Free radical oxidation of coriolic acid (13-(S)-hydroxy-9Z,11E-octadecadienoic acid)

The reaction of (13S,9Z,11E)-13-hydroxy-9,11-octadecadienoic acid (1a), one of the major peroxidation products of linoleic acid and an important physiological mediator, with the Fenton reagent (Fe(2+)/EDTA/H(2)O(2)) was investigated. In phosphate buffer, pH 7.4, the reaction proceeded with >80% substrate consumption after 4h to give a defined pattern of products, the major of which were isolated as methyl esters and were subjected to complete spectral characterization. The less polar product was identified as (9Z,11E)-13-oxo-9,11-octadecadienoate (2) methyl ester (40% yield). Based on 2D NMR analysis the other two major products were formulated as (11E)-9,10-epoxy-13-hydroxy-11-octadecenoate (3) methyl ester (15% yield) and (10E)-9-hydroxy-13-oxo-10-octadecenoate (4) methyl ester (10% yield). Mechanistic experiments, including deuterium labeling, were consistent with a free radical oxidation pathway involving as the primary event H-atom abstraction at C-13, as inferred from loss of the original S configuration in the reaction products. Overall, these results provide the first insight into the products formed by oxidation of 1a with the Fenton reagent, and hint at novel formation pathways of the hydroxyepoxide 3 and hydroxyketone 4 of potential (patho)physiological relevance in settings of oxidative stress.     

Precursor forms of neurotensin (NT) in cat: processing with pepsin yields NT-(3-13) and NT-(4-13)

Basic proteins present in 0.1 N HCl extracts of feline CNS and intestine were found to liberate immunoreactive neurotensin (iNT) when treated with hog pepsin. These protein substrates were separated using Sephadex G-25, Sephadex G-75 and reverse-phase HPLC. In a calibrated SDS-polyacrylamide gel electrophoresis system, the major substrate from cat ileum exhibited a molecular weight of ca 16 kDa and minor substrates were observed at 30, 40 and 65 kDa. As shown previously for synthetic NT, pepsin-treatment of feline ileal NT converted it into the fully immunoreactive NT-(4-13) fragment (yield, 95%). When treated with pepsin, the partially purified ileal substrates gave rise to 4 immunoreactive peptides, one of which (ca 15% of total) eluted with the same retention time as NT-(4-13) while the major peptide formed (ca 40% of total) eluted near to the position of NT-(3-13). Both these products reacted equally well with two different antisera towards the C-terminal 5- and 8-residues of NT and were not recognized by an N-terminal antiserum. Experiments using various proteases demonstrated that the NT-related sequence(s) were located internally in each substrate and suggested that they were bounded by double basic residues. Substrate activity in isotonic homogenates of feline spinal cord, brain, adrenal and ileum cosedimented with iNT during equilibrium centrifugation, apparently in association with vesicle and/or synaptosomal particles. These findings indicate that basic proteins, colocalized with NT in vesicle-like particles of CNS, adrenals and ileum, could serve as precursors to this peptide, being liberated by pepsin-related enzyme(s).     

The biosynthesis of ovothiol A (N-methyl-4-mercaptohistidine). Identification of S-(4'-L-histidyl)-L-cysteine sulfoxide as an intermediate and the products of the sulfoxide lyase reaction.

