Clerodane Diterpenoids from <i>Croton crassifolius</i>

Seven new clerodane diterpenoids (<b>1</b>–<b>7</b>) were isolated from roots of <i>Croton crassifolius</i>, along with six known compounds. The structures were elucidated by extensive spectroscopic methods (IR, UV, HRESIMS, 1D NMR, and 2D NMR), and the structures of <b>1</b>, <b>3</b>, <b>4</b>, and <b>7</b> were confirmed by single-crystal X-ray diffraction analyses. Compounds <b>1</b>–<b>13</b> were evaluated for in vitro antiviral activity against herpes simplex virus type 1 using the cytopathic effect reduction assay