Folate Complexes Research Articles

Polymorphic substitutions in folate cycle genes as predictors of hyperhomocysteinemia in children

Introduction. Mutant alleles of genes of folate cycle enzymes can lead to the significant deterioration of its function and varying severity of pathology. Several defects in these genes lead to severe hyperhomocysteinemia, the most common form of which is a deficiency of cystathionine beta-synthase B. 
 Aim: to establish polymorphic substitutions in the genes of folate cycle enzymes that contribute to the formation of hyperhomocysteinemia in children.
 Materials and methods. Two hundred seventy one children aged of 13–18 years were examined. The analysis of genetic polymorphisms of the folate cycle was carried out using a molecular genetic method. Quantitative determination of the blood homocysteine and folic acid level was performed by chemiluminescent immunoassay on microparticles. Statistical data processing was carried out using Statistica 6.1 application programs (StatSoft Inc., USA). 
 Results. The frequency of the T allele of the MTHFR 677 gene was revealed to be higher in adolescents of the main group compared with the control (p = 0.043). The frequency of the homozygous genotype 66 AA of the MTRR gene in children of the comparison group was significantly higher (p = 0.049), however, the heterozygous genotype 66 AG of the MTRR gene was significantly more often detected in adolescents of the main group (p = 0.008). The average concentrations of homocysteine in children of the main group were 11.6 mmol/L, in adolescents of the control group 9.3 mmol/L (p = 0.021). Hyperhomocysteinemia in children of the main group was detected in 217 (80.1%) adolescents, and in 57 (49.6%) children of the control group (p < 0.001). The baseline serum folate level was determined in the children of the main group. The average amount of vitamin B9 in the blood of children of the main group was 3.7 ng/ml, and in 145 (53.5%) children this indicator was significantly reduced.
 Conclusion. Low levels of folic acid contribute to an increase in homocysteine in blood plasma. Taking vitamin B9 and vitamin folate complexes significantly reduces the level of homocysteine in blood plasma (p < 0.001).

Novel Gallium(III), Germanium(IV), and Hafnium(IV) Folate Complexes and Their Spectroscopic, Thermal Decomposition, Morphological, and Biological Characteristics.

In this study, we describe novel gallium(III), germanium(IV), and hafnium(IV) folate complexes, including their synthesis and analyses. The synthesized folate complexes were also subject to thermal analysis (TGA) to better examine their thermal degradation and kinetic properties. The folate complexes had high stability and were nonspontaneous. The Coats–Redfern and Horowitz–Metzger equations were used to determine thermodynamic parameters and describe the kinetic properties. These complexes were synthesized through the chemical interactions in neutralized media between the folic acid drug ligand (FAH2) with GaCl3, GeCl4, and HfCl4 metal salts at 1 : 2 (metal : ligand) molar ratio. The conductance measurements have low values due to their nonelectrolytic behavior. The X-ray powder diffraction solid powder pattern revealed a semicrystalline nature. In vitro, we screened the synthesized folate chelates for antibacterial and antifungal activities. The inhibition of four bacterial and two fungi pathogens (E. coli, B. subtilis, P. aeruginosa, S. aureus, A. flavus, and Candida albicans) was improved using a folic acid drug relative to the control drug.

Synthesis, spectroscopic, structural and morphological characterizations of magnesium(II), calcium(II), strontium(II) and barium(II) folate complexes

This article aimed to synthesis and characterizations of metal folic acid as a vitamin B9 drug (H2FO) complexes. Using this bi-dentate ligand, complexes of magnesium(II), calcium(II), strontium(II) and barium(II) with general formula [M2(FO)(H2O)6(Cl)2].2H2O have been synthesized. The synthesized folate complexes were characterized by number of techniques using elemental analysis, molar conductance, (FTIR, Raman laser, 1HNMR & electronic) spectroscopy and particle size analysis using X-ray powder diffraction (XRD) spectra. The elemental analysis results suggest the stoichiometry to be 2 : 1 (M : L). All the synthesized complexes are non-electrolytic nature as confirmed by molar conductance measurements. Infrared spectral data indicate the coordination between the folate ligand and the central metal ion via the folate anion which acts as a dicarboxylate ligand with the metal ion coordinated to both the α and β carboxylate groups of the glutamic acid moiety. Spectral studies suggest six-coordination geometry for all complexes.

