ABSTRACT
A novel monofunctional benzyldithiocarbamate, C(6)H(5)CH(2)NHCSSNa (I), and a bifunctional p-xylidine-bis(dithiocarbamate), NaSSCNHCH(2)C(6)H(4)CH(2)NHCSSNa (II), as sodium salts, were synthesized by reaction between p-xylylenediamine or benzylamine with CS(2) in the presence of NaOH. They were characterized by spectroscopic techniques such as (1)H NMR, IR, and elemental analysis. These water-soluble compounds were examined for their inhibition of both activities of mushroom tyrosinase (MT) from a commercial source of Agricus bisporus. l-3,4- Dihydroxyphenylalanine (L-DOPA) and l-tyrosine were used as natural substrates for the catecholase and cresolase enzyme reactions, respectively. Kinetic studies showed noncompetitive inhibition of I and mixed type inhibition of II on both activities of MT. The inhibition constant (K(I)) of II was smaller than that of I. Raising the temperature from 27 to 37 degrees C caused a decrease in K(I) values of I and an increase in values of II. The binding process for inhibition of I was only entropy driven, which means that the predominant interaction in the active site of the enzyme is hydrophobic; meanwhile, the electrostatic interaction can be important for the inhibition of II due to the enthalpy driven binding process. Fluorescence studies showed a decrease of emission intensity without a shift of emission maximum in the presence of different concentrations of compounds. An extrinsic fluorescence study did not show any considerable change of the tertiary structure of MT. Probably, the conformation of inhibitor-bound MT is stable and inflexible compared with uninhibited MT.
Subject(s)
Carbamates , Enzyme Assays , Fungal Proteins/antagonists & inhibitors , Monophenol Monooxygenase/antagonists & inhibitors , Thiocarbamates/chemistry , Thiocarbamates/chemical synthesis , Thiocarbamates/pharmacology , Agaricales/enzymology , Carbamates/chemical synthesis , Carbamates/chemistry , Carbamates/pharmacology , Entropy , Fungal Proteins/chemistry , Fungal Proteins/metabolism , Hydrophobic and Hydrophilic Interactions , Monophenol Monooxygenase/chemistry , Monophenol Monooxygenase/metabolism , Protein Binding , Protein Conformation , Static ElectricityABSTRACT
Three iso-alkyldithiocarbonates (xanthates), as sodium salts, C3H7OCS2Na (I), C4H9OCS2Na (II) and C5H11OCS2Na (III), were synthesized, by the reaction between CS2 with the corresponding iso-alcohol in the presence of NaOH, and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) from a commercial source of Agricus bisporus. 4-[(4-methylbenzo)azo]-1,2-benzendiol (MeBACat) and 4-[(4-methylphenyl)azo]-phenol (MePAPh) were used as synthetic substrates for the enzyme for the catecholase and cresolase reactions, respectively. Lineweaver-Burk plots showed different patterns of mixed and competitive inhibition for the three xanthates and also for cresolase and catecholase activities of MT. For cresolase activity, I and II showed a mixed inhibition pattern but III showed a competitive inhibition pattern. For catecholase activity, I showed mixed inhibition but II and III showed competitive inhibition. These new synthesized compounds are potent inhibitors of MT with K(i) values of 9.8, 7.2 and 6.1 microM for cresolase inhibitory activity, and also 12.9, 21.8 and 42.2 microM for catecholase inhibitory activity for I, II and III, respectively. They showed a greater inhibitory potency towards the cresolase activity of MT. Both substrate and inhibitor can be bound to the enzyme with negative cooperativity between the binding sites (alpha > 1) and this negative cooperativity increases with increasing length of the aliphatic tail in these compounds in both cresolase and catecholase activities. The cresolase inhibition is related to the chelating of the copper ions at the active site by a negative head group (S-) of the anion xanthate, which leads to similar values of K(i) for all three xanthates. Different K(i) values for catecholase inhibition are related to different interactions of the aliphatic chains of I, II and III with hydrophobic pockets in the active site of the enzyme.
