Bioisosteric Modification of To042: Synthesis and Evaluation of Promising Use-Dependent Inhibitors of Voltage-Gated Sodium Channels

Three analogues of To042, a tocainide-related lead compound recently reported for the treatment of myotonia, were synthesized and evaluated in vitro as skeletal muscle sodium channel blockers possibly endowed with enhanced use-dependent behavior. Patch-clamp experiments on hNav1.4 expressed in HEK293 cells showed that N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine, the aryloxyalkyl bioisostere of To042, exerted a higher use-dependent block than To042 thus being able to preferentially block the channels in over-excited membranes while preserving healthy tissue function. It also showed the lowest active transport across BBB according to the results of P-glycoprotein (P-gp) interacting activity evaluation and the highest cytoprotective effect on HeLa cells. Quantum mechanical calculations and dockings gave insights on the most probable conformation of the aryloxyalkyl bioisostere of To042 in solution and the target residues involved in the binding, respectively. Both approaches indicated the conformations that might be adopted in both the unbound and bound state of the ligand. Overall, N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine exhibits an interesting toxico-pharmacological profile and deserves further investigation.

Biased action of the CXCR4-targeting drug plerixafor is essential for its superior hematopoietic stem cell mobilization

Following the FDA-approval of the hematopoietic stem cell (HSC) mobilizer plerixafor, orally available and potent CXCR4 antagonists were pursued. One such proposition was AMD11070, which was orally active and had superior antagonism in vitro; however, it did not appear as effective for HSC mobilization in vivo. Here we show that while AMD11070 acts as a full antagonist, plerixafor acts biased by stimulating β-arrestin recruitment while fully antagonizing G protein. Consequently, while AMD11070 prevents the constitutive receptor internalization, plerixafor allows it and thereby decreases receptor expression. These findings are confirmed by the successful transfer of both ligands' binding sites and action to the related CXCR3 receptor. In vivo, plerixafor exhibits superior HSC mobilization associated with a dramatic reversal of the CXCL12 gradient across the bone marrow endothelium, which is not seen for AMD11070. We propose that the biased action of plerixafor is central for its superior therapeutic effect in HSC mobilization.

Interaction of protonated merocyanine dyes with amines in organic solvents

2,6-Diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate (1a) and 4-[(1-methyl-4(1H)-pyridinylidene)-ethylidene]-2,5-cyclohexadien-1-one (2a) were protonated in organic solvents (dichloromethane, acetonitrile, and DMSO) to form 1b and 2b, respectively. The appearance of the solvatochromic bands of 1a and 2a was studied UV-vis spectrophotometrically by deprotonation of 1b and 2b in solution in the presence of the following amines: aniline (AN), N-methylaniline (NMAN), N,N-dimethylaniline (NDAN), n-butylamine (BA), diethylamine (DEA), and triethylamine (TEA). Titrations of 1b and 2b with the amines were carried out and the binding constants were determined from the titration curves in each solvent, using a mathematical model adapted from the literature which considers the simultaneous participation of two dye: amine stoichiometries, 1:1 and 1:2. The data obtained showed the following base order for the two compounds in DMSO: BA>DEA>TEA, while aromatic amines did not cause any effect. In dichloromethane, the following base order for 1b was verified: TEA>DEA>BA≫NDAN, while for 2b the order was: TEA>DEA>BA, suggesting that 1b is more acidic than 2b. The data in acetonitrile indicated for 1b and 2b the following order for the amines: DEA>TEA>BA. The diversity of the experimental data were explained based on a model that considers the level of interaction of the protonated dyes with the amines to be dependent on three aspects: (a) the basicity of the amine, which varies according to their molecular structure and the solvent in which it is dissolved, (b) the molecular structure of the dye, and (c) the solvent used to study the system.

Synthesis, pharmacological and in silico evaluation of 1-(4-di-hydroxy-3,5-dioxa-4-borabicyclo[4.4.0]deca-7,9,11-trien-9-yl)-2-(tert-butylamino)ethanol, a compound designed to act as a beta2 adrenoceptor agonist

In this study, 1-(4-di-hydroxy-3,5-dioxa-4-borabicyclo[4.4.0]deca-7,9,11-trien-9-yl)-2-(tert-butylamino)ethanol, (BR-AEA), was designed, synthesized, characterized and tested in docking studies and in vitro. Previous to its synthesis, a set of compounds, including well-known ligands and boron containing compounds, were studied under docking simulations. BR-AEA showed greater affinity than these well-known agonists and was found to be slightly closer than salbutamol to the residues in the TM5 and TM3 of the beta(2) adrenoceptor (beta(2)AR), making a greater number of interactions with them, including some that are apparently key to greater affinity and beta(2)AR activation. This study suggests that affinity is closely related to the interactions of the boron atom, as well as the capacity of boronic acid moieties to make a network of hydrogen bonds with the beta(2)AR. In vitro, the relaxing effects of BR-AEA on isolated guinea pig tracheal rings were compared with salbutamol. The EC(50) values for BR-AEA were at least five-fold lower than for salbutamol, showing the greater potency of the former. Additionally, propranolol and ICI 118,551 showed competitive antagonism in relation to the relaxing effect of the test compound (pA(2) 6.204+/-0.367 and 9.089+/-0.470, respectively).

Caffeic acid derivatives production by hairy root cultures of Echinacea purpurea

Inoculation of leaf explants of Echinacea purpurea (Moench) with Agrobacterium rhizogenes induced hairy roots with the capacity to produce biologically active caffeic acid derivatives (CADs), especially cichoric acid. The kinetics of growth, the uptake of macronutrients, and the accumulation of CADs were investigated in heterotrophically cultured hairy roots for a 50 day period. A maximum of 12.2 g L(-1) dry biomass was achieved in MS nutrients supplemented with 30 g L(-1) sucrose on day 40. The mathematical relationship between hairy root growth and conductivity was established during the exponential phase in Erlenmeyer flasks. HPLC analyses of methanolic (0.1% phosphoric acid; 70:30, v/v) extracts from hairy roots revealed the presence of important CADs: cichoric acid (19.21 mg g(-1) dry biomass), caftaric acid (3.56 mg g(-1) dry biomass), and chlorogenic acid (0.93 mg g(-1) dry biomass). These results demonstrate that biotechnological production of CADs in hairy roots of E. purpurea is possible. Furthermore, these hairy root cultures offer, for the very first time, an excellent biological model to study the biosynthetic pathway of medicinally important CADs.

