1. Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche e Farmacologiche, Università del Piemonte Orientale, Viale Ferrucci 33, 28100 Novara, Italy, Consorzio per lo Studio dei Metaboliti Secondari (CSMS), Viale S. Ignazio 13, 09123 Cagliari, Italy, Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, 29−39 Brunswick Square, London WC1N 1AX, U.K., and Department of Organic Chemistry, Lund University, P.O. Box 124, 221 00 Lund, Sweden