Capacidade antioxidante, efeitos anticarcinogênicos e absorção de polifenóis de de manga (Mangifera indica L.) in vitro

• Autor(a) principal: Bertoldi, Michele Corrêa
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/417
• topic: Câncer; Manga; Compostos fenótipos; Cancer; Mango; Phenotypes compounds; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS

Polyphenols found in mango pulp, including gallotannins, flavonol glycosides, gallic acid, benzophenone derivatives and mangiferin have shown anticancer activity. Biological activities of polyphenols have been related to their bioavailability. Deglycosylation by β-glucosidases is a critical step in the metabolism and absorption of dietary polyphenols in humans, which might influence their anticancer properties. The objective of this study was to elucidate the anti-cancer effects of mango polyphenols of several varieties (Francis, Kent, Ataulfo, Tommy Atkins and Haden) in different types of cancer. The antiproliferative effects of mango polyphenols were studied in vitro using different cancer cell lines including Molt-4 leukemia, A-549 lung, MDA-MB-231 breast, LnCap prostate, SW-480 colon cancer cells and the non-cancer colon cell line CCD-18Co. Molecular mechanisms involved on the anti-cancer activities of mango polyphenols were assessed. The effect of mango polyphenols on gene expression, cell cycle regulation and reactive oxygen species production on colon cancer cells SW-480 were investigated by RT-PCR, flow cytometry and fluorescence intensity measurement, respectively. The effect of the hydrolysis of mango polyphenols with β-glucosidase on their antioxidant activity, cancer cell-growth suppression activity and in vitro intestinal absorption through human colon adenocarcinoma Caco-2 cell monolayers was evaluated. In addition, the antiproliferative effect of high and low molecular weight polyphenols rich-fractions on colon (SW-480) and breast (MDA-MB-231) cancer cells was studied. Cell lines were incubated with Ataulfo and Haden phenolic extracts, which were selected based on their superior antioxidant capacity compared to the other varieties. Ataulfo and Haden polyphenols inhibited the growth of all human cancer cell lines. SW-480 (colon cancer), MOLT-4 (leukemia) and MDA-MB-231 (breast-cancer) were statiscally equally most sensitive to Ataulfo, whereas SW-480 and MOLT-4 were the most sensitive cell lines to Haden, as determined by cell counting. The efficacy of phenolic extracts from all mango varieties in inhibiting cell growth was tested on SW- 480 colon carcinoma cells. Ataulfo and Haden demonstrated superior efficacy, followed by Kent, Francis and Tommy Atkins. At 5 mg GAE/L, Ataulfo inhibited the growth of colon SW-480 cancer cells by ~79% while the growth of non-cancer colonic myofibroblasts CCD-18Co cells was not inhibited. The growth inhibition exerted by Ataulfo and Haden polyphenols on SW-480 cells was associated with an increased mRNA expression of pro-apoptotic biomarkers (caspase 8, Bax and Bim) and cell cycle regulators (PKMYT1), cell cycle arrest and an alteration in the generation of reactive oxygen species. Phenolic extracts from mango pulp contained gallic acid, mangiferin, phenolic acid derivatives and gallotannins, which were characterized by HPLC-DAD and HPLC-ESI-MSn analysis before and after enzymatic hydrolysis (0.17 mg β- glucosidase 1000 KU/g mango pulp/ 4 h / 35°C). Phenolic acids including gallic, caffeic, ferulic, p-coumaric and p-hydroxybenzoic acids consisted the main compounds derived from enzymatic hydrolysis. Caco-2 cell monolayers were incubated for 2h on the apical side with hydrolyzed and non-hydrolyzed mango extracts. Gallic, caffeic, ferulic, p-coumaric, vanillic and p-hydroxybenzoic acids were detected on the basolateral side for hydrolyzed extract but only gallic acid was detected for the nonhydrolyzed extract. High molecular weight polyphenols, mangiferin and gallotannins, were not transported. Mango pulp polyphenols (control) from all varieties inhibited the proliferation of HT-29 colon (0-27 μg of gallic acid equiv/mL) and MDA-MB-231 breast (0-24 μg GAE/ mL) human cancer cells by up to 99.8 and 89.9 %, respectively. Despite enhanced absorption facilitated by enzymatic hydrolysis, a significant increase in antioxidant activity, phenolic content and antiproliferative effects on breast and colon cancer cells was not observed. Additionally, both high (422; 788-1852 Da) and low (138-194 Da) molecular weight polyphenols rich-fractions equally inhibited cell proliferation of colon and breast cancer cells at the same extent (0-20 μg of gallic acid equiv/mL), which may indicate that the anti-cancer efficacy of mango polyphenolics is not dependent on enzymatic hydrolysis. These results corroborate previous findings from in vivo studies, which suggest that the most of mango polyphenols are not absorbed intact through the small intestine, but may be hydrolyzed by intestinal enzymes into low molecular weight aromatic acids, which would be later absorbed; or when polyphenols are not absorbed, they likely reach the large intestine, modulating the gut microflora, and thus they contribute to reduce the risk of colon carcinogenesis. Overall, polyphenols from several mango varieties exerted anti-cancer effects, and these effects may not require enzymatic hydrolysis by β-glucosidase.