Fibroblast Growth Factor 21 Signaling Activation by Selected Bioactive Compounds from Cocoa Shell Modulated Metabolism and Mitochondrial Function in Hepatocytes

Objectives To evaluate the effect of selected bioactive compounds from cocoa shell and its aqueous extract on the activation of fibroblast growth factor 21 (FGF21) signaling in hepatocytes and the resulting modulation of lipid and glucose metabolism, oxidative stress, and mitochondrial function. Methods The bioactive compounds from cocoa shells were extracted using water and characterized by UPLC-MS/MS. An in vitro model of non-alcoholic fatty liver disease was used: HepG2 cells were co-treated with either pure theobromine (TH), protocatechuic acid (PCA), procyanidin B2 (PB2), epicatechin (EPI), catechin (CAT) (10–50 µmol L−1), or the aqueous extract from cocoa shells (CAE, 20–100 µg mL−1) in the presence or absence of palmitic acid (PA, 500 µmol L−1). FGF21 receptor interaction with cocoa shell phytochemical was evaluated in silico. Biomarkers of cell metabolism were assessed 24 h after the co-treatment in cell supernatants and lysates using chemical, biochemical, and immunochemical techniques. Results Phytochemicals from cocoa shell were able to interact in silico with FGF21 receptor (biding energies from −6.0 to −11.0 kcal mol−1) denoting a potential interaction causing FGF21 receptor response. FGF21 hepatic signaling was activated (1.1 to 2.3-fold enhance in ERK1/2 phosphorylation). CAE, TH, PCA, PB2, EPI, and CAT diminished PA-elicited lipid accumulation (5–86%, P < 0.05) by reducing fatty acid synthase expression, and stimulated lipolysis (1–87%, P < 0.05) through the up-regulation of lipoprotein lipase expression. CAE and therein-bioactive compounds, mainly TH and PCA, promoted glucose uptake (4–35%, P < 0.05) via the increase in the phosphorylation of the insulin receptor (2.2-fold, P < 0.05), protein kinase B (2.8-fold, P < 0.05), AMPKα (2.0-fold, P < 0.05), and ERK1/2 (2.8-fold, P < 0.05) phosphorylation. Oxidative stress was prevented (50–100%, P < 0.05), and the loss of mitochondrial content (15–100%, P < 0.05) and function, measured as ATP production, alleviated (28–100%, P < 0.05). Conclusions Results demonstrated that the major bioactive compounds, primarily TH and PCA, found in cocoa shell could activate FGF21 signaling and regulated hepatic lipid and glucose metabolism, preventing insulin resistance, oxidative stress, and mitochondrial dysfunction. Funding Sources USDA-NIFA-HATCH, and the Spanish Ministry of Science and Innovation.