Lignan, sesquilignans and dilignans, novel HIV-1 protease and cytopathic effect inhibitors purified from the rhizomes of Saururus chinensis

Five lignans were isolated from the ethyl acetate extracts of Saururus chinensis rhizomes and evaluated for anti-HIV-1 activity. Their structures were elucidated as two dilignans, manassantin A (1), manassantin B (2), two sesquilignans, saucerneol B (3) and saucerneol C (4), and a new lignan, saururin B (5) by spectroscopic analysis. Of these components, manassantin A (1) and saururin B (5) showed dose-dependent inhibitory activities on HIV-1 protease with IC50 values of 38.9 and 5.6 μM. In addition, manassantins A (1), B (2) and saucerneol B (3) inhibited HIV-1-induced cytopathic effects in a human T lymphoblastoid cell line with IC100 values of 1.0, 1.0 and 0.2 μM, respectively. Of these active constituents, saucerneol B (3) showed the most potent and selective anti-HIV-1 activity (IC100 of 0.2 μM, CC0 of >125.0 μM, and SI of >520.8).