| Neohesperidin dihydrochalcone is a kind of citrus flavonoid derivative with st rong sweet taste,which has many physiological functions such as anti-oxidation,liver protection,anti-inflammatory and anti-apoptosis effects.It is a new generation of sweet substances with great application potential,however,the low water solubility of neohesperidin dihydrochalcone greatly limits the application and promotion of it.In order to reduce the difficulty and cost in the production of neohesperidin dihydrochalcone and improve its water solubility,In this paper,naringin was used to synthesize neohesperidin dihydrochalcone,and the key steps were optimized.The effect of acid and base conditions on the synthesis of neohesperidin aldol reaction was discussed.The effects of pH,sweetener,cyclodextrin and its derivatives on the water solubility of neohesperidin dihydrochalcone were studied.The solubilization mechanism of cyclodextrin and its derivatives on neohesperidin dihydrochalcone were explored.The main results were as follows:(1)The optimal yield of neohesperidin was obtained when l-proline was used as catalyst,the ratio of material to liquid(W/V)was 1:10,the molar ratio of catalyst,isovanillin and PN was 1:1:1,the reaction temperature was 80°C and the reaction time was 120 min.In addition,for this aldol reaction,either incre asing or decreasing the pH would increase the yield.By using metal catalyst(palladium carbon)and skeleton nickel,the hidden danger of hydrogen gas in actual production can be avoided through Transfer hydrogenation.The yield of this method is 84.85%.(2)The effects of pH value,sweetener,cyclodextrin and their derivatives on the water solubility of neohesperidin dihydrochalcone were studied.It was found that all of them had great effects on the water solubility of neohesperidin dihydrochalcone.The solubility of neohesperidin dihydrochalcone in alkaline condition is much higher than that in acidic and neutral conditions;saccharin sodium,sodium cyclamate and potassium glycyrrhizinate could all increase the solubility of neohesperidin dihydrochalcone,and solubilization effect is:potassium glycyrrhizinate>saccharin sodium>sodium cyclamate,which is closely related to the ionization equilibrium of neohesperidin dihydrochalcone in aqueous solution;Hp-?-CD,?-CD and?-CD all increased the solubility of neohesperidin dihydrochalcone,while?-CD almost did not change the solubility of neohesperidin dihydrochalcone.It is concluded that the spatial matching between neohesperidin dihydrochalcone and cyclodextrin cavity is an important factor affecting the solubilization of neohesperidin dihydrochalcone by different cyclodextrins.8.26×10-3mol/L±0.10×10-3 mol/L neohesperidin dihydrochalcone can be dissolved in 10×10-3 mol/L mol/L Hp-?-CD,which is 10 times more than pure water.(3)The mechanism of Hp-?-CD solubilizing neohesperidin dihydrochalcone was studied.The formation of neohesperidin dihydrochalcone inclusion complex is an enthalpy-controlled-exothermic process.On the whole,neohesperidin dihydrochalcone replaced Hp-?-CD.The unstable high enthalpy water in cycl odextrin molecule makes the system change from disorder to order,and the energy of inclusion complex system decreases.The decrease of entropy is disadvantageous to the reaction,but the larger enthalpy change compensates for the disadvantageous entropy c hange.It is found that van der Waals force and electrostatic interaction drive part of the structure of neohesperidin dihydrochalcone into Hp-?-CD.The inclusion complex was formed in the cavity of cyclodextrin,and the structure of cyclodextrin and cyclo dextrin remained relatively stable through multiple hydrogen bonds. |
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