5-Heptadecylresorcinol Regulates the Metabolism of Thermogenic Fat and Improves the Thermogenic Capacity of Aging Mice via a Sirtuin 3-Adenosine Monophosphate-Activated Protein Kinase Pathway.5-Heptadecylresorcinol (AR-C17), a well-known biomarker for whole grain rye consumption, is a primary homolog of alkylresorcinols.  In this study, the effects of AR-C17 on the thermogenesis of brown adipocytes and 3T3-L1 adipocytes were investigated.  The results showed that AR-C17 increased sirtuin 3 (Sirt3) expression, and the expressions of specific thermogenic genes in adipocytes were increased.  Furthermore, AR-C17 increased the mitochondrial functions during the thermogenic activation of adipocytes.  In in vivo study, AR-C17 increased the cold tolerance and thermogenic capacity of adipose tissues in aging mice.  In addition, Sirt3 activity was required for AR-C17-induced thermogenesis.  Meanwhile, AR-C17 increased adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, and AMPK was involved in the regulation of AR-C17 on thermogenic adipocytes.  Mechanically, AR-C17 upregulated a Sirt3-AMPK positive-feedback loop in adipocytes and further increased the expression of uncoupling protein 1 to activate thermogenesis.  This study indicated that AR-C17 could be a promising thermogenic activator of adipocytes to alleviate obesity and aging-associated metabolic diseases.
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