8-epi-Muralioside, an iridoid glucoside from Linaria arcusangeli

A new polyhydroxylated iridoid glucoside, 1, was isolated from Linaria arcusangeli. The structure of 1 could arise from a regioselective acid-catalyzed-like opening of the epoxide ring of antirrhinoside, the main iridoid constituent of the plant. Compound 1 is the 8-epimer of muralioside, previously isolated from Cymbalaria muralis.