Crude extracts of Crithidia fasciculata catalyse the formation of 4-mercapto-L-histidine, an intermediate in the biosynthesis of ovothiol A (N1-methyl-4-mercaptohistidine), in the presence of histidine, cysteine, Fe2+ and pyridoxal phosphate. This activity was present in a 35-55% ammonium sulfate fraction that was shown to produce a transsulfuration intermediate in the absence of pyridoxal phosphate. The transsulfuration intermediate was isolated and identified as S-(4'-L-histidyl)-L-cysteine sulfoxide. The synthase activity, partially purified by anion-exchange chromatography, was shown to require oxygen and could be used to synthesize a number of isotopically labeled S-(4'-L-histidyl)-L-cysteine sulfoxides. Sulfoxide lyase activity was partially resolved from the synthase by anion-exchange chromatography. The phenylhydrazone of the product derived from the cysteine moiety of the sulfoxide coeluted with the phenylhydrazone of pyruvate on HPLC, but this assignment could not be confirmed by mass spectral analysis. S-(4'-[14C]L-histidyl)-[U-13C3,15N]L-cysteine sulfoxide was synthesized and converted to products of the lyase reaction in the presence of lactate dehydrogenase and NADH. The 13C-labeled product was identified by 13C-NMR spectroscopy as lactate and the primary product of the lyase reaction is therefore pyruvate. With S-(4'[3H]L-histidyl)-[14C]L-cysteine sulfoxide as the substrate [14C]lactate, [14C]cysteine and [3H]4-mercaptohistidine could be detected as products of the lyase reaction, but the sum of the two thiol species exceeded the amount of sulfoxide substrate used. Evidence is presented that this anomaly was due to the utilization of sulfur from dithiothreitol for the formation of cysteine.     

In-vitro antibacterial, antifungal activity of some transition metal complexes of thiosemicarbazone Schiff base (HL) derived from N4-(7'-chloroquinolin-4'-ylamino) thiosemicarbazide

The synthetic, spectroscopic, and biological studies of Cu(II), Ni(II), Zn(II), Co(II), Mn(II), Fe(III) and Cr(III) complexes of N(4)-(7'-chloroquinolin-4'-ylamino)-N(1)-(2-hydroxy-benzylidene)thiosemicarbazone (HL) obtained by the reaction of N(4)-(7'-chloroquinolin-4'-ylamino)thiosemicarbazide with 2-hydroxybenzaldehyde. The structures of the complexes were determined on the basis of the elemental analyses, spectroscopic data (IR, electronic, (1)H and (13)C NMR and Mass spectra) along with magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses. Electrical conductance measurement revealed the non-electrolytic nature of the complexes. The resulting colored products are mononuclear in nature. On the basis of the above studies, only one ligand was suggested to be coordinated to each metal atom by thione sulfur, azomethine nitrogen and phenolic oxygen to form mononuclear complexes in which the thiosemicarbazone behaves as a monobasic tridendate ligand. The ligand and its metal complexes were tested against Gram + ve bacteria (Staphylococcus aureus), Gram - ve bacteria (Escherichia coli), fungi (Candida albicans) and (Fusarium solani). The tested compounds exhibited significant activity.     

Identification of a butyrophenone analog as a potential atypical antipsychotic agent: 4-[4-(4-chlorophenyl)-1,4-diazepan-1-yl]-1-(4-fluorophenyl)butan-1-one

The synthesis and exploration of novel butyrophenones have led to the identification of a diazepane analogue of haloperidol, 4-[4-(4-chlorophenyl)-1,4-diazepan-1-yl]-1-(4-fluorophenyl)butan-1-one (compound 13) with an interesting multireceptor binding profile. Compound 13 was evaluated for its binding affinities at DA subtype receptors, 5HT subtype receptors, H-1, M-1 receptors and at NET, DAT, and SERT transporters. At each of these receptors, compound 13 was equipotent or better than several of the standards currently in use. In in vivo mouse and rat models to evaluate its efficacy and propensity to elicit catalepsy and hence EPS in humans, compound 13 showed similar efficacy as clozapine and did not produce catalepsy at five times its ED(50) value.     

