myo-inositol hexakisphosphate: Coordinative versatility of a natural product

Naturally occurring phytic acid: an advanced Brønsted acid catalyst for direct amination reactions of allylic alcohols

Phytic acid is abundant in various plant-based foods and is considered agricultural waste. Here, we demonstrate the effectiveness of this organophosphorus acid as a sustainable catalyst for the direct amination reactions of allylic alcohols. This approach is successfully performed in air using technical grade solvents, affording allylanilines in moderate to excellent yields. Challenging electron-rich anilines react effectively, and their corresponding Friedel-Crafts side products can be minimised under the optimised reaction conditions. A variety of asymmetrically substituted allylic alcohols are tolerated, while the scope is extended to amide, and C-, O- and S-nucleophiles.

Insoluble-Phytate Improves Plant Growth and Arsenic Accumulation in As-Hyperaccumulator Pteris vittata: Phytase Activity, Nutrient Uptake, and As-Metabolism

Phytate, the principal P storage in plant seeds, is also an important organic P in soils, but it is unavailable for plant uptake. However, the As-hyperaccumulator Pteris vittata can effectively utilize soluble Na-phytate, while its ability to utilize insoluble Ca/Fe-phytate is unclear. Here, we investigated phytate uptake and the underlying mechanisms based on the phytase activity, nutrient uptake, and expression of genes involved in As metabolisms. P. vittata plants were cultivated hydroponically in 0.2-strength Hoagland nutrient solution containing 50 μM As and 0.2 mM Na/Ca/Fe-phytate, with 0.2 mM soluble-P as the control. As the sole P source, all three phytates supported P. vittata growth, with its biomass being 3.2-4.1 g plant-1 and Ca/Fe-phytate being 19-29% more effective than Na-phytate. Phytate supplied soluble P to P. vittata probably via phytase hydrolysis, which was supported by 0.4-0.7 nmol P min-1 g-1 root fresh weight day-1 phytase activity in its root exudates, with 29-545 μM phytate-P being released into the growth media. Besides, compared to Na-phytate, Ca/Fe-phytate enhanced the As contents by 102-140% to 657-781 mg kg-1 in P. vittata roots and by 43-86% to 1109-1447 mg kg-1 in the fronds, which was accompanied by 21-108% increase in Ca and Fe uptake. The increased plant As is probably attributed to 1.3-2.6 fold upregulation of P transporters PvPht1;3/4 for root As uptake, and 1.8-4.3 fold upregulation of arsenite antiporters PvACR3/3;1/3;3 for As translocation to and As sequestration into the fronds. This is the first report to show that, besides soluble Na-phytate, P. vittata can also effectively utilize insoluble Ca/Fe-phytate as the sole P source, which sheds light onto improving its application in phytoremediation of As-contaminated sites.

DNA damage-induced autophagy is regulated by inositol polyphosphate synthetases in Candida albicans

DNA damage-induced autophagy is a new type of autophagy that differs from traditional macroautophagy; however, this type of autophagy has not been identified in the pathogenic fungus Candida albicans. Inositol polyphosphates are involved in the regulation of DNA damage repair and macroautophagy; however, whether inositol polyphosphates are involved in the regulation of DNA damage-induced autophagy remains unclear. In this study, we identified DNA damage-induced autophagy in C. albicans and systematically investigated the mechanisms of inositol polyphosphate pathway regulation. We found that the core machinery of macro autophagy is also essential for DNA damage-induced autophagy, and that inositol polyphosphate synthetases Kcs1, Ipk1, and Vip1 play a critical role in autophagy. In this study, we focused on Kcs1 and Vip1, which are responsible for the synthesis of inositol pyrophosphate. The kcs1Δ/Δ and vip1Δ/Δ strains exhibited reduced number of phagophore assembly sites (PAS) and autophagic bodies. The recruitment of autophagy-related gene 1 (Atg1) to PAS was significantly affected in the kcs1Δ/Δ and vip1Δ/Δ strains. Target of rapamycin complex 1 kinase activity was elevated in kcs1Δ/Δ and vip1Δ/Δ strains, which significantly inhibited the initiation of autophagy. Atg18 Localization was altered in these mutants. The absence of Kcs1 or Vip1 caused the downregulation of RAD53, a key gene in the DNA damage response. These data provide further understanding of the mechanism of autophagy regulation in C. albicans.

