New cinnamic acid derivatives with potential neuroprotective activities from the stems of Melicope ptelefolia

A phytochemical investigation on the stems of Melicope ptelefolia led to the isolation of four new cinnamic acid derivatives, meliptefoliaric A-D (1–4), together with one known related analogue (5). The chemical structures of new cinnamic acid derivatives (1–4) were ambiguously established on the basis of comprehensive spectroscopic methods. All these isolated compounds 1–5 were tested in vitro for their neuroprotective effects against 6-hydroxydopamine induced cell death in human neuroblastoma SH-SY5Y cells. Cinnamic acid derivatives 1–5 displayed remarkable neuroprotective activities possessing EC50 values ranging from 0.10 ± 0.02–10.71 ± 0.28 μM.