Biosynthesis of the 2-(aminomethyl)-4-(hydroxymethyl)furan subunit of methanofuran

2H- and 13C-labeled precursors were used to establish the pathway for the biosynthesis of the 2-(aminomethyl)-4-(hydroxymethyl)furan (F1) component of methanofuran in methanogenic archaebacteria. The extent and position of the label incorporated into F1 were measured from the mass spectrum of the diacetyl derivative of F1. [1,2-13C2]Acetate was found to be incorporated into two separate positions of the F1 molecule as a unit. The extent of incorporation of 13C2 into each of these positions was the same as that observed for the incorporation of acetate into the alanine and proline produced by the cells. From [2,2,2-2H3]acetate, deuterium was incorporated into two separate sites of the F1 molecule, one containing up to two deuteriums and the other only one. On the basis of the fragmentation pattern of the F1 diacetyl derivative, it was determined that two deuteriums were incorporated into the hydroxymethyl group at C-4 and one was incorporated at C-3 of the furan ring. The extent and distribution of the incorporated deuterium at the C-4 methylene were the same as that observed for C-6 of the glucose produced by the cells. On the basis of this and additional information presented in this paper, it is concluded that F1 is generated by the condensation of dihydroxyacetone phosphate with pyruvate. The resulting dihydroxy-substituted tetrahydrofuran after elimination of 2 mol of water would produce the phosphate ester of 2-carboxy-4-(hydroxymethyl)furan. Reduction of the carboxylic acid to an aldehyde and subsequent transamination would produce the phosphate ester of F1.     

Synthesis, cytotoxicity, and anti-inflammatory evaluation of 2-(furan-2-yl)-4-(phenoxy)quinoline derivatives. Part 4

A number of 2-(furan-2-yl)-4-phenoxyquinoline derivatives have been synthesized and evaluated for anti-inflammatory evaluation. 4-[(2-Furan-2-yl)quinolin-4-yloxy]benzaldehyde (8), with an IC(50) value of 5.0 microM against beta-glucuronidase release, was more potent than its tricyclic furo[2,3-b]quinoline isomer 3a (>30 microM), its 4'-COMe counterpart 7 (7.5 microM), and its oxime derivative 13a (11.4 microM) and methyloxime derivative 13b (>30 microM). For the inhibition of lysozyme release, however, oxime derivative 12a (8.9 microM) and methyloxime derivative 12b (10.4 microM) are more potent than their ketone precursor 7 and their respective tricyclic furo[2,3-b]quinoline counterparts 4a and 4b. Among them, 4-[4-[(2-furan-2-yl)-quinolin-4-yloxy]phenyl]but-3-en-2-one (10) is the most active against lysozyme release with an IC(50) value of 4.6 microM, while 8 is the most active against beta-glucuronidase release with an IC(50) value of 5.0 microM. (E)-1-[3-[(2-Furan-2-yl)quinolin-4-yloxy]phenyl] ethanone oxime (11a) is capable of inhibiting both lysozyme and beta-glucuronidase release with IC(50) values of 7.1 and 9.5 microM, respectively. For the inhibition of TNF-alpha formation, 1-[3-[(2-furan-2-yl)quinolin-4-yloxy]phenyl]ethanone (6) is the most potent with an IC(50) value of 2.3 microM which is more potent than genistein (9.1 microM). For the inhibitory activity of fMLP-induced superoxide anion generation, 11a (2.7 microM), 11b (2.8 microM), and 13b (2.2 microM) are three of the most active. None of above compounds exhibited significant cytotoxicity.     

Brevican is degraded by matrix metalloproteinases and aggrecanase-1 (ADAMTS4) at different sites

Brevican is a member of the lectican family of chondroitin sulfate proteoglycans that is predominantly expressed in the central nervous system. The susceptibility of brevican to digestion by matrix metalloproteinases (MMP-1, -2, -3, -7, -8, -9, -10, and -13 and membrane type 1 and 3 MMPs) and aggrecanase-1 (ADAMTS4) was examined. MMP-1, -2, -3, -7, -8, -10, and -13 degraded brevican into a few fragments with similar molecular masses, whereas the degradation products of aggrecanase-1 had apparently different sizes. NH(2)-terminal sequence analyses of the digestion fragments revealed that cleavages of the brevican core protein by these metalloproteinases occurred commonly within the central non-homologous domain. MMP-1, -2, -3, -7, -8, -10, and -13 preferentially attacked the Ala(360)-Phe(361) bond, whereas aggrecanase-1 cleaved the Glu(395)-Ser(396) bond, which are similar to the cleavage sites observed with cartilage proteoglycan (aggrecan) for the MMPs and aggrecanase-1, respectively. These data demonstrate that MMP-1, -2, -3, -7, -8, -10, and -13 and aggrecanase-1 digest brevican in a similar pattern to aggrecan and suggest that they may be responsible for the physiological turnover and pathological degradation of brevican.     

