Zeaxanthin, a type of carotenoid, has been proven to exhibit anti-lipogenesis effect; however, the detailed mechanism of this effect is less known. Herein, we evaluated the effects of zeaxanthin on the inhibition of adipogenesis in 3T3-L1 adipocytes and obesity in high-fat diet fed C57BL/6J mice. Zeaxanthin significantly decreased the intracellular lipid content in a dose-dependent manner (5-15 μM) in adipocytes without causing cytotoxicity. In high-fat-diet-induced obese mice, oral administration of 20 mg kg zeaxanthin attenuated the progression of obesity and improved dyslipidemia. It exhibits an anti-adipogenic effect via down-regulating the transcriptional factors and adipocyte-specific genes involved in adipogenesis, both in vitro and in vivo. Furthermore, zeaxanthin treatment reversed the MDI (0.5 mM 3-isobutyl-1-methylxanthine, 1.0 μM dexamethasone, and 1.0 μg mL insulin) and HFD (high-fat diet)-induced inhibition of AMPK phosphorylation in adipocytes and epididymal adipose tissues, respectively, thereby modulating the energy metabolism. These results indicated that zeaxanthin plays anti-adipogenic and anti-obesity roles by inducing AMPK activation, inhibiting lipogenesis, and decreasing intracellular lipid content, adipocyte size, and adipose weight.
The monomeric phenolic components of adzuki bean seed coat polyphenols (ABSCPs) were analysed, and their antibacterial activity and mechanism against two tested bacteria (Escherichia coli ATCC8797 and Staphylococcus aureus ATCC12600) were evaluated for their potential application in preservation of fresh raw beef. ABSCP contained 13 kinds of monomeric phenols, and the minimum inhibition concentration (MIC) of ABSCP against E. coli and S. aureus was 1250 and 625 μg ml −1 , respectively. The mechanism of ABSCP against E. coli and S. aureus was associated with increased cell protein and nucleic acid leakage, increased cell membrane potential, decreased intracellular ATP concentration and morphological changes in bacterial cell. In addition, ABSCP with whey protein isolate (WPI) was applied to fresh raw beef and this remarkably retarded microbial growth by maintaining the total microbial quality below the acceptable limit of 6 lg CFU g −1 for 14 days. Lower pH and total volatile base nitrogen values were observed in the coated samples during refrigerated storage (4 °C). As a result, we found that ABSCP, as a natural food bacteriostatic agent, can effectively inhibit the growth of E. coli and S. aureus and combined with WPI to apply to fresh raw beef to extend its shelf life.Keywords Adzuki bean seed coat polyphenols, antimicrobial activity and mechanism, Escherichia coli, fresh raw beef, Staphylococcus aureus.
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