A new study has found that extracts of the geranium plant Pelargonium sidoides inactivate human immunodeficiency virus type 1(HIV-1) and prevent the virus from invading human cells.

Scientists from the Helmholtz Zentrum Munchen report that these extracts represent a potential new class of anti-HIV-1 agents for the treatment of AIDS.

They demonstrated that root extracts of the medicinal plant Pelargonium sidoides (PS) contain compounds that attack HIV-1 particles and prevent virus replication.

A team spearheaded by Dr. Markus Helfer and Prof. Dr. Ruth Brack-Werner from the Institute of Virology and Prof. Dr. Philippe Schmitt-Kopplin from the Analytical BioGeoChemistry research unit (BGC) performed a detailed investigation of the effects of PS extracts on HIV-1 infection of cultured cells.

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. Chemical analyses revealed that the antiviral effect of the PS extracts is mediated by polyphenols. Polyphenol mixtures isolated from PS extracts retain high anti-HIV-1 activity but are even less toxic for cells than the crude extract.

Safety of PS-extracts has been established in several clinical trials. In Germany PS extracts are licensed as a herbal medicine and used to reduce symptoms of acute bronchitis.

"PS-extracts are a very promising lead for the development of the first scientifically validated phytomedicine against HIV-1. PS extracts attack HIV-1 with a mode-of-action that is different from all anti-HIV-1 drugs in clinical use. Therefore a PS-based phytomedicine may be a valuable supplement for established anti-HIV therapies," research group leader Brack-Werner said.

Furthermore, PS extracts are attractive candidates for increasing anti-HIV-1 therapy options in resource-limited settings, since they are easy to produce and do not require refrigeration. The results of our study and the proven safety of PS extracts encourages their testing in HIV-1 infected individuals as next step," the researcher added.

The study is published in the journal PLOS ONE.