Hoodia gordonii extract contains steroid glycosides, fatty acids, plant sterols and polar organic material. Certain steroid glycosides show appetite suppressant activities following oral ingestion. This study describes the validation of a bioanalytical method for the quantification of one of the steroid glycosides, H.g.-12 (≈ 10% (w/w) of the extract), in mouse, rat, rabbit and human plasma. The method utilises a liquid-liquid extraction with methyl-tert-butyl ether followed by chromatographic separation on a 2.1 × 50 mm C(18) Genesis high performance liquid chromatography (HPLC) column and detection on a triple quadrupole mass spectrometer. Detection of H.g.-12 and its stable isotope internal standards is performed using positive TurboIonspray™ ionisation in multiple reaction monitoring mode. The validation procedure demonstrated assay sensitivity, linearity, accuracy, precision and selectivity over the calibration range of 0.5-150 ng/mL in human plasma (500 μL sample volume), 1.0-100 ng/mL in rat and rabbit plasma (150 μL sample volume) and 1.0-250 ng/mL in mouse plasma (150 μL sample volume) with good recoveries (≥ 77%). H.g.-12 was stable in plasma for ≥ 6 months at -20°C, for up to 4h at ambient temperature (ca22°C) and after 3 freeze-thaw cycles. Plasma extracts were stable for up to 24h at ambient temperature.
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