The natural dibenzylbutyrolactone type lignanolide (-)-arctigenin (2), an inhibitor of human immunodeficiency virus type-1 (HIV-1) replication in infected human cell systems, was found to suppress the integration of proviral DNA into the cellular DNA genome. 11b In the present study 2 was tested with purified HIV-1 integrase and found to be inactive in the cleavage (3'- processing) and integration (strand transfer) assays. However, the semisynthetic 3-O- ...