Chemical Constituents from the Roots and Stems of Erycibe obtusifolia and Their In Vitro Antiviral Activity

Abstract

Three new quinic acid derivatives, 4-<i>O</i>-caffeoyl-3-<i>O</i>-sinapoylquinic acid methyl ester (<b>1</b>), 5-<i>O</i>-caffeoyl-4-<i>O</i>-syringoylquinic acid methyl ester (<b>2</b>), and 4-<i>O</i>-caffeoyl-3-<i>O</i>-syringoylquinic acid methyl ester (<b>3</b>), as well as four new coumarin glycosides, 7-<i>O</i>-(3-<i>O</i>-sinapoyl-<i>β</i>-<sc>D</sc>-glucopyranosyl)-6-methoxycoumarin (<b>12</b>), 7-<i>O</i>-(6-<i>O</i>-sinapoyl-<i>β</i>-<sc>D</sc>-glucopyranosyl)-6-methoxycoumarin (<b>13</b>), 7-<i>O</i>-(2-<i>O</i>-sinapoyl-<i>β</i>-<sc>D</sc>-glucopyranosyl)-6-methoxycoumarin (<b>14</b>), and 7-<i>O</i>-(6-<i>O</i>-syringoyl-<i>β</i>-<sc>D</sc>-glucopyranosyl)-6-methoxycoumarin (<b>15</b>), together with eight known compounds (<b>4</b>–<b>11</b>) were isolated from the roots and stems of <i>Erycibe obtusifolia</i>. Their structures were elucidated on the basis of spectroscopic analysis and chemical evidence. All the compounds were screened for their <i>in vitro</i> antiviral activity against respiratory syncytial virus with a cytopathic effect reduction assay. Among them, the di-<i>O</i>-caffeoyl quinates <b>8</b>–<b>11</b> displayed a potent <i>in vitro</i> anti-respiratory syncytial virus effect.