Sulforaphane and myricetin act synergistically to induce apoptosis in 3T3­L1 adipocytes.

ABSTRACT

The aim of the present study was to investigate whether sulforaphane (SFN) and myricetin (Myr) synergistically induce apoptosis in adipocytes. The viability of mature 3T3­L1 adipocytes treated with 40 µM SFN and/or 100 µM Myr was assessed using an MTT assay. Apoptosis was assessed by Hoechst 33258 nuclear staining, and by detection of single­stranded DNA using an enzyme­linked immunosorbent assay. Compared with the effects of each compound alone, the combination of SFN and Myr synergistically reduced cell viability, induced apoptosis, increased pro­apoptotic Bcl­2 associated X protein expression, decreased anti­apoptotic B­cell lymphoma­2 expression, enhanced Bcl­2­associated death promoter (Bad) translocation from the cytoplasm to the mitochondria, and reduced Bad phosphorylation at Ser112. These effects were accompanied by increased cleavage of caspase 3 and poly­ADP­ribose­polymerase. In addition, combined SFN and Myr treatment significantly decreased the protein expression levels of phosphorylated AKT serine/threonine kinase 1 (Akt) at Ser473, as well as the phosphorylation of the downstream protein ribosomal protein, S6 kinase ß­1. Therefore, SFN plus Myr was a more potent inducer of apoptosis in 3T3­L1 adipocytes than either compound alone. The results of the present study suggest that the mechanism of SNF/Myr­induced apoptosis involved activation of the Akt­mediated mitochondrial apoptotic pathway. This may aid treatment of animal models of obesity and preclinical testing.