Enhancement of vitamin B6 production driven by omics analysis combined with fermentation optimization.

BACKGROUND: Microbial engineering aims to enhance the ability of bacteria to produce valuable products, including vitamin B6 for various applications. Numerous microorganisms naturally produce vitamin B6, yet the metabolic pathways involved are rigorously controlled. This regulation by the accumulation of vitamin B6 poses a challenge in constructing an efficient cell factory. RESULTS: In this study, we conducted transcriptome and metabolome analyses to investigate the effects of the accumulation of pyridoxine, which is the major commercial form of vitamin B6, on cellular processes in Escherichia coli. Our omics analysis revealed associations between pyridoxine and amino acids, as well as the tricarboxylic acid (TCA) cycle. Based on these findings, we identified potential targets for fermentation optimization, including succinate, amino acids, and the carbon-to-nitrogen (C/N) ratio. Through targeted modifications, we achieved pyridoxine titers of approximately 514 mg/L in shake flasks and 1.95 g/L in fed-batch fermentation. CONCLUSION: Our results provide insights into pyridoxine biosynthesis within the cellular metabolic network for the first time. Our comprehensive analysis revealed that the fermentation process resulted in a remarkable final yield of 1.95 g/L pyridoxine, the highest reported yield to date. This work lays a foundation for the green industrial production of vitamin B6 in the future.

Functional and structural properties of pyridoxal reductase (PdxI) from Escherichia coli: a pivotal enzyme in the vitamin B6 salvage pathway.

Pyridoxine 4-dehydrogenase (PdxI), a NADPH-dependent pyridoxal reductase, is one of the key players in the Escherichia coli pyridoxal 5'-phosphate (PLP) salvage pathway. This enzyme, which catalyses the reduction of pyridoxal into pyridoxine, causes pyridoxal to be converted into PLP via the formation of pyridoxine and pyridoxine phosphate. The structural and functional properties of PdxI were hitherto unknown, preventing a rational explanation of how and why this longer, detoured pathway occurs, given that, in E. coli, two pyridoxal kinases (PdxK and PdxY) exist that could convert pyridoxal directly into PLP. Here, we report a detailed characterisation of E. coli PdxI that explains this behaviour. The enzyme efficiently catalyses the reversible transformation of pyridoxal into pyridoxine, although the reduction direction is thermodynamically strongly favoured, following a compulsory-order ternary-complex mechanism. In vitro, the enzyme is also able to catalyse PLP reduction and use NADH as an electron donor, although with lower efficiency. As with all members of the aldo-keto reductase (AKR) superfamily, the enzyme has a TIM barrel fold; however, it shows some specific features, the most important of which is the presence of an Arg residue that replaces the catalytic tetrad His residue that is present in all AKRs and appears to be involved in substrate specificity. The above results, in conjunction with kinetic and static measurements of vitamins B6 in cell extracts of E. coli wild-type and knockout strains, shed light on the role of PdxI and both kinases in determining the pathway followed by pyridoxal in its conversion to PLP, which has a precise regulatory function.

Rapid Diagnostic Platform for Personalized Vitamin B6 Detection in Erythrocytes via PLP Cofactor Mimics.

Personalized assessment of vitamin levels in point-of-care (POC) devices is urgently needed to advance the recognition of diseases associated with malnutrition and unbalanced diets. We here introduce a diagnostic platform, which showcases an easy and rapid readout of vitamin B6 (pyridoxal phosphate, PLP) levels in erythrocytes as a first step toward a home-use POC. The technology is based on fluorescent probes, which bind to PLP-dependent enzymes (PLP-DEs) and thereby indirectly report their occupancy with endogenous B6. For example, low vitamin levels result in high probe binding, yielding a strong signal and vice versa. Antibodies against signature human PLP-DEs were immobilized on microarrays to capture probe labeled enzymes for fluorescent detection. Calibrating the system with defined B6 levels revealed a concentration-depended readout as well as sufficient sensitivity for its detection in erythrocytes. To account for individual differences in protein expression, a second antibody was used to normalize protein abundance. This sandwiched assay correctly reported relative B6 levels in human erythrocyte samples, as confirmed by classical laboratory diagnostics. In principle, the platform layout can be easily expanded to other crucial vitamins beyond B6 via an analogous probe strategy.

