PLP Concentrations Research Articles

Vitamin B6 regulates IL-33 homeostasis to alleviate type 2 inflammation.

Interleukin-33 (IL-33) is a crucial nuclear cytokine that induces the type 2 immune response and maintains immune homeostasis. The fine-tuned regulation of IL-33 in tissue cells is critical to control of the type 2 immune response in airway inflammation, but the mechanism is still unclear. Here, we found that healthy individuals had higher phosphate-pyridoxal (PLP, an active form of vitamin B6) concentrations in the serum than asthma patients. Lower serum PLP concentrations in asthma patients were strongly associated with worse lung function and inflammation. In a mouse model of lung inflammation, we revealed that PLP alleviated the type 2 immune response and that this inhibitory effect relied on the activity of IL-33. A mechanistic study showed that in vivo, pyridoxal (PL) needed to be converted into PLP, which inhibited the type 2 response by regulating IL-33 stability. In mice heterozygous for pyridoxal kinase (PDXK), the conversion of PL to PLP was limited, and IL-33 levels were increased in the lungs, aggravating type 2 inflammation. Furthermore, we found that the mouse double minute 2 homolog (MDM2) protein, an E3 ubiquitin-protein ligase, could ubiquitinate the N-terminus of IL-33 and sustain IL-33 stability in epithelial cells. PLP reduced MDM2-mediated IL-33 polyubiquitination and decreased the level of IL-33 through the proteasome pathway. In addition, inhalation of PLP alleviated asthma-related effects in mouse models. In summary, our data indicate that vitamin B6 regulates MDM2-mediated IL-33 stability to constrain the type 2 response, which might help develop a potential preventive and therapeutic agent for allergy-related diseases.

Physical and Mechanical Properties of Starch Foam Reinforced with Pineapple (Ananas comosus) Leaves Powder

Investigation of capability of high potential pineapple (Ananas comosus) leaves powder (PLP) as reinforcing material on the starch-based foam production has not been reported. This study was aimed to characterize the physical and mechanical properties of starch foam formed from the mixture of cassava starch and PLP. The foams were made using a baking process on a thermo-pressing machine at temperature of 170°C and 180°C of the lower and upper mold temperature during 120 seconds. The starch foams were formulated with four different concentrations (0, 5, 10, and 15%) of PLP as reinforcement and tested for their characteristics of mechanical (compressibility) strength, water adsorption, morphological structure, density, color appearance, and biodegradability. Addition of PLP up to 15% improved the physical and mechanical properties of the foams.

Impact of lifestyle factors on dietary vitamin B6 intake and plasma pyridoxal 5'-phosphate level in UK adults: National Diet and Nutrition Survey Rolling Programme (NDNS) (2008-2017).

Reduction in dietary vitamin B6 intake is associated with an increased relative risk of diseases such as cancer, atherosclerosis and cognitive dysfunction. The current research has assessed vitamin B6 intakes and PLP concentrations as a marker of vitamin B6 status among the UK adult (≥ 19 years) population. This study was carried out using a cross-sectional analysis of the National Diet and Nutrition Survey Rolling Programme (NDNS) (2008-2017). The impacts of lifestyle factors, including type of diet, smoking, alcohol consumption, and commonly used medications grouped by therapeutic usage, were determined, and data were analysed using IBM SPSS®. Results are expressed as medians (25th-75th percentiles), with P values ≤ 0·05 considered statistically significant. Among UK adults, the median intakes of total population of dietary vitamin B6 met the reference nutrient intake and median plasma PLP concentrations were above the cut-off of vitamin B6 deficiency; however, we found an association between reduction in vitamin B6 intake and plasma PLP concentration and age group (P < 0·001). Smokers had significantly lower plasma PLP concentrations than non-smokers (P < 0·001). Moreover, regression analysis showed some commonly used medications were associated with plasma PLP levels reduction (P < 0·05). Taken together, we report on a tendency for dietary vitamin B6 intake and plasma PLP concentrations to decrease with age and lifestyle factors such as smoking and medication usage. This information could have important implications for smokers and in the elderly population using multiple medications (polypharmacy).

Convenient Genetic Encoding of Phenylalanine Derivatives through Their α-Keto Acid Precursors.

The activity and function of proteins can be improved by incorporation of non-canonical amino acids (ncAAs). To avoid the tedious synthesis of a large number of chiral phenylalanine derivatives, we synthesized the corresponding phenylpyruvic acid precursors. Escherichia coli strain DH10B and strain C321.ΔA.expΔPBAD were selected as hosts for phenylpyruvic acid bioconversion and genetic code expansion using the MmPylRS/pyltRNACUA system. The concentrations of keto acids, PLP and amino donors were optimized in the process. Eight keto acids that can be biotransformed and their coupled genetic code expansions were identified. Finally, the genetic encoded ncAAs were tested for incorporation into fluorescent proteins with keto acids.