Glycerol, ethylene glycol and propanediol elicit pimaricin biosynthesis in the PI-factor-defective strain Streptomyces natalensis npi287 and increase polyene production in several wild-type actinomycetes

Production of pimaricin by Streptomyces natalensis ATCC 27448 is elicited by the PI-factor, an autoinducer secreted by the producer strain during the rapid growth phase. Exogenous PI-factor restored pimaricin production in a mutant strain npi287 defective in PI-factor biosynthesis. During purification of the PI-factor, a second pimaricin-inducing fraction different from PI-factor was isolated from the culture broth of wild-type S. natalensis ATCC 27448. After purification by HPLC and analysis by MS and NMR, this active fraction was shown to contain glycerol and lactic acid. Pure glycerol restored pimaricin production in liquid cultures of the autoinducer-defective npi287 mutant. A similar effect was exerted by ethylene glycol, 1,2-propanediol and 1,3-propanediol but not by higher polyalcohols or by glycerol acetate or glycerol lactate esters. Glycerol stimulated (30–270 %) the production of six different polyene macrolide antibiotics by their respective producer strains. Addition of glycerol to the inducer-defective npi287 strain restored pimaricin production but did not result in extracellular or intracellular accumulation of PI-factor. Exogenously added PI-factor was internalized by the cells in the presence of glycerol, and a mixture of both PI-factor and glycerol produced a slightly higher inducing effect on pimaricin production than PI-factor alone. In summary, glycerol, ethylene glycol and propanediol exert a bypass of the PI-factor inducing effect on pimaricin biosynthesis.

Comparison of four mass analyzers for determining carbosulfan and its metabolites in citrus by liquid chromatography/mass spectrometry

Four liquid chromatography/mass spectrometry (LC/MS) systems, equipped with single quadrupole, triple quadrupole (QqQ), quadrupole ion trap (QIT) and quadrupole time-of-flight (QqTOF) mass analyzers, were evaluated for the analysis of carbosulfan and its main transformation products. The comparison of quantitative aspects (sensitivity, precision and accuracy) was emphasized. Results showed that the triple quadrupole instrument reaches at least 20-fold higher sensitivity (LOD from 0.04 to 0.4 microg kg(-1)) compared to the single quadrupole (4-70 microg kg(-1)), the QIT (4-25 microg kg(-1)) and the QqTOF (4-23 microg kg(-1)) instruments. Recoveries were over 70% for all the analytes, except dibutylamine and 7-phenolcarbofuran. Repeatabilities (within-day) were slightly better by the single quadrupole (5-10%) and the QqQ (5-9%) than by the QIT (12-16%) and the QqTOF (9-16%). Both the QqTOF and QIT offer a linear dynamic range of two orders of magnitude whereas the single quadrupole and QqQ of, at least, three orders of magnitude. The method was applied to analyze carbosulfan field-treated orange samples, in which carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine were found. As an example, the mean carbosulfan concentration was 20 +/- 0.6 microg kg(-1) measured by the QqQ, 22 +/- 1.2 microg kg(-1) by the single quadrupole, 25 +/- 2.8 microg kg(-1) by the QIT, and 20 +/- 1.8 microg kg(-1) by the QqTOF. Although the QqQ is more sensitive and precise, the mean values obtained by the four instruments are acceptable and comparable. The potential of each technique for the verification of the identity of residues detected in oranges is discussed using the concept of identification points.

Microbial synthesis of chiral amines by (R)-specific transamination with Arthrobacter sp. KNK168

Arthrobacter sp. KNK168 shows (R)-enantioselective transaminase [(R)-transaminase] activity, which converts prochiral ketones into the corresponding chiral (R)-amines in the presence of an amino donor. The cultural conditions and reaction conditions for asymmetric synthesis of chiral amines with this microorganism were examined. The transaminase was inducible, and its production was enhanced by the addition of sec-butylamine and 3-amino-2,2-dimethylbutane to the culture medium. (R)-1-Phenylethylamine was a good amino donor for amination of 3,4-dimethoxyphenylacetone with Arthrobacter sp. KNK168. Under the optimum conditions, 126 mM (R)-3,4-dimethoxyamphetamine (DMA) [>99% enantiomeric excess (ee)] was synthesized from 154 mM 3,4-dimethoxyphenylacetone and 154 mM (R)-1-phenylethylamine through the whole cell reaction with an 82% conversion yield. (R)-Enantiomers of other amines, such as (R)-4-methoxyamphetamine, (R)-1-(3-hydroxyphenyl)ethylamine and (R)-1-(3-hydroxyphenyl)ethylamine, were also synthesized from the corresponding carbonyl compounds through asymmetric amination with Arthrobacter sp. KNK168.

Cytochrome P450 enzyme-mediated degradation of Echinacea alkylamides in human liver microsomes

Echinacea preparations are widely used herbal remedies for the prevention and treatment of colds. In this study we have investigated the metabolism by human liver microsomes of the alkylamide components from an Echinacea preparation as well as that of pure synthetic alkylamides. No significant degradation of alkylamides was evident in cytosolic fractions. Time- and NADPH-dependent degradation of alkylamides was observed in microsomal fractions suggesting they are metabolised by cytochrome P450 (P450) enzymes in human liver. There was a difference in the susceptibility of 2-ene and 2,4-diene pure synthetic alkylamides to microsomal degradation with (2E)-N-isobutylundeca-2-ene-8,10-diynamide (1) metabolised to only a tenth the extent of (2E,4E,8Z,10Z)-N-isobutyldodeca-2,4,8,10-tetraenamide (3) under identical incubation conditions. Markedly less degradation of 3 was evident in the mixture of alkylamides present in an ethanolic Echinacea extract, suggesting that metabolism by liver P450s was dependent both on their chemistry and the combination present in the incubation. Co-incubation of 1 with 3 at equimolar concentrations resulted in a significant decrease in the metabolism of 3 by liver microsomes. This inhibition by 1, which has a terminal alkyne moiety, was found to be time- and concentration-dependent, and due to a mechanism-based inactivation of the P450s. Alkylamide metabolites were detected and found to be the predicted epoxidation, hydroxylation and dealkylation products. These findings suggest that Echinacea may effect the P450-mediated metabolism of other concurrently ingested pharmaceuticals.

PI Factor, a Novel Type Quorum-sensing Inducer Elicits Pimaricin Production in Streptomyces natalensis

A chemically novel autoinducer (PI factor) has been purified from cultures of the pimaricin producer Streptomyces natalensis ATCC27448. The chemical structure of the PI molecule was identified as 2,3-diamino-2,3-bis (hydroxymethyl)-1,4-butanediol. Pimaricin biosynthesis in S. natalensis npi287, a mutant impaired in pimaricin production, was restored by supplementation with either A-factor from Streptomyces griseus IFO13350 or with PI factor. S. natalensis did not synthesize A-factor. The PI autoinducer was active at very low concentrations (50-350 nm). A threshold level of 50 nm was required to observe the induction effect. The dose-response curve was typical of a quorum-sensing type mechanism. The biosynthesis of PI factor was associated with cell growth of S. natalensis, both in defined and complex media. Supplementation of the wild-type S. natalensis with pure PI (300 nm) resulted in a stimulation of 33% of the production of pimaricin. These results indicate that the endogenous synthesis of PI factor is limiting for pimaricin biosynthesis in the wild-type strain. This water-soluble PI factor belongs to a novel class of autoinducers in Streptomyces species different from the classical butyrolactone autoinducers. Because restoration of pimaricin production in the npi287 mutant is conferred by both A-factor and PI factor, S. natalensis appears to be able to integrate different quorum signals from actinomycetes.

