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1.
The growth-regulating activity of a number of substituted monophenols and related compounds has been assessed in the wheat cylinder, pea segment, pea curvature and tomato-leaf epinasty tests and the effect on activity of position, size and electronic nature of the substituents has been studied. The results indicate that, for high auxin activity, electron-attracting substituents, having certain steric properties must be substituted in the 2- and 6-positions. Furthermore, at least one of these ortho-substituents must be capable of intramolecular bonding with the hydrogen of the phenolic hydroxyl group. Any substituent in the para-position to the hydroxyl group leads to complete loss of activity and activity is reduced by meta-substitution. This new group of phenolic plant growth regulators is considered in relation to other synthetic auxins from the viewpoints of structural requirements for activity and current theories on mode of action. 相似文献
2.
Laetitia C. M. Commandeur Ralph J. May Heinrich Mokross Donna L. Bedard Walter Reineke Harrie A. J. Govers John R. Parsons 《Biodegradation》1996,7(6):435-443
In contrast to the degradation of penta-and hexachlorobiphenyls in chemostat cultures, the metabolism of PCBs by Alcaligenes sp. JB1 was shown to be restricted to PCBs with up to four chlorine substituents in resting-cell assays. Among these, the PCB congeners containing ortho chlorine substituents on both phenyl rings were found to be least degraded. Monochloro-benzoates and dichlorobenzoates were detected as metabolites. Resting cell assays with chlorobenzoates showed that JB1 could metabolize all three monochlorobenzoates and dichlorobenzoates containing only meta and para chlorine substituents, but not dichlorobenzoates possessing an ortho chlorine substituent. In enzyme activity assays, meta cleaving 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase activities were constitutive, whereas benzoate dioxygenase and ortho cleaving catechol 1,2-dioxygenase activities were induced by their substrates. No activity was found for pyrocatechase II, the enzyme that is specific for chlorocatechols. The data suggest that complete mineralization of PCBs with three or more chlorine substituents by Alcaligenes sp. JB1 is unlikely.Abbreviations PCB
polychlorinated biphenyls
- CBA
chlorobenzoate
- D
di
- Tr
tri
- Te
tetra
- Pe
penta-
- H
hexa 相似文献
3.
Rima Ezzeddine Anwar Al-Banaw Artak Tovmasyan James D. Craik Ines Batinic-Haberle Ludmil T. Benov 《The Journal of biological chemistry》2013,288(51):36579-36588
Tetra-cationic Zn(II) meso-tetrakis(N-alkylpyridinium-2 (or -3 or -4)-yl)porphyrins (ZnPs) with progressively increased lipophilicity were synthesized to investigate how the tri-dimensional shape and lipophilicity of the photosensitizer (PS) affect cellular uptake, subcellular distribution, and photodynamic efficacy. The effect of the tri-dimensional shape of the molecule was studied by shifting the N-alkyl substituent attached to the pyridyl nitrogen from ortho to meta and para positions. Progressive increase of lipophilicity from shorter hydrophilic (methyl) to longer amphiphilic (hexyl) alkyl chains increased the phototoxicity of the ZnP PSs. PS efficacy was also increased for all derivatives when the alkyl substituents were shifted from ortho to meta, and from meta to para positions. Both cellular uptake and subcellular distribution of the PSs were affected by the lipophilicity and the position of the alkyl chains on the periphery of the porphyrin ring. Whereas the hydrophilic ZnPs demonstrated mostly lysosomal distribution, the amphiphilic hexyl derivatives were associated with mitochondria, endoplasmic reticulum, and plasma membrane. A comparison of hexyl isomers revealed that cellular uptake and partition into membranes followed the order para > meta > ortho. Varying the position and length of the alkyl substituents affects (i) the exposure of cationic charges for electrostatic interactions with anionic biomolecules and (ii) the lipophilicity of the molecule. The charge, lipophilicity, and the tri-dimensional shape of the PS are the major factors that determine cellular uptake, subcellular distribution, and as a consequence, the phototoxicity of the PSs. 相似文献
4.
John R. Cashman Ketankumar K. Parikh George J. Traiger Robert P. Hanzlik 《Chemico-biological interactions》1983,45(3):341-347
Thiobenzamide is known to be hepatotoxic in the rat and the relative hepatotoxicity of para-substituted thiobenzamides has previously been shown to depend strictly on the electronic character of the para substituent. We have now extended this study to include ortho and meta monosubstituted thiobenzamides. Among the meta-substituted compounds, hepatotoxicity varies in strict accordance with the electronic character of the substituent, whereas the ortho-substituted compounds show no toxicity at comparable doses regardless of the nature of the substituent. Explanations for these substituent effects are provided in terms of the chemical reactivity of the compounds and their corresponding S-oxide and S,S-dioxide metabolites. 相似文献
5.