Synthesis and evaluation of 4-(substituted styryl/alkenyl)-3,5-bis(4-hydroxyphenyl)-isoxazoles as ligands for the estrogen receptor

A series of 3,5-bis (4-hydroxyphenyl) isoxazoles bearing a styryl/alkyl vinyl group at the 4-position were prepared and evaluated as ligands for the estrogen receptor-alpha (ERα). The target compounds were prepared using the Suzuki reaction to couple an iodo-isoxazole intermediate with a series of styryl/alkenyl boronic acids, followed by O-demethylation. The products were evaluated for their estrogen receptor-α ligand binding domain (ERα-LBD) binding affinity using a competitive binding assay. The 4-(4-hydroxystyryl) derivative 4h displays binding properties similar to those of the previously described pyrazole class of ER ligands, indicating that the ERα-LBD tolerates the presence of the added vinyl group at the 4-position of the isoxazole ring.     

Partial resolution of racemic trans-4-[5-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxyl-2-yl]benzoic acids by the diastereomer method with (R)- or (S)-1-phenylethylamine

The partial resolution is described of a series of racemic trans-4-[5-(4-alkoxyphenyl)-2,5-dimethylpyrrolidine-1-oxyl-2-yl]benzoic acids (1), which are the key intermediates for the synthesis of chiral organic radical liquid crystalline compounds and are crystallized to give racemic compounds. Racemic acid 1 [(+/-)-1] with a long alkyl chain (C7 to C13) could be resolved by the conventional diastereomeric salt formation using (R)- or (S)-1-phenylethylamine (2) as the resolving agent, whereas resolution of (+/-)-1 with a short alkyl chain (C4 to C6) was unsuccessful. Use of six equiv of (R)- or (S)-2 for the initial diastereomeric salt formation of (+/-)-1 with a C7-C13 alkyl chain, followed by recrystallization of the resulting salts once or twice, gave 2S,5S- or 2R,5R-enriched 1, respectively, in an ee range of 75-92% and with an overall recovery of 11-27%, based on the original quantity of (+/-)-1.     

Enantioseparation of racemic 4-aryl-3,4-dihydro-2(1H)-pyrimidones on chiral stationary phases based on 3,5-dimethylanilides of N-(4-alkylamino-3,5-dinitro)benzoyl L-alpha-amino acids

Three novel chiral packing materials for high-performance liquid chromatography were prepared by covalently binding of (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonylamino]propan-amide (7), (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonylamino]-4-methylpentanamide (8), and (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonyl-amino]-2-phenylacetamide (9) to aminopropyl silica. The resulting chiral stationary phases (CSPs 1-3) proved effective for the resolution of racemic 4-aryl-3,4-dihydro-2(1H)-pyrimidone derivatives (TR 1-14). The mechanism of their enantioselection, supported by the elution order of (S)-TR 13 and (R)-TR 13 and molecular modeling of the complex of the slower running (S)-TR 13 with CSP 1 is discussed.     

Beta-oxidation of 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid by MOLT-4 lymphocytes.

