salicylates and 3-5-dichlorosalicylic-acid

The present work demonstrates a detailed characterization of the interaction of a bio-active drug molecule 3,5-dichlorosalicyclic acid (3,5DCSA) with a model transport protein Bovine Serum Albumin (BSA). The drug molecule is a potential candidate exhibiting Excited-State Intramolecular Proton Transfer (ESIPT) reaction and the modulation of ESIPT photophysics within the bio-environment of the protein has been exploited spectroscopically to monitor the drug-protein binding interaction. Apart from evaluating the binding constant (K (±10%) = 394 M(-1)) the probable location of the neutral drug molecule within the protein cavity (hydrophobic subdomain IIA) is explored by AutoDock-based blind docking simulation. The rotational relaxation dynamics of the drug within the protein has been interpreted on the lexicon of the two-step and wobbling-in-cone model. Circular dichroism (CD) spectroscopy delineates the effect of drug binding on the protein secondary structure in terms of decrease of α-helical content of BSA with increasing drug concentration. Also the esterase activity of the drug:protein conjugate system is found to be reduced in comparison to the native protein.

Topics: Animals; Anti-Infective Agents; Cattle; Chlorobenzoates; Circular Dichroism; Fluorescence Polarization; Models, Molecular; Protein Binding; Protein Structure, Secondary; Salicylates; Serum Albumin, Bovine; Spectrometry, Fluorescence; Spectrophotometry

Aldose reductase (ALR2) belongs to the aldo-keto reductase (AKR) superfamily of enzymes, is the first enzyme involved in the polyol pathway of glucose metabolism and has been linked to the pathologies associated with diabetes. Molecular modelling studies together with binding constant measurements for the four inhibitors Tolrestat, Minalrestat, quercetin and 3,5-dichlorosalicylic acid (DCL) were used to determine the type of inhibition, and correlate inhibitor potency and binding energies of the complexes with ALR2 and the homologous aldehyde reductase (ALR1), another member of the AKR superfamily. Our results show that the four inhibitors follow either uncompetitive or non-competitive inhibition pattern of substrate reduction for ALR1 and ALR2. Overall, there is correlation between the IC(50) (concentration giving 50% inhibition) values of the inhibitors for the two enzymes and the binding energies (DeltaH) of the enzyme-inhibitor complexes. Additionally, the results agree with the detailed structural information obtained by X-ray crystallography suggesting that the difference in inhibitor binding for the two enzymes is predominantly mediated by non-conserved residues. In particular, Arg312 in ALR1 (missing in ALR2) contributes favourably to the binding of DCL through an electrostatic interaction with the inhibitor's electronegative halide atom and undergoes a conformational change upon Tolrestat binding. In ALR2, Thr113 (Tyr116 in ALR1) forms electrostatic interactions with the fluorobenzyl moiety of Minalrestat and the 3- and 4-hydroxy groups on the phenyl ring of quercetin. Our modelling studies suggest that Minalrestat's binding to ALR1 is accompanied by a conformational change including the side chain of Tyr116 to achieve the selectivity for ALR1 over ALR2.

Topics: Aldehyde Reductase; Animals; Catalytic Domain; Chlorobenzoates; Computer Simulation; Crystallography, X-Ray; Enzyme Inhibitors; Humans; Imides; Inhibitory Concentration 50; Kinetics; Models, Molecular; Naphthalenes; Quercetin; Quinolones; Recombinant Proteins; Salicylates; Structure-Activity Relationship; Swine; Thermodynamics

The crystal structure of human 20alpha-hydroxysteroid dehydrogenase (AKR1C1) in ternary complex with the coenzyme NADP (+) and the potent inhibitor 3,5-dichlorosalicylic acid was determined at a resolution of 1.8 A. The inhibitor is held in place by a network of hydrogen bonding interactions with the active site residues Tyr55, His117, and His222. The important role of the nonconserved residues Leu54, His222, Leu306, and Leu308 in inhibitor binding and selectivity was determined by site-directed mutagenesis.

Topics: 20-alpha-Hydroxysteroid Dehydrogenase; Binding Sites; Chlorobenzoates; Coenzymes; Crystallography, X-Ray; Enzyme Inhibitors; Humans; Isoenzymes; Models, Molecular; Mutation; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Salicylates; Structural Homology, Protein

The structure of aldehyde reductase (ALR1) in ternary complex with the coenzyme NADPH and 3,5-dichlorosalicylic acid (DCL), a potent inhibitor of human 20alpha-hydroxysteroid dehydrogenase (AKR1C1), was determined at a resolution of 2.41A. The inhibitor formed a network of hydrogen bonds with the active site residues Trp22, Tyr50, His113, Trp114 and Arg312. Molecular modelling calculations together with inhibitory activity measurements indicated that DCL was a less potent inhibitor of ALR1 (256-fold) when compared to AKR1C1. In AKR1C1, the inhibitor formed a 10-fold stronger binding interaction with the catalytic residue (Tyr55), non-conserved hydrogen bonding interaction with His222, and additional van der Waals contacts with the non-conserved C-terminal residues Leu306, Leu308 and Phe311 that contribute to the inhibitor's selectivity advantage for AKR1C1 over ALR1.

