Unexpected Secoiridoid Glucosides from <i>Manulea corymbosa</i>

Abstract

From an extract of <i>Manulea corymbosa</i> were isolated four known secoiridoid glucosides (<b>1</b>–<b>4</b>), 10 new monoterpenoid esters of secologanol, namely, manuleosides A–I (<b>5</b>–<b>11</b>, <b>13</b>, and <b>14</b>) and dimethyl rhodanthoside A (<b>12</b>), and four new phenylpropanoid esters of carbocyclic iridoid glucosides, manucorymbosides I–IV (<b>15</b>–<b>18</b>). Also, the caffeoyl phenylethanoid glycoside verbascoside was isolated. The presence of secoiridoids apparently derived from loganic acid in the family Scrophulariaceae is unprecedented and greatly unexpected