MOLT-4 lymphocytes metabolize 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12(S)-HETE via beta-oxidation with retention of the hydroxyl group at the omega 9 carbon atom. The isolation of 6-hydroxy-4,8-tetradecadienoic acid documents that these cells have the capacity to catabolize the conjugated diene system. 12(S)-HETE was also metabolized to 3,12-dihydroxy-8,10,14-eicosatrienoic acid and 1,9-dihydroxy-5,7,11-heptadecatriene as well as to 17- and 19-carbon aldehydes. When MOLT-4 cells were incubated with the beta-oxidation product, 10-hydroxy-6,8,12-octadecatrienoic acid, it was in part further catabolized but in addition it served as an anabolic precursor as defined by the accumulation 3,12-dihydroxy-8,10,14-eicosatrienoic acid as well as 1,11-dihydroxy-7,9,13-nonadecatriene. Neither 10-hydroxy-6,8,12-octadecatrienoic acid nor 13-hydroxy-5,8,11-octadecatrienic acid was as potent in inhibiting phytohemagglutin-induced lymphocyte mitogenesis as were their parent compounds--i.e., 12(S)- and 15(S)-HETE. These findings argue against the hypothesis that beta-oxidation products of 12(S)- and 15(S)-HETE are the potential modulators of lymphocyte function. However, neither the pathway for synthesis, nor the role of odd chain aldehydes and diols as potential lipid mediators was determined in this study.     

Aromatic ring cleavage of a non-phenolic beta-O-4 lignin model dimer by laccase of Trametes versicolor in the presence of 1-hydroxybenzotriazole

The novel cleavage products, 2,3-dihydroxy-1-(4-ethoxy-3-methoxyphenyl)-1-formyloxypropane (II) and 1-(4-ethoxy-3-methoxyphenyl)-1,2,3-trihydroxypropane-2,3-cyclic carbonate (III) were identified as products of a non-phenolic beta-O-4 lignin model dimer, 1,3-dihydroxy-2-(2,6-dimethoxylphenoxy)-1-(4-ethoxy-3-methoxypheny l)propane (I), by a Trametes versicolor laccase in the presence of 1-hydroxybenzotriazole (1-HBT). An isotopic experiment with a 13C-labeled lignin model dimer, 1,3-dihydroxy-2-(2,6-[U-ring-13C] dimethoxyphenoxy)-1-(4-ethoxy-3-methoxyphenyl)propane (I-13C) indicated that the formyl and carbonate carbons of products II and III were derived from the beta-phenoxy group of beta-O-4 lignin model dimer I as aromatic ring cleavage fragments. These results show that the laccase-1-HBT couple could catalyze the aromatic ring cleavage of non-phenolic beta-O-4 lignin model dimer in addition to the beta-ether cleavage, Calpha-Cbeta cleavage, and Calpha-oxidation.     

Formation of 4-ethoxy-4'-nitrosodiphenylamine in the reaction of the phenacetin metabolite 4-nitrosophenetol with glutathione

Phenacetin, a constituent of several analgesic and antipyretic formulations has been made responsible for a variety of toxic and carcinogenic actions. 4-Nitrosophenetol, the N-oxydation product of intermediate 4-phenetidine, forms methemoglobin and binds covalently to sulfhydryl groups of proteins and glutathione. In the reaction of 4-nitrosophenetol with glutathione and other thiols an intermediate so-called "semimercaptal" is formed from which N-(thiol-S-yl)-4-phenetidine S-oxide, N-(thiol-S-yl)-4-phenetidine and 4-phenetidine derive. Besides thiol adducts, a yellow compound is formed which was isolated as a pure crystalline product (elemental analysis) and identified by FAB-MS, EI-MS, 13C-, 1H-NMR, and UV-VIS spectroscopy as 4-ethoxy-4'-nitrosodiphenylamine. This nitrosoarene is formed by an unknown mechanism from 4-nitrosophenetol and 4-phenetidine under liberation of ethanol. In human erythrocytes this compound is easily reduced to 4-amino-4'-ethoxydiphenylamine (FAB-MS, EI-MS, 13C-NMR). During the reaction of 4-nitrosophenetol with red cells only traces of 4-ethoxy-4'-nitrosodiphenylamine were formed, whereas up to 10% appeared as the reduction product 4-amino-4'-ethoxydiphenylamine. This latter compound is unstable in red cells and is metabolized further to unidentified products.     

