Abstract
Garlic (Allium sativum) has been shown to have antiviral activity, but the compounds responsible have not
been identified. Using direct pre-infection incubation assays, we determined the in vitro virucidal effects of fresh garlic extract, its polar fraction, and the following
garlic associated compounds: diallyl thio-sulfinate (allicin), allyl methyl thiosulfinate,
methyl allyl thiosulfinate, ajoene, alliin, deoxyalliin, diallyl disulfide, and diallyl
trisulfide. Activity was determined against selected viruses including, herpes simplex
virus type 1, herpes simplex virus type 2, parainfluenza virus type 3, vaccinia virus,
vesicular stomatitis virus, and human rhinovirus type 2. The order for virucidal activity
generally was: ajoene ≥ allicin ≥ allyl methyl thiosulfinate ≥ methyl allyl thiosulfinate.
Ajoene was found in oil-macerates of garlic but not in fresh garlic extracts. No activity
was found for the garlic polar fraction, alliin, deoxyalliin, diallyl disulfide, or
diallyl trisulfide. Fresh garlic extract, in which thiosulfinates appeared to be the
active components, was virucidal to each virus tested. The predominant thiosulfinate
in fresh garlic extract was allicin. Lack of reduction in yields of infectious virus
indicated undetectable levels of intracellular antiviral activity for either allicin
or fresh garlic extract. Furthermore, concentrations that were virucidal were also
toxic to lleLa and Vero cells. Virucidal assay results were not influenced by cytotoxicity
since the compounds were diluted below toxic levels prior to assaying for infectious
virus. These results indicate that virucidal activity and cytotoxicity may have depended
upon the viral envelope and cell membrane, respectively. However, activity against
non-enveloped virus may have been due to inhibition of viral adsorption or penetration.
Additionally, the composition of various commercial garlic products, including garlic
powder tablets and capsules, oil-macerated garlic, steam-distilled garlic oils, garlic
aged in aqueous alcohol, and fermented garlic oil was determined as well as the virucidal
activities of the products against herpes simplex virus type 1 and parainfluenza virus
type 3. Virucidal activities of commercial products were dependent upon their preparation
process. Those products producing the highest levels of allicin and other thiosulfinates
had the best virucidal activities.
Key words
Allium sativum
- allicin - antiviral - garlic - thiosulfinates - virucidal activity