PYRIDOX(AM)INE 5'-PHOSPHATE OXIDASE3 of Arabidopsis thaliana maintains carbon/nitrogen balance in distinct environmental conditions.

The identification of factors that regulate C/N utilization in plants can make a substantial contribution to optimization of plant health. Here, we explored the contribution of pyridox(am)ine 5'-phosphate oxidase3 (PDX3), which regulates vitamin B6 homeostasis, in Arabidopsis (Arabidopsis thaliana). Firstly, N fertilization regimes showed that ammonium application rescues the leaf morphological phenotype of pdx3 mutant lines but masks the metabolite perturbance resulting from impairment in utilizing soil nitrate as a source of N. Without fertilization, pdx3 lines suffered a C/N imbalance and accumulated nitrogenous compounds. Surprisingly, exploration of photorespiration as a source of endogenous N driving this metabolic imbalance, by incubation under high CO2, further exacerbated the pdx3 growth phenotype. Interestingly, the amino acid serine, critical for growth and N management, alleviated the growth phenotype of pdx3 plants under high CO2, likely due to the requirement of pyridoxal 5'-phosphate for the phosphorylated pathway of serine biosynthesis under this condition. Triggering of thermomorphogenesis by growth of plants at 28 °C (instead of 22 °C) did not appear to require PDX3 function, and we observed that the consequent drive toward C metabolism counters the C/N imbalance in pdx3. Further, pdx3 lines suffered a salicylic acid-induced defense response, probing of which unraveled that it is a protective strategy mediated by nonexpressor of pathogenesis related1 (NPR1) and improves fitness. Overall, the study demonstrates the importance of vitamin B6 homeostasis as managed by the salvage pathway enzyme PDX3 to growth in diverse environments with varying nutrient availability and insight into how plants reprogram their metabolism under such conditions.

4'-Deoxypyridoxine disrupts vitamin B6 homeostasis in Escherichia coli K12 through combined inhibition of cumulative B6 uptake and PLP-dependent enzyme activity.

Pyridoxal 5'-phosphate (PLP) is the active form of vitamin B6 and a cofactor for many essential metabolic processes such as amino acid biosynthesis and one carbon metabolism. 4'-deoxypyridoxine (4dPN) is a long known B6 antimetabolite but its mechanism of action was not totally clear. By exploring different conditions in which PLP metabolism is affected in the model organism Escherichia coli K12, we showed that 4dPN cannot be used as a source of vitamin B6 as previously claimed and that it is toxic in several conditions where vitamin B6 homeostasis is affected, such as in a B6 auxotroph or in a mutant lacking the recently discovered PLP homeostasis gene, yggS. In addition, we found that 4dPN sensitivity is likely the result of multiple modes of toxicity, including inhibition of PLP-dependent enzyme activity by 4'-deoxypyridoxine phosphate (4dPNP) and inhibition of cumulative pyridoxine (PN) uptake. These toxicities are largely dependent on the phosphorylation of 4dPN by pyridoxal kinase (PdxK).

Pyridoxine biosynthesis protein MoPdx1 affects the development and pathogenicity of Magnaporthe oryzae.