Poly(ortho-, meta-, and para-γ-nitrobenzyl-L -glutamates) were studied by circular dichroism (CD) and optical rotatory dispersion (ORD) in two helicogenic solvents, hexafluoroisopropanol (HFIP) and dichloroethane (EDC), and two non-helicogenic solvents, dichloracetic acid (DCA) and trifluoroacetic acid (TFA). The corresponding glutamates were also studied in DCA and TFA. The symmetric nitrobenzylic chromophore is optically active when the polymers are in solution in DCA and TFA. The corresponding glutamates are also optically active under the same conditions. Thus, it was not possible to explain the origin of the optical activity of the side-chain chromophore when the polymer is in solution in a helicogenic solvent. Nevertheless, from a side-chain dichroic band, a helix–coil transition curve was determined and the stability of each poly(γ-nitrobenzyl-L -glutamate) given; this stability depends on the position of the nitro substituent on the aromatic ring. 相似文献
6.
Chiyozo Takayama Osamu Kirino Yoshio Hisada Akira Fujinami 《Bioscience, biotechnology, and biochemistry》2013,77(6):1547-1552
The antifungal activity of 441-acyl derivatives of 3-(3,5-dichlorophenyl)-2,4-imidazol- idinedione against Botrytis cinerea, and of 10 1-sulfonyl compounds against Aiternaria kikuchi- ana were assayed by the agar medium dilution method. The structure-activity relationships for the substituents of the acyl and sulfonyl moieties were analyzed with such physicochemical parameters as hydrophobic π, inductive electronic σ1, and steric E′cs and B1 values by multiple regression. The activity of the acyl derivatives against B. cinerea was related parabolically to the hydrophobicity of the substituents. The stronger the electron-donating power, the larger the overall steric bulkiness, and the smaller the minimum width in the direction perpendicular to the bond axis of the substituents, the greater was the activity. The activity of the sulfonyl derivatives against A. kikuciana was related only to the hydrophobicity of the substituents. 相似文献
7.
Enza Lacivita Marcello Leopoldo Paola De Giorgio Francesco Berardi Roberto Perrone 《Bioorganic & medicinal chemistry》2009,17(3):1339-1344
In order to design a potential drug, it is important to know its pKa because the protonation state of the molecule will be critical for ligand–receptor interaction and for the pharmacokinetic of the molecule. pKa values of a series of 1-(substitutedphenyl)-4-propylpiperazines were measured to study how the presence of a substituent on the phenyl ring modulates the basicity of N-4 nitrogen. pKa values indicated that the position of the substituent was crucial. In general, the introduction of the substituent in ortho-position of the phenyl ring increased the basicity of the molecule. This effect appeared to be related to steric and conformational effects and not to the electronic properties of the substituent. On the other hand, meta- and para-substituted derivatives showed a slight decrease of pKa that was qualitatively consistent with the electronic properties of the substituent. 相似文献
8.
Munei Y Shimamoto K Harada M Yoshida T Chuman H 《Bioorganic & medicinal chemistry letters》2011,21(1):141-144
We proposed a novel QSAR (quantitative structure-activity relationship) procedure called LERE (linear expression by representative energy terms)-QSAR involving molecular calculations such as ab initio fragment molecular orbital and generalized Born/surface area ones. We applied LERE-QSAR to two datasets for the free-energy changes during complex formation between carbonic anhydrase and a series of substituted benzenesulfonamides. The first compound set (Set I) and the second one (Set II) include relatively small substituents and alkyl chains of different lengths in the benzene ring, respectively. Variation of the inhibitory activity in Set I is expressed as the combination of Hammett σ and the hydrophobic substituent constant π in classical QSAR, and variation in Set II only by π. LERE-QSAR analyses clearly revealed that effects of σ and π on the activity variations in Sets I and II are consistently explainable with the energy terms in the LERE formulation, and provide more detailed and direct information as to the binding mechanism. The proposed procedure was demonstrated to provide a quantitative basis for understanding ligand-protein interactions at the electronic and atomic levels. 相似文献
9.
