Determination of Gnetol in Murine Biological Matrices by Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS): Application in a Biodistribution Study

Gnetol (<i>trans</i>-2,3',5',6-tetrahydroxystilbene), a naturally occurring stilbene structurally related to resveratrol (<i>trans</i>-3,5,4'-trihydroxystilbene; RES), has been reported to possess multiple health-promoting activities. In order to support its potential nutraceutical application, a reliable chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed and validated for the quantitative determination of gnetol in mouse plasma and tissue samples, using isotopically labeled RES-¹³C₆ serving as the internal standard (IS). Electrospray ionization (ESI) was performed in negative mode, with multiple reaction monitoring (MRM) transitions <i>m</i>/<i>z</i> 243.2 → 175.0 for gnetol and <i>m</i>/<i>z</i> 233.1 → 191.0 for the IS. Chromatographic separation was achieved on a reversed-phase HPLC column using a 5-min gradient delivery of acetonitrile and 2 mM ammonium acetate at 0.5 mL/min and 40 °C. The linear calibration curve covered the concentration range of 5.0-1500 ng/mL, and the method validation confirmed its selectivity, accuracy, precision, stability, and dilution integrity. The developed method was subsequently applied to a biodistribution study in mice after oral administration of gnetol at 400 µmol/kg (equivalent to 97.7 mg/kg). Gnetol was rapidly absorbed and extensively distributed in key pharmacologically relevant organs. Despite its poor aqueous solubility, oral uptake was not significantly hindered. Collectively, these findings demonstrate that gnetol exhibits favorable absorption and tissue distribution profiles, supporting its promise as a candidate for nutraceutical development.