Tyrosinase inhibitory components from <i>Aloe vera</i> and their antiviral activity

<p>A new compound, 9-dihydroxyl-2'-<i>O</i>-(<i>Z</i>)-cinnamoyl-7-methoxy-aloesin (<b>1</b>), and eight known compounds (<b>2</b>–<b>9</b>) were isolated from <i>Aloe vera.</i> Their structures were elucidated using 1D/2D nuclear magnetic resonance and mass spectra. Compound <b>9</b> exhibited reversible competitive inhibitory activity against the enzyme tyrosinase, with an IC<sub>50</sub> value of 9.8 ± 0.9 µM. A molecular simulation revealed that compound <b>9</b> interacts via hydrogen bonding with residues His244, Thr261, and Val283 of tyrosinase. Additionally, compounds <b>3</b> and <b>7</b> were shown by half-leaf assays to exhibit inhibitory activity towards <i>Pepper mild mottle virus</i>.</p>