Triterpene Saponins from the Aerial Parts of Trifolium medium L. var. <i>sarosiense</i>

Abstract

Seven previously unreported triterpene glycosides (<b>1</b>–<b>7</b>) were isolated from methanol extract of the aerial parts of Trifolium medium var. <i>sarosiense</i> (zigzag clover). Their structures were established by the extensive use of 1D and 2D NMR experiments along with ESI-MS and HRMS analyses. Compounds <b>1</b>–<b>7</b> are oleanane derivatives characterized by the presence of a keto group at C-22 of an aglycone and a primary alcoholic function at C-24 and differing functions at C-30. Among these, compounds <b>1</b>–<b>3</b> and <b>6</b> showed a secondary alcoholic function at C-11, which is methoxylated in compounds <b>4</b> and <b>7</b>. Compound <b>5</b> was shown to possess a known aglycone, wistariasapogenol A; however, it is described here for the first time as a saponin constituent of the <i>Trifolium</i> genus. Some aspects of taxonomic classification of zigzag clover are also discussed