Antiviral Activities of Alcohols against HSV-1 Hilmar Hilmarsson, Hall dor Thor mar Previous studies have shown that various fatty acids have microbicidal activities against a number of pathogens. Exactly how the fatty acids kill microbes is unknown, but it has been shown that they cause disintegration of enveloped viruses like vesicular stomatitis virus. Alcohols may act in a similiar way, i. e.
penetrate the envelope of the virus by hydrophobic effect, making it permeable to small molecules and thus killing the virus. The nature of this effect may be elucidated by comparison of the activities of alcohols and the corresponding fatty acids. In this study, saturated and unsaturated medium- and long-chain monohydroxy alcohols, corresponding to fatty acids that show activities against viruses, were tested against herpes simplex virus type 1 (HSV-1).
Virus in high titer was mixed with an equal volume of alcohol diluted in maintenance medium and the mixture incubated at 37^0 C. Samples were titrated in 10-fold dilutions on Vero cells. The titers (log 10 T CID 50) of alcohol mixtures were subtracted from the titer of the control mixture and the difference, i.
e. the reduction in titer, used as a measure of the antiviral activity of the alcohols. When tested at 10 mM concentration for 10 min three alcohols, i. e.
n-decyl (10: 0), lauryl (12: 0) and myristoleyl (14: 1), caused a significant reduction in HSV-1 titer. N-decyl alcohol reduced the titer more than 3 million-fold (> 6. 5 log 10) and lauryl and myristoleyl alcohols about 10 thousand-fold. At 1 min incubation only n-decyl alcohol showed a significant activity with 100-fold reduction in titer.
In contrast, at a longer incubation time (2 hrs) lauryl alcohol was the most active causing more than one million-fold reduction in titer at a concentration of 2. 5 mM, compared to a 1000-fold reduction by n-decyl alcohol. When compared to the inactivation of HSV-1 by the corresponding fatty acids, the alcohols show less and particulary much slower effects. The difference in the polar groups of alcohols and fatty acids, i. e. hydroxyl group versus carboxyl group, somehow makes the alcohol less active against the virus, possibly because of a difference in the hydrophilic / hydrophobic balance of the molecules..