Anti-herpes simplex virus activity of n-docosanol correlates with intracellular metabolic conversion of the drug

The 22-carbon fatty alcohol, n-docosanol, exhibits in vitro antiviral activity against several lipid-enveloped viruses including herpes simplex viruses 1 and 2 by a mechanism that interferes with normal viral entry into target cells. We previously reported that mammalian cells incorporate significant quantities of radiolabeled n-docosanol. Herein, we report that cells extensively metabolize the internalized fatty alcohol. This is evidenced by incorporation of up to 60% of cell-associated radiolabel into phospholipids that copurify with phosphatidylcholine and phosphatidylethanolamine. Analysis by chemical (Vitride) reduction suggests that a significant portion of n-docosanol is oxidized to n-docosanoic acid and then incorporated as an acyl group on polar lipids. A measurable amount of radiolabel, however, is resistant to Vitride reduction, consistent with incorporation of n-docosanol into ether lipids. The rate and extent of metabolic conversion of n-docosanol vary with the cell type and surfactant used to suspend the compound. Furthermore, the anti-HSV activity of n-docosanol is quantitatively proportional to the amount of metabolism observed. These findings suggest that the anti-HSV activity of n-docosanol involves cellular uptake and metabolism of the drug.