Medicinal plants are widely used in bolivian folk medicine for the treatment of infectious diseases. We have selected one, Clinopodium bolivianum (Benth.) Kuntze, known as “Khoa”, to investigate its potential anti-HIV activity, since traditionally it has been used to treat other viral infectious diseases. We have carried out an antiviral bioassay-guided fractionation of different extracts of C. bolivianum. An antiviral crude polysaccharide was obtained, SBAS, rich in glucose, galactose, mannose, arabinose, xylose, rhamnose and only traces of galacturonic acid. SBAS exhibited antiviral activity with a mechanism of action unrelated to the mannose-lectin DC-SIGN receptors but with a strong viral neutralization activity. In summary, a purified polysaccharide from C. bolivianum have been identified as the main compound responsible of its antiviral activity. SBAs proved to be a neutralizing agent with high antiviral capacity in vitro, so it could be part of new microbicide formulations to prevent HIV transmission.

Medicinal plants are widely used in Bolivian folk medicine for the treatment of infectious diseases. We have selected one, Clinopodium bolivianum (Benth.) Kuntze, known as “Khoa”, to investigate its potential anti-HIV activity since, traditionally, it has been used to treat other viral infectious diseases. We have carried out an antiviral bioassay-guided fractionation of different extracts of the aerial parts of C. bolivianum. An antiviral crude polysaccharide was obtained, (SBA_S), which is rich in glucose, galactose, mannose, arabinose, xylose, and rhamnose and only has traces of galacturonic acid. SBA_S exhibited antiviral activity with a mechanism of action unrelated to the mannose–lectin DC-SIGN receptors but with a strong viral neutralization activity. In summary, a purified polysaccharide from C. bolivianum has been identified as the main compound responsible for its antiviral activity. SBAs proved to be a neutralizing agent with high antiviral capacity in vitro, so they could be part of new microbicide formulations to prevent HIV transmission.