Diacetylenic isobutylamides of Echinacea: synthesis and natural distribution

The syntheses of three diacetylenic isobutylamides of Echinacea angustifolia have been achieved by direct synthetic routes by way of a common intermediate. The key step is the alkylation of the anion of the silylated diacetylene. We report the presence of all three diacetylenic isobutylamides in six of the nine Echinacea species: E. angustifolia, E. sanguinea, E. simulata, E. tennesseensis, E. atrorubens and E. laevigata. The accumulation of these amides is sensitive to organ type and age.

Dual 5-HT1A agonists and 5-HT re-uptake inhibitors by combination of indole-butyl-amine and chromenonyl-piperazine structural elements in a single molecular entity

The dual serotonin (5-HT) re-uptake inhibitor and 5-HT(1A) receptor agonist vilazodone was found to increase central serotonin levels in rat brain. In the course of structural modifications of vilazodone 3-[4-[4-(2-oxo-2H-1-benzopyran-6-yl)-1-piperazinyl]-butyl]-1H-indole-5-carbonitrile 8i and its fluorine analogue 6-[4-[4-(5-fluor-3-indolyl)-butyl]-1-piperazinyl]-2H-1-benzopyran-2-one have been identified. These unsubstituted chromenones are equally potent at the 5-HT(1A) receptor and 5-HT transporter. The implementation of nitrogen functionalities in position 3 of the chromenones resulted in compounds acting as agonists at the 5-HT(1A) receptor and as 5-HT re-uptake inhibitors like vilazodone. Ex vivo 5-HT re-uptake inhibition and in vitro 5-HT agonism were determined in the PCA- and GTPgammaS-assay, respectively. The potential of these chromenones to increase central 5-HT levels was measured in microdialysis studies and especially the derivatives 3-[4-[4-(3-amino-2-oxo-2H-chromen-6-yl)-piperazin-1-yl]-butyl]-1H-indole-5-carbonitrile 8f, ethyl (6-[4-[4-(5-cyano-1H-indol-3-yl)-butyl]-piperazin-1-yl]-2-oxo-2H-chromen-3-yl)-carbamate 8h and N-(6-[4-[4-(5-cyano-1H-indol-3-yl)-butyl]-piperazin-1-yl]-2-oxo-2H-chromen-3-yl)-acetamide 8k give rise to rapid development of increased serotonin levels in rat brain cortex, lasting longer than 3h.

Kinetic resolution of (R,S)-sec-butylamine using omega-transaminase fromVibrio fluvialis JS17 under reduced pressure

The kinetic resolution of (R,S) sec-butylamine with the omega-transaminase (TA) from Vibrio fluvialis JS17 was performed under reduced pressure (e.g., 150 torr) to selectively remove an inhibitory product (2-butanone). The evaporation kinetics of 2-butanone at 150 torr in the buffer solution followed the first-order rate law, and the evaporation rate constant was 2.19 1/h, and independent of pH, while the evaporation kinetics of sec-butylamine is dependent on pH. A simple mathematical model of the evaporation of sec-butylamine allowing the estimation of its concentration in the reaction media was developed. The evaporation rate constant of its free amine form and the protonated amine form were 1.00 1/h, and nearly zero, respectively. Although the optimum pH of the omega-TA activity for sec-butylamine is 9.0, the optimal pH of the enzyme reaction under reduced pressure was pH 7.0, due to the higher evaporation rate of sec-butylamine at higher pH above 7.0. Using the recombinant Escherichia coli BL21 overexpressing omega-TA, 400 mM racemic sec-butylamine was resolved successfully to 98% ee of (R)-sec-butylamine with 53% conversion at 150 torr and pH 7.0.

Synthesis and characterization of model compounds of the lysine tyrosyl quinone cofactor of lysyl oxidase

4-n-Butylamino-5-ethyl-1,2-benzoquinone (1(ox)) has been synthesized as a model compound for the LTQ (lysine tyrosyl quinone) cofactor of lysyl oxidase (LOX). At pH 7, 1(ox) has a lambda(max) at 504 nm and exists as a neutral o-quinone in contrast to a TPQ (2,4,5-trihydroxyphenylalanine quinone) model compound, 4, which is a resonance-stabilized monoanion. Despite these structural differences 1(ox) and 4 have the same redox potential (ca. -180 mV vs SCE). The structure of the phenylhydrazine adduct of 1(ox) (2) is reported, and 2D NMR spectroscopy has been used to show that the position of nucleophilic addition is at C(1). UV-vis spectroscopic pH titration of phenylhydrazine adducts of 1(ox) and 4, 2, and 11, respectively, reveals a similar red shift in lambda(max) at alkaline pH with the same pK(a) (approximately 11.8). In contrast, the red shift in lambda(max) at acidic pH conditions yields different pK(a) values (2.12 for 2 vs -0.28 for 11), providing a means to distinguish LTQ from TPQ. Reactions between in situ generated 4-ethyl-1,2-benzoquinone and primary amines give a mixture of products, indicating that the protein environment must play an essential role in LTQ biogenesis by directing the nucleophilic addition of the epsilon-amino group of a lysine residue to the C(4) position of a putative dopaquinone intermediate. Characterization of a 1,6-adduct between an o-quinone and butylamine (3-n-butylamino-5-ethyl-1,2-benzoquinone, 13) confirms the assignment of LTQ as a 1,4-addition product.

Conservation of nonpeptide antigen recognition by rhesus monkey V gamma 2V delta 2 T cells

We have previously found that monkey Vgamma2Vdelta2(+) T cells mount adaptive immune responses in response to Mycobacterium bovis bacillus Calmette-Guérin infections. We have now analyzed rhesus monkey gammadelta T cell responses to nonpeptide Ags and superantigens. Like human Vgamma2Vdelta2(+) T cells, rhesus monkey gammadelta T cells are stimulated when exposed to prenyl pyrophosphate, bisphosphonate, and alkylamine Ags. Responsiveness was limited to gammadelta T cells expressing Vgamma2Vdelta2 TCRs. Rhesus monkey Vgamma2Vdelta2(+) T cells also responded to the superantigen, staphyloccocal enterotoxin A. Sequencing of the rhesus monkey Vgamma2Vdelta2 TCR revealed a strong sequence homology to human Vgamma2Vdelta2 TCR that preserves important sequence motifs. Moreover, chimeric TCRs that pair human Vgamma2 with monkey Vdelta2 and monkey Vgamma2 with human Vdelta2 retain reactivity to nonpeptide Ags and B cell lymphomas. A molecular model of the rhesus monkey Vgamma2Vdelta2 TCR has a basic region in the complementarity-determining region 3 binding groove that is similar to that seen in the human Vgamma2Vdelta2 TCR and preserves the topology of the complementarity-determining region loops. Thus, recognition of nonpeptide prenyl pyrophosphate, bisphosphonate, and alkylamine Ags is conserved in primates suggesting that primates can provide an animal model for human gammadelta T cell Ag responses.