B vitamins are essential micro-organic compounds for the development of humans and animals. Vitamin B6 comprises a group of components including pyridoxine, pyridoxal, and pyridoxamine. In addition, vitamin B6 acts as the coenzymes in amino acid biosynthesis, decarboxylation, racemic reactions, and other biological processes. In this study, we found that the expressions of a gene encoding pyridoxine biosynthesis protein (PDX1) were significantly upregulated in the early infectious stages in M. oryzae. Furthermore, deletion of MoPDX1 slowed vegetative growth on different media, especially on MM media, and the growth defect was rescued when MoPdx1-protein was expressed in mutants strains and when commercial VB6 (pyridoxine) was added exogenously. However, VB6 content in different strains cultured in CM media has no significant difference, suggested that MoPdx1 was involved in de novo VB6 biosynthesis not in uptake process, and VB6 regulates the vegetative growth of M. oryzae. The ΔMopdx1 mutants presented abnormal appressorium turgor, slowed invasive growth and reduced virulence on rice seedlings and sheath cells. MoPdx1 was located in the cytoplasm and present in spore and germ tubes at 14 hours post inoculation (hpi) and then transferred into the appressorium at 24 hpi. Addition of VB6 in the conidial suspentions could rescue the defects of appressorium turgor pressure at 14 hpi or 24 hpi, invasive growth and pathogenicity of the MoPDX1 deletion mutants. Indicated that MoPdx1 affected the appressorium turgor pressure, invasive growth and virulence mainly depended on de novo VB6, and VB6 was biosynthesized in conidia, then transported into the appressorium, which play important roles in substances transportation from conidia to appressorium thus to regulate the appressorium turgor pressure. However, deletion of MoPDX1 did not affect the ability that scavenge ROS produced by rice cells, and the mutant strains were unable to activate host defense responses. In addition, co-immunoprecipitation (Co-IP) assays investigating potential MoPdx1-interacting proteins suggested that MoPdx1 might take part in multiple pathways, especially in the ribosome and in biosynthesis of some substances. These results indicate that vitamins are involved in the development and pathogenicity of M. oryzae.

Chemical Modifications of Pyridoxine for Biological Applications: An Overview.

Pyridoxine and its derivatives, pyridoxamine, and pyridoxal have been recognized for more than 70 years and are known for regulating cellular biology and metabolism. During the past few decades, the anti-oxidant and anti-inflammatory properties of pyridoxine and its vitamers were explored. However, an interesting turnabout was observed in pyridoxine chemical modification in the last two decades. The various important pathophysiological aspects of pyridoxine and its derivatives on several cellular systems have been discovered by researchers. Recent findings have shown that many diseases, like cancer, diabetes, hypertension, tuberculosis, epilepsy, and neurodegenerative diseases are linked to the alteration of pyridoxine. Herein, our main focus is to review the importance of pyridoxine and its derivatives obtained by various chemical modifications, in various disease areas and to recognize important directions for future research.

Vitamin B6 Supplementation Reduces Symptoms of Depression in College Women Taking Oral Contraceptives: A Randomized, Double-Blind Crossover Trial.

Oral contraceptive (OC) users have a heightened risk of low plasma concentrations of vitamin B6, a cofactor in the tryptophan-serotonin pathway critical to mood regulation. The purpose of this crossover study was to determine whether vitamin B6 supplementation reduced symptoms of depression and improved mood states in college women using OC. Participants were healthy (aged 18-25 yrs), did not take dietary supplements, and used OC (estrogen with progestin) consistently for at least 1 year. During the 12-week, randomized, double-blind crossover trial (4-week treatment periods [100 mg vitamin B6 daily or placebo] separated by a 4-week washout) participants (n = 8) maintained normal exercise and eating patterns and recorded tablet consumption daily. The Beck Depression Inventory-II (BDI-II) and Profile of Mood States (POMS) were used to assess mental health before and after each 4-week treatment period. Average dietary vitamin B6 intakes did not vary during the trial (1.2-1.4 mg/d), whereas vitamin B6 status rose significantly following the B6 supplementation period compared to the other three time points. BDI-II scores were reduced 20% by vitamin B6 supplementation in comparison to an 11% rise with placebo ingestion (p = 0.046). POMS scores were not significantly impacted by vitamin B6 supplementation. These preliminary data support a growing literature suggesting the benefits of B6 supplementation for reducing symptoms of depression in young women using OC.

Vitamins and their derivatives synergistically promote hair shaft elongation ex vivo via PlGF/VEGFR-1 signalling activation.

