A new guaiane derivative and other constitutents from Ameghinoa Patagonica Spegazzini

Abstract

Continuing with our investigations on the subtribe Nassauviinae (Mutisieae, Compositae), we analyzed the monotypic species Ameguinoa patagonica Spegazzini. From the aerial parts, a sesquiterpene C17H26O3 , [M]+ 278, was isolated. Its structure was established by mono and bidimentional 1 H and 13C NMR, IR and mass spectrometry. 13C NMR showed 17 signals, four of them corresponding to methyl groups at δ 19.6 (C-13), 21.1 (acetate methyl), 21.7 (C-14) and 23.5 ppm (C-15); four methylenes at δ 24.6 (C-2), 35.3 (C-6), 41.2 (C-3) and 111.5 ppm (C-12); five methynes at d 46.5 (C-1), 49.5 (C-7), 53.8 (C-5), 74.5 (C-8) and 128.3 ppm (C-9) and four quaternary carbons at δ 80.0 (C-4), 140.2 (C-10), 147.3 (C11) and 170.3 ppm (acetate carbonyl). 1 H NMR, COSY, HSQC, HMBC and NOE experiments established the structure of the new guaiane as 9,11-guaiadien-4β,8β-diol 8-monoacetate (1α,5α,7α form). Tricosane, pentacosane, heptacosane, nonacosane, untriacosane, 1-octadecanol, 1-eicosanol, 1-docosanol, phytol, sitosterol, campesterol, α-amyrin and β-amyrin were also identified. Trixane derivatives, characteristic metabolites of the subtribe Nassauviinae, were not found.