Bioaccesibility and bioavalability of bioactive compounds present in coffee silverskin extract

Abstract

[Introduction]: Health promoting effects associated to coffee silverskin extract (CSE) largely depend on the bioaccesibility and bioavailability of chlorogenic acid (CGA) and caffeine and it is evaluated in the present study. [Methods]: CSE was in vitro gastrointestinal digested mimicking human conditions. Bioaccesibility of CSE's compounds was assayed by analysis of proteins, total phenolic compounds (TPC), CGA, caffeine and antioxidant capacity after the in vitro digestion. CGA and caffeine in vivo bioavailability was evaluated using male Wistar rats (n=32) divided into four groups (n=8). A Control group received 1 ml of sterile water; CSE group received CSE (128 mg/kg body-weight equivalent to 0.88 mg CGA/kg body-weight and 2.55 mg caffeine/kg body-weight); CGA group received 1.5 mg CGA/kg body-weight and caffeine group received 5 mg caffeine /kg body-weight. Doses were administered diluted in 1 ml of water by gavage. Animals were housed singly in metabolic cages. Urine samples were serially collected for every 1 hour up to 6 h, then every 2 hours up to 10 h and then up to 24 h. CGA and caffeine and their major metabolites, hippuric acid and paraxanthine were determined in urine by UPLC-MS/MS analysis. [Results]: Bioaccesibility of TPC, CGA and caffeine decreased due to digestion in 39%, 80% and 25%, respectively. On the contrary, the overall antioxidant capacity of CSE remained in 82% (ABTS) and 74% (ORAC) after in vitro digestion suggesting the formation of novel antioxidant during the process. Results on bioavailability indicated caffeine was highly metabolized to paraxanthine after CSE intake while free CGA wasn't bioavailable. [Conclusions, discussion and/or practical application]: Our findings seem to indicate that CSE health effects might be linked to its antioxidant character or a synergic effect of different components present in CSE including caffeine and its metabolites, but cannot be ascribed to free CGA.