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Results for “Picolinic Acids”

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PubMed1987

Influence of picolinic acid on the uptake of 65zinc-amino acid complexes by the everted rat gut.

Three hundred fifty rats were used in three experiments to: 1) validate the everted gut procedure as an in vitro technique for estimating Zn absorption, 2) determine the effect of increasing ratios of picolinic acid (PA) to Zn on Zn absorption and 3) determine the effect of PA on absorption of Zn and amino acid complexes at pH 6, 7 and 8. In the first experiment the time delay between tissue collection with subsequent storage in ice-cold saline and start of tissue incubation was 0, 10, 20 or 30 min. A linear decrease was observed for 65Zn uptake with increasing delay time. Lysine absorption was not affected by delay time. In the second experiment, molar ratios of PA:Zn of 0, .5, 1.0, 1.5, 2.0 and 2.5 with Zn held constant were evaluated. A linear decrease in 65Zn absorption from 65ZnCl2 occurred as the molar ratio of PA to Zn increased. In the third experiment, 0 and 5 molar ratios of PA to a constant Zn level were evaluated using 65ZnCl2, 65Zn-14C-methionine (ZnMet) and 65Zn-3H-lysine (ZnLys) at pH 6, 7 and 8. The addition of PA decreased Zn absorption regardless of Zn source. The data suggest that the Zn sources used were of similar biological value. The data do not support the theory that PA facilitates Zn absorption.

Animals↗
PubMed1987

Tryptophan deficiency and picolinic acid: effect on zinc metabolism and clinical manifestations of pellagra.

In five experiments, rats were fed tryptophan (Tryp)-deficient diets with 6-12 micrograms/g zinc (Zn) and, in one experiment, a Zn-deficient diet to test the effect on clinical manifestations, plasma and bone Zn, and ability of picolinic acid (PA) or extra (12 micrograms/g) Zn to compensate. Tryp deficiency caused classical manifestations of pellagra although niacin intake was in excess of normal requirements. At marginal Zn intakes, oral PA caused a significant increase of plasma Zn and, compared with Tryp-adequate controls, Tryp deficiency resulted in lower plasma Zn and plasma:bone Zn ratios. Extra Zn (total 24 micrograms/g) was ineffective. Subcutaneous PA showed a tendency to lower plasma Zn. PA had no effect on clinical manifestations. We conclude that a Tryp metabolite other than nicotinic acid is necessary in the prevention of pellagra. Our hypothesis links this finding with the observed Tryp and PA effect on Zn metabolism.

Animals↗
PubMed1999

Investigation of Coordinational Properties of Europium(III) Complexes with Picolinic Acid Using Eu(III) Excitation Spectroscopy.

The 7F0 --> 5D0 excitation spectra of Eu(III) complexed with picolinic acid were investigated using Eu(III) excitation spectroscopy. Six overlapping peaks are seen in the excitation spectra, indicating the formation of six species. The structures of the six species are proposed here and described in terms of both coordination by carboxylate and N-chelation. Copyright 1999 Academic Press.

Journal Article↗
PubMed2002

Antifungal activity of macrophages engineered to produce IFNgamma: inducibility by picolinic acid.

Macrophages are important antimicrobial effectors, whose efficacy is greatly enhanced by interferon-gamma (IFNgamma). We recently engineered a mouse macrophage cell line to express the IFNgamma gene in a inducible manner. Such macrophages, Mphi10, include a construct containing the IFNgamma gene under the control of the synthetic promoter HRE3x-Tk. Picolinic acid (PA) is a catabolite of tryptophan, known to exert costimulatory activities on macrophages and expected to act on transcriptional elements within HRE3x-Tk promoter. Since evidence exists on the efficacy of engineered macrophages as carriers of therapeutic genes against tumors, we tested Mphi10, under basal conditions and following exposure to PA, as IFNgamma-producing cells in in vitro models of fungal infection. We found that Mphi10 constitutively exhibited anticryptococcal and anticandidal activity, low but detectable levels of IFNgamma mRNA and undetectable levels of nitric oxide synthase (iNOS) transcripts. Treatment with PA caused time-dependent enhancement of antifungal activity. The phenomenon was associated with the induction of both IFNgamma and iNOS gene expression and was followed by IFNgamma and NO production. The effect of the Mphi10-produced IFNgamma on other cells was also investigated by a transwell co-culture system. A major enhancement of phagocytosis and antifungal activity was observed in BV2 microglial cells that had been co-cultured with Mphi10. Such an increase was only evident when Mphi10 had been pretreated with PA and was abrogated by concomitant addition of anti-IFNgamma antibodies. In conclusion, we show that Mphi10 respond to PA with the production of IFNgamma, which retains the ability to induce antifungal activity in the producing macrophages as well as in other macrophage populations. The potential use of Mphi10 as vectors for therapeutic genes in infectious diseases is discussed.