Antagonists of the human CCR5 receptor as anti-HIV-1 agents. Part 2: structure-activity relationships for substituted 2-Aryl-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-(piperidin-1-yl)butanes

(2S)-2-(3,4-Dichlorophenyl)-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-[spiro(2,3-dihydrobenzthiophene-3,4'-piperidin-1'-yl)]butane S-oxide (3) has been identified as a potent CCR5 antagonist lead structure having an IC50 = 35 nM. Herein, we describe the structure-activity relationship studies directed toward the requirement for and optimization of the C-2 phenyl fragment. The phenyl was found to be important for CCR5 antagonism and substitution was limited to small moieties at the 3-position (13 and 16: X= H, 3-F, 3-Cl, 3-Me).

Studies of the chemical selectivity of hapten, reactivity, and skin sensitization potency. 2. nmr studies of the covalent binding of the (13)c-labeled skin sensitizers 2-[13C]- and 3-[13C]hex-1-ene- and 3-[13C]hexane-1,3-sultones to human serum albumin

3-[(13)C]- and 2-[(13)C]hex-1-ene-1,3-sultones (1a and 1b, respectively) and 3-[(13)C]hex-1-ene-1,3-sultone 2a were incubated with human serum albumin in phosphate buffer at pH 8.1. In both cases, the main reaction was a hydrolysis via an S(N) reaction at position 3, but several adducts were also formed. Hex-1-ene-1,3-sultone, which is a strong skin sensitizer, appears also to be a strongly oxophilic molecule reacting mainly at position 3 through an S(N) reaction to give adducts on tyrosines. This sultone was also able to react with a single lysine residue, also via an initial S(N) reaction at position 3, followed by an intramolecular Michael addition at position 2 to form a mixture of aziridinium intermediates which were subsequently hydrolyzed to give an amino alcohol derivative as the final product. The same reaction carried out on acetylated human serum albumin seems to indicate that the target lysine could be Lys199, which is known to be easily acetylated. Hexane-1,3-sultone, which is a weak sensitizer, appears to be an even more oxophilic molecule, making adducts on tyrosines through an S(N) reaction at position 3. No reaction was observed on Lys199. The difference in skin sensitization potential seems therefore to be more related to the selective ability of modifying lysine residues than to the more general ability to modify tyrosine residues.

New pathway of amine oxidation respiratory chain of Paracoccus denitrificans IFO 12442

The physiological electron acceptor of quinohemoprotein amine dehydrogenase (QH-AmDH) from Paracoccus denitrificans IFO 12442 was identified by biochemical and electrochemical methods. Of three types of heme c-containing proteins purified together with QH-AmDH from the periplasm of n-butylamine-grown cells, only constitutive cytochrome c-550 was reduced by the addition of QH-AmDH and n-butylamine. Reconstitution of the respiratory chain revealed that cytochrome c-550 mediates the electron transfer from QH-AmDH to the terminal oxidase. This is a new pathway of the amine oxidation respiratory chain of P. denitrificans.

Cellular localization and metabolic function of n-butylamine-induced amine oxidases in the fungus Aspergillus niger AKU 3302

Using transmission electron microscopy, the amine oxidase activity in Aspergillus niger AKU 3302 was localized to the outer side of the cell wall but not inside the cell using the cerium perhydroxide deposition method. The presence of cerium in the deposit was confirmed by energy-dispersive microanalysis of X-rays. Interestingly, immunocytochemical localization using gold labeling with a specific antibody indicated the presence of amine oxidase protein inside the cell wall and not only on the outer surface. Besides labeling of the cell wall, a high level of labeling was also observed inside the cell in what seemed to be secretory vesicle structures. It is proposed that the highly active amine oxidase AO-I is located in the cell wall and serves primarily as a detoxifying agent, preventing amines from entering and damaging the cell. The amine oxidation exhibits an interesting spatial orientation involving a release of toxic hydrogen peroxide into the extracellular space. The inactive amine oxidase protein located inside the cell is most probably the amine oxidase AO-II, found in cell homogenates. It is also likely that the less active AO-II is an improperly folded precursor of AO-I, which acquired low-level activity after cell homogenization in the presence of Cu(II) and oxygen due to autooxidative formation of topaquinone.

The utilization of 4-aminobutylphosphonate as sole nitrogen source by a strain of Kluyveromyces fragilis

A strain of the yeast Kluyveromyces fragilis was screened for its ability to utilize a range of synthetic and natural organophosphonate compounds as the sole source of phosphorus, nitrogen or carbon. Only 4-aminobutylphosphonate was utilized as sole nitrogen source with protein yields increasing proportionally with substrate concentrations up to 10 mM. No 4-aminobutylphosphonate metabolizing enzyme activity was detectable in cell-free extracts prepared from K. fragilis pregrown on 2.5 mM 4-aminobutylphosphonate. None of the organophosphonates tested served as a source of carbon or phosphorus for K. fragilis.

Lysyl oxidase coupled with catalase in egg shell membrane

The activity of lysyl oxidase was found in egg shell membrane (ESM) of hens. The activity was determined by measuring the enzymatic conversion of n-butylamine and Nalpha-acetyl-L-lysine to n-butyraldehyde and Nalpha-acetyl-L-allysine, respectively. ESM lysyl oxidase was significantly inhibited by beta-aminopropionitrile, chelating agents, and deoxygenation, consistent with the known properties of lysyl oxidase. Nevertheless, ESM lysyl oxidase was insoluble in urea solution, suggesting that it complexes with ESM. These findings support previous reports indicating the presence of lysine-derived cross-links in ESM and the necessity of lysyl oxidase located in the isthmus of the hen oviduct for the biosynthesis of ESM. Lysyl oxidase secreted around the egg white from the isthmus may initiate the cross-linking reaction of ESM protein, and remain as the constituent of ESM. Moreover, the H(2)O(2) released by lysyl oxidase in ESM was completely decomposed by coexisting catalase activity. ESM lysyl oxidase activity was greatly elevated in the presence of H(2)O(2), probably due to the O(2) produced by catalase. These findings indicate that lysyl oxidase is coupled with catalase in ESM. This coupling enzyme system was considered to be involved in the biosynthesis of ESM and to protect the embryo against H(2)O(2).

Solid phase synthesis of benzamidine and butylamine-derived hydantoin libraries

We have constructed a number of benzamidine- and butylamine-based hydantoin compounds by means of an efficient route using solid phase synthesis in which neat diisopropylamine was employed for a novel cyclization/traceless cleavage step. All library compounds were obtained in excellent yield and high purity.

Neonatal administration of the selective serotonin reuptake inhibitor Lu 10-134-C increases forced swimming-induced immobility in adult rats: a putative animal model of depression?

Chronic administration of the tricyclic antidepressant clomipramine to neonatal rats from postnatal days 8 to 21 is reported to induce several behavioral changes in adult life, and it may serve as an animal model of human depressive disorder. Findings include increased immobility time in the forced swim test and locomotor hyperactivity in the open field test. Clomipramine is a serotonergic reuptake inhibitor, which suggests that altered development of the serotonergic system could account for the observed behavioral changes in the adult rat. The present study was carried out with a selective serotonin reuptake inhibitor (SSRI) to investigate whether the serotonin system, in particular, is involved in the neonatal animal model. The substance, Lu 10-134-C (LU), was characterized in monoamine reuptake and receptor binding assays and found to be an SSRI. Rats received LU during postnatal days 8 to 21 (2.5-15 mg/kg b. i.d.), and they were assessed in open field, forced swim and social interaction tests at the age of 4 months. Behavior of LU-treated rats and saline controls did not differ in the open field and social interaction tests. However, in the forced swim tests LU-treated neonates showed prolonged immobility time compared with saline controls. In conclusion, chronic LU treatment during neonatal life produces long-term changes in the forced swim test, but not in the open field and social interaction tests. The behavioral changes in the forced swim test suggest that the central serotonergic system may be involved in the putative neonatal animal model of depression.