Hajime Iwamura Toshio Fujita Shiro Koyama Koichi Koshimizu Zenzaburo Kumazawa 《Phytochemistry》1980,19(7):1309-1319
The substituent effect of N6-alkyl and -aralkyl adenines on the promotion of the growth of tobacco callus was analysed quantitatively using physico-chemical substituent parameters and regression analysis. The results indicated an optimum steric condition for activity in terms of the maximum width of the N6-substituents from the bond-axis connecting the N6-atom with its α carbon atom. The electron withdrawing effect of the N6-substituent enhances the activity. The substituent effect on the cytokinin activity of phenyl- and diphenyl- urea derivatives determined by Bruce and Zwar using the tobacco pith-block assay was also analysed. The results suggest that position-specific steric and hydrophobic effects of aromatic substituents participate in the variation in activity rationalizing the general trend of the activity; meta >para >ortho derivatives, for both series of compounds. The electronic effect is significant for the activity of diphenylureas but not for that of phenylureas which show somewhat different modes of interaction between the two series at the site of action. Based on inferences made from the correlations, hypothetical maps for the mode of interaction of these three sets of compounds at the site of action have been proposed. 相似文献
10.
B. K. Sharma S. K. Sharma P. Singh Susheela Sharma 《Journal of enzyme inhibition and medicinal chemistry》2013,28(2):168-173
The tyrosine kinase inhibitory action of the derivatives of N-Phenyl-N′-{4-(4-quinolyloxy)phenyl}urea is quantitatively analyzed using multiple regression analysis. The analysis has helped to ascertain the role of different substituents in explaining the observed inhibitory actions of these compounds for two receptors, namely vascular endothelial growth factor receptor 2 (VEGFR-2) and platelet-derived growth factor receptor α (PDGFRα). From a derived significant correlation equation for inhibition of VEGFR-2, it was concluded that a less hydrophobic molecule with ortho-substituent(s), exerting less steric hindrance and para-substituent devoid of hydrogen-bond acceptor property augment the inhibition action. Besides, a 3-substituent transmitting a higher negative field effect is advantageous to improve the pIC50 value of a compound. The correlation equation, derived for the inhibition of PDGFRα, has revealed that a less hydrophobic molecule, having a 3-substituent which transmits a more negative resonance effect, is helpful in raising its activity. Likewise, in the middle phenyl ring, absence of a fluoro substituent augments the inhibitory activity. Based on derived QSAR equations pertaining to VEGF-2 and PDGFα receptors, the drawn guidelines for selection of substituents, may be used to synthesize potent compounds in future. 相似文献
11.
The enantioselective hydroformylation catalyzed by [(R,R)-Diop]Pt(SnCl3)Cl7 and the enantioselective hydroisopropoxycarbonylation catalyzed by [(R,R)-Diop]PdCl28 or by [(R,R)-Diop-dbp]PdCl29 of some para-substituted 2-phenylpropenes (para substituents = NO2, H, CH3O, Cl, CF3) was investigated in order to recognize possible electronic influences on the regioselectivity and on the enantioface selection which take place in such carbonylation reactions. The catalytic systems used gave no carbonylation products when the nitro compound was the substrate. 7 and 8 show similar regioselectivities, the less branched isomer being exclusively formed for all substrates except p-methoxy-2-phenylpropene which gave small amounts of the alternative regioisomer. The enantioselectivity depends on the σp effect of the substituent in both cases; the differences are, however, rather small and the trend is opposite in the two cases. The regioselectivity displayed by 9 is still in favour of the less branched isomer but it is high only in the case of p-trifluoromethyl-2-phenylpropene. Larger differences with respect to the other catalytic systems were also observed for enantioselectivity but the trend for both regioselectivity and enantioselectivity is not linear. 相似文献
12.
Synthesis and Enantioseparation Ability of Xylan Bisphenylcarbamate Derivatives as Chiral Stationary Phases in HPLC
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Ten novel xylan bisphenylcarbamate derivatives bearing meta‐ and para‐substituents on their phenyl groups were synthesized and their chiral recognition abilities were evaluated as the chiral stationary phases (CSPs) for high‐performance liquid chromatography (HPLC) after coating them on macroporous silica. The chiral recognition abilities of these CSPs depended on the nature, position, and number of the substituents on the phenyl moieties. The introduction of an electron‐donating group was more attractive than an electron‐withdrawing group to improve the chiral recognition ability of the xylan phenylcarbamate derivatives. Among the CSPs discussed in this study, xylan bis(3,5‐dimethylphenylcarbamate)‐based CSP seems to possess the highest resolving power for many racemates, and the meta‐substituted CSPs showed relatively better chiral recognition than the para‐substituted ones. For some racemates, the xylan bis(3,5‐dimethylphenylcarbamate) derivative exhibited higher enantioselectivity than the CSP based on cellulose tris(3,5‐dimethylphenylcarbamate). Chirality 27:518–522, 2015 © 2015 Wiley Periodicals, Inc. 相似文献
13.
