Stability constants for metal complexation by isomers of mimosine and related compounds

Stünzi, Hans; Harris, Lyndsay; Perrin, DD; Teitei, T

doi:10.1071/ch9802207

Cited by 38 publications

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“…malt01 2), as binding groups for various' metal ions. This and its isomers as chelating agents for various divalent (9,10) and trivalent metals (1 1).…”

Section: Introductionmentioning

confidence: 99%

Physical and structural studies of N-substituted-3-hydroxy-2-methyl-4(1H)-pyridinones

Nelson¹,

Karpishin²,

Rettig³

et al. 1988

Can. J. Chem.

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A series of 3-hydroxy-2-methyl-4(1H)-pyridinones has been prepared with the substituents H, CH3, n-C6HII, and CH2CH2NH2 at the ring N. The dipyridinone 1,6-bis(3-hydroxy-2-methyl-4( 1 H)-pyridinn 1yl)hexane has also been synthesized. The products with H and CH3 substituents have been studied by single crystal X-5ay diffraction. Crystals of 3-hydroxy-2-methyl-4-pyridinone are monoclinic, a = 6.835 1(4), b = 10.2249(4), c = 8.6525(4) A, P = 105.215(4)", Z = 4, space group P21 n and those of 3-hydroxy-l,2-dimethyl-4-pyridinone are orthorhombic, a = 7.3036(4), b = 13.0490(6), c = 13.7681(7) 9' , Z = 8, space group Pbca. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.037 and 0.044 for 914 and 857 reflections with I 2 3 a ( I ) , respectively. Bond lengths and angles in the two compounds were normal. All the compounds have been studied by mass spectrometry, and by infrared and proton nmr spectroscopies. The importance of hydrogen bonding to both the solution and solid state properties of these compounds has been confirmed by these techniques. Introduction There is considerable literature on 4-pyridinones (1) but a limited amount of information is available on the 3-hydroxy-4-pyridinones. Much of the preparative work on the latter is scattered and inaccessible, having been reported in the form of patents, and we discovered when we became interested in them, that a considerable effort was required before we had the requisite compounds for further study.As part of a project to examine neutral water soluble complexes of aluminum, gallium, and other metals, we have prepared and characterized a series of N-substituted-3-hydroxy-2-methyl-4-pyridinones (1) to be used as ligands for these metals in aqueous solution. Recently, there has been significant interest in these compounds, and the related pyrones (e.g. malt01 2), as binding groups for various' metal ions. This

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“…malt01 2), as binding groups for various' metal ions. This and its isomers as chelating agents for various divalent (9,10) and trivalent metals (1 1).…”

Section: Introductionmentioning

confidence: 99%

Physical and structural studies of N-substituted-3-hydroxy-2-methyl-4(1H)-pyridinones

Nelson¹,

Karpishin²,

Rettig³

et al. 1988

Can. J. Chem.

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“…The pK a1 values of amphoteric protonated 3-hydroxy-4-pyridinones are of the same magnitude as that of entacapone. [16][17][18][19][20][21][22] The deprotonation of entacapone can be described as the dissociation of the catecholic group. Figure 1 show strong proton dissociation and complex formation in acidic solutions.…”

Section: Resultsmentioning

confidence: 99%

Iron(III)-Chelating Properties of the Novel Catechol O-Methyltransferase Inhibitor Entacapone in Aqueous Solution

Orama

Tilus

Taskinen

et al. 1997

Journal of Pharmaceutical Sciences

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The iron(III) complex formation of entacapone, a novel catechol O-methyltransferase (COMT) inhibitor, has been studied at 25 degrees C in aqueous 0.1 mol/L NaCl solution by using the electromotive force titration method. Entacapone functions as a bidentate ligand chelating through the catecholate oxygen atoms and forms stable iron(III) complexes with the formation constant of a tris complex: log beta-613 ([FeL3(3-)][H]6+/[Fe3+][H2L]3) = -6.9 +/- 0.1. Distribution curves show that entacapone is highly effective for iron(III) in moderately dilute solution (10(-3) mol/L) whereas in very dilute solution (10(-6) mol/L) the iron hydroxo complexes together with FeL3(3-) dominate under physiological pH 7.4. Comparison of iron(III) species distribution in a competitive two-ligand entacapone-catechol system reveals that the complexation of entacepone is favored at high and low dilution.

