Antiviral activity of Cleome rosea extracts from field-grown plants and tissue culture-derived materials against acyclovir-resistant Herpes simplex viruses type 1 (ACVr-HSV-1) and type 2 (ACVr-HSV-2)

Extracts from Cleome rosea were investigated for their activity against acyclovir-resistant strains of Herpes simplex type 1 (ACVr-HSV-1) and type 2 (ACVr-HSV-2). Methanolic and acidified (1% (v/v) HCl) methanolic extracts were prepared from field-grown plants and in vitro propagated plants, as well as from calli and cell suspension cultures. The extracts presented low cytotoxicity and caused virus titer reduction above 70%, with different mechanisms of action. Extracts from leaves of field-grown plants inhibited viral infection mainly by affecting the virus particle itself (virucidal effect), while extracts from calli acted mainly on cell receptors. On the other hand, all extracts evaluated affected the virus entry across the cell membrane and the intracellular viral replication at similar percentages, causing reduction on titers in the range of 68–90%. This study validated the potential use of in vitro materials as sources of antiherpetic agents from C. rosea.