1) Institute of Petroleum Chemistry and Catalysis, Academy of Sciences of the Republic of Bashkortostan and Ufa Scientific Center, Russian Academy of Sciences; 2) N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 223-225, May-June, 2003. Original article submitted May 10, 2003. 0009-3130/03/3903-0285$25.00 © 2003 Plenum Publishing Corporation 285 RO 1 3 5 7 9 10 11 13 15 17 30 29 19 21 28 27 24 23 A B C 26 D E 1a: R = Ac; 1b: R = H 25 Chemistry of Natural Compounds, Vol. 39, No. 3, 2003 PMR AND 13 C NMR SPECTRA OF BIOLOGICALLY ACTIVE COMPOUNDS. XII.* TARAXASTEROL AND ITS ACETATE FROM THE AERIAL PART OF Onopordum acanthium L. M. Khalilov, 1 A. Z. Khalilova, 1 E. R. Shakurova, 1 UDC 547.92 I. F. Nuriev, 1 V. V. Kachala, 2 A. S. Shashkov, 2 and U. M. Dzhemilev 1 Crystalline taraxasterol and its acetate were isolated for the first time from Onopordum acanthium. Two- dimensional COSY, HSQC, and HMBC NMR experiments were carried out for complete assignment of signals in the PMR and 13 C NMR. Chemical shifts of stereochemically important methyl C atoms C-28 and C-29 were measured. Key words: Onopordum acanthium L., two-dimensional spectrum, PMR, 13 C NMR, HSQC, HMBC, COSY, TOCSY, ROESY spectra. Scotch thistle (Onopordum acanthium L., Asteraceae) is a biennial herbaceous plant. It has application in medical practice as a bactericide, cardiotonic, and hemostatic agent and is used against hypotonicity [2-4]. The lactones arctiopicrin and onopordopicrin [2] were isolated from leaves of Scotch thistle; alcohols lupeol and amyrin as their acetates [5] from seeds. Our goal was to isolate and establish the structure of new biologically active terpenoids from Onopordum acanthium using PMR and 13 C NMR spectra. The aerial part of Onopordum acanthium was investigated for the presence of biologically active compounds. Extraction by CHCl 3 and chromatography over a silica-gel column using ethylacetate:hexane afforded pure crystalline compounds. IR spectra and 13 C NMR spectra of one of the compounds were similar to those of taraxasteryl acetate 1a [6, 7]. However, the melting point of the isolated compound (232-234°C) differed substantially from the literature value (256-257°C [8]). Therefore, we investigated the NMR spectra of the isolated compounds. Table 1 lists the principal PMR and 13 C NMR spectral properties for taraxasterol (1b) and its acetate (1a). ______ *For No. XI, see [1]. Work supported by RFBR Grants Nos. 00-03-40132, 01-04-49274, 02-03-97901.