Protective effect of alkaloids from Piper longum in rat dopaminergic neuron injury of 6-OHDA-induced Parkinson’s disease Advances in studies on pharmacological effects of piperlongumine Textual research of herbal medicine Piper longum Comparative metabolism of three amide alkaloids from Piper longum in five different species of liver microsomes Advances in studies on pharmacological effects of piperlongumine  Chemical constituents from air-dried Piper longum Chemical constituents from Piper longum Chemical constituents from Piper longum