BACKGROUND: Although vitamins or their derivatives (Vits), such as panthenyl ethyl ether, tocopherol acetate, and pyridoxine, have been widely used in topical hair care products, their efficacy and mode of action have been insufficiently studied. OBJECTIVE: To elucidate the biological influence of Vits on hair follicles and determine the underlying mechanisms. METHODS: A mouse vibrissa hair follicle organ culture model was utilized to evaluate the effects of Vits on hair shaft elongation. Gene and protein expression analyses and histological investigations were conducted to elucidate the responsible mechanisms. A human hair follicle cell culture was used to assess the clinical relevance. RESULTS: In organ culture models, the combination of panthenyl ethyl ether, tocopherol acetate, and pyridoxine (namely, PPT) supplementation significantly promoted hair shaft elongation. PPT treatment enhanced hair matrix cell proliferation by 1.9-fold compared to controls, as demonstrated by Ki67-positive immunoreactivity. PPT-treated mouse dermal papillae exhibited upregulated Placental growth factor (Plgf) by 1.6-fold compared to controls. Importantly, the addition of PlGF neutralizing antibodies to the ex vivo culture diminished the promotive effect on hair growth and increase in VEGFR-1 phosphorylation achieved by PPT. A VEGFR-1 inhibitor also inhibited the promotion of hair growth. Microarray analysis suggested synergistic summation of individual Vits' bioactivity, putatively explaining the effect of PPT. Moreover, PPT increased PlGF secretion in cultured human dermal papilla cells. CONCLUSION: Our findings suggested that PPT promoted hair shaft elongation by activating PlGF/VEGFR-1 signalling. The current study can shed light on the previously underrepresented advantage of utilizing Vits in hair care products.

Pyridoxine Has a Potential to Prevent the Appearance of Pigmented Spots: Effects on the Phagocytosis and Differentiation of Keratinocytes.

Pyridoxine (VB6) is a vitamin that is essential to maintain the homeostasis of the human body by contributing to various metabolic reactions. In the skin, although some studies have shown that VB6 is involved in regulating homeostasis through the attenuation of intracellular oxidative stress, there are few reports regarding the effects of VB6 on the prevention or improvement of skin aging. Thus, we conducted this study to determine the potential anti-skin pigmentation effect of VB6 focusing on the phagocytosis of melanosomes (MSs) by keratinocytes. The phagocytosis of MSs by keratinocytes is activated by oxidative stress and is an important factor of skin pigmentation and the eventual appearance of pigmented spots. First, we confirmed the antioxidant property of VB6 that enhanced the expression of several intracellular antioxidants via nuclear erythroid factor 2-related factor 2 (Nrf2). Although the incorporation of fluorescent beads (FBs), which are used as pseudo-MSs, into keratinocytes was increased under higher oxidation conditions caused by UVB and by the depletion of intracellular glutathione, treatment with VB6 suppressed the increased incorporation of FBs into those keratinocytes via Nrf2 activation. Furthermore, VB6 restored the decreased expression of differentiation marker proteins in keratinocytes caused by FB incorporation. Taken together, the results show that VB6 has the potential to prevent the appearance of pigmented spots by suppressing the activation of phagocytosis in keratinocytes caused by oxidative stress, and by restoring the differentiation of keratinocytes disrupted by FB incorporation.

Investigation of the vitamins B1, B2, and B6 vitamers bioaccessibilities of canned, dried legumes after in vitro gastrointestinal digestion system.

Legumes are rich in minerals, B group vitamins, fiber, and protein. Intake of essential nutrients is vital in adequate and balanced nutrition. As it is crucial to evaluate final nutrient amounts, cooking losses and bioaccessibility values are determinant factors. This study investigates the quantity and vitamins B1, B2, and B6 vitamers bioaccessibilities in different dried, canned legume samples using an in vitro digestion model. High-performance liquid chromatography was used to determine the amount of each vitamin. Vitamin B1 bioaccessibility in canned legumes was found above 72% except for red lentils (23%), vitamin B2 bioaccessibility was above 63% except for green lentils (44%), while total vitamin B6 bioaccessibility (57%) was lower than vitamins B1 and B2. The form of pyridoxine with the highest bioaccessibility for vitamin B6 forms was found between 66 and 89%, except for peas and red lentils. Besides, pyridoxamine form bioaccessibility was very low compared to pyridoxal form. We believe bioaccessibility might relate to temperature, pH, bonds with polypeptides and polysaccharides, and dietary fibers. As seen, the concept of bioaccessibility gains importance in the final nutrient amount.

