Liquid–liquid extraction and liquid chromatography–mass spectrometry detection of curcuminoids from bacterial culture medium

•Liquid–liquid extraction improves curcuminoid recovery from bacterial growth medium.•Ethyl actate can recover ∼80–86% of curcuminoids as detected by LC–MS.•The high solubility of curcuminoids in ethyl acetate improves recovery.•In contrast, ∼25% curcumin is extracted with acetonitrile.•The method allows studies of bacterial metabolism of curcumin and similar compounds.

Liquid chromatography–mass spectrometry (LC–MS) has been used to detect polyphenolic curcuminoids found in turmeric but studies of metabolism by bacterial and mammalian cells in vitro are compromised by poor recovery from the culture medium. We report a liquid–liquid extraction procedure with ethyl acetate and use LC–MS to quantify extracted curcuminoids. Ethyl acetate allows recoveries of ∼80–86% of curcuminoids from the bacterial growth medium, bacterial cell lysate and combined bacterial cell and growth medium matrices; a clear improvement over acetonitrile where recoveries were ∼25–66%. This optimised method will enable studies of curcuminoid metabolism and may be applicable to other hydrophobic polyphenolic compounds.