Lipid peroxidation, cyclooxygenase enzyme and tumor cell proliferation inhibitory compounds in Cornus kousa fruits

The genus Cornus is well known for its medicinal properties. Bioassay-guided isolation and characterization of C. kousa fruits afforded kaempferol 3-O-rhamnoside (1), myricetin 3-O-rhamnoside (2), kaempferol 3-O-glucoside (3), cornin (4) and stenophyllin (5) in addition to ursolic acid and beta-sitosterol. These compounds are isolated for the first time from C. kousa. Compounds 1-5 inhibited Fe(2+) catalyzed lipid peroxidation by 63%, 57%, 61%, 53%, and 51%, at 23, 22, 23, 129, and 108 microM, respectively. Similarly, they inhibited COX-1 and -2 enzymes activities by 24% and 47%, 40% and 37%, 20% and 37%, 52% and 63%, and 48% and 55% respectively, at 231, 215, 226, 258, and 217 microM, respectively. At 129 microM, compound 4 displayed growth inhibition of HCT-116 (colon), MCF-7 (breast), NCI-H460 (lung), SF-268 (central nervous system CNS), and AGS (stomach) human tumor cell lines by 31%, 29%, 40%, 9%, and 28%, respectively. Similarly, compound 5 inhibited the growth of colon, breast, lung, CNS, and stomach tumor cell lines by 0%, 27%, 35%, 16%, and 27%, respectively, at 108 microM.