ABSTRACT
Tyrosinase (EC 1.14.18.1) is the key enzyme of most food enzymatic oxidation. Tyrosinase inhibitors are important in food industry. In the present paper, 2-chlorcinnamic acid and 2,4-dichlorocinnamic acid were synthesized and the inhibitory kinetics on mushroom tyrosinase were investigated. The results showed that both compounds synthesized could inhibit tyrosinase activity. For monophenolase activity, both chlorocinnamic acids could extended the lag time and decrease the steady-state activities, 2-chlorcinnamic acid extended the lag time just by 5%, and 2,4-dichlorcinnamic acid extended the lag time more than by 30.4%. For diphenolase activity, the IC50 values of 2-chlorcinnamic acid and 2,4-dichlorocinnamic acid were determined to be 0.765 mM and 0.295 mM, respectively. The inhibition kinetics showed that 2-chlorcinnamic acid and 2,4-dichlorocinnamic acid displayed a reversible and uncompetitive mechanism. The inhibition constants were determined to be 0.348 mM and 0.159 mM, respectively. The research may supply the basis for designing new tyrosinase inhibitors.
Subject(s)
Agaricales/enzymology , Cinnamates/pharmacology , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Kinetics , Monophenol Monooxygenase/metabolism , Oxidation-Reduction/drug effects , Oxidoreductases/antagonists & inhibitors , Oxidoreductases/metabolismABSTRACT
The inhibitory kinetics of furfuryl alcohol, furfural and furoic acid on mushroom tyrosinase have been investigated. The results showed that these furan compounds were reversible inhibitors of the enzyme. Furthermore, furfuryl alcohol and furfural were found to be mixed-type inhibitors while furoic acid is uncompetitive inhibitor. The inhibition constants have been confirmed and the order of the inhibiting ability was furfural>furoic acid>furfuryl alcohol. They indicate that the functional groups on the furan ring play a crucial role in the inhibition on the enzyme. In addition, it was also found that these furan compounds could inhibit the proliferation of Salmonella bacteria and Bacillus subtilis to different extents. The minimum inhibitory concentration (MIC) values of furfuryl alcohol, furfural and furoic acid against B. subtilis and S. bacteria were 0.115, 0.027, 0.015 and 0.115, 0.029, 0.009 µM, respectively. The minimum bactericidal concentration (MBC) values of that were 0.115, 0.027, 0.015 and 0.231, 0.121, 0.030 µM, respectively.
Subject(s)
Anti-Infective Agents/pharmacology , Bacillus subtilis/growth & development , Enzyme Inhibitors/pharmacology , Fungal Proteins/antagonists & inhibitors , Furaldehyde/pharmacology , Furans/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Salmonella/growth & development , Anti-Infective Agents/chemistry , Enzyme Inhibitors/chemistry , Fungal Proteins/chemistry , Furaldehyde/chemistry , Furans/chemistry , Monophenol Monooxygenase/chemistryABSTRACT
Tyrosinase (EC 1.14.18.1), a copper-containing multifunctional oxidase, was known to be a key enzyme for biosynthesis in fungi, plants and animals. In this work, the inhibition properties α-naphthol and ß-naphthol toward the activity of tyrosinase have been evaluated, and the effects of α-naphthol and ß-naphthol on monophenolase and diphenolase activity of tyrosinase have been investigated. The results showed that both α-naphthol and ß-naphthol could potently inhibit both monophenolase activity and diphenolase activity of mushroom tyrosinase, and that ß-naphthol exhibited stronger inhibitory effect against tyrosinase than α-naphthol. For monophenolase activity, ß-naphthol could not only lengthen the lag time but also decrease the steady-state activity, while α-naphthol just only decreased the steady-state activity. For diphenolase activity, both α-naphthol and ß-naphthol displayed revisible inhibition. Kinetic analyses showed that both α-naphthol and ß-naphthol were competetive inhibitors.
Subject(s)
Agaricales/enzymology , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Naphthols/pharmacology , Enzyme Activation/drug effects , Enzyme Inhibitors/chemistry , Inhibitory Concentration 50 , Kinetics , Monophenol Monooxygenase/metabolism , Naphthols/chemistryABSTRACT
The effects of fatty acids, octanoic acid, (2E, 4E)-hexa-2,4-dienoic acid, hexanoic acid, (2E)-but-2-enoic acid, and butyric acid on the activities of mushroom tyrosinase have been investigated. The results showed that the fatty acids can potently inhibit both monophenolase activity and diphenolase activity of tyrosinase, and that the unsaturated fatty acids exhibited stronger inhibitory effect against tyrosinase than the corresponding saturated fatty acids, and the inhibitory effects were enhanced with the extendability of the fatty acid chain. For the monophenolase activity, the fatty acids could not only lengthen the lag period, but also decrease the steady-state activities. For the diphenolase activity, fatty acids displayed reversible inhibition. Kinetic analyses showed that octanoic acid and hexanoic acid were mixed-type inhibitors and (2E,4E)-hexa-2,4-dienoic acid and (2E)-but-2-enoic acid were noncompetitive inhibitors. The inhibition constants have been determined and compared.
Subject(s)
Agaricales/enzymology , Enzyme Inhibitors/pharmacology , Fatty Acids/pharmacology , Fungal Proteins/antagonists & inhibitors , Fungal Proteins/metabolism , Monophenol Monooxygenase/antagonists & inhibitors , Monophenol Monooxygenase/metabolism , Down-Regulation , Enzyme Inhibitors/chemistry , Fatty Acids/chemistry , KineticsABSTRACT
Tyrosinase (EC 1.14.18.1) is a key enzyme in pigment biosynthesis of organisms. trans-Cinnamaldehyde thiosemicarbazone, a derivative of benzaldehyde thiosemicarbazone, was synthesized as an inhibitor of tyrosinase. The inhibitory effects of this compound on the activity of mushroom tyrosinase were investigated. The results showed that trans-cinnamaldehyde thiosemicarbazone could potently inhibit both monophenolase activity and diphenolase activity of tyrosinase. For monophenolase activity, trans-cinnamaldehyde thiosemicarbazone could not only lengthen the lag time but also decrease the steady-state rate. For diphenolase activity, the IC(50) value was determined to be 5.72 microM. Kinetic analyses showed that trans-cinnamaldehyde thiosemicarbazone was a reversible and mixed type inhibitor on this enzyme. The inhibition constants (K(I) and K(IS)) were determined to be 4.45 and 8.85 muM, respectively. Furthermore, the antibacterial activity against Bacillus subtilis, Escherichia coli, Staphyloccocus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, and Agrobacterium tumefaciens was investigated. The results showed that trans-cinnamaldehyde thiosemicarbazone was more effective against B. subtilis and S. aureus with the same minimum inhibitory concentration (MIC) of 50 microg/mL and with the same minimum bactericidal concentration (MBC) of 50 microg/mL.
