Eremophilane-Type Sesquiterpenoids From the Endophytic Fungus Rhizopycnis vagum and Their Antibacterial, Cytotoxic, and Phytotoxic Activities

Abstract

Fourteen new eremophilane-type sesquiterpenoids, named rhizoperemophilanes A~N (<b>1</b>~<b>14</b>), together with eight known congeners, were isolated from the culture of the endophytic fungus <i>Rhizopycnis vagum</i>. The structures of the new compounds were elucidated by extensive spectroscopic analyses, as well as ECD calculations and the modified Mosher's method for the assignment of the absolute configurations. Rhizoperemophilane J (<b>10</b>) contains an uncommon C-4/C-11 epoxy ring, while rhizoperemophilane N (<b>14</b>) features an unprecedented 3-nor-eremophilane lactone-lactam skeleton. These metabolites were evaluated for their antibacterial, cytotoxic, and phytotoxic activities. Among them, compounds <b>11</b>, <b>16</b>, and <b>20</b> displayed antibacterial activities, while <b>14</b> showed selective cytotoxicity against NCI-H1650 and BGC823 tumor cells. Moreover, compounds <b>5</b>, <b>6</b>, <b>12</b>, <b>13</b>, <b>16</b>, and <b>19</b> exhibited strong phytotoxic activities against the radicle elongation of rice seedlings.