RibU is an essential determinant of Listeria pathogenesis that mediates acquisition of FMN and FAD during intracellular growth.

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are essential riboflavin-derived cofactors involved in a myriad of redox reactions across all forms of life. Nevertheless, the basis of flavin acquisition strategies by riboflavin auxotrophic pathogens remains poorly defined. In this study, we examined how the facultative intracellular pathogen Listeria monocytogenes, a riboflavin auxotroph, acquires flavins during infection. A L. monocytogenes mutant lacking the putative riboflavin transporter (RibU) was completely avirulent in mice but had no detectable growth defect in nutrient-rich media. However, unlike wild type, the RibU mutant was unable to grow in defined media supplemented with FMN or FAD or to replicate in macrophages starved for riboflavin. Consistent with RibU functioning to scavenge FMN and FAD inside host cells, a mutant unable to convert riboflavin to FMN or FAD retained virulence and grew in cultured macrophages and in spleens and livers of infected mice. However, this FMN- and FAD-requiring strain was unable to grow in the gallbladder or intestines, where L. monocytogenes normally grows extracellularly, suggesting that these sites do not contain sufficient flavin cofactors to promote replication. Thus, by deleting genes required to synthesize FMN and FAD, we converted L. monocytogenes from a facultative to an obligate intracellular pathogen. Collectively, these data indicate that L. monocytogenes requires riboflavin to grow extracellularly in vivo but scavenges FMN and FAD to grow in host cells.

Irradiated riboflavin over nonradiated one: Potent antimigratory, antiproliferative and cytotoxic effects on glioblastoma cells.

Riboflavin is a water-soluble yellowish vitamin and is controversial regarding its effect on tumour cells. Riboflavin is a powerful photosensitizer that upon exposure to radiation, undergoes an intersystem conversion with molecular oxygen, leading to the production of ROS. In the current study, we sought to ascertain the impact of irradiated riboflavin on C6 glioblastoma cells regarding proliferation, cell death, oxidative stress and migration. First, we compared the proliferative behaviour of cells following nonradiated and radiated riboflavin. Next, we performed apoptotic assays including Annexin V and caspase 3, 7 and 9 assays. Then we checked on oxidative stress and status by flow cytometry and ELISA kits. Finally, we examined inflammatory change and levels of MMP2 and SIRT1 proteins. We caught a clear antiproliferative and cytotoxic effect of irradiated riboflavin compared to nonradiated one. Therefore, we proceeded with our experiments using radiated riboflavin. In all apoptotic assays, we observed a dose-dependent increase. Additionally, the levels of oxidants were found to increase, while antioxidant levels decreased following riboflavin treatment. In the inflammation analysis, we observed elevated levels of both pro-inflammatory and anti-inflammatory cytokines. Additionally, after treatment, we observed reduced levels of MMP2 and SIRT. In conclusion, radiated riboflavin clearly demonstrates superior antiproliferative and apoptotic effects on C6 cells at lower doses compared to nonradiated riboflavin.

Riboflavin-LSD1 axis participates in the in vivo tumor-associated macrophage morphology in human colorectal liver metastases.

Tumor-associated macrophages (TAMs) are key components of the tumor microenvironment (TME). In colorectal liver metastasis (CLM), TAM morphology correlates with prognosis, with smaller TAMs (S-TAMs) conferring a more favorable prognosis than larger TAMs (L-TAMs). However, the metabolic profile of in vivo human TAM populations remains unknown. Multiparametric flow cytometry was used to freshly isolate S- and L-TAMs from surgically resected CLM patients (n = 14S-, 14L-TAMs). Mass spectrometry-based metabolomics analyses were implemented for the metabolic characterization of TAM populations. Gene expression analysis and protein activity were used to support the biochemical effects of the enzyme-substrate link between riboflavin and (lysine-specific demethylase 1A, LSD1) with TAM morphologies. L-TAMs were characterized by a positive correlation and a strong association between riboflavin and TAM morphologies. Riboflavin in both L-TAMs and in-vitro M2 polarized macrophages modulates LSD1 protein expression and activity. The inflammatory stimuli promoted by TNFα induced the increased expression of riboflavin transporter SLC52A3 and LSD1 in M2 macrophages. The modulation of the riboflavin-LSD1 axis represents a potential target for reprogramming TAM subtypes, paving the way for promising anti-tumor therapeutic strategies.

