Protection adds rigidity in ring structure for pinacol coupling reaction forming diol 4.9, and also prevents unwanted oxidation in the formation of dialdehyde 4.8.
Treatment with periodic acid (dioxane) and piperidine aceate (benzene) gave aldehyde 24 through diol 22 (oxidation) and dialdehyde 23 (aldol condensation).
Two bicyclic sesquiterpenoids are present, polygodial (tadeonal, an unsaturated dialdehyde with a drimane backbone) and waburganal, which has been found responsible for the pungent taste (hence its edibility).
It is an unsaturated dialdehyde as is related to glutaraldehyde and glutaconic acid, but exists in its enol form due to the conjugation with the double bond.
