Pergamon 0031-9422-(95)00091-7 Phytochemistry, Vol. 39, No. 4, pp. 795-800, 1995 Copyright © 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0031-9422/95 $9.50 + 0.130 SESQUITERPENE LACTONES, A LABDANE AND OTHER CONSTITUENTS OF UROLEPIS HECATANTHA AND CHROMOLAENA ARNOTTIANA ADRIANA N. DE GUTII~RREZ,CESAR A. N. CATAL.AN, JESUS G. DIAZ* and WERNER HERZ* Instituto de Quimica Org~inica, Facultad de Bioquimica, Quimica y Farmacia, Universidad Nacional de Tucum~in, Ayacucho 491, 4000 S. M. de Tucum~n, Argentina; *Department of Chemistry, The Florida State University, Tallahassee, FL 32306-3006, U.S.A. (Received 9 Novemeber 1994) Key Word Index-- Urolepis hecatantha; Chromolaena arnottiana; Eupatorieae; Compositae; sesquiter- pene lactones; heliangolides; labdane; benzofurans; Z, E-farnesol derivative; flavonoids. Abstract--Aerial parts of Urolepis hecatantha afforded several heliangolides, a new labdane, the oleate of 9-hydroxy- Z, E-farnesol, a new toxoi and isopentenylacetophenone derivatives as well as a number of common plant constitu- ents. Aerial parts of Chromolaena arnottiana contained 5,Y-dihydroxy-6,7,4'-trimethoxyflavone, 5-hydroxy-6,7,3',4'- teramethoxyflavone, 5-hydroxy, 6,7,Y,4',5'-pentamethoxyflavone, other common plant constituents and a derivative of 3,4-dihydroxyacetophenone. INTRODUCTION Urolepis (DC.) R. King and H. Robins. is a monotypic genus of Eupatorieae, subtribe Gyptidinae, earlier sub- sumed in Eupatorium as section Urolepis [11. In the present paper we describe the chemistry of a collection of Urolepis hecatantha (DC.) R. King and H. Robins. from Bolivia. Isolated were the sesquiterpene lactones eupafor- mosanin (1) [21, eucannabinolide (2a) [3, 41, hyodorilac- tone C (2b) [5, 61, a mixture of 2c [7,81 and 2d [6, 81, a mixture of 3 and 4, the new labdane 5, the oleic acid ester 6, the benzofuran derivatives 7a, b and the methyl ether 8. Other substances identified in the extract were grandifloric acid, the flavonoids retusin (5-hy- droxy-3,7,Y,4'-tetramethoyflavone) and oxyayanin B (5,6,3'-trihydroxy-3,7,4'-trimethoxyflavone), euparin, 6- methoxyeuparin, vomifoliol, pinoresinol and stigma- sterol. Chromolaena arnottiana (Griseb.) R. King and H. Robins. has been studied twice previously. The roots of a collection from Bolivia furnished furanocadinanes and a norcadinane [9] while the roots of a collection from an unspecified location in Argentina contained common chromanes and a benzofuran [101. Aerial parts of the former afforded only common terpenoids and a p-hy- droxycinnamate ester, while aerial parts of the latter gave a cadinane. Our own collection from Catamarca Prov- ince, Argentina, furnished eupatorin (5,Y-dihydroxy- 6,7,4'-trimethoxyflavone), eupatilin (5-hydroxy-6,7,3',4'- tetramethoxyflavone) and 5-hydroxy-6,7,3',4',5',-pentam- ethoxyflavone as well as the 3,4-dihydroxyacetophenone *The C-2 stereochemistry of 9c from Stevia alpina was incor- rectly represented on the formula page of ref. 1-13]. derivative 11, loliolide, ~- and fl-amyrin, stigmasterol and sitosterol. DISCUSSION The components of the mixture of 3 and 4 were identi- fied by their IHNMR spectra (Table 1) and extensive decoupling. In particular the NMR spectrum of 4 closely resembled the spectra of 9a (calbenolide C) [11], 9b (jamaicolide C) [ 12] and 9e [ 13]* if allowance is made for the absence of an esterifying group on the C-8 hydroxyl of 4. This resulted in an upfield shift of H-8 as compared with H-8 of 9a and b, while the coupling constants remained constant. On the other hand, the coupling constants involving H-3 of 4 (12.5 and 4 Hz) differed considerably from those involving H-3 of 9a--c (ca 5 and 3 Hz) indicating that the C-3 stereochemistry was in- verted, while the chemical shift was close to H-3 of 9c and 1 ppm downfield from H-3 of 9a and b. The small values of J7,13 (2.5 and 2 Hz) and J6,7 (2.5 Hz) indicate the presence of a heliangolide while the values of JT.a, Ja.ga and Ja.gb indicate fl-orientation of the substituent on C-8. Lactone 4 may be an artefact as prolonged exposure of the lactone mixture to chloroform-d followed by removal of solvent resulted in essentially complete conversion of lactone 3 to lactone 4. Other than conversion of the methyl singlet of 3 to a pair of slightly broadened olefinic singlets the transformation was accompanied by a signifi- cant diamagnetic shift of H-I, changes in the coupling constants involving H-1 and H-2a,b as well as smaller changes in the chemical shifts of H-9a,b. The structure of 5 was deduced from the mass and 1H NMR spectra (Table 2). Decoupling permitted assign- ment of all signals. Two hydroxyl groups were located at 795