Animals↗
PubMed1984

Picolinic acid in acrodermatitis enteropathica: evidence for a disorder of tryptophan metabolism.

Three children with acrodermatitis enteropathica (AE) were treated with oral zinc dipicolinate (zinc-PA). The daily dose of zinc required to prevent exacerbations, when administered as the dipicolinate complex, was one-third the minimum amount of zinc required as the sulfate salt. The concentration of picolinic acid in the plasma of asymptomatic children with AE was significantly less than that of normal children. However, oral treatment with PA alone was ineffective. The plasma of the three AE children contained a measurable quantity of kynurenine which was undetectable in plasma from normal children. Absorption of an oral zinc load was normal. The results support the hypothesis that the genetic defect in AE is in the tryptophan pathway, although the role of PA in zinc metabolism remains to be defined.

Acrodermatitis↗
PubMed2005

New derivatives of picolinic acid and nicotinic acid with anticonvulsant activity.

Previously obtained Pic-BZA is a potent anticonvulsant with low neurotoxicity, but its half-time of action is only about 15 min. In search for equally effective anticonvulsants but with a longer time of action fourteen Pic-BZA analogs were obtained. The compounds were evaluated in the Anticonvulsant Screening Project (ASP) of Antiepileptic Drug Development Program (ADDP) of NIH. Picolinic acid 2-fluorobenzylamide (Pic-2-F-BZA, 7) appeared to be the most effective compound of the series.

Animals↗
PubMed1987

Effect of zinc source and picolinic acid on 65Zn uptake in an in vitro continuous-flow perfusion system for pig and poultry intestinal segments.

Twenty weanling pigs and fourteen 9-wk-old broiler chickens were used in three continuous-flow in vitro perfusion experiments using noneverted intestinal sacs to 1) determine differences in 65Zn absorption due to location within the intestinal tract, 2) evaluate 65Zn uptake from ZnCl2 and Zn-methionine (ZnMet) with or without added picolinic acid (PA) in pig intestinal sacs and 3) evaluate 65Zn uptake from ZnCl2 and ZnMet in chicken intestinal sacs. No differences in 65Zn uptake due to gut segment position were observed in the pigs. A Zn source x PA interaction was observed for 65Zn uptake into the pig gut tissue and for 65Zn uptake to the serosal side of the gut sacs. Total 65Zn absorption in the pig gut sacs from the two Zn sources was not different, but the addition of a 5 M ratio of PA to Zn depressed 65Zn absorption. No differences were observed in total 65Zn absorption or 65Zn uptake in poultry gut sac tissue. There was, however, greater uptake of 65Zn from ZnCl2 to the serosal side of the sacs than from ZnMet. The data indicate that 65Zn from ZnCl2 and ZnMet is similar in total absorption and that the addition of PA depresses Zn uptake.

Animals↗
PubMed2004

Picolinic acid- or desferrioxamine-inducible autocrine activation of macrophages engineered to produce IFNgamma: an approach for gene therapy.

