A new norsesquiterpene from the roots of Polyalthia laui.

One new norsesquiterpene polyalone A (1), and one new natural product 9-keto-cyclocolorenone (2), along with three known analogues (3-5) were isolated from the roots of Polyalthia laui. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. All compounds were evaluated for their cytotoxic activities and antibacterial activities.