A microgonotropen branched decaaza decabutylamine and its DNA and DNA/transcription factor interactions

The central pyrrole of a site-selective DNA minor groove binding tripyrrole peptide 1 has been attached to a branched decaaza decabutylamine via a -(CH-2)3-NHCO-(CH2)-3 linker to provide the decaaza-microgonotropen (8). The decaaza decabutylamine moiety of 8 was designed to have a much greater affinity to the phosphodiester linkages of the backbone of DNA. Employing Hoechst 33258 (Ht) as a fluorescent titrant, the equilibrium constants for the binding for of 8 to the hexadecameric duplex d(GGCGCA3T3GGCGG)/d(CCGCCA3T3GCGCC) and to calf thymus DNA were determined. The log of the product of equilibrium constants (log Kl1Kl2) for 1:1 and 1:2 complexes formation at A3T3 is 17 (35 degrees C). Results of studies of the inhibition of the binding of several proteins to target DNA are discussed. Binding of the E2F1 transcription factor to its DNA target is 50% inhibited at approximately 2 nM concentration of 8.

Cloning, analysis, and overexpression of the gene encoding isobutylamine N-hydroxylase from the valanimycin producer, Streptomyces viridifaciens

The flavoprotein isobutylamine N-hydroxylase (IBAH) catalyzes the oxidation of isobutylamine to isobutylhydroxylamine, a key step in the biosynthesis of the azoxy antibiotic valanimycin. By using oligonucleotide primers designed from peptide sequence information derived from native IBAH, a fragment of the gene (vlmH) encoding IBAH was amplified by PCR from a genomic library of the valanimycin-producing organism, Streptomyces viridifaciens MG456-hF10. The gene fragment was then employed as a probe to clone the entire vlmH gene from an S. viridifaciens genomic library. Overexpression of the vlmH gene in Escherichia coli gave a soluble protein that was purified to homogeneity. The purified protein exhibited the catalytic activity expected for IBAH. The deduced amino acid sequence of IBAH exhibited the greatest similarity to the Sox/DszC protein from Rhodococcus sp. strain IGT38, a flavoprotein involved in the oxidation of dibenzothiophene to the corresponding sulfone. Significant similarities were also found between the amino acid sequence of IBAH and those of the acyl coenzyme A dehydrogenases.

Linoleic acid oxidation in the presence of amino compounds produces pyrroles by carbonyl amine reactions

The reactions of 13-hydroperoxy-9(Z),11(E)-octadecadienoic acid (13-LOOH) and its degradation product 4,5(E)-epoxy-2(E)-decenal with butylamine and lysine were studied to determine whether pyrrole derivatives isolated in model reactions were produced in complex systems involving hydroperoxides. Incubated reaction mixtures were studied by gas chromatography coupled with mass spectrometry or high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS), and some compounds were isolated by column chromatography or semipreparative HPLC, and identified by 1H- and 13C-nuclear magnetic resonance spectroscopy and MS. The reaction of epoxyalkenals with amino groups produced two types of pyrrole derivatives: 1-substituted 2-(1'-hydroxyalkyl)pyrroles and 1-substituted pyrroles. 1-Substituted 2-(1'-hydroxyalkyl)pyrroles were responsible for the development of color and fluorescence by a polymerization reaction, which implied the formation of dipyrrylmethanes and dipyrrylmethenes. 1-Substituted pyrroles were final products in these reactions and their determination might be used as an index of oxidative stress. The above reactions were also observed between 13-LOOH and amino compounds, and suggested that the pyrrole polymerization mechanism plays a role in the fluorescence observed by reaction of hydroperoxides and amino groups.

The mechanism of nucleophilic substitution of alkylpyrroles in the presence of oxygen

The mechanism of oxidation of alkylpyrroles (1a-d) by molecular oxygen in the presence of nucleophiles is explored. Contrary to previous reports, oxidation of these pyrroles resulted in dimers with both the aromatic rings intact. In the presence of additional nucleophiles these pyrroles entered into substitution reactions. With 2-mercaptoethanol the site of substitution on 1a was the 3-position rather than the side chain. The first-order rate constant for this reaction in acetonitrile with excess oxygen was found to be (7.8 +/- 1.2) x 10(-7) s-1. The rate was unaffected by the presence of either BHT or catechol. Replacing hydrogens at all the potential sites of reaction by deuterium (as in 1aD) did not reduce the rate of substitution. However, the product suffered loss of deuterium from all sites. These observations support a mechanism involving the formation of a complex 20 between the pyrrole and triplet oxygen. Electron transfer from the pyrrole to oxygen in the rate-limiting step is followed by the generation of pyrrolylmethyl intermediate 23 that can react with available nucleophiles including unoxidized pyrroles.

Pharmacokinetics of terodiline and a major metabolite in dogs with a correlation to a pharmacodynamic effect

The pharmacokinetics and pharmacodynamics of the anticholinergic and calcium antagonistic drug terodiline, N-tert-butyl-1-methyl-3,3-diphenylpropylamine, have been studied in beagle dogs. The bioavailability was about 25% (0.15 and 0.5 mg/kg), the terminal half-life 3 hr, the systemic clearance 40 ml/min..kg, the volume of distribution (V beta) about 7 l/kg and the unbound fraction in serum 0.14. p-Hydroxyterodiline and p-hydroxy-m-methoxyterodiline were quantitated and constituted 15-40% and 25%, respectively, of the amount excreted in urine (about 60% of the dose) and were the main metabolites, as in man. The dog was used as an experimental model to study the chronotropic effect. An increased heart rate was observed after acute administration of high doses of terodiline as well as after p-hydroxyterodiline. A 20% increase in heart rate was observed at a mean serum concentration of 1086 and 1010 micrograms/l following intravenous injection of terodiline or p-hydroxyterodiline, respectively. The corresponding unbound concentrations were 150 and 474 micrograms/l. The potency ratios of terodiline/p-hydroxyterodiline was 0.9 +/- 0.2 (based on total concentrations) and 3.2 +/- 0.8 (based on unbound concentrations). The estimated potency of parent drug and main metabolite and the fact that p-hydroxyterodiline constitutes 10-20% of the terodiline steady-state level in man, indicate that the contribution of the metabolite to the chronotropic effect observed in clinical studies is minor.

