A new alkaloid polygonatine C (3-(2’-furaldehyde-5’-methoxymethyl)5,6,7,8 -tetrahydroindolizin-8-one, 1) and a new saponin huangjingsterol B (3-β-hydroxyspirost-5,25-diene-12-one, 2), together with three known compounds 3–5 were isolated from the ethanolic extract of the Stewed Polygonatum cyrtonema Hua. The structures of these new compounds were identified by extensive spectroscopic analysis including 1D and 2D NMR and MS, as well as chemical methods. The new compounds were tested for their Protective effect against Aβ25-35 induced cytotoxicity and oxidative stress damage in PC12 cells. The results indicated that compounds 1–2 can be considered as promising lead compounds for further research on Alzheimer’s disease (AD) treatment. © 2020 Informa UK Limited, trading as Taylor & Francis Group.