10.1021/ol200047v.s001 Christian Abbet Christian Abbet Markus Neuburger Markus Neuburger Trixie Wagner Trixie Wagner Melanie Quitschau Melanie Quitschau Matthias Hamburger Matthias Hamburger Olivier Potterat Olivier Potterat Phyteumosides A and B: New Saponins with Unique Triterpenoid Aglycons from <i>Phyteuma orbiculare</i> L. American Chemical Society 2011 Unique Triterpenoid Aglycons Compound 2 Phyteuma orbiculare oxygen bridges gammaceroid triterpene triterpenoid aglycons Phyteuma orbiculare L.Phyteumosides cyclized onoceroid tetrahydropyran rings New Saponins chemical methods 2011-03-18 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Phyteumosides_A_and_B_New_Saponins_with_Unique_Triterpenoid_Aglycons_from_i_Phyteuma_orbiculare_i_L_/2681962 Phyteumosides A (<b>1</b>) and B (<b>2</b>), two saponins with unprecedented triterpenoid aglycons, were isolated from the aerial parts of <i>Phyteuma orbiculare</i> (Campanulaceae). Their structures were elucidated by spectroscopic and chemical methods and corroborated by X-ray diffraction analyses of the aglycons obtained through enzymatic hydrolysis. The aglycon of <b>1</b> can be considered as an incompletely cyclized onoceroid or gammaceroid triterpene with two additional tetrahydropyran rings arising from oxygen bridges. Compound <b>2</b> possesses a new 17-polypodene aglycon.