Effective regulation of iron acquisition in graminaceous plants. The role of mugineic acids as phytosiderophores

Discovery of mugineic acids as phytosiderophores has shown that some graminaceous monocotyledonous plants have a different iron acquisition strategy (strategy II) from dicotyledonous and nongraminaceous monocotyledonous plants (strategy I). The process of iron acquisition by strategy II plants can be divided into four main steps: biosynthesis, secretion, solubilization, and uptake, all of which are effectively regulated by different systems. The biosynthesis of mugineic acids is controlled by an on-off system which is operated under the control of iron demand in the plant. All mugineic acids share the same biosynthetic pathway from L-methionine to 2'-deoxymugineic acid, but the subsequent steps differ among plant species and even cultivars. The biosynthesis of mugineic acids is associated with the methionine recycling pathway. The secretion of mugineic acids shows a distinct diumal rhythm. Mugineic acids solubilize sparingly soluble inorganic iron by chelation and possess a high chelation affinity for iron, but not for other polyvalent ions such as Ca²⁺, Mg²⁺ and Al³⁺. The iron uptake process is regulated by a specific uptake system that transports the mugineic acid-Fe(III) complex as an intact molecule. This system specifically recognizes the mugineic acid-Fe(III) complexes, but not other mugineic acid-metal or synthetic chelator-Fe(III) complexes, suggesting that binding sites with strict recognition for stereostructure of the complex are located on the plasma membrane. All these regulatory systems are considered to represent an efficient strategy to acquire adequate amounts of iron and to avoid factors unfavorable for iron acquisition such as high pH, high concentrations of bicarbonate, Ca^2- and Mg²⁺, microbial degradation, and uptake of other metals that are common in calcareous soils.     

Transporters of ligands for essential metal ions in plants

Essential metals are required for healthy plant growth but can be toxic when present in excess. Therefore plants have mechanisms of metal homeostasis which involve coordination of metal ion transporters for uptake, translocation and compartmentalization. However, very little metal in plants is thought to exist as free ions. A number of small, organic molecules have been implicated in metal ion homeostasis as metal ion ligands to facilitate uptake and transport of metal ions with low solubility and also as chelators implicated in sequestration for metal tolerance and storage. Ligands for a number of essential metals have been identified and proteins involved in the transport of these ligands and of metal-ligand complexes have been characterized. Here we review recent advances in understanding the role of mugineic acid, nicotianamine, organic acids (citrate and malate), histidine and phytate as ligands for iron (Fe), zinc (Zn), copper (Cu), manganese (Mn) and nickel (Ni) in plants, and the proteins identified as their transporters.     

Concurrent sorption of Zn(II), Cu(II) and Co(II) by Oscillatoria angustissima as a function of pH in binary and ternary metal solutions

This paper reports biosorption of Zn(II), Cu(II) and Co(II) onto O. angustissima biomass from single, binary and ternary metal solutions, as a function of pH and metal concentrations via Central Composite Design generated by statistical software package Design Expert 6.0. The experimental design revealed that metal interactions could be best studied at lower pH range i.e. 4.0-5.0, which facilitates adequate availability of all the metal ions. The sorption capacities for single metal decreased in the order Zn(II)>Co(II)>Cu(II). In absence of any interfering metals, at pH 4.0 and an initial metal concentration of 0.5 mM in the solution, the adsorption capacities were 0.33 mmol/g Zn(II), 0.26 mmol/g Co(II) and 0.12 mmol/g Cu(II). In a binary system, copper inhibited both Zn(II) and Co(II) sorption but the extent of inhibition of former was greater than the latter; sorption values being 0.14 mmol/g Zn(II) and 0.27 mmol/g Co(II) at initial Zn(II) and Co(II) concentration of 1.5 mM each, pH 4.0 and 1mM Cu(II) as the interfering metal. Zn(II) and Co(II) were equally antagonistic to each others sorption; Zn(II) and Co(II) sorption being 0.23 and 0.24 mmol/g, respectively, at initial metal concentration of 1.5 mM each, pH 4.0 and 1mM interfering metal concentration. In contrast, Cu(II) sorption remained almost unaffected at lower concentrations of the competing metals. Thus, in binary system inhibition dominance observed was Cu(II)>Zn(II), Cu(II)>Co(II) and Zn(II) approximately Co(II), due to this the biosorbent exhibited net preference/affinity for Cu(II) sorption over Zn(II) or Co(II). Hence, the affinity series showed a trend of Cu(II)>Co(II)>Zn(II). In a ternary system, increasing Co(II) concentration exhibited protection against the inhibitory effect of Cu(II) on Zn(II) sorption. On the other hand, the inhibitory effect of Zn(II) and Cu(II) on Co(II) sorption was additive. The model equation for metal interactions was found to be valid within the design space.     

