Activation of Nuclear Factor Erythroid 2-Related Factor-2 by Oxylipin from Mangifera indica Leaves

<i>Mangifera indica</i> L., a member of the Anacardiaceae family, is widely cultivated across the globe. The leaves of <i>M. indica</i> are renowned for their medicinal properties, attributed to the abundance of bioactive compounds. This study investigated the effects of mango leaf extract on oxidative stress in HeLa cells. Notably, the n-hexane fraction (MLHx) significantly enhanced antioxidant response element (ARE)-luciferase activity at a concentration of 100 µg/mL, surpassing other fractions. MLHx also promoted the expression of HO-1 mRNA by increasing nuclear NRF2 levels. The molecular mechanism of MLHx involves increased phosphorylation of ERK1/2 and stabilization of NRF2. Bioactivity-guided isolation resulted in the identification of six oxylipins: 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trienoic acid (<b>C-1</b>), 9(R)-hydroxy-octadeca-(10E,12Z,15Z)-trienoic acid (<b>C-2</b>), 13(R)-hydroxy-(9Z,11E)-octadecadienoic acid (<b>C-3</b>), 9(R)-hydroxy-(10E,12Z)-octadecadienoic acid (<b>C-4</b>), 9-oxo-(10E,12E)-octadecadienoic acid (<b>C-5</b>), and 9-oxo-(10E,12Z)-octadecadienoic acid (<b>C-6</b>). These structures were elucidated using comprehensive spectroscopic techniques, including MS and 1H NMR. Additionally, compounds <b>C-7</b> (9-oxo-(10E,12Z,15Z)-octadecatrienoic acid) and <b>8</b> (13-oxo-(9E,11E)-octadecadienoic acid) were characterized by LC-MS/MS mass fragmentation. This study reports the isolation of compounds 1-6 from <i>M. indica</i> for the first time. When tested for their effect on NRF2 activity in HeLa cells, compounds <b>3</b>, <b>5</b>, and <b>6</b> showed strong stimulation of ARE-luciferase activity in a dose-dependent manner.