Associations Between Vitamin B6 Status and Plasma Polyunsaturated Fatty Acids Among US Older Adults: NHANES 2003–2004

ObjectivesPrevious evidence suggests that vitamin B6 deficiency may have a deleterious impact on aging and the metabolism of polyunsaturated fatty acids (PUFA). However, the relationship of aging with vitamin B6 status and PUFA metabolism is poorly understood; population-based studies to assess the relationship between plasma pyridoxal 5′-phosphate (PLP; an active form of vitamin B6) and PUFA status for older adults are lacking. Thus, we examined the associations between plasma PLP concentration and plasma PUFA concentrations and ratios [eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), EPA + DHA, EPA/AA, and (EPA + DHA)/AA] among US older adults. We further investigated the association of adequate (PLP ≥ 20 nmol/L) versus deficient (PLP < 20 nmol/L) vitamin B6 status in those participants with plasma PUFA concentration above the median. MethodsA cross-sectional study analyzed 467 participants aged ≥60 years from the National Health and Nutrition Examination Survey (NHANES) 2003–2004. Nutrient intake data were estimated from two 24-h recalls and from questionnaires on the use of supplements. Plasma PLP and PUFA concentrations were measured. We used multivariable linear regression for obtaining unstandardized (b) and standardized (β) coefficients; multivariable logistic regression for adjusted odds ratios. Covariates included demographic, socioeconomic, dietary variables, physical activity, smoking, alcohol consumption, prescription medication use, and BMI. ResultsPlasma PLP was directly associated with plasma EPA (β = 0.176, b = 0.101, P = 0.002), DHA (β = 0.109, b = 0.046, P = 0.004), EPA + DHA (β = 0.137, b = 0.060, P = 0.002), EPA/AA (β = 0.169, b = 0.089, P = 0.009). The odds of having plasma EPA/AA and (EPA + DHA)/AA concentration above the median were greater in those with adequate vitamin B6 compared with those who were deficient [adjusted OR (aOR): 1.32, 95% CI: 0.8–2.17, P = 0.0001; aOR: 2.08, 95% CI: 1.0–4.33, P = 0.049, respectively]. ConclusionsIn US older adults, plasma PLP was directly associated with plasma EPA, DHA, EPA + DHA, EPA/AA. Adequate vitamin B6 status was associated with having above the median EPA/AA and (EPA + DHA)/AA. These findings suggest that adequate B6 status may positively influence PUFA metabolism in the older US population. Funding SourcesNo funding sources.

Investigation of ALPL variant states and clinical outcomes: An analysis of adults and adolescents with hypophosphatasia treated with asfotase alfa

BackgroundHypophosphatasia (HPP), a rare metabolic disease, can be inherited in an autosomal recessive (biallelic) or an autosomal dominant (monoallelic) manner. Most of the severe, early-onset, frequently lethal HPP in infants is acquired through recessive inheritance; less severe, later-onset, typically nonlethal HPP phenotypes are acquired through either dominant or recessive inheritance. HPP's variable clinical presentation arises from >400 identified ALPL pathogenic variants with likely variable penetrance, especially with autosomal dominant inheritance. This post hoc analysis investigated the relationship between ALPL variant state (biallelic and monoallelic) and clinical outcomes with asfotase alfa in HPP. MethodsData were pooled from two phase 2, randomized, open-label studies in adolescents and adults with HPP; one study evaluated the efficacy and safety of different doses of asfotase alfa (n = 25), and the other assessed the pharmacodynamics and safety of asfotase alfa (n = 19). Patients were grouped by ALPL variant state (biallelic or monoallelic). Available data from both studies included ALPL pathogenic variant state, Baseline characteristics, HPP-specific medical history, and Baseline TNSALP substrate levels (inorganic pyrophosphate [PPi] and pyridoxal 5′-phosphate [PLP]) concentrations). Clinical outcomes over 5 years of treatment were available from only the efficacy and safety study. ResultsIn total, 44 patients with known variant status were included in the pooled analysis (biallelic, n = 30; monoallelic, n = 14). The most common pathogenic variant was c.571G > A (p.Glu191Lys) in biallelic patients (allele frequency: 19/60) and c.1133A > T (p.Asp378Val) in monoallelic patients (allele frequency: 7/28). Median (min, max) Baseline PPi concentrations were significantly higher in patients with a biallelic vs monoallelic variant state (5.3 [2.2, 12.1] vs 4.3 [3.5, 7.4] μM; P = 0.0113), as were Baseline PLP concentrations (221.4 [62.4, 1590.0] vs 75.1 [28.8, 577.0] ng/mL; P= 0.0022). HPP-specific medical history was generally similar between biallelic and monoallelic patients in terms of incidence and type of manifestations; notable exceptions included fractures, which were more common among monoallelic patients, and delayed walking and bone deformities such as abnormally shaped chest and head and bowing of arms or legs, which were more common among biallelic patients. Data from the efficacy and safety study (n = 19) showed that median PPi and PLP concentrations were normalized over 5 years of treatment in patients with both variant states. Median % predicted distance walked on the 6-Minute Walk Test remained within the normal range for monoallelic patients over 4 years of treatment, and improved from below normal (<84%) to normal in biallelic patients. ConclusionsAlthough patients with biallelic variants had significantly higher Baseline PPi and PLP levels than monoallelic variants, both groups generally showed similar pretreatment Baseline clinical characteristics. Treatment with asfotase alfa for up to 5 years normalized TNSALP substrate concentrations and improved functional outcomes, with no clear differences between biallelic and monoallelic variant states. This study suggests that patients with HPP have significant disease burden, regardless of ALPL variant state.