Effect of metal complexation on the bioavailability of nitrilotriacetic acid to Chelatobacter heintzii ATCC 29600

Many polluted sites contain a mixture of organics and heavy metals. Nitrilotriacetic acid has been chosen as a model organic compound to study the effect of metal binding on organic bioavailability and degradation of organics. The effect of varying the ratio of metal to nitrilotriacetic acid on its utilisation has been examined using the gram-negative bacterium Chelatobacter heintzii ATCC 29600. The following parameters of substrate utilisation were examined: growth, degradation, respiration, mineralisation and nitrilotriacetic acid uptake. Complexation of nitrilotriacetic acid by Cu(II), Ni(II), Co(II) and Zn(II) prevented utilisation of nitrilotriacetic acid by C. heintzii; complexation to Fe(III) or Mn(II) did not. The pattern of inhibition was consistent with a 1:1 stoichiometry of metal binding to nitrilotriacetic acid. Inhibition was not due to metal ion toxicity, but was a result of metal-nitrilotriacetic acid complexes being recalcitrant to degradation. In addition, the effect of complexing (phosphate) and non-complexing (PIPES) buffers on bioavailability was examined: Co and Zn prevented degradation of nitrilotriacetic acid in PIPES buffer, but not in phosphate buffer. This was due to the removal of Co and Zn from solution by phosphate precipitation, leaving nitrilotriacetic acid uncomplexed. The results demonstrated that metal-organic complexation can alter the bioavailability of organic pollutants and may also modulate the toxicity of heavy metals.     

A novel barley yellow stripe 1-like transporter (HvYSL2) localized to the root endodermis transports metal-phytosiderophore complexes

Recent advances in our understanding of how graminaceous plants take up insoluble forms of iron from the rhizosphere and mobilize them in plant tissues are primarily based on the identification of various transporters that are specific to metal-phytosiderophore (PS) complexes containing mugineic acid and deoxymugineic acid. Barley (Hordeum vulgare L.) yellow stripe 1 (HvYS1) is a metal-PS transporter that preferentially transports Fe(III)-PS compared with other metal complexes. Here, we report the cloning and characterization of HvYSL2, a novel metal-PS transporter encoding gene. HvYSL2 is composed of 702 amino acids with 14 transmembrane domains, which are conserved among this class of transporters, and exhibits 67.3% identity to HvYS1. Electrophysiological experiments with Xenopus laevis oocytes revealed that HvYSL2 transports PS complexes with Fe(III), Zn(II), Ni(II), Cu(II), Mn(II) or Co(II); this constitutes a broader range of substrate preference than HvYS1. Real-time PCR analysis revealed that HvYSL2 mRNA is expressed in shoots and also in roots, where it is induced under iron-deficient conditions. Moreover, immunohistochemistry in roots revealed that HvYSL2 is localized to the endodermis, whereas HvYS1 is expressed primarily in the epidermis. These data suggest that HvYSL2 is spatially distinct from HvYS1 and plays a unique role in delivering a broad range of essential metals in barley.     

Antifungal potential of binary and mixed-ligand complexes of N,2'-diphenyl acetohydroxamic acid.

Chelating potential of N,2'-DPAHA with 3d metal ions such as Cu(II), Ni(II), Zn(II), and Cd(II) in the presence of Gly and Phen has been investigated. These experiments were designed to study the role of the stability of mixed-ligand complexes in the modulation of its fungicidal potential. The mixed-ligand complexes were found to be more stable than binary complexes. Enhanced stability of mixed-ligand complexes of Ni(II), Co(II), Zn(II), and Cd(II) is presumably due to pi-bonding effects. In the stabilization of the Cu(II) mixed-ligand complex system, the Jahn-Tellar effect may play a vital role, in addition to pi-bonding effects. Fungicidal activity of N,2'-DPAHA and its binary complexes with Cu(II), Ni(II), and Co(II) was examined against Fusarium oxysporum using the inhibition zone technique. Binary complexes of Zn(II) and Cd(II) with N,2'-DPAHA and mixed-ligand complexes M(II)-Gly or Phen-N,2'-DPAHA, where M(II) = Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) were screened against Alternaria alternata by slide germination technique. All mixed-ligand complexes exhibited fungicidal activity but did not improve significantly compared to binary complexes. Synergistic action of primary and secondary ligands has increased the stability of the mixed-ligand complex compared to the binary complex (1:1) of the secondary ligand (N,2'-DPAHA), and the fungicidal potential of the mixed-ligand complex involving N,2'-DPAHA as secondary ligand was not increased.     

