Corymbulosins D–H, 2‑Hydroxy- and 2‑Oxo-clerodane Diterpenes from the Bark of <i>Laetia corymbulosa</i>

A bioactive CH₃OH–CH₂Cl₂ (1:1) extract of the bark of <i>Laetia corymbulosa</i> provided five new clerodane diterpenes with an isozuelanin skeleton, designated as corymbulosins D–H (<b>1</b>–<b>5</b>), as well as the known corymbulosins B (<b>6</b>) and C (<b>7</b>), for which the relative configurations were not previously determined. The structures of <b>1</b>–<b>5</b> were characterized on the basis of 1D and 2D NMR spectroscopic and HRMS analysis. The absolute configurations of all isolated compounds <b>1</b>–<b>7</b> were verified through chemical methods, including modified Mosher esterifications or oxidation of the hydroxy group at C-2, ECD experiments, and spectroscopic data comparison. The isolated compounds were evaluated for antiproliferative activity against a small panel of human cancer cell lines

Corymbulosins I–W, Cytotoxic Clerodane Diterpenes from the Bark of <i>Laetia corymbulosa</i>

The isolation studies of a crude MeOH/CH₂Cl₂ (1:1) extract (N005829) of the bark of <i>Laetia corymbulosa</i> yielded 15 new clerodane diterpenes, designated corymbulosins I–W (<b>1</b>–<b>15</b>), as well as four known diterpenes, <b>16</b>–<b>19</b>. The structures of <b>1</b>–<b>15</b> were characterized on the basis of extensive 1D and 2D NMR and HRMS analyses. The absolute configurations of newly isolated compounds <b>1</b>–<b>15</b>, as well as known <b>16</b>–<b>19</b>, which were reported previously with only relative configurations, were determined through ECD experiments, X-ray analysis, chemical methods, including Mosher esterification, and comparison of their spectroscopic data. The isolated compounds were evaluated for cytotoxicity against human cancer cell lines. Flow cytometric and immunocytochemical observations of cells treated with cytotoxic clerodanes demonstrated that the chromatin was fragmented and dispersed with formation of apoptotic microtubules

Corymbulosins I–W, Cytotoxic Clerodane Diterpenes from the Bark of <i>Laetia corymbulosa</i>

The isolation studies of a crude MeOH/CH₂Cl₂ (1:1) extract (N005829) of the bark of <i>Laetia corymbulosa</i> yielded 15 new clerodane diterpenes, designated corymbulosins I–W (<b>1</b>–<b>15</b>), as well as four known diterpenes, <b>16</b>–<b>19</b>. The structures of <b>1</b>–<b>15</b> were characterized on the basis of extensive 1D and 2D NMR and HRMS analyses. The absolute configurations of newly isolated compounds <b>1</b>–<b>15</b>, as well as known <b>16</b>–<b>19</b>, which were reported previously with only relative configurations, were determined through ECD experiments, X-ray analysis, chemical methods, including Mosher esterification, and comparison of their spectroscopic data. The isolated compounds were evaluated for cytotoxicity against human cancer cell lines. Flow cytometric and immunocytochemical observations of cells treated with cytotoxic clerodanes demonstrated that the chromatin was fragmented and dispersed with formation of apoptotic microtubules