Pathogenetic substantiation of personified correction of folate cycle disorders using a complex with metapholine for the congenital malformations prevention

Congenital malformations are pathology with a multifactorial etiology. Among their many endogenous, exogenous factors and hereditary predisposition are important. In particular a decrease in follicular enzymes (MTHFR, MTR, MTRR) activity at the genetic level, as well as a deficiency of vitamins and vitamin-like compounds of group B.Objective: to provide a pathogenetic justification for personified correction of disorders in the folate cycle in biological parents preparing for pregnancy to prevent congenital malformations in their children by using folates containing metafolin (5-MTHF).Materials and methods. The study involved 75 women and 75 men (biological parents) who had children/fetuses with congenital malformations in previous pregnancies, and 75 newborn children of these couples. All of them used the proposed preconceptional preparation. Alleles of folate cycle enzyme genes (MTHFR, MTR, MTRR) were determined by polymerase chain reaction in blood and saliva.Results. A high frequency of polymorphism of the folate cycle enzyme genes was observed in men among subjects (father, mother, child). The indicator was 77.7% compared with 68.7% in mothers and 60.7% in their children. The frequency of homozygous alleles was highest in parents (men) – 19.6%, lower in mothers – 13.1% and in children – 12.7%. Result of heterozygous alleles decreased from children indicator (87.3%) to their mothers (86.7%) and parents (80.4%).Conclusions. Obtained results emphasize the practical importance for determining the alleles of the folate cycle enzyme genes (MTHFR, MTR, MTRR) at the stage of preconception preparation for pregnancy in biological parents and then in their newborn children from the standpoint of preventive medicine. Reduced activity of the corresponding enzymes pathogenetically explains the feasibility of using folate complexes containing active folate metafolin (5-MTHF) in order to prevent congenital malformations.

Novel serum-tolerant lipoplexes target the folate receptor efficiently

Gene transfer using non-viral vectors is a promising approach for the safe delivery of nucleic acid therapeutics. In this study, we investigate a lipid-based system for targeted gene delivery to malignant cells overexpressing the folate receptor (FR). Cationic liposomes were formulated with and without the targeting ligand folate conjugated to distearoylphosphatidyl ethanolamine polyethylene glycol 2000 (DSPE-PEG2000), the novel cytofectin 3β[N(N1,N1-dimethlaminopropylsuccinamidoethane)-carbamoyl]cholesterol (SGO4), which contains a 13atom, 15Å spacer element, and the helper lipid, dioleoylphosphatidylethanolamine (DOPE). Physicochemical parameters of the liposomes and lipoplexes were obtained by zeta sizing, zeta potential measurement and cryo-TEM. DNA-binding and protection capabilities of liposomes were confirmed by gel retardation assays, EtBr intercalation and nuclease protection assays. The complexes were assessed in an in vitro system for their effect on cell viability using the MTT assay, and gene transfection activity using the luciferase assay in three cell lines; HEK293 (FR-negative), HeLa (FR+-positive), KB (FR++-positive). Low cytotoxicities were observed in all cell lines, while transgene activity promoted by folate-tagged lipoplexes in FR-positive lines was tenfold greater than that by untargeted constructs and cell entry by folate complexes was demonstrably by FR mediation. These liposome formulations have the design capacity for in vivo application and may therefore be promising candidates for further development.

Novel 99mTc radiolabeled folate complexes with PEG linkers for FR-positive tumor imaging: synthesis and biological evaluation

The novel complex 99mTc(FA-PEG2-HYNIC)(tricine/TPPTS) was clearly visualized at 120 min p.i. at the FR-positive tumor, highlighting its potential as an effective folate receptor tumor imaging agent.

Synthesis, Spectroscopic and Thermal Characterization of Copper(II) and Iron(III) Complexes of Folic Acid and Their Absorption Efficiency in the Blood

The absorption efficiency of any drug in blood is of prime importance. Compounds having the general formula: Kn[M(FO)2(H2O)2] · xH2O, where (M = Cu(II) or Fe(III), n = 2 or 1, FO = folate anion, x = 2 or 3 with respect), were prepared, and their absorption efficiency in rodent's blood was determined. The obtained compounds were characterized by elemental analysis, infrared as well as thermogravimetric analysis and polarization of light. The results suggest that the two folate complexes were formed in 1 : 2 molar ratio (metal : folic acid) which acted as a bidentate ligand through both carboxylic groups. Polarization of light proved that the folate complexes have symmetric geometry. Biological application proved that Cu(II) and Fe(III) complexes were absorbed more efficiently in rodent blood than folic acid itself.