Cu(II) and Zn(II) complexes with hyaluronic acid and its sulphated derivative. Effect on the motility of vascular endothelial cells

With the aim of improving the compatibility of biomaterials to be used for the construction of cardiovascular prosthesis, we have designed bioactive macromolecules resulting from chemical modifications of hyaluronic acid (Hyal). The stability constants of Cu(II) and Zn(II) complexes with the sulphated derivative of hyaluronic acid (HyalS3.5) were evaluated. Two different complexes have been found for each metal ion, CuL, Cu(OH)2L and ZnL, Zn(OH)2L (L means the disaccharide unit of the ligands) in aqueous solution at 37 degrees C. The dihydroxo Cu(II) complex was present in high percentage at pH=7.4. On the contrary, the Zn(II) ion was present with a relatively low percentage of both complexes. The ability to stimulate endothelial cell adhesion and migration was evaluated for Hyal, HyalS3.5 and their complexes with Cu(II) and Zn(II) ions. The results revealed that Hyal and [Cu(OH)2HyalS3.5](4.5)- induced cell adhesion, while [ZnHyalS3.5](2.5)- and [Zn(OH)2HyalS3.5](4.5)- inhibited the process. The chemotactic activity of increasing concentrations of the above complexes was also evaluated, demonstrating that [Cu(OH)2HyalS3.5](4.5)- complex at 1 microM concentration was the most active in inducing cell migration. These results have been also strengthened by analysing adherent cell migration in agarose. In conclusion, sulphated hyaluronic acid coordinated to Cu(II) seems to be a promising matrix molecule for the construction of cardiovascular prosthesis.     

The effect of humic acid and Na2EDDHA on the uptake of Cu,Fe, and Zn by barley in sand culture

Summary Humic acid affected nutrient uptake differently in sand culture. It generally increased Cu uptake, slightly, though insignificantly, increased Fe uptake and practically had no effect on Zn uptake. Such results agree fairly well with the relative stability of humic acid with these metals.When humic acid was added to sand culture at increasing concentration of the metal, it considerably increased dry weight, Cu uptake and Cu concentration through decreasing its toxicity to plant. With Fe, however, humic acid and Na₂EDDHA slightly increased Fe uptake at lower Fe concentration (30 ppm) but significantly reduced both Fe uptake and Fe concentration in plant at higher concentration of Fe compared to the control treatment. Humic acid reduced Zn uptake and Zn concentration in plant at concentrations of 0.5–1.5 ppm Zn, and guarded against Zn toxicity which developed at higher concentration of Zn when no humic acid was added.     

Free metal ion depletion by "Good's" buffers. III. N-(2-acetamido)iminodiacetic acid, 2:1 complexes with zinc(II), cobalt(II), nickel(II), and copper(II); amide deprotonation by Zn(II), Co(II), and Cu(II)

Potentiometric, visible, infrared, electron spin, and nuclear magnetic resonance studies of the complexation of N-(2-acetamido)iminodiacetic acid (H2ADA) by Ca(II), Mg(II), Mn(II), Zn(II), Co(II), Ni(II), and Cu(II) are reported. Ca(II) and Mg(II) were found not to form 2:1 ADA2- to M(II) complexes, while Mn(II), Cu(II), Ni(II), Zn(II), and Co(II) did form 2:1 metal chelates at or below physiological pH values. Co(II) and Zn(II), but not Cu(II), were found to induce stepwise deprotonation of the amide groups to form [M(H-1ADA)4-(2)]. Formation (affinity) constants for the various metal complexes are reported, and the probable structures of the various metal chelates in solution are discussed on the basis of various spectral data.     

Free metal ion depletion by "Good's" buffers. I. N-(2-acetamido)iminodiacetic acid 1:1 complexes with calcium(ii). magnesium(II), zinc(II), manganese(II), cobalt(II), nickel(II), and copper(II).

