Cytotoxic flavonoids and other constituents from the stem bark of <i>Ochna schweinfurthiana</i>

<div><p>Seven flavonoids, hemerocallone (<b>1</b>), 6,7-dimethoxy-3′,4′-dimethoxyisoflavone (<b>2</b>), amentoflavone (<b>4</b>), agathisflavone (<b>6</b>), cupressuflavone (<b>8</b>), robustaflavone (<b>9</b>) and epicatechin (<b>10</b>), together with three other compounds, lithospermoside (<b>3</b>), β-D-fructofuranosyl-α-D-glucopyranoside (<b>5</b>) and 3β-<i>O</i>-D-glucopyranosyl-β-stigmasterol (<b>7</b>), were isolated from the ethyl acetate extract of the stem bark of <i>Ochna schweinfurthiana</i> F. Hoffm. All the compounds were characterised by spectroscopic and mass spectrometric methods, and by comparison with literature data. Cytotoxicity of the extracts and compounds against cervical adenocarcinoma (HeLa) cells was evaluated by MTT assay. Compounds <b>4</b> and <b>6</b> exhibited good cytotoxic activity, with IC₅₀ values of 20.7 and 10.0 μM, respectively.</p></div

Carbazole-, Aspidofractinine-, and Aspidocarpamine-Type Alkaloids from <i>Pleiocarpa pycnantha</i>

Three new alkaloids, janetinine (<b>1a</b>), pleiokomenine A (<b>2</b>), and huncaniterine B (<b>3a</b>), and 13 known compounds, pleiomutinine (<b>3b</b>), huncaniterine A (<b>3c</b>), 1-carbomethoxy-β-carboline (<b>4</b>), evoxanthine (<b>5</b>), deformyltalbotine acid lactone (<b>6</b>), pleiocarpamine (<b>7</b>), <i>N</i>⁴-methyl-10-hydroxygeissoschizol (<b>8</b>), spegatrine (<b>9</b>), neosarpagine (<b>10</b>), aspidofractinine (<b>11</b>), <i>N</i>¹-methylkopsinin (<b>12</b>), pleiocarpine (<b>13</b>), and <i>N</i>¹-methylkopsinin-<i>N</i>⁴-oxide (<b>14</b>), were isolated from the stem bark of <i>Pleiocarpa pycnantha</i>. Janetinine (<b>1a</b>) is a carbazole alkaloid; in pleiokomenine A (<b>2</b>), two aspidofractinine-type alkaloids are bridged by a methylene unit in an unprecedented way, and huncaniterine B (<b>3a</b>) is a pleiocarpamine–aspidofractinine-type dimer. The structures and relative configurations of these compounds were elucidated on the basis of NMR and MS analyses. Their absolute configurations were defined by means of experimental and calculated ECD data, and additionally, the structures of <b>5</b> and <b>13</b> were determined by single crystal X-ray diffraction. Compounds <b>1a</b>, <b>2</b>, <b>3b</b>, <b>4</b>, <b>6</b>, <b>9</b>, and <b>12</b> displayed cancer chemopreventive properties through either quinone reductase induction (<i>CD</i> = 30.7, 30.2, 29.9, 43.5, and 36.7 μM for <b>1a</b>, <b>4</b>, <b>6</b>, <b>9</b>, and <b>12</b>, respectively) and/or NF-κB inhibition with IC₅₀ values of 13.1, 8.4, 9.4, and 8.8 μM for <b>2</b>, <b>3b</b>, <b>6</b>, and <b>12</b>, respectively

Carbazole-, Aspidofractinine-, and Aspidocarpamine-Type Alkaloids from <i>Pleiocarpa pycnantha</i>

Three new alkaloids, janetinine (<b>1a</b>), pleiokomenine A (<b>2</b>), and huncaniterine B (<b>3a</b>), and 13 known compounds, pleiomutinine (<b>3b</b>), huncaniterine A (<b>3c</b>), 1-carbomethoxy-β-carboline (<b>4</b>), evoxanthine (<b>5</b>), deformyltalbotine acid lactone (<b>6</b>), pleiocarpamine (<b>7</b>), <i>N</i>⁴-methyl-10-hydroxygeissoschizol (<b>8</b>), spegatrine (<b>9</b>), neosarpagine (<b>10</b>), aspidofractinine (<b>11</b>), <i>N</i>¹-methylkopsinin (<b>12</b>), pleiocarpine (<b>13</b>), and <i>N</i>¹-methylkopsinin-<i>N</i>⁴-oxide (<b>14</b>), were isolated from the stem bark of <i>Pleiocarpa pycnantha</i>. Janetinine (<b>1a</b>) is a carbazole alkaloid; in pleiokomenine A (<b>2</b>), two aspidofractinine-type alkaloids are bridged by a methylene unit in an unprecedented way, and huncaniterine B (<b>3a</b>) is a pleiocarpamine–aspidofractinine-type dimer. The structures and relative configurations of these compounds were elucidated on the basis of NMR and MS analyses. Their absolute configurations were defined by means of experimental and calculated ECD data, and additionally, the structures of <b>5</b> and <b>13</b> were determined by single crystal X-ray diffraction. Compounds <b>1a</b>, <b>2</b>, <b>3b</b>, <b>4</b>, <b>6</b>, <b>9</b>, and <b>12</b> displayed cancer chemopreventive properties through either quinone reductase induction (<i>CD</i> = 30.7, 30.2, 29.9, 43.5, and 36.7 μM for <b>1a</b>, <b>4</b>, <b>6</b>, <b>9</b>, and <b>12</b>, respectively) and/or NF-κB inhibition with IC₅₀ values of 13.1, 8.4, 9.4, and 8.8 μM for <b>2</b>, <b>3b</b>, <b>6</b>, and <b>12</b>, respectively