Study On The Bioactivities Of Cinnamoyl Amino Acid Ester Derivatives

Cinnamic acid and its derivatives widely distribute in plants, which were found to have the functions of antioxidation, antitumour, free radical scavenging and microorganism inhibition and so on. As a significant fine chemical synthesis intermediate, cinnamic acid is utilized widely in the fields such as flavor and spices, food preservatives, medicine and cosmetics, etc.This thesis mainly studied on bioactivities of cinnamyl amino acid ester (CAAE) derivertives in order to obtain more active ingredients as food preservatives.Nine cinnamyl amino acid ester (CAAE) derivatives were synthesized and their inhibitory effects on the activity of mushroom tyrosinase were investigated. Their IC50 values were determined by absorption spectrophotometry method. Among these derivatives, a3-5 and b1-4 were more active inhibitors. Their enzymatic reaction kinetics of these 7 compounds was further studied. According to the results, a3, a4 and a5 acted as reversible non-competitive inhibitors, while compounds b1-4 acted as reversible mixed-type inhibitors. However, the mixed type of series b still could be divided into two groups, b1, b2 and b4 were mixed-I indicating their competitive effect was stronger than uncompetitive effect. Oppositely, b3 was a mixed-II inhibitor which was more uncompetitive than competitive.b1, b2, b3 and b4 were studied as antioxidants. Scavenging activity on hydroxyl radical and ABTS radical were determined by Fenton reaction system and ABTS reaction system, respectively. Their inhibitory effects on TBARS product in rat brain homogenates induced by FeCl2-ascorbic acid were detected as well as the reducing power by Prussian blue method. Testing results showed that the three compounds, b2, b3 and b4, had antioxidative effects to some degrees, of which b3 was the most active. b1 didn't show any antioxidative activity in the scope of the testing concentrations.The antimicrobial properties of b3 and b4 to Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Aspergillum niger, Penicillium citrinum and Saccharomyces cerevisiae were investigated. According to the results of diameters of the inhibition zone and their minimal inhibitory concentrations (MICs), b3 was found more active than b4 on inhibition of three bacterias, Aspergillum niger and Saccharomyces cerevisiae except Penicillium citrinum. The in situ efficacy was evaluated against E.coli in a food model (fresh grass carp). Their antimicrobial activity enhanced with the increase of the concentrations (2.5 mM and 5 mM, respectively) of the antimicrobial agents. The inhibitory rate of b3 and b4 reached to 85.6% and 73.7% respectively with the same concentration of 5 mM when storaged for 10 days.