Thermodynamic modeling of internal equilibria involved in the activation of trypsinogen

The effect of activating dipeptides, sequentially homologous to the Ile16-Val17N-terminus of bovine beta-trypsin (beta-trypsin), on equilibria involved in the binding of strong ligands (i.e., n-butylamine, the bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor; BPTI) and the porcine pancreatic secretory trypsin inhibitor (Kazal-type inhibitor, type I; PSTI)) to bovine trypsinogen (trypsinogen) was investigated at pH 5.51 (I = 0.1 M) and T = 21.0 +/- 0.5 degrees C; under the same experimental conditions, thermodynamics for the binding of strong ligands to beta-trypsin was also obtained. The equilibria involved in the binding of activating dipeptides and/or inhibitors to beta-trypsin and to its zymogen are described according to an induced-fit formalism, taking into account ligand-linked interaction(s) between different functional and structural domains of the (pro)enzyme possibly involved in the trypsinogen-to-beta-trypsin activation pathway. The analysis of data is focussed on parameters describing interactions between the so-called Ile-Val pocket (where the Ile16-Val17 N-terminus of beta-trypsin or activating dipeptides bind) and the primary and/or secondary recognition subsite(s) (where strong ligands associate) present in the (pro)enzyme. Such an analysis allows to dissect the contributions due to the primary recognition subsite, where small mono-functional ligands (e.g., n-butylamine) bind, from those of the secondary subsite(s), which are additional recognition clefts for macromolecular inhibitors (e.g., BPTI and PSTI).

Carbon assimilation and extracellular antigens of some yeast-like fungi

Many yeast-like fungi assimilated n-hexadecane, butylamine and putrescine as sole carbon sources. Methanol was not assimilated. This points to a physiological similarity to endomycetous, hydrocarbon-utilizing yeasts. Stephanoascus ciferrii assimilated uric acid, adenine and allantoin as sole source of carbon and nitrogen. All strains of Geotrichum candidum and many other yeast-like fungi assimilated acetoin and butan-2,3-diol. Assimilation tests for adenine, uric acid, allantoin, acetoin and butan-2,3-diol were found to be suitable for taxonomic purposes. Extracellular antigens immunologically related to those produced by Geotrichum candidum were detected in the cell-free culture liquids of several yeast-like fungi. The extracellular antigen excreted by Stephanoascus ciferrii was species-specific.

Biotransformation of terodiline. V. Stereoselectivity in hydroxylation by human liver microsomes

The stereoselective hydroxylation of N-tert-butyl-4,4-diphenyl-2-butylamine (Terodiline) was studied in human liver microsomes. Formation of the two main metabolites, N-tert-butyl-4(4-hydroxyphenyl)-4-phenyl-2-butylamine (II) and N-(2-hydroxymethyl-2-propyl)-4,4-diphenyl-2-butylamine (VI), was found to be stereoselective. R-Terodiline was preferentially transformed by phenolic hydroxylation to the 2R,4S-II and 2R,4R-II forms with a pronounced selectivity for the former. The formation rate ratio 2R,4S-II/2R,4R-II was about 6, obtained from two liver preparations. S-Terodiline was mainly hydroxylated to the alcohol 2S-VI although phenolic hydroxylation to the 2S,4S-II and 2S,4R-II also occurred, yielding about equal amounts of the two phenols.

Single-dose pharmacokinetics of terodiline, including a stable isotope technique for improvement of statistical evaluations

A bioequivalence study with terodiline (Mictrol) was performed in 8 healthy volunteers given a 25 mg oral dose of either of two solid dosage forms together with a water solution of the deuterated drug. The solid dosage forms were found to be bioequivalent. Moreover, their pharmacokinetic profiles were the same as for the water solution. The basic pharmacokinetic parameters (means +/- SE) of terodiline were calculated to: biological half-life in serum 60 +/- 4 h, maximum serum concentration 79 +/- 4 micrograms l-1 and the corresponding time 4 +/- 1 h, oral serum clearance 75 +/- 7 ml min-1, urinary excretion 15.3 +/- 1.5 per cent of dose, and renal serum clearance 10.9 +/- 2.2 ml min-1. The within-subject variability (serum-derived parameters) was about 8 per cent (CV per cent) and the between-subject variation 2-4 times higher. A single parameter estimate in subjects of a comparative population can be expected to show a 3-fold variation (95 per cent confidence). The deuterated drug could be used as a covariate to increase the power/precision in the statistical evaluation of the bioequivalence. In that way the 95 per cent confidence interval for the difference between the formulations, as well as the difference that could be detected with 80 per cent power, was reduced 2- to 5-fold. The covariate method was thus in this respect extremely efficient. In bioequivalence studies with drugs where a large number of subjects would be needed using conventional statistical analyses, this method also offers a possibility to considerably reduce the size of the panel, while retaining sufficient power and precision in the estimates.

Biotransformation of terodiline. III. Opposed stereoselectivity in the benzylic and aromatic hydroxylations in rat liver microsomes

1. Terodiline (N-tert-butyl-4,4-diphenyl-2-butylamine) is a racemic drug with anticholinergic and/or calcium antagonistic activity, which is subject to renewed interest as a potential remedy for urinary incontinence. As part of the current investigations on terodiline, the metabolism of its enantiomers is being investigated. 2. The metabolism of the enantiomers of terodiline in rat liver microsomes is slow, as for the racemate, though the S-enantiomer is metabolized more rapidly than its optical antipode. Phenobarbitone pretreatment of the rats enhances the metabolism with a marked increase in the conversion of the S-enantiomer. 3. While aromatic p-hydroxylation greatly exceeds benzylic oxidation in the metabolism of R-terodiline, this situation is reversed in the metabolism of S-terodiline. Moreover, the rate of aromatic p-hydroxylation of racemic terodiline follows that of R-terodiline, while the rate of benzylic hydroxylation of racemic terodiline follows that of S-terodiline. Phenobarbital pretreatment of the rats had little or no effect on aromatic p-hydroxylation but markedly increased benzylic oxidation. 4. Separation of the mixture of p-hydroxylated metabolites into diastereomeric pairs showed that their composition is highly dependent on which form of terodiline is used as substrate. 5. The results from the study are compatible with the participation of multiple forms of cytochrome P-450 enzymes.

Steady-state kinetic analysis for the reaction of ammonium and alkylammonium ions with methylamine dehydrogenase from bacterium W3A1

The steady-state kinetic mechanism for the reaction of n-alkylamines and phenazine ethosulfate (PES) or phenazine methosulfate (PMS) with methylamine dehydrogenase from bacterium W3A1 is found to be of the ping-pong type. This conclusion is based on the observations that 1/v versus 1/[methylamine] or 1/[butylamine] plots, at various constant concentrations of an oxidizing substrate, and 1/v versus 1/[PES] or 1/[PMS] plots, at various constant concentrations of a reducing substrate, are parallel. Additionally, the values of kcat/Km for four n-alkylamines are identical when PES is the oxidizing substrate, as were the kcat/Km values for four reoxidizing substrates when methylamine was the reducing substrate. Last, analysis of steady-state kinetic data obtained when methylamine and propylamine are presented to the enzyme simultaneously and PES and PMS are used simultaneously also supports the involvement of a ping-pong mechanism. The enzymic reaction with either methylamine or PES is dependent on the ionic strength, and the data indicate that each interacts with an anionic site on methylamine dehydrogenase. The presence of ammonium ion at low concentration activates the enzyme, but at high concentration this ion is a competitive inhibitor in the reaction involving methylamine and the enzyme. A complete steady-state mechanism describing these ammonia effects is presented and is discussed in light of the nature of the pyrroloquinoline quinone cofactor covalently bound to the enzyme.