Intercalation vs Adsorption Strategies of Myo-Inositol Hexakisphosphate into Zn-Fe Layered Double Hydroxide: A Tiff between Anion Exchange and Coprecipitation

Myo-inositol hexakisphosphates (IHPs) or phytates are the most abundant organic phosphates having the potential to serve as a phosphorus reserve in soil. Understanding the fate of IHP interaction with soil minerals tends to be crucial for its efficient storage and utilization as a slow-release organic phosphate fertilizer. We have systematically compared the effective intercalation strategy of a phytate onto Zn-Fe layered double hydroxide (LDH) acting as storage/carrier material through coprecipitation and anion exchange. Powder X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, thermogravimetric analysis, FTIR spectra, and molecular modeling demonstrated the formation of phytate-intercalated Zn-Fe LDH through coprecipitation with a maximum loading of 41.34% (w/w) in the pH range of ∼9-10 in a vertical alignment through monolayer formation. No intercalation product was obtained from the anion exchange method, which was concluded based on the absence of shifting in the XRD (003) peak. A change in the zeta potential values from positive to negative and subsequent increase in solution pH, with decreasing phytate concentration, are suggestive of adsorption of IHP onto the LDH surface. The batch adsorption data were best fitted with Langmuir isotherm equation and followed the pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 45.87 mg g-1 at a temperature of 25 ± 0.5 °C and pH 5.63.

Structural Insight on Supramolecular Polyion Salts: Inositol Hexaphosphate Enclosed in Cationic Macrocyclic Clusters

Supramolecular macrocyclic forces have been used to trap phytate, myo-inositol-1,2,3,4,5,6-hexakisphosphate, a key bioanion with multiple roles in metabolic processes. Due to the complex chemistry of six multivalent phosphates surrounding the small, cyclic inositol framework, crystallographic information of simple phytate salts has been elusive. This report represents a combined crystallographic, theoretical, and solution binding investigation of a supramolecular macrocyclic complex of phytate. Together, the results provide significant insight to phytate's intramolecular and intermolecular interactions at the microenvironment level. The macrocycle-phytate aggregates consist of phytate anionic pairs, each partly sandwiched by two 24-membered, amide/amine-based cationic macrocycles. The phytate ion pairs hold the tetrameric macrocyclic array together by six strong intermolecular hydrogen bonds. Both phytates crystallize in 1a5e phosphate conformations (one axial (P2) and five equatorial phosphates). Solution NMR binding studies in 1 : 1 DMSO-d6  : D2 O indicate 2 : 1 macrocycle:phytate associations, suggesting that the sandwich-like nature of the complex holds together in solution. DFT studies indicate the likely occurrence of dynamic intramolecular interchange of phosphate protons, as well as important roles for the axial (P2) phosphate in both intramolecular and intermolecular hydrogen bonding interactions.

Enhancing micronutrient absorption through simultaneous fortification and phytic acid degradation

Phytic acid (PA), an endogenous antinutrient in cereals and legumes, hinders mineral absorption by forming less bioavailable, stable PA-mineral complexes. For individual micronutrients, the PA-to-mineral molar ratio below the critical level ensures better bioavailability and is achieved by adding minerals or removing PA from cereals and pulses. Although several PA reduction and fortification strategies are available, the inability to completely eradicate or degrade PA using available techniques always subdues fortification's impact by hindering fortified micronutrient absorption. The bioavailability of micronutrients could be increased through simultaneous PA degradation and fortification. Following primary PA reduction of the raw material, the fortification step should also incorporate additional essential control stages to further PA inactivation, improving micronutrient absorption. In this review, the chemistry of PA interaction with metal ions, associated controlling parameters, and its impact on PA reduction during fortification is also evaluated, and further suggestions were made for the fortification's success.

Potential Use of Melamine Phytate as a Flame-Retardant Additive in Chicken Feather-Containing Thermoplastic Polyurethane Biocomposites

Using waste materials such as chicken feathers (CF) and biobased flame-retardant additives including melamine phytate (MPht) has become an effective approach for environmentally friendly and sustainable production in recent years. This study explores the flame retardant effectiveness of MPht in thermoplastic polyurethane (TPU)-based biocomposites containing CF. The characterizations of the composites are performed through thermal gravimetric analysis (TGA), limiting oxygen index (LOI), vertical UL-94 (UL-94 V), and mass loss calorimetry (MLC) tests. According to the test results, the highest UL-94 V rating of V0, a LOI value of 29.4%, and the lowest peak heat release rate (pHRR) (110 Kw/m²) and total heat evolved (THE) (39 MJ/m²) values are obtained with the use of 20 wt % MPht. It is demonstrated that MPht acts as an effective flame-retardant filler through the formation of intumescent char in the condensed phase and flame dilution in the gas phase.