Role of the conserved pyridoxal 5'-phosphate-binding protein YggS/PLPBP in vitamin B6 and amino acid homeostasis.

The YggS/PLPBP protein (also called COG0325 or PLPHP) is a conserved pyridoxal 5'-phosphate (PLP)-binding protein present in all 3 domains of life. Recent studies have demonstrated that disruption or mutation of this protein has multifaceted effects in various organisms, including vitamin B6-dependent epilepsy in humans. In Escherichia coli, disruption of this protein-encoded by yggS-perturbs Thr-Ile/Val metabolism, one-carbon metabolism, coenzyme A synthesis, and vitamin B6 homeostasis. This protein is critical for maintaining low levels of pyridoxine 5'-phosphate (PNP) in various organisms. In the yggS-deficient E. coli strain, inhibition of PLP-dependent enzymes, such as the glycine cleavage system by PNP, is the root cause of metabolic perturbation. Our data suggest that the YggS/PLPBP protein may be involved in the balancing of B6 vitamers by mediating efficient turnover of protein-bound B6 vitamers. This paper reviews recent findings on the function of the YggS/PLPBP protein.

Animal species differences in the pyridoxine transport function of SLC19A3: Absence of Slc19a3-mediated pyridoxine uptake in the rat small intestine.

The thiamine transporters, SLC19A2 and SLC19A3, have recently been shown to transport pyridoxine in addition to thiamine, the originally identified substrate, in our study on human orthologs. Based on these results, we characterized the rat and mouse orthologs for pyridoxine transport function. Through the assessment of pyridoxine uptake in human embryonic kidney 293 cells transiently expressing the SLC19A2/3 orthologs, we found that both rat and mouse Slc19a2 can transport pyridoxine, but rat or mouse Slc19a3 cannot. However, all SLC19A2/3 orthologs were capable of thiamine transport. We subsequently demonstrated in the rat small intestine that a carrier-mediated mechanism exists for thiamine uptake, but not for pyridoxine uptake. This is supported by the finding that rat Slc19a3, for which the human ortholog operates for the intestinal uptake of both pyridoxine and thiamine, lacks the pyridoxine transport function. Thus, SLC19A3s from different animal species exhibit differences in pyridoxine transport. Rats and mice, in which Slc19a3 lacks this function, are not suitable model animals for studies involving pyridoxine disposition and related issues.

Pyridoxal Kinase of Disease-causing Human Parasites: Structural and Functional Insights to Understand its Role in Drug Discovery.

Human parasites cause several diseased conditions with high morbidity and mortality in a large section of the population residing in various geographical areas. Nearly three billion people suffer from either one or many parasitic infections globally, with almost one million deaths annually. In spite of extensive research and advancement in the medical field, no effective vaccine is available against prominent human parasitic diseases that necessitate identification of novel targets for designing specific inhibitors. Vitamin B6 is an important ubiquitous co-enzyme that participates in several biological processes and plays an important role in scavenging ROS (reactive oxygen species) along with providing resistance to oxidative stress. Moreover, the absence of the de novo vitamin B6 biosynthetic pathway in human parasites makes this pathway indispensable for the survival of these pathogens. Pyridoxal kinase (PdxK) is a crucial enzyme for vitamin B6 salvage pathway and participates in the process of vitamers B6 phosphorylation. Since the parasites are dependent on pyridoxal kinase for their survival and infectivity to the respective hosts, it is considered a promising candidate for drug discovery. The detailed structural analysis of PdxK from disease-causing parasites has provided insights into the catalytic mechanism of this enzyme as well as significant differences from their human counterpart. Simultaneously, structure-based studies have identified small lead molecules that can be exploited for drug discovery against protozoan parasites. The present review provides structural and functional highlights of pyridoxal kinase for its implication in developing novel and potent therapeutics to combat fatal parasitic diseases.

