The chemical components of <i>Coreopsis tinctoria</i> Nutt. and their antioxidant, antidiabetic and antibacterial activities

Abstract

Seventeen compounds were isolated from the capitula of <i>Coreopsis tinctoria</i> Nutt. with various column chromatographic methods and semi-preparative HPLC. Their structures were identified by the spectroscopic data and comparison with literatures as 2'-hydroxy-4,4'-dimethoxy-chalcone; (<b>1</b>), isoliquiritigenin (<b>2</b>), eriodictyol (<b>3</b>), naringenin (<b>4</b>), maritimetin (<b>5</b>), butin (<b>6</b>), taxifolin (<b>7</b>), luteolin (<b>8</b>), 7,3',4'-trihydroxyflavone (<b>9</b>), 8,3',4'-trihydroxyflavone-7-<i>O</i>-<i>β</i>-d-glucoside (<b>10</b>), quercetin (<b>11</b>), quercetagitin-7-<i>O</i>-<i>β</i>-d-glucoside (<b>12</b>), quercetin-7-<i>O</i>-<i>β</i>-d-glucoside (<b>13</b>), 3,4-dihydroxybenzoic acid (<b>14</b>), caffeic acid (<b>15</b>), coreoside B (<b>16</b>), and <i>myo</i>-inositol (<b>17</b>). Compounds <b>1</b>, <b>4</b>, <b>9</b>, <b>10</b> and <b>17</b> were isolated from <i>C. tinctoria</i> Nutt. for the first time. Compounds <b>7</b> and <b>12</b> possessed the highest antioxidant activity (IC₅₀ = 64.37 and 32.86 µg/ml, respectively) among the tested compounds (IC₅₀ value of positive control was 5.34 µg/ml). Compound <b>7</b> exhibited potent PTP1B enzymatic inhibition with an IC₅₀ value of 7.73 μg/ml (IC₅₀ value of positive control is 1.46 µg/ml). Furthermore, compound <b>5</b> showed strong antibacterial activity against the Gram-positive bacterium, <i>S. aureus</i>.