Subject(s)
Agaricus/enzymology , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Thiones/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Kinetics , Thiones/chemical synthesis , Thiones/chemistryABSTRACT
Three new n-alkyl dithiocarbamate compounds, as sodium salts, C4H9NHCS2Na (I), C6H13NHCS2Na (II) and C8H17NHCS2Na (III), were synthesized and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) from a commercial source of Agaricus bisporus in 10 mM phosphate buffer pH 6.8, at 293K using UV spectrophotometry. Caffeic acid and p-coumaric acid were used as natural substrates for the enzyme for the catecholase and cresolase reactions, respectively. Lineweaver-Burk plots showed different patterns of mixed and competitive inhibition for catecholase and cresolase reactions, respectively. These new synthetic compounds can be classified as potent inhibitors of MT due to Ki values of 0.8, 1.0 and 1.8 microM for cresolase inhibitory activity, and also 9.4, 14.5 and 28.1 microM for catecholase inhibitory activity for I, II and III, respectively. They showed a greater potency in the inhibitory effect towards the cresolase activity of MT. Both substrate and inhibitor can be bound to the enzyme with negative cooperativity between the binding sites (alpha > 1) and this negative cooperativity increases with increasing length of the aliphatic tail in these compounds. The inhibition mechanism is presumably related to the chelating of the binuclear coppers at the active site and the different Ki values may be related to different interaction of the aliphatic chains of I, II and III with the hydrophobic pocket in the active site of the enzyme.
Subject(s)
Agaricales/enzymology , Catechol Oxidase/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Monophenol Monooxygenase/antagonists & inhibitors , Thiocarbamates/pharmacology , Binding Sites , Catechol Oxidase/chemistry , Copper/metabolism , Enzyme Inhibitors/chemistry , Monophenol Monooxygenase/chemistry , Thiocarbamates/chemistryABSTRACT
Two neutral complexes of formula [M(bpy)(cbdca)] [where M is palladium(II) (Pd(II)) or platinum(II) (Pt(II)), bpy is 2,2'-bipyridine and cbdca is anion of 1,1-cyclobutanedicarboxylic acid] have been synthesized. These water soluble complexes have been characterized by chemical analysis and conductivity measurements as well as 1H-NMR, ultraviolet-visible and infrared spectroscopy. In these complexes the ligand cbdca coordinates to Pt(II) or Pd(II) as bidentate with two oxygen atoms. They are nonelectrolyte in conductivity water. These complexes inhibit the growth of P388 lymphocytic leukemia cells and their targets are DNA. They invariably show ID50 values less than cisplatin. [Pt(bpy)(cbdca)] and [Pd(bpy)(cbdca)] have been interacted with calf thymus DNA and bind to DNA through coordinate covalent bond. In addition, the influence of binding of these complexes on the intensity of EtBr-DNA have been studied. They bind to DNA via a nonintercalating mode.
Subject(s)
2,2'-Dipyridyl/chemistry , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , DNA/drug effects , Organometallic Compounds/chemistry , Organometallic Compounds/chemical synthesis , Organometallic Compounds/pharmacology , Organoplatinum Compounds/chemistry , Organoplatinum Compounds/chemical synthesis , Organoplatinum Compounds/pharmacology , 2,2'-Dipyridyl/analogs & derivatives , Animals , Kinetics , Leukemia P388/drug therapy , Leukemia P388/pathology , Magnetic Resonance Spectroscopy , Mice , Nucleic Acid Denaturation/drug effects , Spectrometry, Fluorescence , Spectrophotometry, UltravioletABSTRACT
Four new palladium(II) and platinum(II) complexes of formula [M(dipy)(AA)]+ (where dipy is 2,2'-dipyridylamine, AA is an anion of glycine or L-alanine, and M is Pd(II) or Pt(II)) have been synthesized and characterized with amino acids binding as bidentate ligands. These complexes are 1:1 electrolyte in conductivity water. Of the above four complexes, the two L-alanine complexes show ID50 values against P388 lymphocytic leukemia cells lower than cis-diamminedichloroplatinum(II), whereas the two glycine complexes show ID50 values higher than cisplatin. The interaction of calf thymus DNA with the above complexes shows significant spectral changes in the presence of [Pt(dipy)(gly)]Cl, [Pd(dipy)(ala)]Cl, and [Pt(dipy)(ala)]Cl and the mode of binding between these complexes and DNA seems to be noncovalent.
