Abstract
The cocoa shell is a by-product generated by the cocoa processing industry that could be used as a nutraceutical owing to the significant amounts of bioactive compounds it contains. This work aimed to study the bioaccessibility of phenolic compounds present in the flour (CSF) and an aqueous extract (CSE) from cocoa shells through an in vitro simulated digestion and to assess their antioxidant capacity in vitro by using intestinal and hepatic cell culture models (IEC-6 and HepG2 cells). The bioaccessibility of phenolic compounds was determined using a simulated in vitro digestion model (INFOGEST). Total phenolic compounds (TPC) and antioxidant activity were measured using in vitro techniques. Reactive oxygen species (ROS) were evaluated in IEC-6 and HepG2 cells after t-BOOH stimulation. TPC present in CSE were more bioaccessible than phenolic compounds present in CSF. During digestion, the bioaccessibility of phenolic compounds from CSF fluctuated in the gastric (2.8 mg/g), intestinal (7.6 mg/g), and colonic (5.7 mg/g) phases. Similarly, for the phenolics of CSE, the bioaccessibility increased from 50.6 mg/g in the gastric phase to 53.4 mg/g in the intestinal phase and decreased in the colonic phase to 37.2 mg/g. The in vitro antioxidant capacity followed a similar behavior, increasing throughout the digestion in CSF (8.8- to 10.6-fold) and CSE (6.0- to 7.4-fold). Digested CSF and CSE were not cytotoxic for IEC-6 and HepG2 cells and protected their viability under oxidative stress conditions (93–100%). t-BOOH-induced ROS were prevented by CSF (72–88%) and CSE (81–94%) bioaccessible fractions in both intestinal and hepatic cells. In conclusion, cocoa shells are a source of potentially bioavailable antioxidant phenolic compounds that may protect cells from oxidative stress.
Highlights
The cocoa processing industry generates large quantities of by-products, including cocoa shells, representing between 12 and 20% of the cocoa bean [1]
The objective of this study was to evaluate the bioaccessibility of phenolic compounds in cocoa shell flour and in an extract obtained from cocoa shell flour through an in vitro digestion model, as well as the study of the antioxidant capacity in vitro and by using intestinal and hepatic cell culture models (IEC-6 and HepG2 cells)
Chlorogenic acid, Folin-Ciocalteu reagent, 2,21-azino-bis (3ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), potassium persulfate, (±)-6Hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), tert-butyl hydroperoxide, dimethyl sulfoxide (DMSO), 2′,7′-dichlorodihydro-fluorescein diacetate (DCFDA), quercetin, and insulin were purchased from Sigma Chemical (Sigma-Aldrich, St Louis, MO, USA)
Summary
The cocoa processing industry generates large quantities of by-products, including cocoa shells, representing between 12 and 20% of the cocoa bean [1]. The cocoa shell has been validated as a novel antioxidant dietary fiber food ingredient, allowing its incorporation to develop foods with health-promoting properties [4] In this regard, the determination of bioactive compounds is not enough to predict the possible beneficial effects in vivo of the cocoa shell, as the digestive process can transform the original compounds present in food into metabolites that reach the blood system. In vitro models do not entirely simulate human conditions, they provide a more straightforward and cheaper alternative to in vivo models [6] In this sense, evaluating the impact of bioactive antioxidant compounds at the cellular level is essential since they can exert a protective effect against oxidative stress conditions. The objective of this study was to evaluate the bioaccessibility of phenolic compounds in cocoa shell flour and in an extract obtained from cocoa shell flour through an in vitro digestion model, as well as the study of the antioxidant capacity in vitro and by using intestinal and hepatic cell culture models (IEC-6 and HepG2 cells)
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