Urinary metabolites of N-nitrosodibutylamine and N-nitrodibutylamine in the rat: identification of N-acetyl-S-alkyl-L-cysteines

N-Acetyl-S-butyl-L-cysteine, N-acetyl-S-3-oxobutyl-L-cysteine and N-acetyl-S-3-hydroxybutyl-L-cysteine have been isolated and identified (as their methyl esters) from the urine of rats given N-nitrosodibutylamine (NDBA), N-nitrodibutylamine (NO2DBA) and their 1-acetoxy derivatives. Greater amounts of these N-acetyl-S-alkyl-L-cysteines were detected in the urine after administration of NDBA than of NO2DBA, and greater urinary excretion of the three N-acetyl-S-alkyl-L-cysteines was observed with 1-acetoxy NDBA than with 1-acetoxy NO2DBA. This suggests that the markedly different biological activities of NDBA and NO2DBA might be due, in part, to a difference in their alkylating abilities in vivo.

Effect of butylated hydroxyanisole on in vitro and in vivo nitrosation of dibutylamine

The effect of the food additive butylated hydroxyanisole on the nitrosation of dibutylamine was studied in vitro and in vivo, in rats. At the highest concentration tested, butylated hydroxyanisole significantly inhibited the in vitro formation of N-nitrosodi-n-butylamine from dibutylamine and nitrite by 35%. This effect was not observed in animals given dibutylamine, NaNO2 and butylated hydroxyanisole by gavage in the same ratio that produced an effect in vitro. The oral administration of butylated hydroxyanisole to rats given 0.5% nitrate in the drinking water and dibutylamine (0.38 mmol/kg 3 times/day p.o.) was also with no effect, although the experimental model used proved suitable for studying the modulating effect on endogenous nitrosation of different chemicals such as ascorbic acid or potassium thiocyanate. The discrepancy between in vitro and in vivo results is discussed.

Two fatalities resulting from Tessalon (benzonatate)

Two fatal cases involving Tessalon (benzonatate) were quantitated by ultraviolet (UV) and high performance liquid chromatography (HPLC). The first case involved an infant found choking; Tessalon perles were found with the child. The second case involved a successful suicide of an 18-year-old that consumed a "handful" of phenytoin and benzonatate and expired within 1 hr of the ingestion. Blood, brain and kidney concentrations are reported. These are believed to be the first two reported cases involving this compound.

Oxidation of amines by yeasts grown on 1-aminoalkanes or putrescine as the sole source of carbon, nitrogen and energy

The maximum growth rate of Trichosporon cutaneum CBS 8111 in chemostat cultures was 0.185 h-1 on ethylamine and 0.21 h-1 on butylamine, that of Candida famata CBS 8109 was 0.32 h-1 on putrescine. The amine oxidation pattern of the ascomycetous strains studied, viz. Candida famata CBS 8109, Stephanoascus ciferrii CBS 4856 and Trichosporon adeninovorans CBS 8244 was independent of the amine that had been used as the growth substrate. It resembled that of benzylamine/putrescine oxidase found in other ascomycetous yeasts. However, differences in pH optimum and substrate specificity were observed between the amine-oxidizing systems of these three species. The amine oxidation pattern of cell-free extracts of Trichosporon cutaneum CBS 8111 varied with the amine that was used as growth substrate. The enzyme system produced by Cryptococcus laurentii CBS 7140 failed to oxidize isobutylamine and benzylamine, and showed a high pH optimum. The synthesis of amine oxidase in the four yeast strains studied was not repressed by ammonium chloride and was weakly repressed by glucose but was strongly repressed if both compounds were present in the growth medium.

Reaction pathway of bovine aortic lysyl oxidase

The catalysis of amine oxidation by lysyl oxidase has been probed to assess for the likely order of substrate binding and product release and to discriminate between mechanistic alternatives previously proposed for other copper-dependent amine oxidases using molecular oxygen as a substrate. Lineweaver-Burk plots revealed a pattern of parallel lines when the oxidation of n-butylamine was followed at different fixed concentrations of oxygen consistent with a "ping-pong" kinetic mechanism in which the aldehyde is produced and released before the binding of oxygen, the second substrate. Initial burst experiments revealed the ability of lysyl oxidase to form and release n-butyraldehyde in amounts stoichiometric with functional active site content in the absence of oxygen, consistent with the ping-pong kinetics obtained. Reciprocal plots of n-butylamine oxidation in the presence of fixed concentrations of the reaction products were consistent with a Uni Uni Uni Bi ping-pong kinetic mechanism with the aldehyde being the first, H2O2 the second, and ammonia the last departing product. Moreover, spectral studies of the oxidation of p-hydroxybenzylamine by lysyl oxidase indicated that the enzyme does not process the amine substrate to a noncovalently bound p-hydroxybenzaldimine intermediate subsequently to be hydrolyzed to p-hydroxybenzaldehyde. The kinetic mechanism of lysyl oxidase thus appears to be similar to those described for diamine oxidase and pig plasma monoamine oxidase.

A new type of methylamine oxidase: the sole oxidase produced during growth of Sporobolomyces albo-rubescens on primary alkylamines

Under conditions known to separate methylamine oxidase from benzylamine oxidase in other yeast strains, only a single oxidase could be detected in Sporobolomyces albo-rubescens. This occurred irrespective of whether methylamine or n-butylamine was the nitrogen source for growth. The oxidase did not attack benzylamine. It was concluded that this organism can only produce a methylamine oxidase. The enzyme was purified to 90% homogeneity and found to have properties significantly different from the methylamine oxidases previously characterised. It lost only 40% of its activity in 30 min at 45 degrees C, whereas methylamine oxidases previously described had half-lives of from 2 to 9 min at 45 degrees C. It showed also a lower activity with short chain 1-aminoalkanes and a higher activity with longer chain 1-aminoalkanes than other methylamine oxidases, and had a significantly smaller subunit molecular weight (57,000 compared with 80,000).

Metabolic fate of N-nitrodibutylamine in the rat

The metabolic fate of N-nitrodibutylamine (NO2DBA) and N-nitrobutylamine (NO2BA) was investigated in the rat. Eight N-nitramines, including glucuronides, were isolated and identified from urine of rats given NO2DBA. They were produced by omega, omega-1, omega-2 and alpha oxidations of the N-nitramine. The in vivo metabolic pattern of NO2DBA was similar to that of N-nitrosodibutylamine, except that the monodealkylated metabolite NO2BA was also isolated and characterized. When NO2BA was administered to rats, no N-nitramine other than a small amount of unchanged NO2BA was identified in the urine. Besides N-nitramines, N-acetyl-S-(butyl, 3-oxobutyl and 3-hydroxybutyl)-L-cysteines were isolated and identified (as their methyl esters) from the urine of rats given both NO2DBA and NO2BA. The relative ratio of these three L-cysteine derivatives obtained from NO2DBA was quite similar to that from NO2BA, indicating that NO2DBA produces in vivo a chemical species with butylating ability through NO2BA.