Subject(s)
2,2'-Dipyridyl/chemistry , Amino Acids/metabolism , Antineoplastic Agents/chemical synthesis , DNA/metabolism , Palladium/chemistry , Platinum/chemistry , Alanine/chemistry , Animals , Antineoplastic Agents/metabolism , Antineoplastic Agents/therapeutic use , Cattle , Cisplatin/therapeutic use , Glycine/chemistry , Leukemia P388/drug therapy , Magnetic Resonance Spectroscopy , Palladium/metabolism , Palladium/therapeutic use , Platinum/metabolism , Platinum/therapeutic use , SpectrophotometryABSTRACT
Four water soluble complexes of the type [M(bpy)(a-x)]NO3, where M is Pd(II) or Pt(II), bpy is 2,2-bipyridine, and a-x is anion of 2-pyridinecarboxylic acid or 2-pyrazinecarboxylic acid, have been found to bind calf thymus DNA, possibly through hydrogen binding. [M(bpy)(2-py)]NO3 complexes (2-py is an anion of 2-pyridinecarboxylic acid) show I.D.50 values smaller than cisplatin whereas [M(bpy)(2-pyz)]NO3 complexes (2-pyz is an anion of 2-pyrazinecarboxylic acid) show I.D.50 values larger than cisplatin against P388 cancer cells.
Subject(s)
2,2'-Dipyridyl/analogs & derivatives , Antineoplastic Agents/metabolism , DNA/metabolism , Palladium/chemistry , Platinum/chemistry , Pyrazines/metabolism , Pyridines/metabolism , Animals , Antineoplastic Agents/therapeutic use , Cattle , Cisplatin/metabolism , Cisplatin/therapeutic use , Leukemia P388/drug therapy , Palladium/metabolism , Palladium/therapeutic use , Platinum/metabolism , Platinum/therapeutic use , Pyrazines/therapeutic use , Pyridines/therapeutic use , SpectrophotometryABSTRACT
Four new binuclear complexes of formula [M2(bipy)2(BAA)]Cl2 (where M is Pt(II) or Pd(II), bipy is 2,2'-bipyridine, and BAA is a dianion of meso-alpha-alpha'-diaminoadipic acid (DAA) or meso-alpha,alpha'-diaminosuberic acid (DSA) have been synthesized. These complexes have been characterized by chemical analysis and ultraviolet-visible, infrared, and 1H NMR spectroscopy. The mode of binding of ligands in these complexes has been ascertained by infrared and detailed 1H NMR spectroscopy. These complexes are 1:2 electrolyte in conductivity water. They have also been tested against P388 lymphocytic leukemia cells and their target is DNA molecules. [Pt2(bipy)2(DSA)]Cl2, [Pd2(bipy)2(DSA)Cl2, and [Pd2(bipy)2(DAA)]Cl2 show I.D.50 values comparable or lower than cis-diamminedichloroplatinum(II) and [Pt(bipy)(Ala)]Cl. In addition, binding studies of [Pt2(bipy)2(DSA)]Cl2 and [Pd2(bipy)2(DAA)]Cl2 to calf thymus DNA have been carried out and the mode of binding seems to be hydrogen bonding, as suggested earlier for analogous mononuclear amino acid-DNA complexes.