Development and Clinical Evaluation of a High-Throughput LC-MS/MS Assay for Vitamin B6 in Human Plasma and Serum.

Pyridoxal 5'-phosphate (PLP) is the primary circulatory form of vitamin B6, an essential cofactor for numerous biochemical enzymatic reactions. Conventional PLP analysis using high-performance liquid chromatography (HPLC) with fluorescence requires derivatization and long injection-to-injection time. Development of high-throughput LC-MS/MS assays is desirable. Stable isotope labeled internal standard was added to aliquots of samples, proteins were precipitated using trichloroacetic acid, and supernatants were analyzed by multiple reaction monitoring using LC-MS/MS in positive ion mode. Analysis time for PLP was 3.0 min using single column HPLC separation and 2.4 min using alternating column regeneration (ACR). Clinical evaluation of the method included review of results (n = 102 386) from routine performance of the assay. The assay was linear to 500 nmol/L; limit of quantification was 5 nmol/L. Imprecision (CV) of the assay was <5%. Equivalent performance was observed for single HPLC column and ACR. In 62% of routinely analyzed patient samples, PLP concentrations were within the reference interval; higher PLP concentrations were observed in samples from males than from females. Vitamin B6 deficiency was lowest in children and highest in elderly adults. Lower PLP concentrations were observed in samples collected during winter/spring than during summer/fall. We observed lower concentrations in plasma collected in lithium heparin tubes, suggesting PLP degradation caused by the anticoagulant. This LC-MS/MS method allows PLP determination using simple sample preparation and short analysis time. We observed association of PLP concentrations with age, sex, and season of sample collection. Our data indicate that lithium heparin anticoagulant tubes reduce measured PLP concentration.

Riboflavin Is an Important Determinant of Vitamin B-6 Status in Healthy Adults

Riboflavin is required to generate the active form of vitamin B-6 (pyridoxal 5'-phosphate; PLP) in tissues, but the relevance of this metabolic interaction for nutritional status of vitamin B-6 is unclear because riboflavin biomarkers are rarely measured in human studies. The purpose of this study was to identify the determinants of biomarkers of vitamin B-6 and riboflavin status and to examine the relationship between these nutrients in healthy adults. Multiple linear regression was performed on observational data in 407 healthy adults aged 18-92 y who did not use B-vitamin supplements. Vitamin B-6 status was assessed by plasma PLP concentrations and erythrocyte glutathione reductase activation coefficient (EGRac) was used as a functional indicator of riboflavin status. Dietary intakes of vitamin B-6 and riboflavin were below the average requirements in 10% and 29% of participants, respectively. Suboptimal status of vitamin B-6 (PLP ≤30.0nmol/L) was more prevalent in adults aged ≥60 y than in younger participants (i.e., 14% compared with 5%), whereas a high proportion (i.e., overall 37%) of both age groups had deficient riboflavin status (EGRac ≥1.40). In multiple regression analysis, EGRac (P=0.019) was a significant determinant of plasma PLP, along with dietary vitamin B-6 intake (P=0.003), age (P<0.001), BMI (kg/m2) (P=0.031), and methylenetetrahydrofolate reductase gene (MTHFR) genotype (P<0.001).Significant determinants of EGRac were dietary riboflavin intake (P<0.001), age (P<0.001)and MTHFR genotype (P=0.020). Plasma PLP showed a stepwise decrease across riboflavin status categories from optimal (EGRac ≤1.26) to low (EGRac 1.27-1.39) to deficient status (P=0.001), independent of dietary vitamin B-6 intake. The findings are consistent with the known metabolic dependency of vitamin B-6 on riboflavin status and indicate that riboflavin may be the limiting nutrient, particularly in older people, for maintaining adequate vitamin B-6 status.

Covalent immobilization of recombinant Citrobacter koseri transaminase onto epoxy resins for consecutive asymmetric synthesis of L-phosphinothricin.

Transaminase responsible for alienating prochiral ketone compound is applicable to asymmetric synthesis of herbicide L-phosphinothricin (L-PPT). In this work, the covalent immobilization of recombinant transaminase from Citrobacter koseri (CkTA) was investigated on different epoxy resins. Using optimum ES-105 support, a higher immobilized activity was obtained via optimizing immobilization process in terms of enzyme loading, coupling time and initial PLP concentration. Crucially, due to blocking unreacted epoxy groups on support surface with amino acids, the reaction temperature of blocked immobilized biocatalyst was enhanced from 37 to 57°C. Its thermostability at 57°C was also found to be superior to that of free CkTA. The Km value was shifted from 36.75mM of free CkTA to 39.87mM of blocked immobilized biocatalyst, demonstrating that the affinity of enzyme to the substrate has not been apparently altered. Accordingly, the biocatalyst performed the consecutive synthesis of L-PPT for 11 cycles (yields>91%) with retaining more than 91.13% of the initial activity. The seemingly the highest reusability demonstrates this biocatalyst has prospective for reducing the costs of consecutive synthesis of L-PPT with high conversion.