Systematic Analysis of the Effect of Genomic Knock-Out of Non-Essential Promiscuous HAD-Like Phosphatases YcsE, YitU and YwtE on Flavin and Adenylate Content in Bacillus Subtilis.

Studying the metabolic role of non-essential promiscuous enzymes is a challenging task, as genetic manipulations usually do not reveal at which point(s) of the metabolic network the enzymatic activity of such protein is beneficial for the organism. Each of the HAD-like phosphatases YcsE, YitU and YwtE of Bacillus subtilis catalyzes the dephosphorylation of 5-amino-6-ribitylamino-uracil 5'-phosphate, which is essential in the biosynthesis of riboflavin. Using CRISPR technology, we have found that the deletion of these genes, individually or in all possible combinations failed to cause riboflavin auxotrophy and did not result in significant growth changes. Analysis of flavin and adenylate content in B. subtilis knockout mutants showed that (i) there must be one or several still unidentified phosphatases that can replace the deleted proteins; (ii) such replacements, however, cannot fully restore the intracellular content of any of three flavins studied (riboflavin, FMN, FAD); (iii) whereas bacterial fitness was not significantly compromised by mutations, the intracellular balance of flavins and adenylates did show some significant changes.

Molecular genetic analysis of candidate genes for glutaric aciduria type II in a cohort of patients from Queensland, Australia.

Glutaric aciduria type II (GAII) is a heterogeneous genetic disorder affecting mitochondrial fatty acid, amino acid and choline oxidation. Clinical manifestations vary across the lifespan and onset may occur at any time from the early neonatal period to advanced adulthood. Historically, some patients, in particular those with late onset disease, have experienced significant benefit from riboflavin supplementation. GAII has been considered an autosomal recessive condition caused by pathogenic variants in the gene encoding electron-transfer flavoprotein ubiquinone-oxidoreductase (ETFDH) or in the genes encoding electron-transfer flavoprotein subunits A and B (ETFA and ETFB respectively). Variants in genes involved in riboflavin metabolism have also been reported. However, in some patients, molecular analysis has failed to reveal diagnostic molecular results. In this study, we report the outcome of molecular analysis in 28 Australian patients across the lifespan, 10 paediatric and 18 adult, who had a diagnosis of glutaric aciduria type II based on both clinical and biochemical parameters. Whole genome sequencing was performed on 26 of the patients and two neonatal onset patients had targeted sequencing of candidate genes. The two patients who had targeted sequencing had biallelic pathogenic variants (in ETFA and ETFDH). None of the 26 patients whose whole genome was sequenced had biallelic variants in any of the primary candidate genes. Interestingly, nine of these patients (34.6%) had a monoallelic pathogenic or likely pathogenic variant in a single primary candidate gene and one patient (3.9%) had a monoallelic pathogenic or likely pathogenic variant in two separate genes within the same pathway. The frequencies of the damaging variants within ETFDH and FAD transporter gene SLC25A32 were significantly higher than expected when compared to the corresponding allele frequencies in the general population. The remaining 16 patients (61.5%) had no pathogenic or likely pathogenic variants in the candidate genes. Ten (56%) of the 18 adult patients were taking the selective serotonin reuptake inhibitor antidepressant sertraline, which has been shown to produce a GAII phenotype, and another two adults (11%) were taking a serotonin-norepinephrine reuptake inhibitor antidepressant, venlafaxine or duloxetine, which have a mechanism of action overlapping that of sertraline. Riboflavin deficiency can also mimic both the clinical and biochemical phenotype of GAII. Several patients on these antidepressants showed an initial response to riboflavin but then that response waned. These results suggest that the GAII phenotype can result from a complex interaction between monoallelic variants and the cellular environment. Whole genome or targeted gene panel analysis may not provide a clear molecular diagnosis.

Causes and Clinical Sequelae of Riboflavin Deficiency.

