Cytotoxic Evaluation of Alkaloids and Isoflavonoids from the Australian Tree Erythrina vespertilio

A new glucoalkaloid, vespertilioside, together with three known alkaloids, including 11-beta-methoxyglucoerysovine, erysotrine, and hypaphorine, were isolated from the fruits of E. vespertilio Benth. In addition, three known isoflavonoids, including phaseollin, alpiniumisoflavone, and phaseollidin, were identified from the plant stems. The structures of compounds were determined by 1D/2D NMR and mass experiments. The cytotoxic activity of all compounds was evaluated against a metastatic prostate cancer cell line (PC3) and neonatal foreskin fibroblast (NFF) using a real-time label-free cell analyser. Among the tested compounds, phaseollidin showed cytotoxic activities against PC3 (IC50 = 8.83 +/- 1.87 mu M) and NFF (0.64 +/- 0.37 mu M) cell lines.