Macrophage (Mphi)-based vectors are highly mobile cellular shuttles designed to deliver therapeutic genes within the tissues. We engineered a mouse Mphi cell line to express the murine interferon-gamma (IFNgamma) under the control of an inducible promoter containing the hypoxia-responsive element, which can be triggered by hypoxia and other stimuli. We show that this Mphi vector can be induced to produce IFNgamma under normoxic conditions by stimulation with picolinic acid (PA), a catabolite of tryptophan, or desferrioxamine (DFX), an iron-chelating drug. The Mphi vector responds to IFNgamma with the induction of IRF-1 and of other IFNgamma-inducible genes, the expression of Ia antigens and induction of phagocytic activity. Inducible nitric oxygen synthase gene expression, nitric oxide production, as well as TNFalpha secretion were enhanced by PA or DFX as the sole stimuli. None of the above responses could be triggered individually by PA or DFX in control, normal Mphi, indicating that the Mphi vector overcame the need for costimulatory molecules derived from the immune system for its full activation. Furthermore, we demonstrate that extracellular iron can downregulate such response, thereby identifying an additional tool for the fine tuning of the Mphi vector response to stimulation.

Animals↗
PubMed1984

Phenoxy and picolinic acid herbicides and small-intestinal adenocarcinoma in sheep.

A study of age and sex matched groups of adult female sheep from 88 flat, hill, and high-country farms was conducted in the South Island of New Zealand to investigate the influence of breed and certain environmental factors on the prevalence rate of small-intestinal adenocarcinoma (SIA). 20 678 female sheep aged 5.5-7.5 years were examined at slaughter, 125 cases of SIA were found (6 per thousand) in animals from 61 farms (69%) and the prevalence rate for individual farm groups varied from 0 to 38 per thousand. Differences in tumour rate between breed groups were significant but differences between farm type were not. Exposure to phenoxy (Ph), picolinic acid (Pi) herbicides, or both (PhPi) was associated with significant increases in tumour rate. The increase in rate was significant for exposure to each of the 3 herbicide groups. Exposure to recently sprayed feed stuffs was associated with a significantly larger increase in tumour rate than exposure to less recently sprayed food. There was no difference between tumour rates of sheep exposed to Ph herbicides with or without 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Rates rose significantly with the total number of Ph, Pi, PhPi sprays used on the farm. The variation in rates associated with herbicides is sufficient to explain the breed differences recorded.

Adenocarcinoma↗
PubMed1983

[Substituted picolinic acids as DBH inhibitors. Inhibition of dopamine beta-hydroxylase and antihypertensive action].

The authors determined the dissociation constant, the constant of copper complex formation, the inhibitory action on the catecholamine biosynthesis enzyme dopamine beta-hydroxylase (DBH; copper glycoprotein), as well as the antihypertensive effect on spontaneously hypertensive rats of a series of substituted picolinic or fusaric acids (FA; 5-n-butylpicolinic acids). The substances investigated may be characterized as weak to medium-strong acids which form stable copper(II) complexes in solution and in the solid state. The concentrations required for a 50% inhibition of DBH range between 10(-6) and 10(-5) mol/l. The picolinic acid structure is of greater importance to enzyme inhibition than the butylpyridine structure. From the inhibition type of FA it may be deduced that the mechanism of inhibition cannot be explained only by the complex formation of the enzyme copper. Most of these derivatives are of hypotensive activity; some others exert a hypertensive effect. A quantitative correlation between the action on blood pressure and the enzyme inhibition cannot be established without calculation (quantitative structure-activity analysis). The hypotensive activity is above all due to DBH inhibition in the angiovascular region and in the suprarenal gland.

Animals↗
PubMed2004

Density functional calculation of the 2D potential surface and deuterium isotope effect on 13C chemical shifts in picolinic acid N-oxide. Comparison with experiment.

2D free energy surfaces V = V(rOH, rO...O) for the intramolecular H-bond in the title compound were calculated by the DFT method and used in the calculation of primary and secondary chemical shifts of the compound dissolved in chloroform and acetonitrile. Solvent effects were accounted for by the SCRF/PCM method. The corresponding two-dimensional chemical shift surfaces with included solvent reaction field were obtained using the Continuous Set of Gauge Transformations approach at the B3LYP/6-311+G(2d,2p) level of theory. The chemical shifts were estimated as quantum averages along the two internal coordinates in the hydrogen bond and along several vibrational levels according to the Boltzmann distribution at room temperature. Fairly good agreement between the experimental and calculated isotope effects was obtained. 1D and 2D NMR spectra of solutions of picolinic acid N-oxide and its deuterated analogue were recorded and assigned.

Journal Article↗