Casca de jabuticaba: metabolização e implicações na prevenção das complicações do diabetes

Abstract

The aim of this study was to evaluate the profile of phenolic compounds from jaboticaba peel powder (JPP), their bioaccessibility after simulation of gastrointestinal digestion and the involvement of gut microbiota in phenolic metabolization. Additionally, the effects of JPP on oxidative stress and hepatic complications in a rat model of type 2 diabetes melittus (type 2 DM) were also evaluated. Two jaboticaba species (M. trunciflora and M. jaboticaba) were analyzed in HPLC-DAD-Q-TOF-MS/MS. Some differences were observed in the phenolic compounds profile between both JPP species. JPP from M. trunciflora (JPP-MT) had higher content of free phenolic compounds, the predominant class being hydrolyzable tannins, while anthocyanins were the major class in the JPP from M. jaboticaba (JPP-MJ). The in vitro bioaccessibility study after simulation of gastrointestinal digestion of PCJ-MT showed extensive hydrolysis of hydrolyzable tannins, especially in the intestinal step, releasing gallic and ellagic acid monomers. Anthocyanins had mild degradation in salivary and gastric conditions but extensive degradation in the intestinal condition, resulting in low bioaccessibility. Most hydrolyzable tannins and flavonols had greater bioaccessibility than anthocyanins in JPP. However, due to the high content of anthocyanins and hydrolyzable tannins in JPP matrix, cyanidin-3-glycoside was the most abundant phenolic compound in the bioaccessible fraction, followed by ellagic acid that was produced by the hydrolysis of ellagitannins. In addition, the fermentation study using JPP-MT previously digested by gastrointestinal simulation (JPP-IN) and feces from healthy human volunteers (up to 48 h of incubation) showed that gut microbiota plays a key role in the metabolism of the JPP phenolic compounds. JPP-IN incubation with human feces promoted the progressive catabolism of hydrolyzable tannins and anthocyanins yielding new metabolites of smaller molecular weight such as urolithins (A, B, C, D, M5, M6 and M7) originating from the metabolism of ellagitannins, and protocatechuic acid that originates from cyanidin 3-glycoside. All these metabolites can be absorbed and contribute to the health benefits of JPP. In addition, JPP provided substrate for selective bacterial growth, the counts of Bifidobacterium and Lactobacillus remained unchanged after 48 h of fermentation with JPP-IN, whereas Enterobacteria growth was decreased. JPP fermentation also increased short chain fatty acid (SCFA) production in the first 2 h of fermentation that is strongly related to the soluble fraction of JPP (soluble dietary fiber). The consumption of JPP-MJ in a rat model of type 2 DM reduced oxidative stress and improved hepatic complications. Thus, it was verified that the consumption of JPP increased the synthesis of glutathione and positively modulated the redox balance of GSH/GSSG, as well as reduced hyperglycemia and liver injury in rats with type 2 DM. This evidence suggest that despite their low bioaccessibility, the high content of phenolic compounds in JPPs contributes to the protection against type 2 DM complications. In addition, the microbial metabolism of JPP generates bioactive metabolites such as urolithins and protocatechuic acid that likely contribute to the health benefits of JPP along with its prebiotic action and the high levels of SCFA produced during JPP fermentation.