Vicarious nucleophilic substitution reactions are a versatile way of introducing substituents into aromatic and heteroaromatic electron-deficient compounds. In this project, a kinetic study of these reactions by applying quantum mechanics concepts, such as reaction force, force constant, and electronic reaction flow was proposed. Furthermore, absolute theoretical scales of electrophilicity by applying density functional theory electronic indices were established to classify a series of five and six-membered nitroheteroarenes, and nitrobenzenes with substituents in ortho, meta and para positions. The theoretical model was validated by comparison with experimental kinetic results. Calculations using B3LYP/6-311G(d,p) level of theory allowed analysis of the reactivity patterns and the mechanisms of these chemical reactions. The theoretical scale properly accounts for the activating/deactivating effects promoted by the substituents and agrees with the ability of these substituents to accept or donate electrons, electron acceptor substituents are those that increase electrophilicity, and electron donors those that reduce it. 相似文献
14.
Masami Abe Hironori Umetsu Takao Nakai Denkichi Sasage 《Bioscience, biotechnology, and biochemistry》2013,77(7):1955-1957
The Hill-reaction inhibitory activity of 30 derivatives of 2-difluoromethylthio-1,3,5-triazine was determined using chlorella. The structure-activity relationships were analyzed using the hydrophobic parameter (log P), the electronic substituent constant (c) and the steric substituent constant (Es). The Hill-reaction inhibitory activity showed a parabolic relationship to log P and the steric substituent parameters at 4,6-dialkylamino- positions in the triazine ring. The equation revealed that optimum hydrophobicity and size of the substituents were necessary for high activity. 相似文献
15.
Shuichi Ishida Mitsuo Ida Osamu Yamada 《Bioscience, biotechnology, and biochemistry》2013,77(4):410-421
Formation of a sulfonium-like intermediate was assumed in the hydrolysis of the 2-bromoethylthiobenzenes. A linear free energy relationship was found between the hydrolysis rate of a certain substituted 2-bromoethylthiobenzene and the molar fraction of water in the solvent. The effect of the substituent on the rate constant was attributed not only to the activation energy but also to the entropy change of activation. The negative ρ-value in the formation of the sulfonium-like intermediate in aqueous solution was comparable with that obtained in the ρ-σ-π analysis for ovicidal activity of the compounds.For the reaction of the substituted 2-bromoethylthiobenzenes with highly excess amount of 4-(p-nitrobenzyl)-pyridine, the ρ-value was found to be negative, which means that the formation of the sulfonium-like intermediate is a rate determining step. Whichever might be more important, the hydrolysis or alkylation, as to the ovicidal action of the compounds, the formation of the sulfonium-like intermediate, could be considered to be an essential step. 相似文献
16.
G. Sauret-Ignazi Jean Gagnon Claude Béguin Michel Barrelle Yves Markowicz Jean Pelmont Ariane Toussaint 《Archives of microbiology》1996,166(1):42-50
Alcaligenes eutrophus CH34 used benzoate as a sole source of carbon and energy, degrading it through the 3-oxoadipate pathway. All the enzymes
required for this degradation were shown to be encoded by chromosomal genes. Catechol 1,2-dioxygenase activity was induced
by benzoate, catechol, 4-chlorocatechol, and muconate. The enzyme is most likely a homodimer, with an apparent molecular weight
of 76,000 ± 500. According to several criteria, its properties are intermediate between those of catechol 1,2-dioxygenases
(CatA) and chlorocatechol 1,2-dioxygenases (ClcA). The determined K
m for catechol is the lowest among known catechol and chlorocatechol dioxygenases. Similar K
m values were found for para-substituted catechols, although the catalytic constants were much lower. The catechol 1,2-dioxygenase from strain CH34 is
unique in its property to transform tetrachlorocatechol; however, excess substrate led to a marked reversible inhibition.
Some meta- and multi-substituted catechols behaved similarly. The determined K
m (or K
i) values for para- or meta-substituted catechols suggest that the presence of an electron-withdrawing substituent at one of these positions results
in a higher affinity of the enzyme for the ligand. Results of studies of recognition by the enzyme of various nonmetabolised
aromatic compounds are also discussed.