Pyridoxine-Dependent Epilepsy as a Cause of Neonatal Seizures.

Pediatric seizures are a common reason for emergency department visits. The highest risk of seizures in children is during the neonatal period. A low index of suspicion is important to facilitate the early assessment, workup, and treatment of inborn errors of metabolism to optimize developmental outcomes. We present the rare case of a 9-day-old with seizures refractory to multiple anticonvulsant medications who was diagnosed with pyridoxine-dependent epilepsy. We review differences in the management of neonatal seizures from older patients, the utility of a trial of pyridoxine in refractory neonatal seizures, and the importance of preparing for emergent airway management given pyridoxine's ability to cause apnea and central nervous system depression.

Mechanism of Pyridoxine 5'-Phosphate Accumulation in Pyridoxal 5'-Phosphate-Binding Protein Deficiency.

The pyridoxal 5'-phosphate (PLP)-binding protein (PLPBP) plays an important role in vitamin B6 homeostasis. Loss of this protein in organisms such as Escherichia coli and humans disrupts the vitamin B6 pool and induces intracellular accumulation of pyridoxine 5'-phosphate (PNP), which is normally undetectable in wild-type cells. This accumulated PNP could affect diverse metabolic systems through the inhibition of some PLP-dependent enzymes. In this study, we investigated the as-yet-unclear mechanism of intracellular accumulation of PNP due to the loss of PLPBP protein encoded by yggS in E. coli. Genetic studies using several PLPBP-deficient strains of E. coli lacking a known enzyme(s) in the de novo or salvage pathways of vitamin B6, including pyridoxine (amine) 5'-phosphate oxidase (PNPO), PNP synthase, pyridoxal kinase, and pyridoxal reductase, demonstrated that neither the flux from the de novo pathway nor the salvage pathway solely contributed to the PNP accumulation caused by the PLPBP mutation. Studies of the strains lacking both PLPBP and PNPO suggested that PNP shares the same pool with PMP, and showed that PNP levels are impacted by PMP levels and vice versa. Here, we show that disruption of PLPBP perturbs PMP homeostasis, which may result in PNP accumulation in the PLPBP-deficient strains. IMPORTANCE A PLP-binding protein (PLPBP) from the conserved COG0325 family has recently been recognized as a key player in vitamin B6 homeostasis in various organisms. Loss of PLPBP disrupts vitamin B6 homeostasis and perturbs diverse metabolisms, including amino acid and α-keto acid metabolism. Accumulation of PNP is a characteristic phenotype of PLPBP deficiency and is suggested to be a potential cause of the pleiotropic effects, but the mechanism of this accumulation has been poorly understood. In this study, we show that fluxes for PNP synthesis/metabolism are not responsible for the accumulation of PNP. Our results indicate that PLPBP is involved in the homeostasis of pyridoxamine 5'-phosphate, and that its disruption may lead to the accumulation of PNP in PLPBP deficiency.

Preventing Vitamin B6-Related Neurotoxicity.

