OBJECTIVE: Huminates are phenolic polymers with anionic character that form spontaneously in soil by degradation of organic materials. Analogous compounds with a mean Mol. Wt. of 1000 dalton were synthesized by controlled auto-oxidation of the bi-phenoles hydrochinon and catechin. We have evaluated the inhibition of HIV infection in cell culture by the synthetic huminates and studied the mechanism of the observed inhibition. METHODS: Infectivity of HIV-1LAI in MT-2 cells was measured by counting of syncytia formed five days after infection. The inhibitors were either present during the whole assay period, or alternatively virus or cells were treated with inhibitors for 30 min followed by washing prior to infection. In addition, the capacity of the huminates to block the reverse transcriptase (RT) in HIV-lysates or the binding of soluble CD4 to gp120 were studied. RESULTS: The catechin- and hydrochinon-derived huminates inhibited the syncytium formation in a dose dependent manner. Inhibitory concentrations (IC50) of 0.15 micrograms/ml and 0.5 micrograms/ml respectively were observed when the inhibitor was present during the whole assay period. Higher concentrations were required when virus or cells were pretreated. However production of virus by permanently infected H9 cells was only slightly decreased. Cytotoxic effects were observed at concentrations higher than 20 micrograms/ml. RT is inhibited at 30 micrograms/ml, but binding of gp120 to CD4 is not affected at this concentration. CONCLUSIONS: Synthetic huminates are potent inhibitors of HIV infection. Since their binding to the virus is sufficient for inhibition they most probably interfere with an early step of infection, that is distinct from binding of gp120 to CD4.

Antiviral Agents/*PHARMACOLOGY Catechin/*PHARMACOLOGY Cell Line Cell Survival/DRUG EFFECTS Dose-Response Relationship, Drug Giant Cells/DRUG EFFECTS Human Humic Acids/CHEMICAL SYNTHESIS/*PHARMACOLOGY HIV-1/DRUG EFFECTS/*PHYSIOLOGY/PATHOGENICITY Phenols/*PHARMACOLOGY Polymers/PHARMACOLOGY Virus Replication/*DRUG EFFECTS ABSTRACT

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