Received: 20 November 1996 / Accepted: 11 April 1996 相似文献
17.
Noncentrosymmetric π conjugated systems with suitable electron donor acceptor groups play a crucial role in material NLO activity. The influence of an electron donating mono substituent at the para position of the phenylene ring of chalcone was investigated as a resource for second harmonic generation. The geometrical optimization of 11 electron donating group substituted chalcones were performed using density functional theory at the B3LYP/6-311G(d,p) level and compared with experimental geometrical parameters of five reported chalcones. All the derivatives are transparent to visible radiation as shown by the electronic absorption spectra investigated by the TDDFT-CAM B3LYP/6-311G(d,p) method, and the maximum absorption wavelength was due to the πPhB?→?π* transition. The first order hyperpolarizability βtot, calculated using the CAM B3LYP/6-311G(d,p) method, increases with the electron donating ability of the substituent, and the largest βtot was observed for dimethylamino substituent. The Hammett substituent constant (σp) shows good linear correlation with β, λmax, and Egap in the ground state. The Brown constant (σp+) was better correlated indicating the polarization of carbonyl group in the excited state. Frontier molecular orbitals also reveal the valence electron excitation. Correlation of σp with various parameters was analyzed to assess the property interrelationship with electronic reorganization in the molecule. The electronic structures of molecular fragments were described in terms of natural bond orbital analysis, which shows intramolecular interactions. 相似文献
18.
Hajipour AR Guo LW Pal A Mavlyutov T Ruoho AE 《Bioorganic & medicinal chemistry》2011,19(24):7435-7440
The sigma-2 (σ2) receptor has been suggested to be a promising target for pharmacological interventions to curb tumor progression. Development of σ2-specific ligands, however, has been hindered by lack of understanding of molecular determinants that underlie selective ligand-σ2 interactions. Here we have explored effects of electron donating and withdrawing groups on ligand selectivity for the σ2 versus σ1 receptor using new benzamide-isoquinoline derivatives. The electron-donating methoxy group increased but the electron-withdrawing nitro group decreased σ2 affinity. In particular, an extra methoxy added to the para-position (5e) of the benzamide phenyl ring of 5f dramatically improved (631 fold) the σ2 selectivity relative to the σ1 receptor. This para-position provided a sensitive site for effective manipulation of the sigma receptor subtype selectivity using either the methoxy or nitro substituent. Our study provides a useful guide for further improving the σ2-over-σ1 selectivity of new ligands. 相似文献
19.
Intraventricular injection into the rat brain of four trace amines and a catecholamine resulted in rapid exponential loss of the amines in the first 30 minutes after injection. The half-lives were: phenylethylamine 3.8 min,para-tyramine 5.1 min,meta-tyramine 7.4 min and dopamine 8.0 min. Tryptamine showed a biphasic loss with half-lives of 4.7 min (over the 5 to 10 min period) and 14.1 min (10 to 30 min). The half-lives were substantially increased by deuterium labeling at the alpha carbon position: phenylethylamine 4.8 min,para-tyramine 8.8 min,meta-tyramine 14.1 min, dopamine 13.0 min and tryptamine 6.0 min (5 to 10 min period) and 28.7 min (10 to 20 min). The loss of the amines was reduced by monoamine oxidase inhibition by pargyline hydrochloride and the deuterium isotope effect was abolished. It is noteworthy that the half-life of dopamine was similar to those of the trace amines in this time period and that the trace amine half-lives after i.v. injection was longer than those obtained from measurements of increases of concentrations of endogenous amines after MAOI in vivo and that of dopamine shorter than values calculated from turnover measurements. 相似文献
20.
Yiqun Geng Amit Kumar Hassan M. Faidallah Hassan A. Albar Ibrahim A. Mhkalid Richard R. Schmidt 《Bioorganic & medicinal chemistry》2013,21(16):4793-4802
Several C-(α-d-glucopyranosyl)-phenyldiazomethanes, with different substituent groups at the para-position of the phenyl ring, were prepared. The stabilities of these diazo compounds were investigated through NMR and UV monitoring. The para-cyano substituted diazo compound was found to be stable in neutral media (pH 7.0 buffer) and could be isolated. Inhibitory activity investigations indicated that this compound is an irreversible inhibitor against α-glucosidase from Saccharomyces cerevisiae. 相似文献