An extract from the common herb oregano has shown promise against the equine arteritis virus, the pathogen behind an important disease in horses.
Outbreaks of equine viral arteritis can result in significant economic losses to the horse industry due to high rates of foal loss in pregnant mares, the death of young foals, and the establishment of the carrier state in stallions, who can spread the virus through their semen.
Most infections are subclinical, but horses can suffer fever, depression, weight loss, a fall in the number of white cells in their blood, swelling of the lower limbs, conjunctivitis, a nasal discharge, respiratory problems, skin rash, and temporary subfertility in affected stallions.
There is no specific antiviral treatment available for the disease.
Researchers from Brazil tested an extract from Origanum vulgare, removed from the plant using ethanol, after which the alcohol was evaporated off, in a series of laboratory experiments.
They also isolated a number of compounds from the crude extract − caffeic acid, p-coumaric acid, rosmarinic acid, quercetin, luteolin, carnosol, carnosic acid, kaempferol and apigenin − so that the study team could monitor their individual performance against the virus.
The virus was incubated with the various agents at either 37 degrees Celsius or 20°C, after which their effect on the virus was assessed.
There was significant virucidal activity noted with the crude extract, as well as with caffeic acid, p-coumaric acid, quercetin, carnosic acid and kaempferol.
Daiane Einhardt Blank and her colleagues, writing in the journal Semina: Ciências Agrárias, said caffeic acid, p-coumaric acid, carnosic acid, kaempferol and mainly quercetin, contributed to the activity of the extract.
The extract may represent a good prototype for the development of a new antiviral agent against the pathogen, they said.
The researchers are affiliated with a range of institutions in Brazil.
Anti-equine arteritis virus activity of ethanolic extract and compounds from Origanum vulgare
Daiane Einhardt Blank, Rayra Almeida Corrêa, Rogério Antônio Freitag, Marlete Brum Cleff, Silvia de Oliveira Hübner
Semina: Ciências Agrárias. 2017;38(2):759-764 DOI 10.5433/1679-0359.2017v38n2p759