Bioaccessibility and metabolism of anthocyanins: effects of fermentation, encapsulation, and microbiota interactions

Anthocyanins have been widely studied for their health benefits; however, these compounds exhibit low bioaccessibility and bioavailability due to degradation and limited absorption in the gastrointestinal tract, which may restrict their effects. Therefore, innovative strategies to enhance the stability and maximize the benefits of anthocyanins are essential, especially for applications in food and supplements. In this context, this study investigated the bioaccessibility and metabolism of anthocyanins, focusing on digestion, interactions with gut microbiota, and the effects of fermentation and encapsulation on the stability and bioactivity of these compounds. The biotransformation of phenolic compounds was studied during the production of jabuticaba wine, and the results showed that anthocyanins underwent biotransformation. Significant increases were observed in total phenolic compounds (4.91 ± 0.07 times), total anthocyanins (5.62 ± 1.17 times), cyanidin-3-glucoside (C3G) (2.05 ± 0.74 times), gallic acid (GA) (57.02 ± 3.70 times), and protocatechuic acid (PA) (3.70 ± 0.51 times) compared to the non-fermented control. Additionally, an increase in the bioaccessibility of C3G, GA, and PA was observed. Jabuticaba wine also exhibited antiproliferative effects against cancer cells, antioxidant activities, and enzymatic inhibition properties. To improve anthocyanin stability during digestion, jabuticaba extract was encapsulated with whey protein (WP) or pea protein (PP) combined with gum arabic (GA). Encapsulation improved anthocyanin bioaccessibility, particularly in the PP:GA 1:2 (v/v) and WP:GA 1:2 (v/v) samples, with increases of 33% and 25%, respectively, compared to the unencapsulated extract. Encapsulation also delayed degradation, increased anthocyanin retention, and enhanced the production of metabolites and short-chain fatty acids (SCFAs) during the colonic phase. Cyanidin-3-glucoside exhibited superior antioxidant and anti- inflammatory effects compared to its main metabolites, significantly reducing reactive oxygen species and pro-inflammatory markers in colon cancer cells (HT29-MTX). The encapsulation of the extract using chitosan (CH) and GA as wall materials was also investigated, increasing bioaccessibility and targeted release of anthocyanins to the colon. The in vitro metabolism of anthocyanins and SCFA production were analyzed in individuals with different body mass index (BMI) values. It was observed that the microbiota metabolized 37.45–54.01% of C3G in the lean group, 40.84–61.74% in the overweight group, and 36.06–69.16% in the obese group after 48 hours. These results showed variations in anthocyanin metabolism within each group, indicating that even among individuals with similar BMI, differences in gut microbiota composition may impact C3G metabolism. The anthocyanin extract also altered SCFA levels compared to control fermentations (without the extract). In summary, this thesis provided an overview of anthocyanin metabolism and bioaccessibility, demonstrating how fermentation and encapsulation influenced metabolism and increased the bioaccessibility of these compounds. Additionally, individual variability in gut microbiota composition was identified as an important factor in anthocyanin metabolism, highlighting the need to consider these variations when studying the health benefits of anthocyanins. Keywords: cyanidin-3-glucoside; jabuticaba; short-chain fatty acids (scfas); microbiota; digestion