Miyabeacin: A new cyclodimer presents a potential role for willow in cancer therapy

Willow (Salix spp.) is well known as a source of medicinal compounds, the most famous being salicin, the progenitor of aspirin. Here we describe the isolation, structure determination, and anti-cancer activity of a cyclodimeric salicinoid (miyabeacin) from S. miyabeana and S. dasyclados . We also show that the capability to produce such dimers is a heritable trait and how variation in structures of natural miyabeacin analogues is derived via cross-over Diels-Alder reactions from pools of ortho -quinol precursors. These transient ortho -quinols have a role in the, as yet uncharacterised, biosynthetic pathways around salicortin, the major salicinoid of many willow genotypes.