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“…... 38 Figure 5.2: (a) Intake of leucaena (100% leucaena treatment only) in Bos indicus steers in response to decreasing urinary DHP excretion for weeks 2-10 (denoted as data labels) (DMI = −1.27 ×10 −4 × total urinary DHP + 18.2; R 2 = 0.97, P < 0.001), and (b) rate of decline in mean total DHP excretion for steers fed diets containing 25% leucaena (total urinary DHP = −840 × week + 7062; R 2 = 0.89), 50% leucaena (total urinary DHP = −1211 × week + 11600; R 2 = 0.97) and 100% leucaena (total urinary DHP = −3533 × week + 29056; R 2 = 0.96)(P < 0.001). DHP: hydroxypyridone; DMI: Adapted from Curtis and Atkinson (1972), Stunzi et al (1980) and Scarrow et al (1985). ........................................................................................................................ 94 Nurchi et al (2012).…”

Section: List Of Tablesmentioning

confidence: 99%

Unravelling Leucaena leucocephala toxicity: ruminant studies in eastern Indonesia and Australia

Halliday¹

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The forage tree legume leucaena [Leucaena leucocephala (Lam.) de Wit ssp. glabrata (Rose) Zarate] is a high-quality ruminant feed vitally important as a source of protein for livestock production in tropical regions. However, the presence of the acutely toxic nonprotein amino acid mimosine in leaves and seeds, and its breakdown to chronically toxic hydroxypyridones (DHP), was believed to limit its productivity and adversely affect animal health. The Australian development of a fermenter-cultured oral inoculum containing the DHP-degrading ruminal bacterium Synergistes jonesii in the 1980s was thought to overcome this issue; however, anecdotal evidence of leucaena toxicity symptoms occurring in inoculated animals remained. In response, a program of research was initiated to investigate the efficacy of S. jonesii as well as other methods of protection against toxicity in ruminants. Broadly, this involved two areas of research, namely the effectiveness of: (a) microbiological degradation via S. jonesii; and (b) non-microbial metabolic detoxification. Key objectives were to: (a) determine the efficacy of inoculation with S. jonesii both within Indonesia and Australia; (b) profile the toxicity status of ruminants in eastern Indonesia; (c) investigate the impact of mineral supplementation on 2,3-DHP toxicity; and (d) determine the extent of in vivo conjugation of DHP and its role in protecting ruminants against toxicity. Initially, an Indonesian study involving the transfer of rumen fluid from "protected" ruminants to naïve Bali bulls was conducted. Sequential monitoring of DHP levels in urine indicated that there was no effect of inoculation. Secondly, a controlled animal house experiment was conducted in Australia to measure the impact of high leucaena diets on production in naïve steers and the effect of inoculation with the commercial S. jonesii inoculum. Key findings were: (1) inoculation had no effect on total DHP excretion; (2) indigenous S. jonesii strains were present in naïve animals prior to inoculation; (3) DHP did not suppress thyroid hormone production; and (4) high levels of the isomer 2,3-DHP were present without accompanying signs of toxicity. The leucaena toxicity status of ruminants in eastern Indonesia was then assessed in a survey across the four islands of Lombok, Sumbawa, Sumba and West Timor. A number of different strains of S. jonesii, including the ATCC type strain (78.1), were detected, however S. jonesii was always at low population levels and always accompanied by high levels of undegraded 2,3-DHP in urine. Despite this apparent failure of S. jonesii to degrade DHP, there was no observed impact on animal productivity or health. Accordingly, vii Contributions by others to the thesis This thesis is the original work of Michael Halliday.

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Stability constants for metal complexation by isomers of mimosine and related compounds

Cited by 38 publications

References 0 publications

Physical and structural studies of N-substituted-3-hydroxy-2-methyl-4(1H)-pyridinones

Physical and structural studies of N-substituted-3-hydroxy-2-methyl-4(1H)-pyridinones

Iron(III)-Chelating Properties of the Novel Catechol O-Methyltransferase Inhibitor Entacapone in Aqueous Solution

Unravelling Leucaena leucocephala toxicity: ruminant studies in eastern Indonesia and Australia

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