RESUMO
BACKGROUND: Neuraminidase inhibitors (NAIs) are the only class of antivirals in clinical use against influenza virus approved worldwide. However, approximately 1-3% of circulating strains present resistance mutations to oseltamivir (OST), the most used NAI. Therefore, it is important to catalogue new molecules to inhibit influenza virus, especially OST-resistant strains. Natural products from tropical plants used for human consumption represent a worthy class of substances. Their use could be stimulated in resource-limited setting where the access to expensive antiviral therapies is restricted. METHODS: We evaluated the anti-influenza virus activity of agathisflavone derived from Anacardium occidentale L. RESULTS: The neuraminidase (NA) activity of wild-type and OST-resistant influenza virus was inhibited by agathisflavone, with IC50 values ranging from 20 to 2.0 µM, respectively. Agathisflavone inhibited influenza virus replication with EC50 of 1.3 µM. Sequential passages of the virus in the presence of agathisflavone revealed the emergence of mutation R249S, A250S and R253Q in the NA gene. These changes are outside the OST binding region, meaning that agathisflavone targets this viral enzyme at a region different than conventional NAIs. CONCLUSION: Altogether our data suggest that agathisflavone has a promising chemical structure for the development of anti-influenza drugs.
Assuntos
Anacardium/química , Biflavonoides/farmacologia , Inibidores Enzimáticos/farmacologia , Neuraminidase/antagonistas & inibidores , Orthomyxoviridae/efeitos dos fármacos , Compostos Fitoquímicos/farmacologia , Animais , Biflavonoides/química , Biflavonoides/isolamento & purificação , Sobrevivência Celular/efeitos dos fármacos , Cães , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Células Madin Darby de Rim Canino/efeitos dos fármacos , Células Madin Darby de Rim Canino/virologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Neuraminidase/metabolismo , Orthomyxoviridae/enzimologia , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
Resveratrol is a promising chemopreventive agent that mediates many cellular targets involved in cancer signaling pathways. p53 has been suggested to play a role in the anticancer properties of resveratrol. We investigated resveratrol-induced cytotoxicity in H1299 cells, which are non-small lung cancer cells that have a partial deletion of the gene that encodes the p53 protein. The results for H1299 cells were compared with those for three cell lines that constitutively express wild-type p53: breast cancer MCF-7, adenocarcinomic alveolar basal epithelia A549 and non-small lung cancer H460. Cell viability assays revealed that resveratrol reduced the viability of all four of these cell lines in a dose- and time-dependent manner. MCF-7, A549 and H460 cells were more sensitive to resveratrol than were H1299 cells when exposed to the drug for 24 h at concentrations above 100 µM. Resveratrol also increased the p53 protein levels in MCF-7 cells without altering the p53 mRNA levels, suggesting a post-translational modulation of the protein. The resveratrol-induced cytotoxicity in these cells was partially mediated by p53 and involved the activation of caspases 9 and 7 and the cleavage of PARP. In H1299 cells, resveratrol-induced cytotoxicity was less pronounced and (in contrast to MCF-7 cells) cell death was not accompanied by caspase activation. These findings are consistent with the observation that MCF-7 cells were positively labeled by TUNEL following exposure to 100 µM resveratrol whereas H1299 cells under similar conditions were not labeled by TUNEL. The transient transfection of a wild-type p53-GFP gene caused H1299 cells to become more responsive to the pro-apoptotic properties of resveratrol, similarly to findings in the p53-positive MCF-7 cells. Our results suggest a possible therapeutic strategy based on the use of resveratrol for the treatment of tumors that are typically unresponsive to conventional therapies because of the loss of normal p53 function.