Neuroprotective Activity Of Cyanidin-3-glucoside And Its Mechanism

Cyanidin-3-O-glucoside(C3G)is one of anthocyanins widely occur in plants.It has various biological activities such as antioxidant and anti-inflammatory.It has been reported that anthocyanins could cross the blood-brain barrier and show neuroprotective effect.After being ingested,C3 G will turn into cyanidin(Cy)through deglycosylation under fermentation of intestinal microbes.However,Cy is easily oxidized under physiological p H.Protocatechuic acid(PCA)and phloroglucin aldehyde are commonly identified oxidized products of Cy and C3 G.The final products that enter systemic circulation could be the oxidation mixture product(OP)of Cy after intake of C3 G.There has no study reported about the biological activity of OP.In addition,cell models were generally adapted for evaluation of the protective effect of C3 G on nerve injury,only few studies have been done by animal model.In order to further clarify the neuroprotective effect of C3 G and its possible mechanism,the antioxidant and anti-inflammatory activities of C3 G,Cy,OP and PCA were compared in BV2 cell model,firstly.And then the neuroprotective effect of C3 G on neural damage induced by endogenous or exogenous compounds were systematically explored by using Caenorhabditis elegans(C.elegans)and zebrafish models,respectively.The specific research and results were as follows:1.The oxidation process of Cy under neutral p H conditions in vitro was tracked by high performance liquid chromatography-mass spectrometer,then the composition and content of oxidation product were obtained.The results showed that PCA which accounted for 8.3% of the initial concentration of Cy and little phloroglucinol aldehyde were detected in oxidation mixture product OP when Cy was completely oxidized.2.BV2 microglia was stimulated by lipopolysaccharide(LPS)to establish neuroinflammation and oxidative stress cell models.The protective effect of C3 G,Cy,OP and PCA on inflammation and oxidative damage were studied.The results showed that C3 G,Cy and OP inhibited production of pro-inflammatory factors including IL-6,IL-1?,NO and PGE2,and promoted production of anti-inflammatory factor IL-10 at the same time.Also,the content of intracellular reactive oxygen species(ROS)was decreased and the activity of antioxidant enzymes was increased by pretreating cells with C3 G,Cy and OP.At last,the inflammation and oxidative stress of BV2 cells induced by LPS was significantly alleviated.C3 G,Cy and OP showed similar anti-inflammatory and antioxidant activities at the same concentration.However,PCA at the corresponding concentration in OP did not show the significant antioxidant and anti-inflammatory activity,which suggest that the activity of OP was not contributed by PCA producted from oxidation of Cy.Further study is needed to explore the bioactivities and mechanism of OP.3.The accelerated expression of A? gene in CL2355 C.elegans was induced by increasing culture temperature to establishe nerve injury model.The protective effect of C3 G on neurotoxicity caused by the accumulation of endogenous compound A?and its possible mechanism was explored.The results showed that the memory health and chemotaxis of CL2355 C.elegans were significantly improved by C3 G.Expression of A? which was induced by rising temperature was also decreased.Besides,the content of ROS in CL2355 C.elegans was decreased and the activity of antioxidant enzymes was elevated,which suggested that C3 G may exert neuroprotective effect by alleviating the oxidative stress of C.elegans.There was no statistically significant difference in neuroprotective effect between pretreatment group and long-term treatment group with C3 G at the same concentration.4.Zebrafish embryos were exposed to bisphenol A(BPA)to establish a neurotoxicity model.The neuroprotective effect of C3 G on neurotoxicity induced by exogenous compound BPA and its possible mechanism was studied.The results showed that behavior and neurodevelopment of zebrafish which were pretreated with C3 G were significantly improved.The expression of neurodevelopment-related genes were increased,including Elavl3,?1-tubulin,Gap43,Zn5,Syn2? and Mbp.In addition,apoptosis of cells in zebrafish was also recuced by C3 G through inhibiting the expression of apoptosis-related genes,including Bax,Caspase 3 and Caspase 9,and increasing the expression of anti-apoptotic gene Bcl-2.The level of GSH and the activities of SOD,GPx and CAT in zebrafish were also increased by C3 G.These results indicated that C3 G might inhibit cell apoptosis by alleviating the oxidative stress in zebrafish,and then alleviate neurotoxicity of zebrafish embryos induced by BPA.The results of studies could offer basis for the evaluation of neuroprotective effects of anthocyanins against the toxicities caused by internal or external substance and the potential mechanism.