Chemotaxonomy of Pseudowintera: Sesquiterpene dialdehyde variants are species markers

A sesquiterpene dialdehyde coumarate was isolated from the recently described species Pseudowintera insperata. HPLC analyses of leaves of the four Pseudowintera species, all endemic to New Zealand, showed that sesquiterpene dialdehydes are good species markers. Two sesquiterpene dialdehydes, the 1β- E-coumaroyl-5α-hydroxypolygodial plus the known 1β- E-cinnamoyl-5α-hydroxypolygodial, were isolated from the recently described species Pseudowintera insperata. This discovery is a further example of the rare sesquiterpene dialdehyde coumarate/cinnamate combination being found exclusively in the family Winteraceae. Another sesquiterpene dialdehyde, isopaxidal, with the rare rearranged drimane skeleton, was isolated from Pseudowintera axillaris. The sesquiterpene dialdehyde contents of leaves of 25 individual plants of the four Pseudowintera species, all endemic to New Zealand, were measured by HPLC. P. insperata individuals all had high levels (3.0–6.9% of leaf dry wt.) of the coumarate, P. axillaris had high levels (2.2–6.9%) of paxidal, and Pseudowintera colorata from different areas of New Zealand contained varying levels of polygodial (1.4–2.9%) and 9-deoxymuzigadial (0–2.9%). Therefore the sesquiterpene dialdehydes are good species markers.