Topics: Aldehyde Reductase; Animals; Binding Sites; Chlorobenzoates; Crystallography, X-Ray; Enzyme Inhibitors; Hydrogen Bonding; Hydrogen-Ion Concentration; Models, Molecular; Molecular Structure; NADP; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins; Salicylates; Swine; X-Ray Diffraction

To investigate the involvement of cytochrome P450s in the metabolism of plants treated with xenobiotic agrochemicals, bean leaves were treated with 3,5-dichlorosalicylic acid (DC-SA), a priming agent of plant defense and 2,6-dichloroisonicotinic acid (DC-INA), a chemical inducer of systemic acquired resistance. Through the use of directed differential display reverse transcription polymerase chain reactions, a differentially expressed cDNA amplicon, found to be up-regulated by both DC-SA and DC-INA treatment, was identified as a cytochrome P450 cDNA, CYP98A5. The nucleotide sequence indicates extensive homology to 3'-hydroxylases of p-coumaroyl esters. Dot blot analysis of leaves treated with various SA and isonicotinic acid derivatives showed enhanced expression of CYP98A5 due to DC-SA and DC-INA. Northern blot analysis of a time-dependent induction study of CYP98A5 in treated bean leaves indicated that DC-SA induces CYP98A5 mRNA transcripts earlier than DC-INA. Both inducers resulted in high transcript levels 24-48 h after treatment. The up-regulation of CYP98A5 is supportive of the conditioning and sensitizing effects of DC-SA and DC-INA to elicit a more rapid and effective defense response.

Topics: Amino Acid Sequence; Base Sequence; Chlorobenzoates; Cloning, Molecular; Cytochrome P-450 Enzyme System; DNA Primers; DNA, Complementary; DNA, Plant; Enzyme Induction; Genes, Plant; Isonicotinic Acids; Molecular Sequence Data; Phaseolus; Plant Leaves; Polymerase Chain Reaction; RNA, Messenger; RNA, Plant; Salicylates; Sequence Homology, Amino Acid

An effective and novel approach to obtaining electrorheological particles with high performance through the formation of host-guest complexes has been achieved. The significant preponderance of the host-guest complex formation is that the host structure can be controlled easily by adding different guests. Based on this point, six supramolecular complexes of beta-cyclodextrin cross-linking polymer with salicylic acid (beta-CDP-1), 5-chlorosalicylic acid (beta-CDP-2), 3,5-dichlorosalicylic acid (beta-CDP-3), 5-nitrosalicylic acid (beta-CDP-4), 3,5-dinitrosalicylic acid (beta-CDP-5), or 3-hydroxy-2-naphthoic acid (beta-CDP-6) particles were synthesized. The electrorheological yield stresses of the suspensions of these particles in silicone oil have been investigated under DC electric fields. It was found that the yield stress of the typical beta-CDP-1 ER fluid was 5.6 kPa in 4 kV/mm, which is much higher than that of pure beta-cyclodextrin polymer (beta-CDP), that of pure salicylic acid as well as that of the mixture of the host with the guest. It is clearly indicated that the formation of supramolecular complexes between beta-CDP and salicylic acid can enhance the ER properties of the host. The similar results for other supramolecular complexes with different guests have also been obtained under the same DC electric fields. The yield stress of supramolecular complexes is strongly affected by the structure of guests. Among the six investigated guests, 3-hydroxy-2-naphthoic acid gave the highest ER property having a yield stress of 9.8 kPa under 4 kV/mm DC while cross-linked with beta-CDP to form beta-CDP-6. The yield stress of beta-CDP-6 was significantly increased by 72% in comparison with that of the pure beta-CDP. However, the yield stress of beta-CDP-1-5 slightly increased by 34-41% as compared with that of the pure beta-CDP. The achieved results indicate that the ER effect of host-guest complexes can be greatly affected by the changes of the tremendous guest structure, whereas the slight guest structural transposition, such as altering different groups of a guest, can only obtain the adjacent electrorheological behavior. The dielectric properties of these host-guest complexes also proved that the ER effect can be affected by the properties of guest.

Topics: beta-Cyclodextrins; Chlorobenzoates; Electrophoresis; Molecular Structure; Naphthols; Particle Size; Polymers; Rheology; Salicylates; Salicylic Acid; Silicone Oils; Static Electricity