Chemical Analysis of Dacrydium cupressinum to Help Save the Kākāpō

The world’s largest flightless parrot, the kākāpō, are a critically endangered species with 209 individuals remaining. Conservation efforts involving close monitoring, supplementary feeding, genetic analysis, and artificial insemination have increased the kākāpō population from a low of 51 individuals in 1995. Slow breeding cycles, low fertility, and a lack of available predator free habitat currently hinder recovery efforts.

Rimu (Dacrydium cupressinum) berries are a favourite food of kākāpō. Breeding generally coincides with rimu masting which limits the kākāpō reproductive cycle to approximately once every three years. The breeding triggers for kākāpō are not yet fully understood. It has been hypothesised that phytoestrogens present in rimu fruit act as a breeding trigger by increasing the fecundity of both females and males.

Natural products extraction and chromatography techniques guided by nuclear magnetic resonance (NMR) spectroscopy were used to search for potential phytoestrogens. Aided by an oestrogenic bioassay, phytoestrogenic compounds were detected in the water and methanol extracts of rimu plant structures consumed by kākāpō. Compound 48 was isolated, a compound that shares structural similarity with the known phytoestrogen podocarpic acid (27), a known high-level constituent of rimu heartwood. Spectroscopic evidence for other compounds sharing structural similarity to 27 was also detected in fractions of rimu plant structures.