Lignans are phenylpropanoid dimers distributed very widely in the plant kingdom. There are various kinds of lignan depending on the mode of dimerization of phenylpropanoid. Gomisin is a dibenzocyclooctadiene-type lignan compound and a component of Schizandra fruit extracts (30-32, 70). There are various types of gomisins, A, B, C, D, E, F, G, J, and N; some possess central nervous system depressant, analgesic, antitussive, and/or Ca antagonist activities (42, 69). As for the antiviral activities of lignans, it has been reported that tetrahydronaphthalene-type lignans have selective inhibitory activities on herpes simplex virus and cytomegalovirus (41, 43) and that dibenzylbutanolide-type lignans have an inhibitory effect on human immunodeficiency virus (HIV) replication (63). However, the ratio of toxic dose to effective dose (selective index) of dibenzylbutanolide-type lignan was no more than 5, suggesting that this could not be used as a clinically effective anti-HIV agent.In continuation of our search for anti-HIV agents (19, 20, 26, 52), we report in this paper new gomisin J derivatives which have potent anti-HIV activities with much higher selective indices than that of dibenzylbutanolide-type lignan. The highest selective index among gomisin J derivatives was over 300.
MATERIALS AND METHODSChemicals. Gomisin J was isolated as previously described (32). Halogenated derivatives (Fig. 1) of gomisin J were synthesized from gomisin J by using halogenizing agents such as N-bromosuccinimide. Detailed descriptions of synthesis and characterization will be published elsewhere. Structures of pure, newly synthesized compounds were determined by nuclear magnetic resonance and infrared analyses. These compounds were kindly provided by Tanaka, Tsumura Central Research Institute, Ibaraki, Japan. 3Ј-Azido-3Ј-deoxythymidine (AZT) and 2Ј,3Ј-ddC were purchased from Sigma Chemical Co. ). These cells were grown in 25 mM HEPES (N-hydroxyethylpiperazine-NЈ-2-ethanesulfonic acid)-buffered RPMI 1640 (GIBCO) supplemented with 10% fetal calf serum, 100 U of penicillin per ml, 100 g of streptomycin per ml, and 0.25 g of amphotericin B per ml. At this concentration, amphotericin B is effective as an antimycotic in tissue culture but has no inhibitory activity for HIV replication (50, 64).