A new homoisoflavone from <i>Portulaca oleracea</i> L<i>.</i> and its antioxidant activity

Abstract

A new compound was identified as 3-(2-hydroxybenzyl)-5,7-dimethoxy-4<i>H</i>-chromen-4-one (or 2'-dihydroxy-5,7-dimethoxy-homoisoflavone), oleracone F (<b>1</b>), together with <i>p</i>-hydroxy ethyl cinnamate (<b>2</b>) and 4-hydroxy-3-methoxy ethyl cinnamate (<b>3</b>) isolated from the <i>Portulaca oleracea</i> L. for the first time and six known compounds, salicylic acid (<b>4</b>), <i>β</i>-carboline-3-carboxylic acid (<b>5</b>), aurantiamide (<b>6</b>), portulacanone A (<b>7</b>), B (<b>8</b>) and C (<b>9</b>)<i>.</i> Their structures were determined using spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance and high-resolution electrospray ionization time-of-flight mass spectrometry. Notably, oleracone F (<b>1</b>) presented scavenging activity in 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical quenching assay, with IC₅₀ value of 17.78 μM.