Biotransformation of terodiline I. Identification of metabolites in dog urine by mass spectrometry

Nine metabolites of terodiline (N-tert-butyl-4,4-diphenyl-2-butylamine) have been identified in dog urine by various chromatographic techniques and mass spectrometry. The main metabolic pathway is aromatic hydroxylation, leading to the quantitatively most important metabolite, N-tert-butyl-4-(4-hydroxyphenyl)-4-phenyl-2-butylamine, and to two dihydroxylated metabolites, one mono substituted in both rings (N-tert-butyl-4,4'-bis(4-hydroxyphenyl)-2-butylamine), and one disubstituted in one ring (N-tert-butyl-4-(3,4-dihydroxyphenyl)-4-phenyl-2-butylamine). The latter is further metabolized by methylation, forming N-tert-butyl-4-(4-hydroxy-3-methoxyphenyl)-4-phenyl-2-butylamine, the second most abundant metabolite. Still another metabolite is formed by hydroxylation in the tert-butyl group to N-(2-hydroxymethyl-2-propyl)-4,4-diphenyl-2-butylamine. A very minor dihydroxylated metabolite results from oxidation both in an aromatic ring and in the tert-butyl group, giving N-(2-hydroxymethyl-2-propyl)-4-(4-hydroxyphenyl)-4-phenyl-2-butylamine. Oxidation of the carbon adjacent to the nitrogen and subsequent deamination gives the two ketones 4-(4-hydroxyphenyl)-4-phenyl-2-butanone and 4-(4-hydroxy-3-methoxyphenyl)-4-phenyl-2-butanone. Reduction of the carbonyl function in the former yields the corresponding alcohol, 4-(4-hydroxyphenyl)-4-phenyl-2-butanol. Some unchanged terodiline is also present. All metabolites formed by functionalization appear to be extensively conjugated, presumably with glucuronic acid.

The biosynthesis of hypusine (N epsilon-(4-amino-2-hydroxybutyl)lysine). Alignment of the butylamine segment and source of the secondary amino nitrogen

The unusual amino acid hypusine is produced in a single protein of mammalian cells by a novel posttranslational event in which a lysine residue is conjugated with the four-carbon moiety from the polyamine spermidine to form an intermediate deoxyhypusine, and in which this intermediate is subsequently hydroxylated. Specifically isotopically labeled precursors of hypusine were used to identify the biosynthetic origin of some of the atoms of hypusine and thus to provide further insight into the mechanism of this in vivo chemical modification reaction. Radiolabel from [1,4-3H] putrescine, [1,8-3H]spermidine, and [5-3H]spermidine entered hypusine during growth of Chinese hamster ovary cells. The occurrence of this label at positions 1 and 4, at position 4, and at position 1, respectively, in the 4-amino-2-hydroxybutyl portion of hypusine revealed an alignment of atoms identical to that in the butylamine segment of spermidine. Growth of cells with [epsilon-15N]lysine as the source of lysine yielded hypusine enriched in 15N, whereas only isotope-free hypusine during growth by [4-15N]spermidine. These was found in cells whose spermidine was replaced during growth by [4-15N]spermidine. These findings are in accordance with a proposal that the first phase of hypusine biosynthesis, the production of intermediate deoxyhypusine, occurs through transfer of the butylamine moiety from spermidine to the epsilon-amino nitrogen of protein-bound lysine. The technique of thermospray high-performance liquid chromatography/mass spectrometry provided positive identification of 15N in hypusine through final separation and on-column direct analysis of this amino acid. Methods of preparation are given for spermidine of high specific radioactivity, labeled specifically at position 5 with 3H, and for spermidine with 15N at the 4-position.

In vitro binding of butyric acid and crotonic acid by the soluble glutathione S-transferases from rat liver

The in vitro interaction of butyric acid, crotonic acid and n-butylamine with rat liver glutathione S-transferase (GST) was studied, using glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB) as substrates. Both acids inhibited the GST activity in crude extracts in a dose dependent manner; the amine did not. The GST isoenzymes were inhibited at different degrees. Kinetic studies never revealed competitive inhibition kinetics, with GSH nor with CDNB as the variable substrate. Titration of remaining GSH in appropriate incubation mixtures revealed no GST catalyzed conjugation with GSH. It is concluded that butyric and crotonic acid interact with GST by direct binding to these proteins via their carboxyl group. This binding could have a protective function against these compounds.

4-Aminobutyraldehyde dehydrogenase activity in rat brain

An enzyme with NAD+-dependent 4-aminobutyraldehyde dehydrogenase activity was purified about 360-fold from rat brain extract. AMP-Sepharose chromatography was effective in separating the enzyme from other NAD+-dependent aldehyde dehydrogenases included in the extract. The KmS for the substrates NAD+ and 4-aminobutyraldehyde were 4.8 x 10(-4) and 8.3 x 10(-5) M, respectively. The pH optimum for the enzyme was about 8.0. The ratio of activities toward 4-aminobutyraldehyde, propionaldehyde, succinate semialdehyde, and benzaldehyde was 1.00:0.17:0.24:0.09:0.03 when the activity toward 4-aminobutyraldehyde was set equal to 1.00. The enzyme activity in subcellular fractions of rat brain was localized in cytosol.

Pharmacokinetics of terodiline in human volunteers

The pharmacokinetics of terodiline HCl was studied in nine healthy volunteers given 12.5 mg i.v. and p.o. or 20 mg i.v. and 25 mg p.o. on two different occasions. The serum concentrations were measured by gas chromatography--mas spectrometry, using deuterated terodiline HCl as the internal standard. After i.v. administration the kinetics could be described by a two-compartment model with a mean distribution half life of 0.3 h and a mean elimination half life of 63 h. The serum clearance and apparent volume of distribution varied about 4-fold with mean values of 4.8 1/h and 417 1, respectively. After oral administration, the mean half life of absorption was 0.7 h and that of elimination 65 h. The absolute bioavailability varied between 64% and 105% with a mean of 92%. The long serum half life of terodiline should permit its once daily administration.

A simple routine method for mono and diamine oxidase estimation in human serum

The advantages and disadvantages of previous methods for the routine estimations of serum mono and diamine oxidase are reviewed. 4-hydroxy-3-methoxy phenyl acetic acid reacts wtih hydrogen peroxide and peroxidase to form an intensely fluorescent substance, and a simple method using this reaction as a basis for the estimation is described. The results are tabulated and discussed.

[An experimental investigation of the use of a fluorocarbon (FC 43) as blood substitute]

A fluorocarbonate emulsion was infused into 30 rabbits after the removal of varying amounts of blood. Parameters relating to the transport of respiratory gases and the fundamental features of the macrocirculation were monitored. The animals were sacrificed after 6 or 24 hr and the histological changes in the main parenchymas were assessed. The material injected displayed low toxicity, a good ability to act as a vehicle for oxygen and carbon dioxide, and no tendency to alter the macrocirculation. Numerous problems remain, however, with regard to the stability of fluorocarbonates over the course of time and the effect of their uptake by tissues.