Abstract: The chemical constituents of the fruits of Chaenomeles sinensis (Thouin) Koehne were investigated using chromatographic methods, including Diaion HP-20, Toyopearl HW-40, MCI Gel CHP-20, ODS, Silica gel chromatography and semi-preparative-HPLC. Three compounds were isolated and their structures were elucidated with spectral data and physicochemical properties, which were identified as chaenomeles alkaloid A (1), ginsenine (2) and 1,2,3,4-tetrahydro-1-methyl-β-carboline-3-car-boxylic acid (3). Among those, compound 1 is a new alkaloid, compound 2 and 3 were isolated from this plant for the first time. To investigate the protective effect of compounds 1-3 on Rat adrenal pheochromocytoma (PC-12) injury induced by the β-amyloid protein (Aβ_25-35). The results show that compounds 2 and 3 have a significant protective effect on the PC12 cells exposed to Aβ_25-35.