Iridoids from endemic sardinian Linaria species

Linaria arcusangeli contains a new bisiridoid, named arcusangeloside, besides the known antirrhinoside, linarioside, antirrhide, linaride and 5-glucosylantirrhinoside. The new bisiridoid is formed from a non-glycosidic cyclopentanoid which esterified the iridoid glucoside 5-deoxyantirrhinoside, also isolated as a free compound from the plant extract. L. flava subsp. sardoa contains the new bisiridoid, 5-deoxyantirrhinoside, antirrhinoside, linarioside and antirrhide.