Formation (affinity) constants for 1:1 complexes of N-(2-acetamido)iminodiacetic acid (ADAH₂) with Ca(II), Mg(II), Mn(II), Zn(II), Co(II), Ni(II), and Cu(II) have been determined. Probable structures of the various metal chelates existing in solution are discussed. Values for the deprotonation of the amide group in [Cu(ADA)] and subsequent hydroxo complex formation are also reported. The use of ADA as a buffer is considered in terms of metal buffers complexes which can be formed at physiological pH, i.e., at pH 7.0 there is essentially no free metal ion in 1:1 M²⁺ to ADA solutions.     

Robust building blocks for inorganic crystal engineering

We have prepared two ligands, 4- and 5-carboxylic acid pyrimidine, and synthesized and crystallographically characterized seven coordination complexes thereof. The need for potentially structurally disruptive counterions is eliminated by deprotonation of the carboxylic acid moieties; the carboxylates present in each structure act as counterions and balance the charge on the divalent metal ions leading to charge-neutral complex ions. The four new M(II)-complexes with 4-carboxylic acid pyrimidine (M = Ni, Cu, Zn, and Co) are isostructural as are the three M(II) complexes with 3-carboxylic acid pyrimidine (M = Ni, Cu, and Zn), indicating robust and reliable coordination modes for both ligands.     

Free metal ion depletion by “good's” buffers: II. N-(2-acetamido)-2-aminoethanesulfonic acid (ACESH): Complexes with Calcium(II), Magnesium(II), Manganese(II), Cobalt(II), Zinc(II), Nickel(II), and Cooper(II)

Potentiometric, visible, and infrared studies of the complexation of N-(2-acetamido)-2-aminoethanesulfonic acid (ACESH) by Ca(II), Mg(II), Mn(II), Co(II), Zn(II), Ni(II), and Cu(II) are reported. Ca(II), Mg(II), and Mn(II) were found not to complex with ACES^?, while Co(II), Zn(II), Ni(II), and Cu(II) were found to form 2:1, ACES^? to M²⁺, complexes, and [Cu(ACES)₂] was found to undergo stepwise deprotonation of the amide groups to form [Cu(H_?1ACES)₂^2?]. Formation (affinity) constants for the various metal complexes are reported, and the probable structures of the various metal chelates in solution are discussed.     

Mechanism of adsorption of hard and soft metal ions to Saccharomyces cerevisiae and influence of hard and soft anions.

The applicability of the hard-and-soft principle of acids and bases in predicting metal adsorption characteristics in a biological context was investigated for metabolism-independent uptake of the metal ions Sr2+, Mn2+, Zn2+, Cu2+, Cd2+, and Tl+ by Saccharomyces cerevisiae. Metal adsorption increased with external metal concentration (5 to 50 microM), although some saturation of uptake of the harder ions examined, Sr2+, Mn2+, and Zn2+, was evident at the higher metal concentrations. Cation displacement experiments indicated that, with the exception of Tl+, relative covalent bonding (H+ displacement) of the metals was greater at low metal concentrations, while weaker electrostatic interactions (Mg2+ plus Ca2+ displacement) became increasingly important at higher concentrations. These results were correlated with curved Scatchard and reciprocal Langmuir plots of metal uptake data. Saturation of covalent binding sites was most marked for the hard metals, and consequently, although no relationship between metal hardness and ionic/covalent bonding ratios was evident at 10 microM metal, at 50 microM the ratio was generally higher for harder metals. Increasing inhibition of metal uptake at increasing external anion concentrations was partially attributed to the formation of metal-anion complexes. Inhibitory effects of the hard anion SO42(-) were most marked for uptake of the hard metals Sr2+ and Mn2+, whereas greater relative effects on adsorption of the softer cations Cu2+ and Cd2+ were correlated with complexation by the soft anion S2O32(-). Inhibition of uptake of the borderline metal Zn2+ by SO42(-) and that by S2O32(-) were approximately equal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anti-oxidant, in vitro, in vivo anti-inflammatory activity and antiproliferative activity of mefenamic acid and its metal complexes with manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II)

