Chemical Constituents of Anneslea fragrans and Their Antiausterity Activity against the PANC-1 Human Pancreatic Cancer Cell Line

An ethanolic extract of Anneslea fragrans leaves showed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under a nutrient-deprived condition, with a PC₅₀ value of 9.6 μg/mL. Phytochemical investigation of this active extract led to the isolation of two new secondary metabolites, fragranones A (1) and B (2), along with 15 previously reported compounds. The structure elucidation of the new compounds was achieved by HRFABMS, acid hydrolysis, NMR, and ECD spectroscopic analysis. Fragranone A (1) is the first example of a rare natural product bearing an acetonide glucose moiety. Fragranone B (2) is representative of a rare class of natural products with a threonolactone unit linked to a chalcone through an ether linkage. The isolated compounds exhibited antiausterity activity against PANC-1 cells under nutrient-deprived conditions, and betulin (14) was found to be the most potent compound tested, with a PC₅₀ value of 8.4 μM. In addition, fragranone A (1) was found to suppress PANC-1 cancer cell migration in real time.