High inhabitation activity of CMCS/Phytic acid/Zn2+ nanoparticles via flash nanoprecipitation (FNP) for bacterial and fungal infections

Plant diseases prompted by fungi and bacteria are one of the most serious threats to global crop production and food security. The destruction of these infections posed a major challenge to plant protection by chemical control. Herein, we develop CMCS/PA/Zn²⁺ nanoparticles (NPs) using carboxymethyl chitosan (CMCS), phytic acid (PA) and metal ions (Zn²⁺) via flash nanoprecipitation (FNP) strategy. Metal complexes of PA with specified antibacterial and antifungal activities are expected to hold the potential and play a significant role in antimicrobial treatment. The size and size distribution of NPs was confirmed through Dynamic and Static Light Scatterer (DSLS). In acidic-infection microenvironment, the CMCS/PA/Zn²⁺ NPs can disintegrate and release Zn²⁺ in situ thus stimulated the corresponding antimicrobial activity. These CMCS/PA/Zn²⁺ NPs showed outstanding antibacterial efficacy (98 %) against S. aureus and E. coli bacteria in vitro, as well as an impressive antifungal efficacy of 98 % and 81 % against R. solani and B. cinerea at 50 μg/mL respectively. This study contributes a prospective idea to the development of organic-inorganic hybrid NPs as environmentally-friendly and safe agricultural antimicrobials.

A study on Sr/Zn phytate complexes: structural properties and antimicrobial synergistic effects against Streptococcus mutans

Phytic acid (PA) is an abundant natural plant component that exhibits a versatility of applications benefited from its chemical structure, standing out its use as food, packing and dental additive due to its antimicrobial properties. The capacity of PA to chelate ions is also well-established and the formation and thermodynamic properties of different metallic complexes has been described. However, research studies of these compounds in terms of chemistry and biological features are still demanded in order to extend the application scope of PA complexes. The main goal of this paper is to deepen in the knowledge of the bioactive metal complexes chemistry and their bactericide activity, to extend their application in biomaterial science, specifically in oral implantology. Thus, this work presents the synthesis and structural assessment of two metallic phytate complexes bearing the bioactive cations Zn²⁺ and Sr²⁺ (ZnPhy and SrPhy respectively), along with studies on the synergic biological properties between PA and cations. Metallic phytates were synthesized in the solid-state by hydrothermal reaction leading to pure solid compounds in high yields. Their molecular formulas were C₆H₁₂0₂₄P₆Sr₄·5H₂O and C₆H₁₂0₂₄P₆Zn₆·6H₂O, as determined by ICP and HRES-TGA. The metal coordination bond of the solid complexes was further analysed by EDS, Raman, ATR-FTIR and solid ¹³C and ³¹P-NMR spectroscopies. Likewise, we evaluated the in vitro ability of the phytate compounds for inhibiting biofilm production of Streptococcus mutans cultures. Results indicate that all compounds significantly reduced biofilm formation (PA < SrPhy < ZnPhy), and ZnPhy even showed remarkable differences with respect to PA and SrPhy. Analysis of antimicrobial properties shows the first clues of the possible synergic effects created between PA and the corresponding cation in different cell metabolic processes. In overall, findings of this work can contribute to expand the applications of these bioactive metallic complexes in the biotechnological and biomedical fields, and they can be considered for the fabrication of anti-plaque coating systems in the dentistry field.

Effect of salinity on the determination of dissolved non-reactive phosphorus and total dissolved phosphorus in coastal waters

The salinity may affect the phosphorus (P) determination accuracy in coastal waters, especially for the dissolved non-reactive P (DNRP) and total dissolved P (TDP). In this work, the competition mechanism between NaCl and DNRP for oxidants (K₂ S₂ O₈ , the most commonly used and recognized oxidant) was identified in different DNRP determinations. Furthermore, salinity influences on determinations of tetrasodium pyrophosphate decahydrate, glyphosate, phytic acid sodium salt hydrate, adenosine-5'-nomophosphate disodium, and TDP were investigated. The results indicated that approximately 10% IHP6 and AMP would be transferred to dissolved reactive P (DRP) during digestion without K₂ S₂ O₈ . When NaCl increased from 0% to 3.5% with fresh water method, the determination of Gly + K₂ HPO₄ and IHP6 + K₂ HPO₄ decreased by 8.0% ± 0.00% and 24% ± 0.01%, respectively. In addition, the determinations of DNRPs and TDP with different salinities in natural coastal waters by fresh water method and seawater method were performed. It showed that when the salinity >5.0 PSU, the DNRPs and TDP determination results presented deviations. At a salinity of 35.0 PSU, the TDP (KH₂ PO₄  + Gly + IHP6 + AMP) reduction measured by two methods was more than 12.3% ± 0.46%. Furthermore, oxidants with higher digestion efficiency than K₂ S₂ O₈ should be developed. PRACTITIONER POINTS: ~10% IHP6 and AMP could be transferred to DRP during digestion without K₂ S₂ O₈ addition. Salinity affects the DNRPs determination results mainly due to competition for oxidants and complexation with metal ions. More than 12.3% TDP in coastal waters could not be measured when the salinity was 35.0 PSU.