Riboflavin, in its cofactor forms flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), plays fundamental roles in energy metabolism, cellular antioxidant potential, and metabolic interactions with other micronutrients, including iron, vitamin B6, and folate. Severe riboflavin deficiency, largely confined to low-income countries, clinically manifests as cheilosis, angular stomatitis, glossitis, seborrheic dermatitis, and severe anemia with erythroid hypoplasia. Subclinical deficiency may be much more widespread, including in high-income countries, but typically goes undetected because riboflavin biomarkers are rarely measured in human studies. There are adverse health consequences of low and deficient riboflavin status throughout the life cycle, including anemia and hypertension, that could contribute substantially to the global burden of disease. This review considers the available evidence on causes, detection, and consequences of riboflavin deficiency, ranging from clinical deficiency signs to manifestations associated with less severe deficiency, and the related research, public health, and policy priorities.

A multifunctional role for riboflavin in the yellow nectar of Capsicum baccatum and Capsicum pubescens.

A few Capsicum (pepper) species produce yellow-colored floral nectar, but the chemical identity and biological function of the yellow pigment are unknown. A combination of analytical biochemistry techniques was used to identify the pigment that gives Capsicum baccatum and Capsicum pubescens nectars their yellow color. Microbial growth assays, visual modeling, and honey bee preference tests for artificial nectars containing riboflavin were used to assess potential biological roles for the nectar pigment. High concentrations of riboflavin (vitamin B2) give the nectars their intense yellow color. Nectars containing riboflavin generate reactive oxygen species when exposed to light and reduce microbial growth. Visual modeling also indicates that the yellow color is highly conspicuous to bees within the context of the flower. Lastly, field experiments demonstrate that honey bees prefer artificial nectars containing riboflavin. Some Capsicum nectars contain a yellow-colored vitamin that appears to play roles in (1) limiting microbial growth, (2) the visual attraction of bees, and (3) as a reward to nectar-feeding flower visitors (potential pollinators), which is especially interesting since riboflavin is an essential nutrient for brood rearing in insects. These results cumulatively suggest that the riboflavin found in some Capsicum nectars has several functions.

Assessment of the Predictive Ability of Theranostics for Corneal Cross-linking in Treating Keratoconus: A Randomized Clinical Trial.

PURPOSE: To validate the ability of theranostic imaging biomarkers in assessing corneal cross-linking (CXL) efficacy in flattening the maximum keratometry (Kmax) index. DESIGN: Prospective, randomized, multicenter, masked clinical trial (ClinicalTrails.gov identifier, NCT05457647). PARTICIPANTS: Fifty patients with progressive keratoconus. INTERVENTION: Participants were stratified to undergo epithelium-off (25 eyes) and epithelium-on (25 eyes) CXL protocols using an ultraviolet A (UV-A) medical device with theranostic software. The device controlled UV-A light both for performing CXL and assessing the corneal riboflavin concentration (riboflavin score) and treatment effect (theranostic score). A 0.22% riboflavin formulation was applied onto the cornea for 15 minutes and 20 minutes in epithelium-off and epithelium-on protocols, respectively. All eyes underwent 9 minutes of UV-A irradiance at 10 mW/cm2. MAIN OUTCOME MEASURES: The primary outcome measure was validation of the combined use of theranostic imaging biomarkers through measurement of their accuracy (proportion of correctly classified eyes) and precision (positive predictive value) to classify eyes correctly and predict a Kmax flattening at 1 year after CXL. Other outcome measures included change in Kmax, endothelial cell density, uncorrected and corrected distance visual acuity, manifest spherical equivalent refraction and central corneal thickness 1 year after CXL. RESULTS: Accuracy and precision of the theranostic imaging biomarkers in predicting eyes that had >0.1 diopter (D) of Kmax flattening at 1 year were 91% and 95%, respectively. The Kmax value significantly flattened by a median of -1.3 D (IQR, -2.11 to -0.49 D; P < 0.001); both the uncorrected and corrected distance visual acuity improved by a median of -0.1 logarithm of the minimum angle of resolution (logMAR; IQR, -0.3 to 0.0 logMAR [P < 0.001] and -0.2 to 0.0 logMAR [P < 0.001], respectively). No significant changes in endothelial cell density (P = 0.33) or central corneal thickness (P = 0.07) were noted 1 year after surgery. CONCLUSIONS: The study demonstrated the efficacy of integrating theranostics in a UV-A medical device for the precise and predictive treatment of keratoconus with epithelium-off and epithelium-on CXL protocols. Concentration of riboflavin and its UV-A light mediated photoactivation in the cornea are the primary factors determining CXL efficacy. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Photoactivated riboflavin inhibits planktonic and biofilm growth of Candida albicans and non-albicans Candida species.

