Avaliação in vitro do efeito citotóxico e imunomodulador de derivados do ácido ursólico

Abstract

The ursolic acid (3β-hydroxy-urs- 12-en- 28-oic acid) is a pentacyclic triterpene constituted by 30 carbon atoms that is usually obtained through the extraction and purification in different plants. The anti-inflammatory, anti-tumoral, immunomodulatory and anti-metastatic activity of ursolic acid (UA) has already been shown in different studies. Structural modifications in important portions of UA can amplify the beneficial biological effects of this compound. With this, it was synthesized 18 semisynthetic compound derivatives of ursolic acid (UAD1UAD18), which can be promising molecules to treat diseases that need new therapeutic options. The aim of this study was to evaluate in vitro the cytotoxic and immunomodulatory effects of these ursolic acid derivatives. To verify the biological activities was realized tests in the adenocarcinoma human alveolar basal epithelial cells (A549) evaluating the cytotoxic and the proapoptotic effects of these compounds. The murine macrophage cells (RAW264.7) were used to evaluate the effects of the UADs on cellular viability, nitric oxide production and tumoral necrosis factor production. In both cells was evaluated the expression of NF-κB. A549 and RAW264.7 were treated with UA or UADs in the concentrations of 7.5µM, 15µM, 30µM, 60µM and 90µM during 3, 24 or 48 hours. The compounds UAD1, UAD5, UAD6, UAD8, UAD11, UAD12, UAD13 and UAD16 were able to reduce the viability and the expression of NF-κB in A549 cells, in at least one of the concentrations. UAD1 was able to reduce the cellular viability in the concentrations of 30µM, 60µM and 90µM, being more effective than UA. Moreover, UAD1, UAD5, UAD6 and UAD8 induced the apoptosis of A549, being, UAD1 and UAD8, significantly more effective than UA. In RAW264.7, only the compounds AUD12, AUD13, AUD15 and AUD16 were not capable of promoting the reduction of NO production. The other compounds reduced the NO production in at least one of the concentrations, without cytotoxicity (IC50). AUD2 showed the better reduction of NO in the lower concentration, with IC50>90µM. The compounds UAD1, UAD3, UAD4, UAD5, UAD6, UAD7, UAD8, UAD11, UAD12, UAD13, UAD14, UAD15 and UAD18 were able to reduce the NF-κB expression in all tested concentrations, however, all the compounds reduced the production of TNF in the RAW264.7 cells in the concentrations of 60µM and 90µM. In conclusion, when was related the structure to the biological activity of the compounds, can be suggested that the esterification at C-28 or the conservation of the hydroxyl at C-3 seems to be important for the cytotoxicity of the compounds against A549 cells. Furthermore, when evaluated the immunomodulatory effect on the inflammatory response, the esterification (C-3 and/or C-28) enhances the action of the ursolic acid derivatives on RAW264.7 cells.