INHIBITION OF DENGUE VIRUS TYPE 2 REPLICATION BY NATURAL AND SYNTHETIC Β-CARBOLINES

VIVIANA CASTILLA; VERÓNICA M. QUINTANA; LUANA É PICCINI; MARÍA A. PONCE; ELSA B. DAMONTE

Belem

Simposio; Fourth Pan- American Dengue Research Network Meeting and V International Symposium on Tropical and Viral Arboviruses Hemorrhagic Fevers; 2014

Pan-American Dengue Research Network

INHIBITION OF DENGUE VIRUS TYPE 2 REPLICATION BY NATURAL AND SYNTHETIC Β-CARBOLINESViviana Castilla, Verónica M. Quintana, Luana E. Piccini, María A. Ponce, Elsa B. Damonte.Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias, Universidad de Buenos Aires, IQUIBICEN- CONICET, Argentina.β-carboline alkaloids are naturally existing plant substances with a wide spectrum of pharmacological effects. Here we investigated the antiviral activity of natural and synthetic β-carbolines against dengue virus type 2 (DENV-2) in Vero cell cultures. The effect of natural harmol, harmine, harmane, norharmane and their synthetic 9-methyl derivatives in cell viability was assessed by the MTS method and the 50% cytotoxic concentration (CC50) was determined. Harmine was the most cytotoxic compound suggesting that the C-7 methoxy group adversely affects cell viability whereas all N-methylated derivatives display higher CC50 values than natural compounds. The antiviral activity was determined by a virus yield inhibition assay. For this purpose, DENV-2 infected cells were treated with non-cytotoxic concentrations of each compound for 48 h and virus yields were quantified by plaque assay. The 50% effective concentration (EC50) was determined and the selectivity index (SI) was calculated as the ratio CC50/EC50. Two compounds, harmol and 9-methyl-harmine were active against DENV-2 with SI values of 56.2 and 61.2. These compounds did not exhibit direct inactivating effect on DENV-2 particles and were inactive against other RNA viruses such as Junin virus or vesicular stomatitis virus. Given the antiviral activity of harmol against DENV-2, we evaluated the activity of harmol aliphatic esters with chains of 2, 3, 4, 5 and 6 carbons; however no antiviral activity was displayed by these compounds. Treatment with harmol or 9-methyl-harmine after DENV-2 adsorption-internalization caused a marked reduction in virus production and number of cells expressing glycoprotein E assessed by immunofluorescence assay, whereas no inhibition was detected in cultures treated with harmol only during virus adsorption-internalization events. Our results showed that methylation of β-carboline pyrrole ring caused a marked reduction in the cytotoxicity of these compounds and two of the assayed compounds are able to selectively inhibit DENV-2 multiplication in cell cultures.