Cocoa Shell Aqueous Phenolic Extract Preserves Mitochondrial Function and Insulin Sensitivity by Attenuating Inflammation between Macrophages and Adipocytes In Vitro

Scope: The aim is to assess the action of an aqueous extract from cocoa shell (CAE) and its main phenolic compounds to prevent the loss of obesity-induced mitochondrial function and insulin sensitivity, targeting inflammation between macrophages-adipocytes in vitro. Methods and results: CAE (31-500 mu g mL(-1)) inhibits 3T3-L1 adipocytes lipid accumulation and induces browning during differentiation. LPS-stimulated RAW264.7 macrophages show reduced inducible nitric oxide synthase and cyclooxygenase-2 expression and lowered pro-inflammatory cytokine production when treated with CAE and pure phenolics. Inflammatory crosstalk created by stimulating adipocytes with macrophage-conditioned media (CM) is arrested; CAE diminishes tumor necrosis factor-a (67%) and promotes adiponectin secretion (12.3-fold). Mitochondrial function, measured by reactive oxygen species production, mitochondrial content, and activity, is preserved in CM-treated adipocytes through up-regulating peroxisome proliferator-activated receptor gamma coactivator 1-a expression. Increases in insulin receptor (9-fold), phosphoinositide 3-kinase (3-fold), protein kinase B (4-fold) phosphorylation, and a decrease in insulin receptor substrate 1 serine phosphorylation induce increased glucose uptake (34%) and glucose transporter 4 translocation (14-fold) in CM-induced adipocytes. Conclusion: CAE phenolics promote a beige phenotype in adipocytes. Macrophages-adipocytes inflammatory interaction is reduced preventing mitochondrial dysfunction and insulin resistance. For the first time, CAE shows a positive effect on adipogenesis and inflammation-related disorders.