New constituents of Leontopodium alpinum and their in vitro leukotriene biosynthesis inhibitory activity

Abstract

Phytochemical investigations of the roots of Leontopodium alpinum Cass. resulted in the isolation and structure elucidation of six novel compounds and two known compounds. Novel constituents could be identified as the polyacetylenes 1-acetoxy-3-angeloyloxy-(4 E,6 E)-tetradeca-4,6-diene-8,10,12-triyne and its (6 Z)-isomer, the kaurenic acid derivative methyl ent-7alpha,9alpha-dihydroxy-15beta-[(2 Z)-2-methyl-but-2-enoyloxy]kaur-16-en-19-oate, the bisabolane derivative (1 R*,3 S*,4 R*,6 S*)-9-(acetoxy)-4-hydroxy-1-[(2Z)-2-methylbut-2-enoyloxy]bisabol-10(11)-ene and the lignans [(2 S,3 R,4 R)-4-(3,4-dimethoxybenzyl)-2-(3,4,5-trimethoxyphenyl)-tetrahydrofuran-3-yl]-methyl-(2 Z)-2-methylbut-2-enoate and its 3,4,5-trimethoxybenzyl derivative. Known compounds, reported here for the first time for the genus Leontopodium, were identified as ent-kaur-16-en-19-oic acid and T-cadinol. The obtained compounds were tested together with 15 previously described compounds of L. alpinum in an ex vivo leukotriene biosynthesis inhibition assay. The highest activities were determined for the bisabolane derivates (IC50: 7.7 to 11.4 microM), one lignan (IC50: 10.7 microM) and the ent-kaurenoate (IC50: 10.4 microM).