Glucoraphanin: a broccoli sprout extract that ameliorates obesity-induced inflammation and insulin resistance.

Obesity is a low-grade sustained inflammatory state that causes oxidative stress in different metabolic tissues, which leads to insulin resistance and nonalcoholic fatty liver disease (NAFLD). Particularly, obesity-induced metabolic endotoxemia plays an important role in the pathogenesis of insulin resistance and inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of antioxidant signaling that serves as a primary cellular defense against the cytotoxic effects of oxidative stress. Pharmacological stimulation of Nrf2 mitigates obesity and insulin resistance in mice; however, Nrf2 activators are not clinically available due to biosafety concerns. A recent study demonstrated that glucoraphanin, a precursor of the Nrf2 activator sulforaphane, ameliorates obesity by enhancing energy expenditure and browning of white adipose tissue, and attenuates obesity-related inflammation and insulin resistance by polarizing M2 macrophages and reducing metabolic endotoxemia. Thus, this review focuses on the efficiency and safety of glucoraphanin in alleviating obesity, insulin resistance, and NAFLD. Abbreviations: ALT, Alanine aminotransferase; AMPK, AMP-activated protein kinase; ATMs, Adipose tissue macrophages; BAT, Brown adipose tissue; CDDO-Im, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid-imidazolide; CDDO-Me, CDDO-methyl ester; DIO, High-fat-diet-induced obese; FFA, Free fatty acid; FGF, Fibroblast growth factor; GTP, Glutamyl transpeptidase; HFD, High-fat diet; IKKβ, Inhibitor of κB-kinase β; IL, Interleukin; JNK, C-Jun N-terminal kinase; KD, Knockdown; Keap1, Kelch-like ECH-associated protein 1; KO, Knockout; LPS, Lipopolysaccharide; NADPH, Nicotinamide adenine dinucleotide phosphate; NAFLD, Non-alcoholic fatty liver disease; NF-κB, Nuclear factor-κB; Nrf2, Nuclear factor E2-related factor 2; ROS, Reactive oxygen species; T2D, Type 2 diabetes; TLR, Toll-like receptor; TNF, tumor necrosis factor; UCP, Uncoupling protein; WAT, White adipose tissue.