Some new complexes of mefenamic acid with potentially interesting biological activity are described. The complexes of mefenamic acid [Mn(mef)(2)(H(2)O)(2)], 1, [Co(mef)(2)(H(2)O)(2)], 2, [Ni(mef)(2)(H(2)O)(2)], 3, [Cu(mef)(2)(H(2)O)](2), 4 and [Zn(mef)(2)], 5, were prepared by the reaction of mefenamic acid, a potent anti-inflammatory drug with metal salts. Optical and infrared spectral data of these new complexes are reported. Monomeric six-coordinated species were isolated in the solid state for Mn(II), Ni(II) and Co(II), dimeric five-coordinated for Cu(II) and monomeric four-coordinated for Zn(II). In DMF or CHCl(3) solution the coordination number is retained and the coordinated molecules of water are replaced by solvent molecules. The anti-oxidant properties of the complexes were evaluated using the 1,1-diphenyl-2-picrylhydrazyl, DPPH, free radical scavenging assay. The scavenging activities of the complexes were measured and compared with those of the free drug and vitamin C. We have explored their ability to inhibit soybean lipoxygenase, beta-glucuronidase and trypsin- induced proteolysis. The complex [Mn(mef)(2)(H(2)O)(2)] exhibits the highest antioxidant activity and the highest inhibitory effect against the soybean lipogygenase (LOX), properties that are not demonstrated by mefenamic acid. Their inhibitory effects on rat paw edema induced by Carrageenan was studied and compared with those of mefenamic acid. The complex [Zn(mef)(2)] exhibited a strong inhibitory effect at 0.1 mmol/Kg B.W. (81.5 +/- 1.3% inhibition), superior to the inhibition induced by mefenamic acid at the same dose (61.5 +/- 2.3% inhibition). Mefenamic acid and its metal complexes have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse fibroblast L-929 cell line. The copper(II) complex displays against T24, MCF-7 and L-929 cancer cell lines, IC(50) values in a microM range similar to that of the antitumor drug cis-platin and they are considered for further stages of screening in vitro and/or in vivo as agents with potential antitumor activity.     

Metal based drugs: design,synthesis and in-vitro antimicrobial screening of Co(II), Ni(II), Cu(II) and Zn(II) complexes with some new carboxamide derived compounds: crystal structures of N-[ethyl(propan-2-yl)carbamothioyl]thiophene-2-carboxamide and its copper(II) complex

A new series of compounds derived from thiophene-2-carboxamide were synthesized and characterized by IR, ¹H-NMR and ¹³C-NMR, mass spectrometry and elemental analysis. These compounds were further used to prepare their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes. All metal(II) complexes were air and moisture stable. Physical, spectral and analytical data have shown the Ni(II) and Cu(II) complexes to exhibit distorted square-planar and Co(II) and Zn(II) complexes tetrahedral geometries. The ligand (L¹) and its Cu(II) complex were characterized by the single-crystal X-ray diffraction method. All the ligands and their metal(II) complexes were screened for their in-vitro antimicrobial activity. The antibacterial and antifungal bioactivity data showed that the metal(II) complexes were found to be more potent than the parent ligands against one or more bacterial and fungal strains.     

Mobilization of Cu and Zn by root exudates of dicotyledonous plants in resin-buffered solutions and in soil

It has been frequently suggested that root exudates play a role in trace metal mobilization and uptake by plants, but there is little in vivo evidence. We studied root exudation of dicotyledonous plants in relation to mobilization and uptake of Cu and Zn in nutrient solutions and in a calcareous soil at varying Cu and Zn supply. Spinach (Spinacia oleracea L.) and tomato (Lycopersicon esculentum L.) were grown on resin-buffered nutrient solutions at varying free ion activities of Cu (pCu 13.0–10.4) and Zn (pZn 10.1–6.6). The Cu and Zn concentrations in the nutrient solution increased with time, except in plant-free controls, indicating that the plant roots released organic ligands that mobilized Cu and Zn from the resin. At same pCu, soluble Cu increased more at low Zn supply, as long as Zn deficiency effects on growth were small. Zinc deficiency was observed in most treatment solutions with pZn ≥ 9.3, but not in nutrient solutions of a smaller volume/plant ratio in which higher Zn concentrations were observed at same pZn. Root exudates of Zn-deficient plants showed higher specific UV absorbance (SUVA, an indicator of aromaticity and metal affinity) than those of non-deficient plants. Measurement of the metal diffusion flux with the DGT technique showed that the Cu and Zn complexes in the nutrient solutions were highly labile. Diffusive transport (through the unstirred layer surrounding the roots) of the free ion only could not explain the observed plant uptake of Cu and of Zn at low Zn²⁺ activity. The Cu and Zn uptake by the plants was well explained if it was assumed that the complexes with root exudates contributed 0.4% (Cu) or 20% (Zn) relative to the free ion. In the soil experiment, metal concentrations and organic C concentrations were larger in the solution of planted soils than in unplanted controls. The SUVA of the soil solution after plant growth was higher for unamended soils, on which the plants were Zn-deficient, than for Zn-amended soils. In conclusion, root exudates of dicotyledonous plants are able to mobilize Cu and Zn, and plants appear to respond to Zn deficiency by exuding root exudates with higher metal affinity.     