Synthesis and biological activity of analogs of dynorphin-A(1-13) substituted in positions 2 and 4: design of [Ala2,Trp4]-Dyn-A(1-13) as a putative selective opioid antagonist

Mono- and di-substituted analogs of dynorphin-A(1-13) (Dyn-A(1-13)) were synthesized by the solid-phase procedure. The products were purified and analyzed for their ability to inhibit the electrically evoked contractions of the guinea pig ileum (GPI) and mouse vas deferens (MVD) and to compete with the binding of [3H]etorphine ([3H]ET) and [3H]ethylketocyclazocine ([3H]EKC) to homogenates of rat brain (mu-, delta-, kappa 2-receptors) and guinea pig cerebellum (kappa-receptor), respectively. Introduction of Ala in position 2 caused a drastic decrease in the activity of the peptide on the smooth muscle preparations (IC50 of 104 and 2.250 nM in the GPI and the MVD as compared with 0.7 and 21 nM for the parent peptide, respectively). Conversely, this analog retained much of the opioid binding activity of Dyn-A(1-13) (relative binding potencies of 15 and 72% for the displacement of [3H]ET and [3H]EKC, respectively). The replacement of Phe4 by Trp also caused drastic decreases in the activity of the peptide in the smooth muscle preparations (relative potencies of 0.8 and 8.8% on the GPI and MVD) while much of the binding potency to the opioid receptors was retained (31 and 67% for the displacement of [3H]ET and [3H]EKC, respectively). [Ala2,Trp4]-Dyn-A(1-13) was the least potent peptide tested in the smooth muscle assays (relative potencies: 0.1 and 0.6%). However, this latter analog still retained some opioid binding activity in the displacement of [3H]ET to rat brain homogenates (3%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Some aryl substituted 2-(4-nitrophenyl)-4-oxo-4-phenylbutanoates and 3-(4-nitrophenyl)-1-phenyl-1,4-butanediols and related compounds as inhibitors of rat liver microsomal retinoic acid metabolising enzymes

Some aryl substituted methyl 2-(4-nitrophenyl)-4-oxo-4-phenylbutanoates generally had poor to moderate inhibitory potency (4-73%) towards rat liver microsomal retinoic acid metabolising enzymes compared with ketoconazole (80%). Conversion to the corresponding 3-(4-nitrophenyl)-1-aryl-1,4-butanediols considerably increased potency (29-78%). The 4-iodophenyl analogue, (30) and the 4-iodo- (45) and 4-methoxyphenyl (46) analogues, were the most potent in both series respectively. The corresponding 5-membered lactones, in the three instances examined, were also potent (52%, 67%, 69%) as were the cis- and trans-isomers of the 5-membered tetrahydrofuran (77%, 65% respectively). Beckmann rearrangement of the oxime methyl 4-(2,4-dichlorophenyl)-4-hydroxyimino-2-(4-nitrophenyl)butanoate (54) gave the expected products (55) and (56), which were potent inhibitors (75%, 74% respectively) of the enzyme whereas the oxime was an activator.     

