The alkaloids of Piper Iongum L.(PLA) improved motor dysfunction and dopamine depletion in a rat model of Parkinsons disease induced by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine.A rapid, accurate, simple, and high-performance liquid chromatography-mass spectrometry method was developed and fully validated to simultaneously detect three Piper Iongum L.antiparkinsonian alkaloids (piperine (PPR),piperlonguminine (PPL), and △α,β-dihydropiperlonguminine (DPPL)) in rat plasma, heart,liver, spleen, lung, kidney, and brain tissues.Rat plasma and tissue homogenates were pretreated with methanol/acetonitrile (1∶1, v/v) using a simple protein precipitation method.Chromatographic separation was achieved on a Phenomenex Gemini C18 column (50 mm x 2.00 mm, 5 μm) with a gradient mobile phase containing 0.1% (v/v) formic acid in water or acetonitrile.The elution was pumped at a flow rate of 0.4 ml/min, and the injection volume was 10 μl with a total running time of 4 min.The analysis was performed by selected reaction monitoring of the transitions m/z 285.9→201.1, m/z 274.3→209.9,and m/z 276.2→134.9 for PPR, PPL, and DPPL, respectively.All three analytes showed good linearity (R > 0.995) in plasma and tissue homogenates, and the lower limit of quantification was 0.20 ng/ml.The distribution of PPR, PPI.and DPPL in all 7 tissues was examined.The highest concentrations for PPR and PPL were observed in the liver, while the highest DPPL concentration was observed in the kidney.Following oral administration,the highest levels of PPR, PPL and DPPL in different tissues were found at approximately 2 h.PPR, PPL and DPPL could cross the blood-brain barrier.The present study provides evidences for that PPR, PPL and DPPL may play roles in improving motor dysfunction and dopamine depletion.