Study On The Isolation,Purification And Structure Identification Of Antioxidant Constituents In Hericium Erinaceus

Hericium erinaceus belongs to Basidiomycetes,Polyporales,Hydnaceae,Hericium.There have been a lot of studies on the antioxidants of Hericium erinaceus,most of which focused on polysaccharides in Hericium erinaceus.In this study,ethanol extraction method was optimized to extract antioxidants from Hericium erinaceus fruiting bodies.Based on ethanol extraction method,the fractions in ethyl acetate phase were selected for further separation by means of silica gel column chromatography and semi-preparative HPLC.The structures of the purified monomeric compounds were also identified.The conclusions of the study are as follows:(1)Based on the single factor and orthogonal experiments,ethanol extraction method was optimized to extract antioxidants from Hericium erinaceus.The optimal conditions were:50%ethanol concentration,1:15 g/mL for ratio of material to liquid,50°C extraction temperature,5 h for extraction time and 2 times of extraction.The ethanol extract of Hericium erinaceus showed excellent scavenging ability for ABTS~+·,DPPH·,·OH and good reducing power.The scavenging rate for ABTS~+·and DPPH·reached 79.85%(at concentration of 0.5mg/mL)and 56.85%(at concentration of 5 mg/mL)respectively.(2)The yields of petroleum ether phase,ethyl acetate phase,n-butanol phase and residual water phase from the ethanol extract of Hericium erinaceus were 3.23%,2.55%,7.99%and42.25%respectively.Among the different polar extraction phases,the ethyl acetate phase contained the highest total phenolic and total flavonoid contents,16.52 mg/g and 10.08 mg/g respectively.Although the ethanol extract of Hericium erinaceus fruiting bodies and its four extraction phases showed certain antioxidant activity,the antioxidant activity of ethyl acetate phase was relatively higher than others at the same concentration.In general,the scavenging rate of the ethyl acetate phase for DPPH·,·OH and ABTS~+·reached 41.64%(at concentration of 2.5 mg/mL),82.84%(at concentration of 2.5 mg/mL)and 89.18%(at concentration of 0.5mg/mL)respectively,but the scavenging rate for·OH was slightly lower than that of petroleum ether,which was 96.85%(at concentration of 2.5 mg/mL).Hence,the ethyl acetate phase was selected for the subsequent further separation.(3)In the further separation,antioxidant components of C1-C10 were obtained in the ethyl acetate phase from the Hericium erinaceus ethanol extract by TLC and silica gel column chromatography.The higher polar fractions showed higher scavenging rate for DPPH·and ABTS~+·.The highest scavenging rate for DPPH·and ABTS~+·reached 50.12%(at concentration of 2.0 mg/mL)and 81.84%(at concentration of 100?g/mL)respectively.Hence,the high polar fractions were available for further separation.(4)Finally,five compounds were isolated and purified from the components C1-C10 by TLC,silica gel column chromatography,semi-preparative HPLC and recrystallization method.Their chemical structures were identified by IR,MS and NMR analysis as:Oleic acid(compound H1),Hericenone I(compound H2),n-Nonacosane(compound H3),Uridine(compound H4)and Hericenone J(compound H5).Among them,Hericenone I and Hericenone J were initially identified as the secondary metabolites of Hericium erinaceus fruiting body,belonging to the isobenzofuranone derivatives.