A systematic analysis of anthocyanins inhibiting human, murine, and equine herpesviruses

Herpesviruses are common animal and human pathogens that cause severe health problems in children, immunocompromised patients, and infected animals with a host range from fish to mammals. Anthocyanin-containing plant extracts have been described as potent antivirals, which might cause fewer harmful side effects than direct-acting antivirals. Here, we report that an extract of Aristotelia chilensis (Molina) Stuntz (Elaeocarpaceae) (MBE) with a high content of the anthocyanin delphinidin suppresses lytic replication of equine, murine and human herpesviruses of replication in vitro.

We treated cultured cells with MBE and purified individual anthocyanins present in the extract to determine the most active compound at different concentrations. We subsequently infected the cultures with human herpesviruses 1 (HSV-1) or 8 (HHV-8), murine cytomegalovirus (CMV), or equine herpesviruses 1 (EHV-1) and determined the number of infected cells and viral infectivity.

MBE inhibited the HSV-1, murine CMV, and EHV-1 by up to 2 orders of magnitude. In the presence of the stabilizing randomly methylated-beta-cyclodextrin, the inhibitory concentration could be lowered significantly. We identified delphinidin as an active antiviral compound and showed that the non-glycosylated delphinidin solved and stabilized with sulfobutylether-beta-cyclodextrin allowed usage of approximately 50 times lower concentrations.

Glycosylated delphinidin derivatives were identified as active antiviral compounds of MBE. This suggests that plant extracts rich in delphinidin-anthocyanins have potent antiviral properties that could be used in treatment and prevention.