Ranunculin (RNC)

Ranunculin is an instable glucoside found in plants of the buttercup family (Ranunculaceae). On maceration, for example when the plant is wounded, it is enzymatically broken down into glucose and the toxin protoanemonin. Ranunculin (I) is the glycosidic precursor of the vesicant protoanemonin present in numerous species of Rannunculaceae and is especially associated with the burning sensation on chewing leaves of buttercup plants. It was first obtained in crystalline form by Hill and van Heyningen who established its gross structure and showed that it undergoes enzymatic cleavage by β-glucosidase to yield the aglucone, which underwent easy dehydration to protoanemonin. These processes were shown to occur readily under autolytic conditions. The S-stereochemistry of the dihydrofuranone ring was deduced by Benn and Yelland, and Boll, as shown in the schematic diagram, and later confirmed by synthesis.