Dolabellane Diterpenoids from the Xisha Soft Coral <i>Clavularia viridis</i>

Abstract

Twelve new members (<b>1</b>-<b>12</b>) of the dolabellane family, co-occurring with three related known diterpenoids (<b>13</b>-<b>15</b>), were isolated from the Xisha soft coral <i>Clavularia viridis</i>. Their structures were determined by extensive spectroscopic analysis, modified Mosher's method, and X-ray diffraction analysis. Clavuperoxylides A (<b>3</b>) and B (<b>4</b>) represent the first examples of dolabellanes containing peroxyl groups, especially the novel peroxide bridge in <b>4</b>, whereas clavufuranolides A-C (<b>9</b>-<b>11</b>) are the first example of dolabellane diterpenoids comprising a tetrahydrofuran ring. The possible biogenetic relationship of all the isolates was proposed. In bioassay, several compounds exhibited considerable cytotoxicity against A549 and P388 cell lines. Compound <b>7</b> exhibited inhibitory activity against protein tyrosine phosphatases 1B (PTP1B), an anti-diabetic target, representing the first report of PTP1B inhibitory activity for dolabellane diterpenoids.