- 11 must bearing a hydroxyl function. This was verified by an ir absorption at 3550 cm-' as well as a 13C-nmrsignal at 6 7 1.8 (C- 11). Spin decoupling allowed the assignment of H-1, H-1', and H-4. The narrow doublet at 6 6.07 (H-9) showed a long range coupling with a multiplet at 6 2.37 (H- l), while irradiation of H-15 changed the signal at 6 1.56 (H-4). The mass spectrum exhibited peaks at mlz 234 for the molecular ion and at mlz 2 19 and 20 1 indicating loss of a methyl group followed by elimination of H,O. 13C-nmr data (see Experimental) also supported the proposed structure . X
4
EXPERIMENTAL wTEm.-The aerial pvts of S. hfmtizinei were collected from Bourg El-Arab,
Alexandria, Egypt, in Mvch 1987. A voucher specimen (A 3 19) is deposited in the Department of Botany, El-Minia University.
EXTRACTION AND ISOLATION O F TERPEairdried aerial pam (1 kg) of S. desfmtuinei were extracted with Et@-MeOH-petroleum ether (40-60") (1: 1: 1) at room tempencure as reported previously (8).The fraction eluted with Et@-petroleum ether (1:3) was funher separated by hplc [RP 8, MeOH-H,O (6:4)] to give 1 (30 mg), 2 (17 mg), 3 (19 mg), and 4 (9 mg). The spectral data of the known compounds 1 (9),2 (lo), and 3(IO)were identical to those reported in literature. NOIW.-The
1I-HYDROXYEREMOPHIL-q(7),9( 10)-DIEN8-ONE [4].+a]24~- 15.0 (c= 2, CHCI,); ir Y max(CHCl3)cm-'3550, 3000, 1650, 1600;ms dz (rel. int.) 234 (65), I234 - 151+ 219 (loo), 1219- 18]+201(85); 'Hnmr(400MHz, CDCI,, T M S as internal standard) 6 6.94 (lH, s,
[w+
H-6),6.07(1H,d,J=1.5H~,H-9),2.37(1H, m,H-1). 1.99(1H,m,H-l'), 1.56(1H,m,H4), 1.46 (6H, S, H-12 and H-13), 1.13 (3H, S, H-14), and 1.08 (3H, d, J = 7 Hz, H-15); I3C nmr (400 MHz, CDCI,, C-1 to C-15) 6 32.5, 30.1, 28.0, 41.7, 43.6, 124.6, 169.4, 188.1, 149.5, 141.1, 71.8, 28.8, 28.9, 17.0, 16.3. (Signals for C-14-3, C-74-10, and C-12 and C-13 may be interchanged.) ACKNOWLEDGMENTS
1 X=H 2
X=BOH,H
3 X=aOH,H
The author thanks the Alexander von Humboldt-Stiftung for the fellowship and Prof.Dr.F. Bohlmann, Technical University of Berlin, West Germany, for the opportunity to work in his group.
272
Journalof Natural Products LITERATURE CITED
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