~ Pergamon PH: S0031.-9422(96)00611-4 Phytochemistry, Vol. 45, No. 2, pp. 369-373, 1997 © 1997 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0031-9422/97 $17.00+0.00 SESQUITERPENE LACTONES AND GLUCOSIDES FROM UROSPERMUM PICROIDES BASreO~ A. A. A. BALBOUL,*AHMED A. AHMED~f and HIDEAKtOTSUKA~: Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, I-2-3 Kasumi, Minami-ku, Hiroshima 734, Japan; ]'Department of Chemistry, Faculty of Science, Minia University, EI-Minia, Egypt (Receivedin revised form 23 September 1996) Key Word Index--Urospermum picroides; Compositae; Lactuceae; sesquiterpene lactone; ses- quiterpene glucoside; germacranolide; urospermal A; dihydrourospermal A. Abstract--An extract of whole plants of Urospermum picroides afforded five new germacronolides and ger- macranolide glycosides. Their structures were elucidated by spectroscopic methods. © 1997 Elsevier Science Ltd. All rights reserved INTRODUCTION Urospermum Scop. belongs to the Leontodontinae, one of the eight subtribes that comprise the tribe Lac- tuceae [1]. The genus contains only two species, U. dalechampii Schmidt and U. picroides (L.) Scop. ex. F.W. Schmidt, both of which have been investigated chemically [2-7]. Phytochemical reinvestigation of the whole U. pic- roides plants collected in the north of Egypt afforded, in addition to the known compounds urospermal A (1) [2], dihydrourospermal A (2) [2], a glucoside of urospermal A (3) [3], a p-hydroxyphenylacetate of the glucoside (4) [4], and five new germacronolides (5-9) which were identified by spectroscopic methods. RESULTSANDDISCUSSION Compounds were purified by chromatography (see Experimental); structures of the known compounds (1-4) were elucidated by comparison with the reported physical data. By HR-FAB-mass spectrometry, the elemental composition of 5 was determined as C~5H2005 which was the same as that of 2, The ~H NMR data for 5 were similar to those of dihy- drourospermal A (2), isolated from a related plant U. dalechampii [2], except for coupling constants between H-7 and H-11 (J = 11 Hz in 2 and 8 Hz in 5) (Table 1). Together with the significant differences in methyl chemical shifts (6c 16.3 and 10.1 in 2 and 5, respec- tively) in the ~3CNMR spectra (Table 2), compound 5 was elucidated to be an epimer of 2 at the 1 l-position, *On leave from Minia University, Egypt. tAuthor to whom correspondenceshould be addressed. namely 1 l fl,13-dihydrourospermal A as shown in Scheme 1 or its antipode. Compound 6 was obtained as colourless crystals with empirical formula C~5H~805. This demanded one more degree of unsaturation than 5. The ~3C NMR spectrum was similar to that of 1. However, an alde- hyde group in 1 was replaced by a carboxyl group, which was then cyclized with the hydroxyl function at C-8 to set up another lactone ring. This was supported by a significant downfield shift of H-8 from 3n 3.99 to 4.73 in the ~H NMR spectrum and an upfield shift of C-1 from 6c 160.2 to 135.6. The orientation of the methyl group at the C-11 position was expected to be the same as that in 2 from the H-H coupling constant between H-7 and H-11 (J = 13 Hz) [5]. Therefore, the structure of this compound was elucidated to be 6 or its antipode. The ~H NMR spectral data for compounds 7, 8 and 9 indicated that these three compounds were ses- quiterpene glucosides. Compound 7 was obtained as colourless crystals of elemental composition C2tH260~0. The ~H and J3C NMR spectroscopic data (Tables 1 and 2) showed signals attributable to one/3- glucopyranoside moiety, while an exo-methylene group appeared as two doublet signals at 3n 5.80 and 6.18 (both H, both d, both J = 3 Hz), and 6c 120.2 (t) and 139.6 (s). The ~3CNMR data showed the presence of two carbonyl signals at 6c 173,0 and 171.0 for C- 12 and C-14, respectively. Therefore, the structure of 7 was determined to be an 11,13-dehydroderivative of 6 as an aglycone with the/3-glucopyranosyl unit on the hydroxyl group at the C-15 position. Compound 8 was obtained as an amorphous pow- der and its elemental composition was found to be C29H320~2. The IH and t3C NMR data indicated that 8 was a p-hydroxyphenylacetate of 7. The position of 369