Blood plasma B vitamins in depression and the therapeutic response to electroconvulsive therapy

A growing body of research has indicated a role for B vitamins in depression, with some previous studies suggesting that B vitamin status in patients with depression can impact on antidepressant response. Here we aimed to investigate B vitamin plasma concentrations in medicated patients with depression (n ​= ​94) compared to age- and sex-matched healthy controls (n ​= ​57), and in patients with depression after electroconvulsive therapy (ECT) in a real-world clinical setting. Our results show that nicotinamide (vitamin B3), N1-methylnicotinamide (vitamin B3 metabolite), and pyridoxal 5′-phosphate (PLP; vitamin B6) concentrations were significantly reduced in patients with depression compared to controls. The Cohen’s d effect sizes for nicotinamide, N1-methylnicotinamide, and PLP were moderate–large (−0.47, −0.51, and −0.59, respectively), and likely to be of clinical relevance. Functional biomarkers of vitamin B6 status (PAr index, 3-hydroxykynurenine: hydroxyanthranilic acid ratio, 3-hydroxykynurenine: xanthurenic acid ratio, and HKr) were elevated in depressed patients compared to controls, suggestive of reduced vitamin B6 function. Over 30% of the patient cohort were found to have low to deficient PLP concentrations, and exploratory analyses revealed that these patients had higher IL-6 and CRP concentrations compared to patients with PLP levels within the normal range. Treatment with ECT did not alter B vitamin concentrations, and B vitamin concentrations were not associated with depression severity or the therapeutic response to ECT. Overall, reduced plasma PLP, nicotinamide, and N1-methylnicotinamide concentrations could have wide ranging effects on pathways and systems implicated in depression. Further studies are required to understand the reasons why patients with depression present with low plasma B vitamin concentrations.

The impact of dental status on perceived ability to eat certain foods and nutrient intakes in older adults: cross-sectional analysis of the UK National Diet and Nutrition Survey 2008\u20132014

BackgroundMany factors determine dietary intake in older adults, including physical health, psychological well-being and socio-economic status. Dental status may also be important. The aim was to examine how dental status impacts perceived ability to eat to certain foods, nutrient intake and nutritional status in UK older adults.MethodsData collected by the National Diet and Nutrition Survey Rolling Programme was analysed. A 4-day food diary assessed dietary intake, while a Computer Assisted Personal Interview collected socio-demographic, health behaviour and oral health information. Participants aged 65 years and over (n = 1053) were categorised into three groups according to their dental status: edentate with dentures (E-DEN, n = 292), dentate with dentures (D-DEN, n = 305) or dentate with no dentures (DEN, n = 456). A total of 515 participants provided a blood sample that was used to assess nutrient concentrations including vitamin B12, vitamin C, ferritin, vitamin B6 (pyridoxal-5-phosphate, PLP), retinol, β-carotene and 25-hydroxyvitamin D (25-OH-D). Multiple regression methods were performed to examine cross-sectional associations between dental status, food selection, nutrient intake and nutritional status.ResultsBoth E-DEN and D-DEN groups, compared with the DEN group, were more likely to report difficulty eating apples, raw carrots, lettuce, nuts, well-cooked steak and crusty bread (P < 0.01). No group differences were observed in perceived ability to eat sliced bread, sliced cooked meats and cheese. The E-DEN group compared with the DEN group had lower mean daily intakes of omega 3 fatty acids (P = 0.006), non-starch polysaccharides (P = 0.001), β-carotene (P = 0.001), folate (P = 0.001), vitamin C (P = 0.008), magnesium (P < 0.001) and potassium (P < 0.001), and had lower plasma vitamin B6 PLP (P = 0.001), vitamin C (P = 0.009) and β-carotene (P = 0.015) concentrations, after adjusting for socio-demographic and health behavioural factors. Compared with the DEN group, the D-DEN group did not have lower nutrient intakes or lower blood nutrient concentrations.ConclusionsWithin this sample of older adults, impaired dental status appears to influence food selection, and intake of important nutrients. Future research should focus on developing dental interventions coupled with dietary counselling to encourage the adoption of healthy eating habits in this high-risk population group.

