[In vitro studies of the antiviral activity of enzymatically oxidized o-diphenolic compounds against herpes simplex virus type 1 and 2 (author's transl)].

Oxidation of the o-diphenolic compounds, catechol, protocatechuic acid, caffeic acid, and chlorogenic acid by o-diphenol oxidase (EC 1.10.3.1) resulted in compounds with antiviral activity against herpes simplex virus types 1 and 2. In the system HSV-1/rabbit kidney primary cells, a 90 per cent plaque reduction was obtained by the oxidation product from 1 mug caffeic acid, 9 mug catechol, 13 mug chlorogenic acid, or 20 mug protocatechuic acid (per ml), respectively. In comparision to the basic compounds or those oxidized in the presence of bovine serum albumin, the inhibitory effect of oxidized o-diphenolic compounds free from albumin was higher. From the basic o-diphenolic compounds, only catechol and caffeic acid showed remarkable antiviral activities in the system investigated. Although there have not experiments on the mechanism of action yet been the compounds are supposed to act during the earliest phases of the HSV-multiplication, because o-diphenolic compounds had been found to be present in the virus-cell system only 90 minutes after infection. In this respect the substances were similar to those of humic acids which also inhibit the adsorption phase of herpes simplex virus. There were no essential differences between herpes simplex virus type 1 and type 2 in respect of their sensitivity to enzymatically oxidized o-diphenolic compounds.