Two new ar-bisabol sesquiterpenes from the stem bark of Fraxinus sielboldiana

Two new ar-bisabol sequiterpenes, (+)-(7S,10S)-10-epi-7,10-epoxy-3-hydroxy-ar-bisabol-11-ol (1) and (+)-(7R,8R,10S)-10-epi-7,10-epoxy-8-hydroxy-ar-bisabol-11-ol (2), have been isolated by a combination of various column chromatographic techniques including reversed-phase semipreparative HPLC from an ethanol extract of the stem bark of Fraxinus sielboldiana. Their structures were determined by spectroscopic methods including IR, MS, and 1D and 2D NMR experiments. This is the first report of sequiterpenes in the genus Fraxinus.