Anthocyanins bioaccessibility and bioactivity of Grumixama (Eugenia brasiliensis), Black Pitanga (Eugenia uniflora), and Capinuriba (Rubus brasiliensis) after in vitro gastrointestinal digestion

The fate of bioactive compounds (BC) after ingestion is a very important subject since it is a major influencer on the expected bioactivity in human body. Since the rise and standardization of in vitro methods for simulating the human gastrointestinal digestions, bioaccessibility studies and its link with the effect of BC became more feasible, faster, and cheaper, when compared to in vivo models. The Brazilian native fruits are attracting much interest of research, industry, and consumers due to their good nutritional composition and positive health effects. Many native fruits are rich in polyphenols, especially anthocyanins, which are antioxidant, anti-inflammatory and have interesting effects, like antiobesity, prebiotic, and cognitive improvements. The aim of this study was to evaluate the effect of in vitro gastrointestinal digestion of Grumixama (Eugenia brasiliensis), Black Pitanga (Eugenia uniflora), and Capinuriba (Rubus brasiliensis) over anthocyanins bioaccessibility and bioactivity. Fruit samples were homogenized fresh and submitted to a three-phase in vitro digestion (oral, gastric, and intestinal). Undigested samples were extracted exhaustively using acidified methanol, while digested samples were centrifuged (21000 g, 20min) and filtered (0.22 µm) to separate the bioaccessible fraction which were directly analysed. Undigested samples and bioaccessible fractions were analysed spectrophotometrically for total anthocyanins, total flavonoids, total phenolics and antioxidant effect (FRAP and ABTS). Moreover samples were analysed with a chromatographic system (Waters, USA) equipped with a triple quadrupole mass detector with an electrospray ionization source (Xevo TQD Zspray, Waters) for identification of anthocyanins profile. Also, UHPLC-DAD analysis was carried out for quantification of major anthocyanins, once compared with commercial standards. Chromatographic separation conditions for both methods were identical: 0.35 mL/min, 1% Formic acid (A) and acetonitrile with 1% Formic acid (B) were used as mobile phase in gradient starting at 1 min from 90:10 (A:B) to 50:50 (A:B) in 4 min, and total runtime was 9 min, the column was an ACQUITY UPLC BEH C18 1.7 µm.
It were identified 9 anthocyanins, being Cyanidin 3-glucoside the major anthocyanin (> 90%) present in the fruits. The higher content of Cyanidin 3-glucoside was, respectively, for Black Pitanga (1258 µg/g), Capinuriba (954 µg/g) and Grumixama (251 µg/g), while the bioaccessibilities were 45%, 30% and 69%. Delphinidin-3-glucoside, Malvidin 3,5-diglucoside and pelargonidin-3-glucoside were also quantified. Capinuriba presented higher bioaccessibility of total anthocyanins (91%) and total flavonoids (64%). Black pitanga presented the higher bioaccessible antioxidant effect after in vitro digestion (140% ABTS, 189% FRAP), meaning that there are much more bioactive compounds which becomes bioactive after being release from the fruit matrix.