Exponential rolling circle amplification coupled with lateral flow dipstick strips as a rapid and sensitive method for the field detection of Karlodinium veneficum

Harmful algal blooms (HABs) caused by microalgae pose a great threat to human health, marine ecosystems, tourism, and aquaculture worldwide. Efficient, sensitive, and simple methods for the detection of harmful microalgal species must be developed to reduce the economic losses and damages caused by HABs. This study successfully established a novel method for the detection of the globally distributed HAB-forming species Karlodinium veneficum. The developed method was based on exponential rolling circle amplification (E-RCA) coupled with lateral flow dipstick (LFD) strips. A special oligonucleotide sequence-padlock probe (PLP) was designed on basis of the molecular cloning and subsequent sequencing of the D1–D2 region of the large subunit ribosomal DNA (LSU rDNA) of K. veneficum. The E-RCA reaction system was then established. E-RCA products could be visually analyzed through 2% agarose gel electrophoresis and the LFD assay. The optimized E-RCA conditions were as follows: PLP concentration of 20 pM, ligation cycle number of 12, ligation temperature of 56 °C, amplification duration of 45 min, and amplification temperature of 61 °C. The developed E-RCA-LFD assay was specific for K. veneficum and did not display cross-reactivity with other microalgal species. The E-RCA-LFD assay was 100-fold more sensitive than conventional polymerase chain reaction (PCR) and had detection limits of 8.0 × 101 ag μL−1 for the genomic DNA of K. veneficum and 5.0 × 101 ag μL−1 (approximately 13 copies μL−1) for recombinant plasmids containing the LSU rDNA D1–D2 regions of K. veneficum. Simulative tests indicated that the E-RCA-LFD assay demonstrated considerably higher sensitivity than conventional PCR and a detection limit of 0.01 cell mL−1. The practicability of the E-RCA-LFD assay was confirmed through tests with field samples. In conclusion, the highly sensitive, specific, and facile E-RCA-LFD assay established in this work may enable the field monitoring of natural samples containing K. veneficum.

Development of Recombinant Methioninase for Cancer Treatment.

The elevated requirement for methionine (MET) of cancer cells is termed MET dependence. To selectively target the MET dependence of tumors for treatment on a large-scale preclinical and clinical basis, the L-methionine α-deamino-γ-mercaptomethane-lyase (EC 4.4.1.11) (methioninase, [METase]) gene from Pseudomonas putida has been cloned in Escherichia coli using the polymerase chain reaction (PCR). Purification using two DEAE Sepharose FF ion-exchange column and one ActiClean Etox endotoxin-affinity chromatography column has been established. Plasmid pMGLTrc03, which has a trc promoter and a spacing of 12 nucleotides between the Shine-Dalgarno sequence and the ATG translation initiation codon, was selected as the most suitable plasmid. The recombinant bacteria produced rMETase at 43% of the total proteins in soluble fraction by simple batch fermentation using a 500L fermentor. Crystals were directly obtained from crude enzyme with 87% yield by a crystallization in the presence of 9.0% polyethylene glycol 6000, 3.6% ammonium sulfate, and 0.18M sodium chloride using a 100L crystallizer. After recrystallization, the enzyme was purified by anion-exchange column chromatography to remove endotoxins and by gel filtration for polishing. Purified rMETase is stable to lyophilization. In order to prevent immunological reactions which might be produced by multiple dosing of rMETase and to prolong the serum half-life of rMETase, the N-hydroxysuccinimidyl ester of methoxypolyethylene glycol propionic acid (M-SPA-PEG 5000) has been coupled to rMETase. The PEGylated molecules (PEG-rMETase) were purified from unreacted PEG with Amicon 30K centriprep concentrators or by Sephacryl S-300 HR gel-filtration chromatography. Unreacted rMETase was removed by DEAE Sepharose FF anion-exchange chromatography. The resulting PEG-rMETase subunit, produced from a PEG/rMETase ratio of 30/1 in the synthetic reaction, had a molecular mass of approximately 53kda determined by matrix-assisted laser desorption/ionization mass spectrometry, indicating the conjugation of two PEG molecules per subunit of rMETase and eight per tetramer. PEG-rMETase molecules obtained from reacting ratios of PEG/rMETase of 30/1 had an enzyme activity of 70% of unmodified rMETase. PEGylation of rMETase increased the serum half-life of the enzyme in rats to approximately 160min compared to 80min for unmodified rMETase. PEG-rMETase could deplete serum MET levels to less than 0.1μM for approximately 8h compared to 2h for rMETase in rats. A significant prolongation of in vivo activity and effective MET depletion by the PEG-rMETase were achieved by the simultaneous administration of pyridoxal 5'-phosphate. rMETase was also conjugated with methoxypolyethylene glycol succinimidyl glutarate 5000 (MEGC-PEG). Miniosmotic pumps containing various concentrations of PLP were implanted in BALB-C mice. PLP-infused mice were then injected with a single dose of 4000 or 8000units/kg PEG-rMETase. Mice infused with 5, 50, 100, 200, and 500mg/mL PLP-containing miniosmotic pumps increased plasma PLP to 7, 24, 34, 60, and 95μM, respectively, from the PLP baseline of 0.3μM. PLP increased the half-life of MEGC-PEG-rMETase holoenzyme in a dose-dependent manner. The extended time of MET depletion by MEGC-PEG-rMETase was due to the maintenance of active MEGC-PEG-rMETase holoenzyme by infused PLP.