BACKGROUND: Vitamin B6 is essential for life and plays a critical role in many biochemical and physiological processes in the human body. The term B6 collectively refers to 6 water-soluble vitamers, and only the pyridoxal 5'-phosphate (PLP) serves as the biologically active form. A plasma PLP concentration above 30 nmol/L (7.4 µg/L) is indicative of an adequate vitamin B6 status for all age and sex groups. The currently recommended daily allowance of B6 (1.5-2 mg/d) from dietary sources frequently results in inadequate B6 status (<20 nmol/L or 5 µg/L) in many elderly patients and patients with comorbid conditions. PLP-based supplements are preferred and should be administered weekly in low doses (50-100 mg) to maintain a stable serum PLP level between 30 and 60 nmol/L or 7.4 and 15 µg/L. AREAS OF UNCERTAINTY: It is challenging for physicians to prescribe a safe dose of B6 supplements because of the narrow therapeutic index. The association between elevated levels of pyridoxine and neuropathy is not well established. PLP-based supplements are shown to be least neurotoxic, but further clinical trials are needed to establish the long-term safety in high doses. DATA SOURCES: PubMed search of randomized control trials and meta-analyses. THERAPEUTIC OPINION: Plasma B6 levels should be ordered as a part of workup of any unexplained anemia before labeling as "anemia of chronic disease." B6 supplementation is also crucial in the management of chronic Mg deficiency resistant to therapy. When B6 is administered daily in supraphysiologic doses, there is a potential for the development of neurotoxicity (typically at levels >100 nmol/L or 25 µg/L). PLP-based supplements are preferred over pyridoxine supplements because of minimal neurotoxicity observed in neuronal cell viability tests. Since B6 metabolites have a long half-life, weekly administration is preferred over daily use to prevent toxicity.

Pyridoxine stimulates filaggrin production in human epidermal keratinocytes.

Pyridoxine (PN), one of the vitamers of vitamin B6, plays an important role in the maintenance of epidermal function and is used to treat acne and rough skin. Clinical studies have revealed that PN deficiency causes skin problems such as seborrheic dermatitis and stomatitis. However, the detailed effects of PN and its mechanism of action in epidermal function are poorly understood. In this study, we examined the effects of PN on epidermal function in normal human epidermal keratinocytes and found that PN specifically causes an increase in the expression of profilaggrin mRNA, among marker genes of terminal epidermal differentiation. In addition, PN treatment caused an increase in the production of filaggrin protein in a concentration-dependent manner. Treatment with P2x purinoceptor antagonists, namely, pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid) tetrasodium salt hydrate and TNP-ATP hydrate, induced an increase in the filaggrin protein levels. Moreover, we showed that elevated filaggrin production induced upon PN treatment was suppressed by ATP (known as P2x purinoceptor agonist). This study is the first to report that PN causes an increase in filaggrin transcription and production, and these results suggest that PN-induced filaggrin production may be a useful target as a daily care component in atopic dermatitis, wherein filaggrin levels are specifically reduced.

Submerged fermentation of Ginkgo biloba seed powder using Eurotium cristatum for the development of ginkgo seeds fermented products.

BACKGROUND: Ginkgo biloba seeds are well known for the significant curative effects on relieving cough and asthma. However, the development of products from ginkgo seeds still falls behind at present, resulting in a great waste of ginkgo seeds' resource. In this work, submerged fermentation of ginkgo seed powder using Eurotium cristatum was studied to investigate its feasibility as a new processing method. RESULTS: To promote the growth of E. cristatum, the optimum fermentation medium was 80.0 g L-1 of ginkgo seed powder with addition of 5.0 g L-1 calcium chloride (CaCl2 ), 4.0 g L-1 magnesium sulfate (MgSO4 ), 1.25 g L-1 zinc sulfate (ZnSO4 ) and 0.65 g L-1 iron(II) sulfate (FeSO4 ). The optimum fermentation conditions were pH 5.8 ± 0.1, inoculum size 5.1 × 106 CFU mL-1 , liquid medium volume 100 mL in 250-mL Erlenmeyer flask and fermentation 4 days. Through fermentation, the production of lovastatin in fermentation broth could reach up to 32.97 ± 0.17 µg mL-1 and the total antioxidant capacity was improved by more than two-fold. In addition, 40.15% of the ginkgotoxin in ginkgo seed powder was degraded while the entire degradation of ginkgolic acids was obtained. Moreover, fermented ginkgo seed powder suspension presented pleasant fragrances, and the activities of amylase and protease were enhanced to 11.30 ± 0.10 U mL-1 and 23.01 ± 0.20 U mL-1 , respectively. CONCLUSIONS: Submerged fermentation using E. cristatum could significantly enhance the functional value and safety of ginkgo seed powder, and had great potential to become a novel processing method for the development of ginkgo seeds fermented products. © 2020 Society of Chemical Industry.