Unusual C,O-Fused Glycosylapigenins from <i>Serjania marginata</i> Leaves

A phytochemical study of a <i>Serjania marginata</i> leaf extract with antiulcer activity afforded 15 compounds, including the new 3-<i>O</i>-α-l-arabinopyranosyl­(1→3)-α-l-rhamnopyranosyl­(1→2)­[β-d-glucopyranosyl­(1→4)]-α-l-arabinopyranosyl­oleanolic acid (<b>1</b>) and 7,5″-anhydroapigenin 8-<i>C</i>-α-(2,6-dideoxy-5-hydroxy-<i>ribo</i>-hexopyranosyl)-4′-<i>O</i>-β-d-glucopyranoside (<b>4</b>). The structures of the new compounds were determined by spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry, and chemical methods. Compound <b>4</b> is a <i>C</i>-hexopyranosylapigenin with an unusual cyclic ether linkage between C-5″ and C-7 of apigenin. The isolated proanthocyanidins have high antioxidant activities, and these compounds are probably responsible for the gastroprotective effect of the extract

Steroidal Saponins from <i>Furcraea hexapetala</i> Leaves and Their Phytotoxic Activity

Four new steroidal saponins (<b>1</b>–<b>4</b>) along with 13 known saponins were isolated from the leaves of <i>Furcraea hexapetala</i>. The new compounds were identified as (20<i>R</i>,22<i>R</i>,25<i>R</i>)-3β-hydroxy-5α-spirostan-12-one 3-<i>O</i>-{α-l-rhamnopyranosyl-(1→4)-<i>O</i>-β-d-glucopyranosyl-(1→3)-<i>O</i>-[β-d-glucopyranosyl-(1→3)-<i>O</i>-β-d-glucopyranosyl-(1→2)]-<i>O</i>-β-d-glucopyranosyl-(1→4)-<i>O</i>-β-d-galactopyranoside} (<b>1</b>), (25<i>R</i>)-3β-hydroxy-5α-spirost-20­(21)-en-12-one 3-<i>O</i>-{α-l-rhamnopyranosyl-(1→4)-<i>O</i>-β-d-glucopyranosyl-(1→3)-<i>O</i>-[β-d-glucopyranosyl-(1→3)-<i>O</i>-β-d-glucopyranosyl-(1→2)]-<i>O</i>-β-d-glucopyranosyl-(1→4)-<i>O</i>-β-d-galactopyranoside} (<b>2</b>), (25<i>R</i>)-5α-spirostan-3β-ol 3-<i>O</i>-{β-d-glucopyranosyl-(1→2)-<i>O</i>-β-d-glucopyranosyl-(1→2)-<i>O</i>-β-d-glucopyranosyl-(1→4)<i>-O</i>-β-d-galactopyranoside} (<b>3</b>), and (25<i>R</i>)-5β-spirostan-3β-ol 3-<i>O</i>-{β-d-glucopyranosyl-(1→6)-<i>O</i>-β-d-galactopyranoside} (<b>4</b>) by spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry, and chemical methods. The phytotoxicity of the isolated compounds against the standard target species <i>Lactuca sativa</i> was evaluated. Structure–activity relationships for these compounds with respect to phytotoxic effects are discussed

Isolation and Structural Determination of Triterpenoid Glycosides from the Aerial Parts of Alsike Clover (Trifolium hybridum L.)

Five azukisapogenol glycosides (<b>1</b>–<b>5</b>) have been isolated from the aerial parts of alsike clover (Trifolium hybridum L.), and their structures were elucidated by combined spectroscopic, spectrometric (1D and 2D NMR; HRESIMS, ESI–MS/MS), and chemical methods. Three of them are new compounds and were identified as 3-<i>O</i>-[-α-l-arabinopyranosyl­(1→2)]-β-d-glucuronopyranosyl azukisapogenol (<b>1</b>), 3-<i>O</i>-[-β-d-glucuronopyranosyl­(1→2)-β-d-glucuronopyranosyl]-29-<i>O</i>-β-d-glucopyranosyl azukisapogenol (<b>2</b>), and 3-<i>O</i>-[-α-l-arabinopyranosyl­(1→2)-β-d-glucuronopyranosyl]-29-<i>O</i>-β-d-glucopyranosyl azukisapogenol (<b>3</b>). The remaining two (<b>4</b>, <b>5</b>) are known compounds but have not been previously described as saponins constituents of the genus Trifolium. Also, azukisapogenol is reported here as a triterpenoid aglycone for the first time in this genus. Finally, the main chemotaxonomic features that may be recognized as specific of Trifolium species were discussed

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

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