The Study Of Synthesis And Activity Of The Amino Acid Ester Derivatives

Food preservatives and food antioxidants have become an interesting research field and many scientists have payed much attention to search for the highly efficient, safe preservatives and antioxidants. In this study, a series of fumaric acid amides of amino acid derivatives(a1~a4, b1~b4) which are antibacterial activity were synthesized by using maleic anhydride and amino acid ester as the raw material. The antibacterial activity of functional groups α, β- unsaturated carbonyl structure of maleic anhydride was used as matrix. By utilizing the antioxidant activity of gallic acid phenolic hydroxyl group, N-(3,4,5-trihydroxybenzoyl)-Ethyl-Phenylalaninate(NTEP) which is antioxidant activity was produced through amidation reaction with phenylalanine ethyl ester hydrochloride.The main contents and some successful results have been listed as following:1) Synthesis and characterization of fumaric acid amides of amino acid derivativesA series of fumaric acid amides of amino acid derivatives were synthesized by using maleic anhydride and amino acid ester as the raw material. Single factor experiments were also carried out to optimize the synthetic technologies.The results showed that the optimal reaction condictions were: n(maleic anhydride):n(amino-acid ester) 1.0:1.0, amidation temperature 55~60℃, amidation time 3 h, anhydrous aluminum chloride as isomerization catalyst, dosage of isomerization catalyst 5%, isomerization temperature 100℃, isomerization time 2 h.2) The study of activity of fumaric acid amides of amino acid derivativesThe antimicrobial activities experiments of Escherichia coli、Staphylococcus aureus、 Salmonella 、Bacillus subtilis and Lactobacillus and the skin test of fumarate ester derivatives of amino acids derivatives were investigated. The results showed that fumaric acid amides of amino acid derivatives have obvious inhibitory effect on experimental bacteria, the antimicrobial effects of b1 and b2 are equal to that of dimethyl fulminate(DMF), and the antimicrobial effects of b3 and b4 are better than DMF. And fumaric acid amides of amino acid derivatives have no stimulation to the skin. The toxicity study on cells L02 and Hep G2 was also studied by using MTT experiment and the results showed that these two cells are not significantly inhibited, presumably fumarate ester derivatives of amino acids have no significant cytotoxicity to the cells.3) Synthesis and characterization of N-(3, 4,5-trihydroxybenzoyl)- Ethyl-PhenylalaninateWith phenylalanine ethyl ester hydrochloride and gallic acid as raw materials, N-(3,4,5-trihydroxybenzoyl)- ethyl-phenylalaninate(NTEP) was produced. And, the structures of NTEP were determined by the melting point determination and 1H NMR. Single factor experiments were also carried out to optimize the synihetic technologies.The results showed that the optimal condictions were: HOBt as activating agent, EDC?HCl as a condensing agent, n(gallic acid): n(phenylalanine ethyl ester hydrochloride) 1.0: 1.2, 3% / 3% as the amount of HOBt/EDC?HCl, reaction time 18 h.4) The study of activity of N-(3,4,5-trihydroxybenzoyl)- Ethyl-PhenylalaninateThe antioxidant activity experiments and inhibition of tyrosinase activity experiments of NTEP were conducted. The results showed that NTEP has strong scavenging ability on DPPH radical, ABTS+ radical and hydroxyl radical, and its reducing power is also strong. Overall, its antioxidant ability was equivalent to gallic acid, and strongger than Vc. Moreover, N-(3,4,5-trihydroxybenzoyl)- ethyl-phenylalaninate has better inhibiting tyrosinase activity than gallic acid.