Inhibitory Effects Of Clove Alcohol Extract On Fatty Acid Synthase And Obesity Development

Disorder of lipid synthesis is closely linked with numerous chronic diseases such as obesity and cancer.This is because energy surplus is profitable to the development of obesity and cancer.Recent studies have shown inhibition of lipid synthesis could be a potential therapeutic target in obesity and cancer.Most present researches of lipid synthesis inhibitors have been identified as fatty acid synthase(FASN).FASN inhibitor could maintain balanced energy through inhibiting the de novo lipogenesis,increasing energy expenditure.As for the known FASN inhibitor such as cerulenin and C75,their applications are limited because of molecular instability and toxic effects.In this study,our interest is to search for novel lipid synthesis inhibitors from the food that belong to medicine food homology.We found a new FASN inhibitor,alcohol extract of clove(AEC),and investigated its effect on the development of diet induced obesity.The main results of this study are as follows:(1)Screened and selected a FASN inhibitor: AEC.Using the phenotypic screening method of lipid synthesis inhibitors,a method based on the oleaginous model organisms Mortierella alpina,we found a potential lipid synthesis inhibitor from 28 different foods of medicine food homology,namely AEC.From the GC-MS analysis,AEC reduced the fatty acid content in Mortierella alpina.The amount of palmitic acid(C16:0)in the human prostatic cancer cell line(LNCaP)and human hepatoma cell line(HepG2)were significantly reduced by AEC treatment.Palmitic acid is the direct products of long-chain fatty acids synthesis catalyzed by FASN,thus AEC would be the potential FASN inhibitor.Western Blot analysis showed that AEC down-regulated FASN expression in LNCaP,HepG2 and differentiated OP9 cells.The results indicated AEC could inhibit the fatty acid synthesis in mammalian cells.(2)AEC inhibits LNCaP cell and HepG2 cell proliferation.AEC effectively inhibited LNCaP and HepG2 cells proliferation and triggered cell cycle arrest in the S-phase.When LNCaP and HepG2 cells were treated with both AEC and palmitic acid(a FASN inhibitor antagonist),the abilities of AEC on cell proliferative inhibition and cell cycle arrest were reduced,which indicated there was a correlation between cell proliferation inhibition and FASN inhibition effect of AEC.(3)Preventive effect of AEC on obesity development.FASN is a therapeutic target in obesity.According to the above conclusion,AEC showed inhibitory effect on FASN,thus we explored its function on obesity.The effect of AEC treatment on lipid metabolism in vitro was examined by exploring its effect on the adipocyte differentiation of OP9 cells.The result showed AEC inhibited OP9 cell differentiation into adipocytes.Then we investigated its function in vivo using a mouse model of diet-induced obesity.AEC significantly prevented the body weight gain induced by high-fat diet.Hematoxylin and eosin staining of liver tissue and epididymal fat showed AEC could reduce the abnormal lipid accumulation.AEC also reduced the content of total triglyceride and low density lipoprotein-cholesterol in serum,indicated that AEC improved disease related dyslipidemia condition.Moreover,the Western Blot analysis and RT-qPCR analysis showed that AEC down-regulated the expression of FASN in liver at both protein and mRNA levels.In summary,we screened and discovered a novel FASN inhibitor AEC.The results of this study provide solid evidence that AEC could inhibit FASN expression in mammalian cells both in vivo and in vitro.In addition,we demonstrated that AEC has the inhibitory effect on obesity development.These results further extend the research fields on FASN inhibitor.