Synthesis, physico-chemical characterization and antimicrobial activity of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with some acyldihydrazones

Complexes of the type [M(bssdh)]Cl and [M(dspdh)]Cl, where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); Hbssdh = benzil salicylaldehyde succinic acid dihydrazone, Hdspdh = diacetyl salicylaldehyde phthalic acid dihydrazone have been synthesized and characterized with the help of elemental analyses, electrical conductance, magnetic susceptibility measurements, electronic, ESR and IR spectra and X-ray diffraction studies. Magnetic moment values and electronic spectral transitions indicate a spin free octahedral structure for Co(II), Ni(II) and Cu(II) complexes. IR spectral studies suggest that both the ligands behave as monobasic hexadentate ligands coordinating through three > C = O, two > C = N- and a phenolate group to the metal. ESR spectra of Cu(II) complexes are axial type and suggest d(x(2)-y(2)) as the ground state. X-ray powder diffraction parameters for [Co(bssdh)]Cl and [Co(dspdh)]Cl complexes correspond to an orthorhombic crystal lattice. The ligands as well as their metal complexes show a significant antifungal and antibacterial activity against various fungi and bacteria. The metal complexes are more active than the parent ligands.     

Transgenic Petunia with the Iron(III)-Phytosiderophore Transporter Gene Acquires Tolerance to Iron Deficiency in Alkaline Environments

Iron is an essential nutrient for all plants. However, terrestrial plants often suffer from iron deficiency in alkaline soil due to its extremely low solubility. Alkaline soil accounts for about 30% of all cultivated ground in the world. Plants have evolved two distinct strategies, I and II, for iron uptake from the soil. Dicots and non-graminaceous monocots use Strategy I, which is primarily based on the reduction of iron(III) to iron(II) and the uptake of iron(II) by the iron-regulated transporter, IRT1. In contrast, graminaceous plants use Strategy II to efficiently acquire insoluble iron(III). Strategy II comprises the synthesis and secretion of iron-chelating phytosiderophores, such as mugineic acids and the Yellow Stripe 1 transporter proteins of the iron(III)-phytosiderophore complex. Barley, which exhibits the highest tolerance to iron deficiency in alkaline soil among graminaceous plants, utilizes mugineic acids and the specific iron(III)-mugineic acids transporter, HvYS1. In this study, we established the transgenic plant Petunia hybrida, which originally had only Strategy I, by introducing the HvYS1 transporter gene derived from barley. When the transgenic plants were grown hydroponically in media containing the iron(III)-2′-deoxymugineic acid complex, free 2′-deoxymugineic acid and its iron(III) complex were detected in the root extract of the transgenic plant by electrospray ionization-Fourier transform-ion cyclotron resonance mass spectrometry. The growth of the transgenic petunia was significantly better than that of the control host in alkaline conditions. Consequently, the transgenic plant acquired a significantly enhanced tolerance to alkaline hydroponic media in the presence of the iron(III)-2′-deoxymugineic acid complex. Furthermore, the flower color of the transgenic plant deepened. The results showed that iron-phytosiderophore complexes and their transporters can potentially be utilized to overcome the worldwide iron uptake problems to diverse plant species that are found in areas with alkaline conditions.     

Syntheses and anti-inflammatory activity of diphenylamine-2,2'-dicarboxylic acid and its metal complexes

Diphenylamine-2,2'-dicarboxylic acid and its Cu(II), Ni(II), Co(II) and Zn(II) complexes have been synthesized and characterized by their elemental analyses, molecular weight determination, molar conductance, infrared and electronic spectra and magnetic measurements. The Zinc complex was tested by different methods for its anti-inflammatory activity and found to be equipotent to naproxen and ibuprofen, though at higher doses.