Subject(s)
Adipates/chemistry , Amino Acids, Diamino/chemistry , Antineoplastic Agents/chemistry , DNA/metabolism , Organometallic Compounds/chemistry , Organoplatinum Compounds/chemistry , Adipates/metabolism , Adipates/pharmacology , Amino Acids, Diamino/metabolism , Amino Acids, Diamino/pharmacology , Animals , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Cattle , Leukemia P388/drug therapy , Magnetic Resonance Spectroscopy , Molecular Structure , Organometallic Compounds/metabolism , Organometallic Compounds/pharmacology , Organoplatinum Compounds/metabolism , Organoplatinum Compounds/pharmacology , Spectrum AnalysisABSTRACT
The effect of vitamin K3 (2-methyl-1,4-naphthoquinone) on Adriamycin (ADR) induced growth inhibition of drug sensitive and multidrug resistant P388 leukemia cells was evaluated. Exposure to ADR concentrations of 100-5000 ng simultaneously with 1 microM vitamin K3 elicited an enhanced inhibition of tumor cell survival. The effect of treatment with ADR alone, or in combination with vitamin K3 on DNA and RNA biosynthesis in the sensitive and resistant tumor cells, was also assessed. DNA and RNA biosynthesis inhibition was increased in P388/S (the parental cell line) and P388/ADR cells (the ADR resistant cell line which exhibits the multidrug resistant (MDR) phenotype) exposed to ADR after pretreatment for 3 h with vitamin K3. Concurrent administration in vivo of vitamin K3 and ADR illustrated a therapeutically significant increase (P less than 0.05) in the life span of sensitive and resistant tumor cell bearing animals. Vitamin K3 caused a depletion of the intracellular glutathione (GSH) levels in P388/S and P388/ADR leukemia cells but at concentrations greater than those that enhanced ADR cytotoxicity. Pretreatment of the tumor cells with 1 microM vitamin K3 induced a 35-50% (P less than 0.001) elevation in the intracellular ADR accumulation in MDR P388 leukemia cells, while such an effect was absent in P388/S tumor cells. DNA binding studies performed utilizing calf thymus DNA, indicated that vitamin K3 enhanced the intercalation potential of ADR and also altered the equilibrium between the free and bound form of ADR in a cell free system. These factors and their possible effects on the potentiation of ADR cytotoxicity and the therapeutic significance of utilizing vitamin K3 as an adjuvant in the chemotherapy of MDR tumors is discussed.
Subject(s)
Doxorubicin/administration & dosage , Drug Resistance , Vitamin K/pharmacology , Animals , Cell Survival/drug effects , DNA/metabolism , DNA, Neoplasm/biosynthesis , Doxorubicin/metabolism , In Vitro Techniques , Leukemia P388 , Leukemia, Experimental/drug therapy , Mice , RNA, Neoplasm/biosynthesis , Spectrum Analysis , Tumor Cells, CulturedABSTRACT
Eleven new complexes of formula [M(NN)(XO3)] (where M is Pd(II) or Pt(II); NN is 2,2'-bipyridine, 1,10-phenanthroline, 2,2'-dipyridylamine, ethylenediamine or (+-)trans-1,2-diaminocyclohexane, and XO3(2-) is SeO3(2-) or TeO3(2-)) have been synthesized. These water soluble complexes have been characterized by chemical analysis and conductivity measurements as well as ultraviolet-visible and infrared spectroscopy. In these complexes the selenite or tellurite ligand coordinates to platinum(II) or palladium(II) as bidentate with two oxygen atoms. These complexes inhibit the growth of P 388 lymphocytic leukemia cells, their targets are DNA. The selenite complexes invariably show I.D.50 values less than cisplatin. However, the I.D.50 values of the tellurite complexes are usually higher than cisplatin, except that of [Pd(dach)(TeO3)] which has comparable I.D.50 values, as compared to cisplatin. [Pt(bipy)(SeO3)] and [Pd(bipy)(SeO3)] have been interacted with calf thymus DNA and bind to DNA through a coordinate covalent bond.