Oligomeric phosphate clusters in macrocyclic channels

Thirty-six-membered ring macrocycles form sandwich-like channels for oligomeric chains of hexaphosphate clusters.

Supramolecular interaction of inositol phosphates with Cu(II): comparative study InsP6-InsP3

myo-inositol phosphates are an important group of biomolecules that are present in all eukaryotic cells. The most abundant member of this family in nature is InsP6 (H12L1), which interacts strongly...

Binding of Cd(II) by Amorphous Aluminum Hydroxide-Organophosphorus Coprecipitates: From Macroscopic to Microscopic Investigation

The mobility of Cd(II) in soils, sediments, and aquatic systems is strongly dependent on adsorption behaviors occurring at the mineral-water interface, and this process may be influenced by the presence of organic phosphorus (OP). In this study, we investigate Cd(II) adsorption onto amorphous aluminum hydroxide (AAH), both in the presence and absence of OP, represented by the widely abundant myo-inositol hexakisphosphate (IHP). Isothermal adsorption experiment coupled with attenuated total reflection Fourier transform infrared (ATR-FTIR) and 1H solid-state NMR spectra were employed. Physiochemical characterization shows that IHP can increase the surface negative charge and the number of surface sites. Isothermal results show that high IHP loading enhances Cd(II) adsorption while no obvious increase is observed at low IHP loading. The overall effect of IHP on Cd(II) sorption depends on the extent of two positive processes, i.e., (1) IHP can form ternary complexes with adsorbed Cd(II) on AAH and (2) IHP can increase the negative surface charge of AAH, and a negative process, i.e., AAH competes with Cd(II) for AAH surface sites. ATR-FTIR results confirm the possible formation of three structurally distinct ternary complexes, i.e., the AAH-IHP-Cd, AAH-Cd-IHP, and AAH-Cd-IHP-Cd. The analysis of 1H solid-state NMR demonstrates that IHP only increases the number of surface OH groups rather than changes their chemical environment and speciation. Cd does not bind to the AAH surface but mainly binds with the OH groups of IHP. All findings of this work suggest that the presence of high dose of OP promotes the retention of Cd(II) in soils, thereby decreasing their bioavailability to biota.

Snapshots of "crystalline" salt-water solutions of inositol hexaphosphate conformers

Supramolecular insight to intra- and inter-ionic interactions in two inositol hexaphosphate conformers as a function of pH was enabled by NMR and crystallographic studies. These findings also shed light on the complex interactive roles of extended salt-water arrays through the crystal "solution" lattice.

Phytic Acid Protects from Oxidative Stress Induced by Iron-Overload and High-Fat Diets in ß2-Microglobulin Knockout Mice

The objective of this study was to examine the protective effect of phytic acid (PA) in reducing oxidative stress in an animal model for human hereditary hemochromatosis (HH) fed high-fat diets. Sixty-four ß2 microglobulin knockout (β2m KO) mice were randomly assigned to three treatments by feeding: control (basal), atherogenic (AT), and polyunsaturated fatty acid (PUFA) diets. One-half of the mice in each treatment group were fed 2% (wt/wt) PA. The ß2m+/+ mice (wild type (WT)) were fed a basal diet. All seven groups were fed for 10 weeks with a 50-ppm iron-containing diet (AIN-93G). Free iron and lipids were measured in serum samples. Nonheme iron, thiobarbituric acid-reactive substances (TBARS), superoxide dismutase (SOD), and catalase concentrations were measured in the liver tissue. Nonheme iron concentration in ß2m KO mice (on the basal diet) was 20× higher (p < 0.0001) than in the WT mice. Compared to the WT mice, ß2m KO mice had a significantly higher concentration of free iron in the serum (p < 0.0001), six-fold higher hepatic TBARs (p < 0.0001), and 18% lower hepatic SOD level. When PA was added to the β2m KO basal diet, a reduction (26 to 50%) of iron concentration was seen in the liver and heart. The addition of PA also significantly reduced TBARs in all three dietary groups of the iron-overloaded group, but most effectively in the control group. An increase in SOD concentration was seen only in the PUFA group, but serum triacylglycerol (TG) concentration was reduced in both dietary fat groups. In conclusion, our results suggest that PA protects against oxidative stress-induced by genetic iron overload alone or when fed high fat.