Vitamin d(4) in mushrooms

An unknown vitamin D compound was observed in the HPLC-UV chromatogram of edible mushrooms in the course of analyzing vitamin D(2) as part of a food composition study and confirmed by liquid chromatography-mass spectrometry to be vitamin D(4) (22-dihydroergocalciferol). Vitamin D(4) was quantified by HPLC with UV detection, with vitamin [(3)H] itamin D(3) as an internal standard. White button, crimini, portabella, enoki, shiitake, maitake, oyster, morel, chanterelle, and UV-treated portabella mushrooms were analyzed, as four composites each of a total of 71 samples from U.S. retail suppliers and producers. Vitamin D(4) was present (>0.1 μg/100 g) in a total of 18 composites and in at least one composite of each mushroom type except white button. The level was highest in samples with known UV exposure: vitamin D enhanced portabella, and maitake mushrooms from one supplier (0.2-7.0 and 22.5-35.4 μg/100 g, respectively). Other mushrooms had detectable vitamin D(4) in some but not all samples. In one composite of oyster mushrooms the vitamin D(4) content was more than twice that of D(2) (6.29 vs. 2.59 μg/100 g). Vitamin D(4) exceeded 2 μg/100 g in the morel and chanterelle mushroom samples that contained D(4), but was undetectable in two morel samples. The vitamin D(4) precursor 22,23-dihydroergosterol was found in all composites (4.49-16.5 mg/100 g). Vitamin D(4) should be expected to occur in mushrooms exposed to UV light, such as commercially produced vitamin D enhanced products, wild grown mushrooms or other mushrooms receiving incidental exposure. Because vitamin D(4) coeluted with D(3) in the routine HPLC analysis of vitamin D(2) and an alternate mobile phase was necessary for resolution, researchers analyzing vitamin D(2) in mushrooms and using D(3) as an internal standard should verify that the system will resolve vitamins D(3) and D(4).     

Synthesis and properties of (4-13C)NAD+. Observation of its binding to yeast alcohol dehydrogenase by 13C-NMR spectroscopy

Starting from (13C)formic acid, acetone and cyanoacetamide samples of (4-13C)nicotinic acid and (4-13C)-nicotinamide were synthesised in an overall and additive yield of 11%. 1H-NMR and mass spectroscopy showed 90% enrichment of 13C in the expected position. NADase-catalysed exchange between thionicotinamide-adenine dinucleotide and (4-13C)nicotinamide furnished (4-13C)NAD+ which was purified, characterized and quantified by 1H-NMR and 13C-NMR spectroscopy and by enzymic assay. The 13C-NMR signal of (4-13C)beta-NAD+ (146.09 ppm) was broadened and shifted (147.83 ppm) upon binding to yeast alcohol dehydrogenase.     

Anthelmintic and antibacterial screening of a new series of N-[4-(4-nitrophenoxy)phenyl]-4-(substituted)-1,3-thiazol-2-amines

A series of N-[4-(4-nitrophenoxy)phenyl]-4-(substituted)-1,3-thiazol-2-amines was synthesized. Structural elucidation was accomplished by ¹H NMR, ¹³C NMR, IR, and elemental analyses of synthesized compounds. The title compounds were derived from 4-(4-nitrophenoxy)phenyl thiourea, which is the key intermediate in the synthesis of nitroscanate, an anthelmintic drug. Among the synthesized compounds, N-[4-(4-nitrophenoxy)phenyl]-4-(4-fluorophenyl)-1,3-thiazol-2-amine and N-[4-(4-nitrophenoxy)phenyl]-4-(4-methoxyphenyl)-1,3-thiazol-2-amine exhibited potent anthelmintic and antibacterial activities.     

Formation of (4R)- and (4S)-4-hydroxyochratoxin A from ochratoxin A by liver microsomes from various species.

Two metabolic products were formed from ochratoxin A by human, pig, and rat liver microsomal fractions in the presence of reduced nicotinamide adenine dinucleotide phosphate. They were isolated from the incubation mixture in the presence of pig liver microsomes by extraction, thin-layer chromatography, and high-pressure liquid chromatography Their structures are suggested to be (4R)- and (4S)-4-hydroxyochratoxin A on the basis of mass and nuclear magnetic resonance spectroscopy. Km and the maximum velocity for the formation of the two metabolites by human, pig, and rat microsomes were determined. Their formation was inhibited by carbon monoxide and metyrapone. The results indicate that the microsomal hydroxylation system is a cytochrome P-450 and that different species are involved in the formation of the two epimeric forms of 4-hydroxyochratoxin A.