Inhibitory effects of manassantin A and B isolated from the roots of Saururus chinensis on PMA-induced ICAM-1 expression.

Cell adhesion inhibitors were isolated from the methanol extract of Saururus chinensis roots by bioactivity-guided fractionation. The active compounds were identified as manassantin A ( 1) and B ( 2), dineolignan compounds. Compounds 1 and 2 inhibited PMA-induced ICAM-1/LFA-1-mediated homotypic aggregation of the HL-60 cells without cytotoxicity with MIC values of 1.0 and 5.5 nM, respectively. Even though 1 and 2 did not affect the adhesion of ICAM-1 to LFA-1, these compounds inhibited PMA-induced ICAM-1 expression in HL-60 cells in a dose-dependent fashion. These results suggest that 1 and 2 inhibit cell aggregation through down-regulation of ICAM-1 expression.