Polyacanthoside A, a new oleanane-type triterpenoid saponin with cytotoxic effects from the leaves of <i>Acacia polyacantha</i> (Fabaceae)

<p>The chemical investigation of the leaves and stem bark of <i>Acacia polyacantha</i> (Fabaceae) led to the isolation of a new oleanane-type triterpenoid saponin named polyacanthoside A <b>1</b> together with fifteen known compounds. Their structures were established from spectral , mainly HRESIMS, 1D NMR and 2D NMR and by comparison with literature data. The cytotoxicity of compound <b>1</b> and the analogues <b>8</b> as well as doxorubicin was determined in a panel of 9 cancer cell lines including sensitive and drug resistant phenotypes. Unlike the analogue <b>8,</b> compound <b>1</b> as well as doxorubicin displayed cytotoxic effects in all the 9 tested cancer cell lines with IC₅₀ values ranged from 8.90 μM (towards CCRF-CEM leukemia cells) to 35.21 μM (towards HepG2 hepatocarcinoma cells) for compound <b>1</b> and from 0.02 μM (towards CCRF-CEM leukemia cells) to 66.83 μM (against CEM/ADR5000 leukemia cells) for doxorubicin.</p

Secondary metabolites with antiproliferative effects from <i>Albizia glaberrima</i> var glabrescens Oliv. (Mimosoideae)

<p>A new 5-dehydroxyflavan, namely Albiziaflavan B or (+)-(2<i>R</i>, 3<i>S</i>, 4<i>R</i>)-3′,4′, 7-trihydroxy-4-methoxy-2,3-<i>trans</i>-flavan-3,4-<i>trans</i>-diol (<b>1)</b> was isolated from the root bark of <i>Albizia glaberrima</i>, together with six known compounds including three flavans: (+)-mollisacacidin (<b>2</b>), (+)-fustin <b>(3</b>) and butin (<b>4</b>); two steroids: chondrillasterol (<b>5)</b> and chondrillasterone (<b>6)</b>, and a triterpenoid: lupeol (<b>7</b>). The structure of <b>1</b> was established by detailed analysis of its spectroscopic data, especially 1D and 2D NMR spectra, HRESIMS and CD data. Compounds <b>1</b>–<b>6</b> were assayed for their antiproliferative effects on two human cancer cells, HeLa at 50 μM (<i>n</i> = 2) and HL60 at 20 μM (<i>n</i> = 2). Compound <b>3</b> and <b>4</b> were the most active on HL60 with IC₅₀ of 8.1 and 8.3 μM, respectively. Compound <b>6</b> was the most active with an IC₅₀ of 4.6 μM on HeLa.</p