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

Abstract

An ethanolic extract of <i>Anneslea fragrans</i> 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 (<b>1</b>) and B (<b>2</b>), 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 (<b>1</b>) is the first example of a rare natural product bearing an acetonide glucose moiety. Fragranone B (<b>2</b>) 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 (<b>14</b>) was found to be the most potent compound tested, with a PC₅₀ value of 8.4 μM. In addition, fragranone A (<b>1</b>) was found to suppress PANC-1 cancer cell migration in real time.