Highly efficient production of chiral amines in batch and continuous flow by immobilized ω-transaminases on controlled porosity glass metal-ion affinity carrier

In this study, two stereocomplementary ω-transaminases from Arthrobacter sp. (AsR-ωTA) and Chromobacterium violaceum (Cv-ωTA) were immobilized via iron cation affinity binding onto polymer-coated controlled porosity glass beads (EziG™). The immobilization procedure was studied with different types of carrier materials and immobilization buffers of varying compositions, concentrations, pHs and cofactor (PLP) concentrations. Notably, concentrations of PLP above 0.1 mM were correlated with a dramatic decrease of the immobilization yield. The highest catalytic activity, along with quantitative immobilization, was obtained in MOPS buffer (100 mM, pH 8.0, PLP 0.1 mM, incubation time 2 h). Leaching of the immobilized enzyme was not observed within 3 days of incubation. EziG-immobilized AsR-ωTA and Cv-ωTA retained elevated activity when tested for the kinetic resolution of rac-α-methylbenzylamine (rac-α-MBA) in single batch experiments. Recycling studies demonstrated that immobilized EziG3-AsR-ωTA could be recycled for at least 16 consecutive cycles (15 min per cycle) and always affording quantitative conversion (TON ca. 14,400). Finally, the kinetic resolution of rac-α-MBA with EziG3-AsR-ωTA was tested in a continuous flow packed-bed reactor (157 μL reactor volume), which produced more than 5 g of (S)-α-MBA (>49% conversion, >99% ee) in 96 h with no detectable loss of catalytic activity. The calculated TON was more than 110,000 along with a space-time yield of 335 g L−1 h−1.

Suboptimal maternal and cord plasma pyridoxal 5' phosphate concentrations are uncommon in a cohort of Canadian pregnant women and newborn infants.

Vitamin B6 is important in fetal development, but little is known of the vitamin B6 status of pregnant women and newborns in North America and potential modifying factors. This prospective study determined maternal and cord plasma concentrations of pyridoxal 5' phosphate (PLP; an indicator of vitamin B6 status) in a convenience sample of 368 Canadian pregnant women and their newborns. The association of maternal intake of vitamin B6 and fetal genetic variants with cord plasma PLP and homocysteine concentrations was also examined. Dietary and supplemental intakes of vitamin B6 were assessed in early and mid to late pregnancy. PLP concentrations were measured in maternal plasma in early pregnancy and at delivery, and in cord plasma. Six fetal variants of the MTHFR and CβS genes were assessed for their association with cord plasma PLP and homocysteine concentrations. Geometric mean (95% CI) PLP concentrations were 107 (98, 116) nmol/L in early pregnancy and 58 (53, 62) nmol/L at delivery, respectively, and 296 (275, 319) nmol/L in cord blood (p<.0001). During early pregnancy and at delivery, 3.6% and 5.5% of women had plasma PLP concentrations <20nmol/L, respectively. Ninety eight percent of the women with supplemental B6 intake of at least the recommended dietary allowance had PLP concentrations >20nmol/L. Fetal genetic variants were not associated with cord PLP and homocysteine concentrations. Vitamin B6 deficiency is uncommon in a cohort of Canadian pregnant women due largely to prevalent vitamin B6 supplement use.

Vitamin B-6 Status in Unsupplemented Pregnant Women Is Associated Positively with Serum Docosahexaenoic Acid and Inversely with the n–6-to-n–3 Fatty Acid Ratio

BackgroundVitamin B-6–deficient diets decrease plasma docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) concentrations in healthy adults. These fatty acids (FAs) are important for fetal neurodevelopment, but the relation between vitamin B-6 status and circulating polyunsaturated FAs (PUFAs) during pregnancy is unknown. ObjectiveWe sought to assess the relation between plasma pyridoxal 5′ phosphate (PLP; the active form of vitamin B-6) and serum DHA, EPA, AA, linoleic acid, eicosadienoic, and α-linolenic acid concentrations during pregnancy. MethodsA prospective cohort study in 186 healthy pregnant Brazilian women (aged 20–40 y) who were not using supplements was conducted in Rio de Janeiro, Brazil. Participants were enrolled in the first trimester of pregnancy (5–13 gestational weeks) and were followed up twice between 20–26 and 30–36 wk of gestation. Longitudinal linear mixed-effects regression models were used to evaluate the associations between 1) first-trimester PLP and PUFA concentrations across pregnancy and 2) ΔPLP (i.e., difference between third- and first-trimester plasma PLP concentrations) and PUFA concentrations across pregnancy. Models were adjusted for gestational week, first-trimester body mass index, smoking habit, and dietary intakes of vitamin B-6, fish, total fat, and PUFAs. ResultsPlasma PLP concentrations (median, IQR) substantially declined during pregnancy from 35.8 nmol/L (28.6–44.3 nmol/L) in the first trimester to 21.0 nmol/L (15.8–26.3 nmol/L) in the second trimester, and 16.8 nmol/L (12.9–20.3 nmol/L) in the third trimester (both P < 0.0001). Changes in plasma PLP concentrations across trimesters were positively associated with serum DHA concentrations (β = 0.252, P = 0.012) and inversely associated with serum n–6-to-n–3 (ω-6-to-ω-3) FA ratio (β = −0.010; P = 0.015), after adjustments for confounders. ConclusionsMaternal vitamin B-6 status during pregnancy was positively associated with the circulating concentration of DHA and inversely associated with n–6:n–3 FAs in Brazilian women who were not taking vitamin supplements. Further study is required to determine the impact of poor vitamin B-6 status on fetal neurodevelopment.

