The iridoid glucoside antirrhinoside (Fig. 1) makes up several percent of the dry weight of the common ornamental plant snapdragon (Antirrhinum majus) (1–3). In general, iridoids such as antirrhinoside mediate important plant–insect and insect–insect interactions. Plants appear to harness iridoid glucosides to deter herbivores. The herbivore is affected by the toxic dialdehydes liberated by deglycosylation of the iridoid in the injured plant tissue or insect gut (4, 5). Some herbivorous insects can sequester iridoid glucosides and exploit the toxic effect for their own defensive systems (6). Additionally, many iridoid glucosides are believed to have beneficial health properties for humans. Foods such as olives may owe some of their health-promoting properties to iridoid ingredients with anti-inflammatory (7), antimicrobial, and anticancer effects (8).