Two new compounds from the dried tender stems of Cinnamomum cassia.

Two new compounds, cinnamic aldehyde cyclic d-galactitol 3'R,4'S-acetal (1) and cinnamomumolide (2), along with six known compounds, syringaresinol (3), lyoniresinol (4), 5,7,3'-trimethoxyl-( - )-epicatechin (5), 5,7-dimethoxyl-3',4'-di-O-methylene-( +/- )-epicatechin (6), 2-methoxyl-4-hydroxy cinnamyl aldehyde (7), and glucosyringic acid (8), have been isolated from the dried tender stems of Cinnamomum cassia. Their structures were elucidated based on spectroscopic data. Compound 2 was elucidated as 8-methoxyl-9-hydroxy-3',4'-methylenedioxy-3S,4R-diphenyl butyrolactone, named cinnamomumolide, which exhibited activity in protecting against the injury caused by hydrogen peroxide oxidation on human umbilical vein endothelial cells, with an EC(50) value of 10.7 microM. Compounds 3-8 were isolated from the title plant for the first time.