hydroxymetabolites

Hydroxymetabolites are organic compounds that contain one or more hydroxyl (–OH) functional groups and are derived from the metabolism of larger biomolecules. The term is used primarily in biochemistry and analytical chemistry to describe secondary products formed through oxidation, hydrolysis, or conjugation reactions in living organisms. Because hydroxyl groups increase solubility in water, hydroxymetabolites often play key roles in transport, detoxification, and signaling processes.

In plant metabolism, hydroxylated flavonoids, phenolic acids, and alkaloids exemplify hydroxymetabolites. For instance, quercetin is converted to quercetin-3-O-glucuronide by glucuronidation, producing a more polar derivative that can be excreted. Similarly, the secondary metabolite paclitaxel is hydroxylated during its biosynthetic pathway to yield intermediates that ultimately form the final drug.

Animal systems generate hydroxymetabolites through phase I and phase II biotransformations that facilitate drug clearance. A classic example is the oxidation of morphine to morphine-6-glucuronide, a potent analgesic metabolite. The presence of hydroxyl groups often signals that a compound is subject to further conjugation, such as sulfation or acetylation, in kidney and liver pathways.

Hydroxymetabolites are frequently detected using liquid chromatography–mass spectrometry (LC–MS) or gas chromatography coupled to tandem mass spectrometry (GC–MS), as their increased polarity promotes ionization efficiencies. In metabolic profiling studies, the enumeration of hydroxymetabolites helps characterize drug metabolism, identify biomarkers of exposure, and elucidate pathways of xenobiotic clearance.