ABSTRACT
4-Dimethylaminobenzaldehyde-thiosemicarbazone (DABT) and 4-dimethylaminobenzaldehyde-N-phenyl-thiosemicarbazone (DABPT) were synthesized and established by (1)H and (13)C NMR and mass spectrum. Both compounds were evaluated for their inhibition activities on mushroom tyrosinase and their anti-tyrosinase kinetics was investigated. The results showed that both compounds exhibited significant inhibitory effects on activity of monophenolase and diphenolase; DABT and DABPT decreased the steady-state rate with 1.54 µM and 1.78 µM as their IC50 values respectively. The inhibitory effects of diphenolase activity exhibited sharp in a dose-dependent manner and their IC50 values were estimated as 2.01 µM and 0.80 µM, respectively. Kinetic analysis showed that their inhibition mechanism was reversible. The inhibition type of DABT was mix-type with inhibition constants KI = 1.77 µM and KIS = 6.49 µM, while that of DABPT displays non-competitive with the inhibition constant KI = 0.77 µM.
Subject(s)
Benzaldehydes/pharmacology , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Semicarbazones/pharmacology , Agaricales/enzymology , Benzaldehydes/chemical synthesis , Benzaldehydes/chemistry , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Kinetics , Monophenol Monooxygenase/metabolism , Oxidoreductases/antagonists & inhibitors , Semicarbazones/chemical synthesis , Semicarbazones/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
2-Chlorobenzaldehyde thiosemicarbazone (2-Cl-BT) and 4-chlorobenzaldehyde thiosemicarbazone (4-Cl-BT) were synthesized, and their inhibitory kinetics on the activity of mushroom tyrosinase were investigated. Results showed that these compounds exhibited significant inhibitory potency on both monophenolase activity and diphenolase activity of tyrosinase. For the monophenolase activity, both compounds could decrease the steady-state activity of the enzyme sharply, without any influence on the lag period. The IC50 values of them were estimated to be 15.4 µM and 6.7 µM, respectively. For the diphenolase activity, both compounds belonged to reversible inhibitors, but their mechanisms were different: 2-Cl-BT was a noncompetitive type inhibitor, while 4-Cl-BT was a mixed-type inhibitor. Their inhibition constants were determined and compared.
Subject(s)
Agaricales/enzymology , Benzaldehydes/chemistry , Enzyme Inhibitors/chemistry , Fungal Proteins/antagonists & inhibitors , Monophenol Monooxygenase/antagonists & inhibitors , Thiosemicarbazones/chemistry , Agaricales/chemistry , Enzyme Inhibitors/chemical synthesis , Fungal Proteins/chemistry , Kinetics , Molecular Structure , Monophenol Monooxygenase/chemistryABSTRACT
The inhibitory effects of hinokitiol, a constituent of the woody oils isolated from Cupressaceae heartwood, on mushroom tyrosinase and melanin formation in B16 melanoma cells as well as its antimicrobial activity were investigated. Our results showed that hinokitiol could strongly inhibit both monophenolase activity and diphenolase activity of the enzyme and the inhibition was reversible. The IC(50) values were estimated as 9.67 µM for monophenolase activity and 0.21 µM for diphenolase activity. The lag time of the monophenolase activity was not obviously lengthened by the compound. Kinetic analyses showed that the inhibition mechanism of hinokitiol was a mixed-type inhibition of the diphenolase activity. Hinokitiol effectively inhibited both cellular tyrosinase activity and melanin biosynthesis in B16 melanoma cells with significant cytotoxicity. Furthermore, it was found that hinokitiol could inhibit the proliferation of Salmonella enteritidis, Escherichia coli, Bacillus subtilis, Staphyloccocus aureus, Klebsiella pneumoniae, and Ralstonia solanacearum to different extents. This research may widen the use of hinokitiol in the fields of food preservation, depigmentation, and insecticide use.
Subject(s)
Anti-Bacterial Agents/pharmacology , Enzyme Inhibitors/pharmacology , Melanins/biosynthesis , Monophenol Monooxygenase/antagonists & inhibitors , Monoterpenes/pharmacology , Tropolone/analogs & derivatives , Agaricales/enzymology , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Food Preservatives/pharmacology , Fungal Proteins/antagonists & inhibitors , Fungal Proteins/metabolism , Gram-Negative Bacteria/drug effects , Gram-Positive Endospore-Forming Rods/drug effects , Kinetics , Melanocytes/drug effects , Melanocytes/enzymology , Melanoma, Experimental , Mice , Microbial Sensitivity Tests , Monophenol Monooxygenase/metabolism , Substrate Specificity , Tropolone/pharmacologyABSTRACT
The effects of dimethyl sulfoxide (DMSO) on the activity of polyphenol oxidase (PPO, EC 1.14.18.1) from blowfly pupae for the oxidation of L-3,4-dihydroxyphenylalanine were studied. The results showed that low concentrations of DMSO could lead to reversible inactivation to the enzyme. The IC(50) value, the inactivator concentration leading to 50% activity lost, was estimated to be 2.35 M. Inactivation of the enzyme by DMSO was classified as mixed type. The kinetics of inactivation of PPO from blowfly pupae in the low concentrations of DMSO solution was studied using the kinetic method of the substrate reaction. The rate constants of inactivation were determined. The results show that k(+0) was much larger than k'(+0), indicating that the free enzyme molecule was more fragile than the enzyme-substrate complex in the DMSO solution. It was suggested that the presence of the substrate offers marked protection of this enzyme against inactivation by DMSO.
Subject(s)
Catechol Oxidase/drug effects , Catechol Oxidase/metabolism , Dimethyl Sulfoxide/pharmacology , Diptera/enzymology , Animals , Catechol Oxidase/chemistry , Dihydroxyphenylalanine/chemistry , Dimethyl Sulfoxide/chemistry , Enzyme Activation/drug effects , Kinetics , Oxidation-Reduction/drug effects , Pupa/enzymology , Solutions , Stereoisomerism , Structure-Activity RelationshipABSTRACT
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.