Synthesis, spectroscopic and thermal characterization of some transition metal complexes of folic acid

Compounds having general formula: [M(FO)(Cl) x (H 2O) y ]· zH 2O, where (M = Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), FO = folate anion, x = 2 or 4, y = 2 or 4 and z = 0, 1, 2, 3, 5 or 15) were prepared. The obtained compounds were characterized by elemental analysis, infrared as well as electronic spectra, thermogravimetric analysis and the conductivity measurements. The results suggested that all folate complexes were formed by 2:1 molar ratio (metal:folic acid) as a bidentate through both of the two carboxylic groups. The molar conductance measurements proved that the folate complexes are electrolytes. The kinetic thermodynamic parameters such as: E*, Δ H*, Δ S* and Δ G* were estimated from the DTG curves. The antibacterial evaluation of the folic acid and their complexes was also done against some Gram positive/negative bacteria as well as fungi.

Organometallic 99mTc-technetium(I)- and Re-rhenium(I)-folate derivatives for potential use in nuclear medicine

The folate receptor (FR) is a high affinity membrane protein which is overexpressed on a wide variety of tumor cells, but highly restricted in normal tissues. Therefore folate derivatives labeled with short living isotopes such as 99mTc (γ, t 1/2 = 6 h) or 188Re (β −, t 1/2 = 17 h) could be used for tumor diagnosis and therapy. In this respect there is a great interest to develop organometallic technetium(I) and rhenium(I) modified folate radiopharmaceuticals. For this purpose folic acid was functionalized with a tridentate picolylamine monoacetic acid chelating system. The chelating system was selectively coupled via an aminohexane spacer to the γ- or α-carboxyl group of the glutamate moiety of folic acid to obtain the corresponding γ- or α-folate derivative or – if directly attached to pteroic acid – the pteroate derivative. The derivatives were reacted with the precursor [M(OH 2) 3(CO) 3] + (M = 99mTc, Re) to form uniform organometallic folate complexes under mild reaction conditions. All compounds were chemically characterized by means of NMR, MS, IR and HPLC. The determination of the IC 50-values for the PAMA-γ-folate derivative (100 nM) and the corresponding organometallic rhenium complex (110 nM) proved retained receptor binding properties. The radiolabeling with [ 99mTc(OH 2) 3(CO) 3] + was achieved in excellent yield (>95%) at low ligand concentration (10 −4 M). The cell binding (>45% of total activity) and internalization (>15% of total activity) of all 99mTc-complexes was very high and specificity for the FR was proved by their complete displacement with excess folic acid. The 99mTc-complexes were positively tested for their plasma stability and for the absence of binding to plasma proteins.

13C NMR studies of complexes of Escherichia coli dihydrofolate reductase formed with methotrexate and with folic acid

13C NMR studies of 13C-labelled ligands bound to dihydrofolate reductase provide (DHFR) a powerful means of detecting and characterizing multiple bound conformations. Such studies of complexes of Escherichia coli DHFR with [4,7,8a,9- 13C]- and [2,4a,6- 13C]methotrexate (MTX) and [4,6.8a- 13C]- and [2,4a,7,9- 13C]folic acid confirm that in the binary complexes, MTX binds in two conformational forms and folate binds as a single conformation. Earlier studies on the corresponding complexes with Lactobacillus casei DHFR indicated that, in this case, MTX binds as a single conformation whereas folate binds in multiple conformational forms (both in its binary complex and ternary complex with NADP +); two of the bound conformational states for the folate complexes are very different from each other in that there is a 180° difference in their pteridine ring orientation. In contrast, the two different conformational states observed for MTX bound to E. coli DHFR do not show such a major difference in ring orientation and bind with N1 protonated in both forms. The major difference appears to involve the manner in which the 4-NH 2 group of MTX binds to the enzyme (although the same protein residues are probably involved in both interactions). Addition of either NADP + or NADPH to the E. coli DHFR-MTX complex results in a single set of 13C signals for bound methotrexate consistent with only one conformational form in the ternary complexes.