Talaromarins A–F: Six New Isocoumarins from Mangrove-Derived Fungus Talaromyces flavus TGGP35

Abstract

Six new isocoumarin derivative talaromarins A-F (<b>1</b>-<b>6</b>), along with 17 known analogues (<b>7</b>-<b>23</b>), were isolated from the mangrove-derived fungus <i>Talaromyces flavus</i> (Eurotiales: Trichocomaceae) TGGP35. Their structures were identified by detailed IR, UV, 1D/2D NMR and HR-ESI-MS spectra. The absolute configurations of new compounds were determined by the modified Mosher's method and a comparison of their CD spectra with dihydroisocoumarins described in the literature. The antioxidant, antibacterial, anti-phytopathogenic and inhibitory activity against α-glucosidase of all the isolated compounds were tested. Compounds <b>6</b>-<b>1</b><b>1</b>, <b>17</b>-<b>19</b> and <b>21</b>-<b>22</b> showed similar or better antioxidant activity than the IC₅₀ values ranging from 0.009 to 0.27 mM, compared with the positive control trolox (IC₅₀ = 0.29 mM). Compounds <b>10</b>, <b>18</b>, <b>21</b> and <b>23</b> exhibited strong inhibitory activities against α-glucosidase with IC₅₀ values ranging from 0.10 to 0.62 mM, while the positive control acarbose had an IC₅₀ value of 0.5 mM. All compounds showed no antibacterial or anti-phytopathogenic activity at the concentrations of 50 μg/mL and 1 mg/mL, respectively. These results indicated that isocoumarins will be useful to developing antioxidants and as diabetes control agents.