Diels-Alder type adducts from Morus cathayana

Abstract

Two natural Diels-Alder type adducts, cathayanon A (1) and cathayanon B (2), resembling sanggenon C (4) and O (3), were isolated from the root bark of Morus cathayana. Their structures were elucidated on the basis of spectroscopic evidence. The structure of 1 was confirmed by the results of X-ray crystallographic analysis. The absolute configurations of 1 and 2 were determined as 2S, 3R,14S, 19S, 20R and 2S, 3R, 14R, 19S, 20R, respectively. The absolute configurations at C-2 and C-3 of two other known isomeric Diels-Alder adducts sanggenon O (3) and C (4) were deduced as 2R, 3S. Pharmacological tests indicated that 1 and 2 exhibited potent activities on the inhibition of HL-60 cell adhesion to BAEC at concentrations of 10(-5) mol l(-1), with inhibitory rates of 44.72 and 39.02%, respectively.