P57AS3 (P57), an oxypregnane steroidal glycoside, is known to be responsible for the appetite suppressing activity of HOODIA GORDONII, a dietary supplement used for weight loss. In this study, bioavailability, pharmacokinetics, and tissue distribution of P57 were determined in CD1 female mice after administration of a single dose of enriched methanolic extract of HOODIA GORDONII (equivalent to a dose of 25 mg of P57/kg) by oral gavage or a single dose of purified P57 (25 mg/kg) intravenously. The level of P57 in plasma and tissues (brain, liver, kidney, and intestine) was determined by UPLC-MS. After oral administration of HOODIA extract, the peak plasma level of P57 was achieved in 0.6 h. Upon intravenous administration, the plasma clearance rate of P57 was 1.09 L/h/kg. P57 was rapidly distributed and eliminated from the tissues within 4 hours. The level of tissue distribution was highest in the kidney followed by liver and brain. Upon oral administration, P57 was not detected in the brain and a very low concentration was seen in the intestine, kidney, and liver. Tissue/plasma ratio was 0.33 for brain, 0.57 for liver, and 0.75 for kidney with IV route and 0.11 for intestine, 0.02 for liver, and 0.04 for kidney with oral route. The half-life of the elimination phase was similar with both routes. The oral bioavailability was 47.5 % and the half-life of the absorption phase was 0.13 h. In conclusion, P57 showed moderate bioavailability and was eliminated rapidly.
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