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Background: Dengue virus (DENV), a member of the family Flaviviridae, is at present the most widespread causative agent of a human viral disease transmitted by mosquitoes. Despite the increasing incidence of this pathogen, there are no antiviral drugs or vaccines currently available for treatment or prevention. In a previous screening assay, we identified a group of N-allyl acridones as effective virus inhibitors. Here, the antiviral activity and mode of action targeted to viral RNA replication of one of the most active DENV-2 inhibitors was further characterized. Results: The compound 10-allyl-7-chloro-9(10H)-acridone, designated 3b, was active to inhibit the in vitro infection of Vero cells with the four DENV serotypes, with effective concentration 50% (EC50) values in the range 12.5-27.1 mu M, as determined by virus yield inhibition assays. The compound was also effective in human HeLa cells. No cytotoxicity was detected at 3b concentrations up to 1000 mu M. Mechanistic studies demonstrated that virus entry into the host cell was not affected, whereas viral RNA synthesis was strongly inhibited, as quantified by real time RT-PCR. The addition of exogenous guanosine together with 3b rescued only partially the infectivity of DENV-2. Conclusions: The acridone derivative 3b selectively inhibits the infection of Vero cells with the four DENV serotypes without a direct interaction with the host cell or the virion but interfering specifically with the intracellular virus multiplication. The mode of antiviral action for this acridone apparently involves the cellular enzyme inosine-monophospahe dehydrogenase together with another still unidentified target related to DENV RNA synthesis., Agencia Nacional de Promocion Cientifica y Tecnologica; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Universidad de Buenos Aires (UBA), Argentina

El objetivo del presente trabajo fue aislar e identificar los alcaloides de las hojas de Ruta Graveolens L., y relacionar sus estructuras químicas con la actividad mutagénica de las hojas, demostrada en un trabajo anterior. Se aislaron 4 alcaloides, denominados "A", "1", "2" y "3", que fueron elucidados estructuralmente mediante espectroscopfa UV e IR, además de sus constantes fisicas y reacciones químicas. El alcaloide "A" fue identificado como alcaloide acridónico, los alcaloides 1 y 2 fueron identificados como alcaloides furoquínolínícos y el alcaloide "3" fue considerado como alcaloide quinolónico. Debido a su alto rendimiento y estructura química, se considera al alcaloide "A" como el principal responsable de la actividad mutagénica de las hojas de Ruta Graveolens L., mientras que los alcaloides "1" y "2" debido al bajo rendimiento, posiblemente no participen en la mutagenicidad del extracto por ausencia de pruebas sobre su estructura., The purpose of this research has been to iso late and identify the alkaloids from the leaves of Ruta graveolens L., and to relate their chemical structure with the mutagenic activity of the leaves, which was demonstrated in a previous report. It were isolated four alkaloids named "A", "1 ", "2" and "3" which were structurally elucidated by their melting point, chemical reactions and by UV and IR spectroscopy. The alkaloid "A" was identified as acridone alkaloid, and the alkaloid "1" and "2" were identified as furoquinoline alkaloids. The remaining one, alkaloid "3" was considered as quinolone alkaloid. Due to its high amount and chemical structure, the alkaloid "A" was considered as the main responsible of the mutagenic activity of the leaves of Ruta graveolens L., while alkaloids "1" and "2" probably do not participate in the mutagenicity of the extract owing to their amount. Finally, the alkaloid "3" was not considered in the mutagenicinity analysis on account of the absence of data about its structure.