Abstract
BackgroundGrape skin, a rich source of phytochemicals, has been reported to possess remarkable anti-obesity activity. Fatty acid synthase (FAS) is a key enzyme catalyzing the synthesis of fatty acid de novo, and has been considered as an anti-obesity target. To elucidate the anti-obesity mechanism of grape skin, we investigated the effects of grape skin extract (GSE) and resveratrol, one of the phytochemicals in GSE, on FAS and FAS over-expressed 3 T3-L1 preadipocyte.MethodsPurified FAS was obtained from chicken liver. Dried grape skin was extracted by 50% ethanol and partitioned by ethyl acetate. Inhibitory effects of GSE and resveratrol on FAS including fast-binding inhibition, time-dependent inhibition, and enzyme kinetics were determined. Inhibitory effects of GSE and resveratrol on 3T3-L1 preadipocyte were also measured.ResultsGSE inhibited the overall reaction and β-ketoacyl reductase (KR) reaction of FAS with IC50 values of 4.61 μg/ml and 20.3 μg/ml. For inhibition by resveratrol, the relevant IC50 values were 11.1 μg/ml and 21.9 μg/ml, respectively. And both GSE and resveratrol showed time-dependent inhibition for FAS, with the kobs values of 0.028 min-1, and 0.040 min-1 respectively. They inhibited the overall reaction of FAS competitively with acetyl-CoA, noncompetitively with malonyl-CoA and in a mixed manner with NADPH. Moreover, the inhibition on KR domain by resveratrol was time-dependent with kobs value of 0.106 min-1. In 3 T3-L1 preadipocytes, resveratrol reduced lipid accumulation remarkably.ConclusionsGSE and resveratrol are potent FAS inhibitors and they bound reversibly to the KR domain of FAS to inhibit the reduction of the saturated acyl groups in fatty acid synthesis. Based on the valid data and deliberate analysis, we proposed that GSE and resveratrol have great medical potential and officinal value in treating obesity and related diseases.
Highlights
Grape skin, a rich source of phytochemicals, has been reported to possess remarkable anti-obesity activity
Fatty acid synthase (FAS) catalyzes the synthesis of long chain saturated fatty acid from the substrates of acetylCoA (Ac-CoA), malonyl-CoA (Mal-CoA) and NADPH by its seven functional domains arranged in sequence [15,16]
The inhibition of FAS activity by different fractions of grape skin extract Four fractions of grape skin were tested to determine their inhibitory activities on FAS
Summary
A rich source of phytochemicals, has been reported to possess remarkable anti-obesity activity. Fatty acid synthase (FAS) is a key enzyme catalyzing the synthesis of fatty acid de novo, and has been considered as an anti-obesity target. Obesity is becoming a worldwide epidemic and is recognized as a worsening factor in a series of chronic diseases [1,2,3]. It plays a central role in the metabolic syndrome, which raises the risk of suffering from cardiovascular disease 1.5 to 3 fold [4,5,6]. The inhibitors restrained the expression of the feeding signal neuropeptide Y, which appeared to be mediated by Mal-CoA, one of the substrates in the FAS catalyzed reaction [14]. Its inhibitors have favorable application prospects in developing into anti-obesity drugs
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