Cassaine diterpenoid glycosides from the seeds of Erythrophleum fordii Oliv. and their antiviral and anti-inflammatory activities.

Seven new cassaine diterpenoids (1-7) along with four known ones (8-11) were isolated from the seeds of Erythrophleum fordii Oliv. (Leguminosae). Their chemical structures were elucidated by extensive spectroscopic data interpretation and chemical methods. Compound 1 is a rare unsymmetrical dimer, which is formed by the linking of another cassaine diterpenoid acid glycoside to the 6-hydroxyl group of the sugar unit in a cassaine amide glycoside through an ester bond. Compound 2 is a cassaine diterpenoid acid derivative featuring an unusual Z double bond at C-13 and C-15. The in vitro antiviral and anti-inflammatory activities of 1-11 were evaluated. The results showed that compounds 1, 2 and 3 showed significant antiviral activities against human respiratory syncytial virus (RSV) with ICs of 6.3, 7.8, and 9.4 μM, respectively. Compound 9 significantly suppressed the expression of nuclear factor-kappa B (NF-κB) with an IC value of 2.6 μM.