The Study On The Regulation Of Monascus Pigments In Directional Fermentation And The Effect Of Hypolipidemic

Monascus pigments are a kind of natural,safe and nutritious food coloring and have a good colorability and multiple functional activities.However,citrinin is the secondary metabolites of Monascus,has a strong toxicity of kidney,and the safety of red yeast rice and its related products is highly concerned.In this paper,additional ammonium chloride to solid and liquid medium,directional regulation of Monascus pigment and reduce the yield of citrinin,and separation and purification by silica gel column chromatography to obtain different Monascus pigments(yellow,orange,and red pigment),and the effects of hyperlipidemia bioactivities of different Monascus pigments were verified in animal models.The main research contents and results are as follows:(1)The addition of ammonium chloride could significantly increase the yields of Monascus pigments but reduce the yield of citrinin in red rice as fermentation matrix.In particular,the production of Monascus yellow pigment and orange pigment were significantly enhanced by the addition of ammonium chloride through high performance liquid chromatography-ultraviolet and visible light(HPLC-UV-Vis)full wavelength scanner.Using quantitative real-time polymerase chain reaction,the relative expression of the key genes(MpFasA2,MpFasB2,mppB,mppC,mppD,mppE,mppR1,MpPKS5 and MpPKS5)responsible for the production of Monascus pigments biosynthesis were detected significantly increased compared with the control group.However,the key genes(ctnA and PksCT)responsible for the production of Monascus citrinin biosynthesis were detected significantly decreased compared with the control group.Furthermore,the differential volatile metabolites of red yeast rice were identified by orthogonal partial least-squares discriminate analysis(OPLS-DA).NH4Cl can lower the production of higher alcohols and increase the production of ethanol.Therefore,the addition of NH4Cl with appropriate amount in solid-state fermentation is beneficial to the biosynthesis of Monascus pigments,especially yellow pigments and orange pigments,and inhibits the synthesis of citrinin.(2)The addition of ammonium chloride could significantly increase the yields of Monascus pigments but reduce the yield of citrinin in the liquid fermentation medium.In particular,the production of Monascus orange pigment were significantly enhanced by the addition of ammonium chloride through HPLC-UV-Vis full wavelength scanner.Using RT-qPCR,the relative expression of the key genes MpPKS5,mppRl and mppR2 responsible for the production of Monascus pigments biosynthesis were detected significantly increased compared with the control group.However,the key genes(ctnA and PksCT)responsible for the production of Monascus citrinin biosynthesis were detected significantly decreased compared with the control group.Therefore,the addition of appropriate NH4Cl amount can be beneficial to the biosynthesis of Monascus pigments,and inhibits the synthesis of citrinin.(3)In this paper,a high-fat diet-induced Wistar rat model of high fat was established,and this model was used to evaluate the effects of different Monascus pigments(yellow,orange,and red pigment,20 mg/kg)on lipid metabolism disorder.Results showed that oral administration of different Monascus pigments markedly alleviated the dyslipidemia through decreasing the serum lipid levels,and inhibiting hepatic lipid accumulation and steatosis.Meanwhile,the excretion of fecal TC,TG and bile acid were promoted.It is suggested that Monascus pigments could effectively inhibit the digestion and absorption of lipid in high-fat diet rats.Monascus yellow pigments mediated transcription by up-regulating the expression of LDLR and inhibiting the expression of SREBP-1C,ACC and HMGCR,thus lowering the concentration of blood cholesterol;Monascus red pigments affectted lipid metabolism by regulating the expression of HMGCR,ACC,G6Pase,FAS and GS.(4)By the high-throughput sequencing technique,and multivariate statistical analysis,the effects of different Monascus pigments on the intestinal microflora structure and correlation analysis of intestinal microflora with biochemical indexes were studied.Monascus pigments supplementation altered the composition of gut microbiota,especially modulated the relative abundance of functionally relevant enterotypes compared with the HFD group.Spearman's correlation analysis revealed that beneficial gut microbiota(such as Oscillibacter sp.,Ruminococcus albus and Clostridium sp.)were negatively correlated with the profile of liver weight/body weight(%).