Study On The Preparation Of Rare Ginsenoside By Hydrolysis With Acidic Amino Acid

Panax ginseng is a kind of the most famous traditional Chinese herbal medicine,which belongs to Araliaceae It has been used in China for more than 4000 years.Ginsenoside is one of the most active component in ginseng,which has a wide range of pharmacological activities.Pharmacological studies showed that the rare ginsenosides obtained by the selective hydrolysis of the glycosidic bond had better pharmacological activity and bioavailability than the original ginsenosides.At present,the preparation methods of rare ginsenosides include acid hydrolysis,alkaline hydrolysis,enzymatic hydrolysis and microbial degradation.Strong acid and strong alkali hydrolysis method is simple and fast,but it not only is difficult to control and easy to cause environmental pollution,but also has poor specificity,strong corrosion,and other shortcomings.There are many defects such as high cost and reaction conditions demanding for enzymatic hydrolysis and microbial degradation.Amino acids are essential nutrients for plants and animals which widely exist in nature.Amino acids have certain biological activity,It can be absorbed and be degraded,with non-toxic side effects.In this study,rare ginsenosides were prepared with low cost and environmental friendly by using the biomass material aspartic acid as the catalyst and raw ginsenoside as raw material,which provides an efficient and green way for the preparation of rare ginsenosides.The main results of this study were as follows:Under the condition of high temperature cooking,PDG and ginsenoside Re were used as raw materials to study the degradation of PDG and ginsenoside Re by aspartic acid.The results showed that ginsenoside(50mg/m L)were hydrolyzed by aspartic acid(5mg/mL)at 120? for 1 h,and the conversion rate of PDG and ginsenoside Re was 100%;Furthermore,8 degradation products were isolated from ginsenoside degradation products by semi preparative high performance liquid chromatography(HPLC).The structures of these compounds were identified by MS and NMR.The results showed that the degradation products of PDG were ginsenoside 20(S)-Rg3,20(R)-Rg3,Rk1 and Rg5,and the transformation approach was PDG ? 20(S)-Rg3/20(R)-Rg3 ? Rk1/Rg5;The degradation products of ginsenoside Re were ginsenoside Rg6,F4,Rk3 and Rh4,and the transformation pathway was Re?Rg6/F4?Rk3/Rh4.Meanwhile,the effect of hydrolysis conditions on the degradation of ginsenosides and Maillard reaction was studied.The results showed that the content of ginsenoside 20(R)-Rg3 and Rg5 increased with the increase of temperature,the content of20(S)-Rg3 and Rk1 decreased with the increase of temperature.The antioxidant experiment resultsshowed that with increasing steaming temperature,the scavenging effect of the reaction product of aspartic acid and PDG on DPPH radical was significantly enhanced(P<0.01).The main substance of antioxidant activity was the Maillard reaction product which was produced by the reaction of aspartic acid and the hydrolysis of sugar on ginsenoside.The ginsenoside Rg3 and ginsenoside Rg2 were prepared by hydrolyzing protopanaxadiol saponins and ginsenoside Re using glutamic acid as the catalyst.The preparation condition was optimized by single factor investigation and orthogonal test,and the reaction products were analyzed by HPLC.The results of orthogonal experiment showed that,when PPD-type saponins(10mg/mL)were hydrolyzed by glutamic acid(10mg/mL)at 80? for 2h,all PPD-type saponins were converted.The conversion rate of ginsenoside Rg3 was 65.12%.When ginsenoside Re(1mg/mL)were hydrolyzed by glutamic acid(2mg/mL)at 80? for 2 h,all ginsenoside Re was converted,the conversion rate of ginsenoside Rg2 was 60.33%.Simulation the processing of red ginseng,after treatment with ginseng,the effects of acidic amino acids and basic amino acids on Ginsenosides and Maillard reaction products were studied.The results showed that ginseng with glutamic acid treatment steamed at 98? for 2 h,the majority of ginsenosides were transformed into rare ginsenosides;when steamed at 120 ? for 2 h all ginsenosides were transformed into rare ginsenosides.However,ginseng with arginine infiltration treatment steamed at 98? for 2 h,no rare ginsenosides were produced.When steamed at 120?for 2 h,only a small amount of saponin was transformed into rare ginsenosides.The results indicated that acidic amino acids could promote the transformation of ginsenosides in red ginseng processing,while the basic amino acids can inhibit the transformation of ginsenosides.At the same time,the browning degree and antioxidant activity of steamed ginseng with different treatments were studied.The results showed that the browning degree of Maillard reaction was significantly increased and the antioxidant activity was enhanced after treatment with acid or alkaline amino acid.