Pelargonium sidoides (PS) contain compounds that attack HIV-1 particles and prevent virus replication
They demonstrated that PS extracts protect blood and immune cells from infection by HIV-1, the most widespread type of HIV. PS extracts block attachment of virus particles to host cells and thus effectively prevent the virus from invading cells.
Helfer, M. et al. (2014), The root extract of the medicinal plant Pelargonium sidoides is a potent HIV-1 attachment inhibitor. Plos One, DOI: 10.1371/journal.pone.0087487