Plasma PLP Concentration and Depressive Symptomatology in older Latino Adults: A Longitudinal Analysis with time‐varying Covariates

BackgroundLow vitamin B‐6 status has been linked to depressive symptomatology. However, most studies have been cross‐sectional and may not have controlled for relevant confounders. Few studies have examined this association in Latino populations at high risk for major depression.ObjectiveOur objective was to examine the longitudinal association of vitamin B‐6 status with depressive symptomatology in a cohort of older Puerto Rican adults, a population previously identified to be at high risk for depressive symptomatology and clinical depression.ResultsIn two level hierarchical linear regression models that account for the clustering of measures of participant's depressive symptomatology (Level‐1) at three different points in time nested within participants (Level‐2); plasma pyridoxyl‐5′‐phosphate (PLP) concentration, a time‐varying predictor, was significantly associated with higher depressive symptomatology over the three time points. This negative association persisted after adjusting for body mass index (BMI), level of physical activity, smoking, alcohol use, hypertension, diabetes, time‐varying vitamins B‐12, folate and D; and baseline dietary intake of magnesium, allostatic load (physiological stress), stressful life events (social stress) and perceived stress (psychological stress), plasma homocysteine concentration (tHCY), and use of antidepressant medication. The slope of the decline in depressive symptomatology over time was steeper in participants with PLP&gt;30 nmol/L vs. participants with suboptimal PLP plasma concentration; however, this difference was not statistically significant.ConclusionsWe found significantly higher depressive symptoms in participants with suboptimal plasma PLP compared to participants with adequate PLP concentration over three time points. Findings from our study highlight the need to adjust for physiological, psychological and social stress when examining the effect of micro‐nutrients on depressive symptoms. Our data suggest that identification and treatment of vitamin B‐6 deficiency may be a useful preventive and intervention approach in older Puerto Rican adults, and potentially other Hispanic subgroups.Support or Funding InformationThis study was funded by the National Heart, Lung, and Blood Institute; National Institutes of Health (Grant 5P50HL105185, Katherine L. Tucker, PhD, Principal Investigator) Longitudinal Associations between Depressive symptomatology (CES‐D) and time‐varying suboptimal PLP status in the Puerto Rican Health study participants Model 1a Model 2b Model 3c Model 4d Model 5e Model 6f β (SE) p‐value β (SE) p‐value β (SE) p‐value β (SE) p‐value β (SE) p‐value β (SE) p‐value Suboptimal Vitamin B‐6 (plasma PLP&lt;30 nmol/L) No use ‐ref ‐ ‐ ‐ ‐ ‐ ‐ Yes 0.68 0.56 0.23 0.57 0.56 0.31 0.52 0.57 0.36 0.34 0.65 0.60 1.16 0.57 0.04 1.06 0.57 0.06 Time −0.47 0.10 &lt; 0.0001 −0.72 0.10 &lt;0.0001 −0.42 0.10 &lt;0.0001 −0.44 0.11 &lt;0.0001 −0.64 0.11 &lt;0.0001 −0.66 0.11 &lt;0.0001 Suboptimal Vitamin B‐6 * Time No use ‐ref ‐ ‐ ‐ ‐ ‐ ‐ Yes 0.23 0.19 0.24 0.15 0.19 0.43 0.17 0.20 0.39 0.11 0.22 0.62 0.09 0.23 0.68 0.11 0.22 0.64 Goodness of fit N 12 15 17 21 24 26 df 3016 2985 2933 2350 2187 2187 Log Likelihood −11537.92 −11394.91 −11198.46 −9008.93 −8011.75 −7996.55 AIC 23099.84 22819.83 22430.92 18059.85 16071.51 16045.09 BIC 23171.98 22909.85 22532.65 18180.86 16208.08 16193.04 Model 1: age + sex + education + BMI Model 2: Model 1 + smoking + alcohol use + physical activity Model 3: Model 2 + hypertension + diabetes Model 4: Model 3 + time‐varying plasma vitamins (B‐12, Folate, D) + baseline energy adjusted magnesium diet intake Model 5: Model 4 + allostatic load + stressful life events + perceived stress Model 6: Model 5 + tHCY + antidepressant drug use

Maternal B vitamins: effects on offspring weight and DNA methylation at genomically imprinted domains.

