The cyclotide Cycloviolacin O2 enhances the in vitro efficacy of antiretroviral drugs

Despite the success of highly active antiretroviral therapy (HAART), AIDS is a global pandemic and many HIV drugs exhibit suboptimal therapeutics due to low absorption, rapid efflux, and drug resistance. Therefore, novel strategies to improve cellular drug uptake are vital. Cyclotides are plant-derived circular peptides commonly used in host defense, and they are also promising leads in biomedical research considering their exceptional structural stability and reduced sensitivity to enzymatic attack compared to linear peptide counterparts. Several cyclotides display anti-HIV activity, which may be regulated by pore formation at the lipid bilayer. We hypothesized that membranes of HIV-1-infected cells and enveloped HIV-1 particles may be preferentially targeted by the cyclotide, Cycloviolacin O2 (CyO2) to significantly enhance antiretroviral efficacy. CyO2 concentrations below 0.5 µM did not show substantial hemolytic activity via red blood cell hemolysis, yet these concentrations enabled rapid pore-formation in HIV-infected T-cells and monocytes as measured via SYTOX-green dye-uptake assays, and they increased drug uptake as evaluated with radiolabeled saquinavir (3H-SQV) uptake assays.

 

 

 

 

 

 

 

 

 

 

 

 

Author(s): Samantha L. Gerlach

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