BackgroundInadequate maternal nutrition during early fetal development can create permanent alterations in the offspring, leading to poor health outcomes. While nutrients involved in one-carbon cycle metabolism are important to fetal growth, associations with specific nutrients remain inconsistent. This study estimates associations between maternal vitamins B12, B6 (pyridoxal phosphate [PLP] and 4-pyridoxic acid [PA]), and homocysteine (Hcy) concentrations, offspring weight (birth weight and 3-year weight gain), and DNA methylation at four differentially methylated regions (DMRs) known to be involved in fetal growth and development (H19, MEG3, SGCE/PEG10, and PLAGL1).MethodsStudy participants (n = 496) with biomarker and birth weight data were enrolled as part of the Newborn Epigenetics STudy. Weight gain data were available for 273 offspring. Among 484 mother-infant pairs, DNA methylation at regulatory sequences of genomically imprinted genes was measured in umbilical cord blood DNA using bisulfite pyrosequencing. We used generalized linear models to estimate associations.ResultsMultivariate adjusted regression models revealed an inverse association between maternal Hcy concentration and male birth weight (β = −210.40, standard error (SE) = 102.08, p = 0.04). The offspring of the mothers in the highest quartile of B12 experienced lower weight gain between birth and 3 years compared to the offspring of the mothers in the lowest (β = −2203.03, SE = 722.49, p = 0.003). Conversely, maternal PLP was associated with higher weight gain in males; higher maternal PLP concentrations were also associated with offspring DNA methylation levels at the MEG3 DMR (p < 0.01).ConclusionsWhile maternal concentrations of B12, B6, and Hcy do not associate with birth weight overall, they may play an important role in 3-year weight gain. This is the first study to report an association between maternal PLP and methylation at the MEG3 DMR which may be an important epigenetic tag for maternal B vitamin adequacy.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-016-0174-9) contains supplementary material, which is available to authorized users.

Decrease in pyridoxal-5′-phosphate concentration and increase in pyridoxal concentration in rat plasma by 4′-O-methylpyridoxine administration

Food poisoning from Ginkgo biloba seeds can cause epilepsy because of a decrease in γ-aminobutyric acid (GABA) concentrations in the brain. We previously demonstrated that 4′-O-methylpyridoxine (MPN) is responsible for this observed toxicity of G biloba seeds; however, the mechanism for the decrease in GABA and plasma concentration profile of MPN has not been clarified. Our hypothesis is that MPN induces a decrease in vitamin B6 concentrations, resulting in a decrease in GABA concentration. This study aimed to characterize the plasma concentration profile of MPN and intrinsic vitamin B6 concentrations (pyridoxal [PL], PL-5′-phosphate [PLP], and 4-pyridoxic acid) using a rat model. Plasma concentrations of B6 vitamers after intravenous MPN administration (5 mg/kg) were determined using high-performance liquid chromatography with a fluorescence detector. The half-life of MPN (0.91 ± 0.05 hours) was shorter in rats than the previously reported value in humans. We found a significant decrease in the plasma concentration of PLP, an active form of vitamin B6, after MPN administration. We also observed an increase in plasma PL and 4-pyridoxic acid concentrations; the increase in PL concentration may be caused by either metabolism of MPN to PL or by MPN-mediated inhibition of PL kinase. The present study is the first in vivo study showing relatively rapid elimination of MPN in rats and a decrease in plasma PLP concentration caused by MPN.

Tryptophan Catabolism and Vitamin B-6 Status Are Affected by Gender and Lifestyle Factors in Healthy Young Adults1–3

Abnormalities of tryptophan (Trp) metabolism through the kynurenine (Kyn) pathway have been reported in various diseases; however, nutritional and lifestyle factors that affect this pathway in healthy individuals are not well documented. Our aim was to examine the effect of vitamin B-6 status and lifestyle factors including the use of vitamin B-6 supplements, alcohol, smoking, and oral contraceptives on Trp and its Kyn metabolites in a cohort of 2436 healthy young adults aged 18-28 y. Anthropometric and lifestyle data were collected by questionnaire. Participants provided blood samples for analysis of Trp, Kyn, anthranilic acid, kynurenic acid (KA), 3-hydroxykynurenine (HK), 3-hydroxyanthranilic acid (HAA), and xanthurenic acid (XA). Vitamin B-6 species were also measured. Serum Trp metabolites were 10-15% higher among men (n = 993) compared with women (n = 1443; P < 0.0001), except for HK and XA. In all participants, serum Trp was positively associated with plasma pyridoxal 5'-phosphate (PLP; r = 0.28, P < 0.0001), reaching a plateau at PLP concentrations of ∼83 nmol/L. HK was inversely associated with PLP (r = -0.14, P < 0.01). Users of vitamin B-6 supplements (n = 671) had 6% lower concentrations of HK than nonusers (n = 1765; P = 0.0006). Oral contraceptive users (n = 385) had lower concentrations of KA (20.7%) but higher XA (24.1%) and HAA (9.0%) than did nonusers (n = 1058; P < 0.0001). After adjustment for gender and other lifestyle variables, XA concentrations were 16% higher in heavy drinkers (n = 713) than in never or occasional drinkers (n = 975; P = 0.0007). Concentrations of 2 other essential amino acids, methionine and arginine, also were positively associated with serum Trp (r = 0.65 and 0.33, respectively; P < 0.0001). In this population of healthy young adults, gender has the largest influence on serum Kyn metabolite concentrations. The significant covariance of Trp with unrelated amino acids suggests that protein intake may be an important consideration in evaluating Kyn metabolism.