Fungal infections caused by Candida species pose a serious threat to humankind. Antibiotics abuse and the ability of Candida species to form biofilm have escalated the emergence of drug resistance in clinical settings and hence, rendered it more difficult to treat Candida-related diseases. Lethal effects of Candida infection are often due to inefficacy of antimicrobial treatments and failure of host immune response to clear infections. Previous studies have shown that a combination of riboflavin with UVA (riboflavin/UVA) light demonstrate candidacidal activity albeit its mechanism of actions remain elusive. Thus, this study sought to investigate antifungal and antibiofilm properties by combining riboflavin with UVA against Candida albicans and non-albicans Candida species. The MIC20 for the fluconazole and riboflavin/UVA against the Candida species tested was within the range of 0.125-2 µg/mL while the SMIC50 was 32 µg/mL. Present findings indicate that the inhibitory activities exerted by riboflavin/UVA towards planktonic cells are slightly less effective as compared to controls. However, the efficacy of the combination towards Candida species biofilms showed otherwise. Inhibitory effects exerted by riboflavin/UVA towards most of the tested Candida species biofilms points towards a variation in mode of action that could make it an ideal alternative therapeutic for biofilm-related infections.

Chiral Supramolecular Organogel Constructed Using Riboflavin and Melamine: Its Application in Photo-Catalyzed Colorimetric Chiral Sensing and Enantioselective Adsorption.

The synthesis of a chiral supramolecular organogel via the hierarchical helical self-assembly of optically active riboflavin and melamine derivatives is described herein. Owing to the photocatalysis of riboflavin and the supramolecular chirality induced in the helically stacked riboflavin/melamine complex, the gel is observed to act as a light-stimulated chiral sensor of optically active alcohols by detecting the change in color from yellow to green. The gel also served as an efficient chiral adsorbent, enabling optical resolution of a racemic compound with high chiral recognition ability.

Riboflavin overproduction on lignocellulose hydrolysate by the engineered yeast Candida famata.

Lignocellulose (dry plant biomass) is an abundant cheap inedible residue of agriculture and wood industry with great potential as a feedstock for biotechnological processes. Lignocellulosic substrates can serve as valuable resources in fermentation processes, allowing the production of a wide array of chemicals, fuels, and food additives. The main obstacle for cost-effective conversion of lignocellulosic hydrolysates to target products is poor metabolism of the major pentoses, xylose and L-arabinose, which are the second and third most abundant sugars of lignocellulose after glucose. We study the oversynthesis of riboflavin in the flavinogenic yeast Candida famata and found that all major lignocellulosic sugars, including xylose and L-arabinose, support robust growth and riboflavin synthesis in the available strains of C. famata. To further increase riboflavin production from xylose and lignocellulose hydrolysate, genes XYL1 and XYL2 coding for xylose reductase and xylitol dehydrogenase were overexpressed. The resulting strains exhibited increased riboflavin production in both shake flasks and bioreactors using diluted hydrolysate, reaching 1.5 g L-1.

Therapeutic efficacy and safety of pathogen-reduced platelet components: Results of a meta-analysis of randomized controlled trials.

BACKGROUND AND OBJECTIVES: Clinical efficacy and safety of pathogen-reduced platelet concentrates (PR-PCs) concerning bleeding prevention are still debated despite conclusive real-world data from multiple countries where PR-PCs are transfused routinely. We performed a meta-analysis of randomized controlled trials (RCTs) comparing the clinical efficacy and safety of conventional platelet components (PCs) and PR-PCs prepared with the amotosalen/ultraviolet A light (INTERCEPT platelet concentrate [I-PC]) or riboflavin/ultraviolet light (Mirasol platelet concentrate [M-PC]) technologies, transfused in thrombocytopenic adult patients. MATERIALS AND METHODS: A literature search was conducted, and 10 RCTs met the criteria for inclusion in this meta-analysis. Summary odds ratios (ORs) of clinically significant bleeding (World Health Organization [WHO] bleeding grade ≥2), severe bleeding (WHO bleeding score ≥3) and all-cause mortality were calculated. RESULTS: The use of I-PC was not associated with an increase in the OR of clinically significant bleeding when compared to non-treated PCs (OR, 1.12; 95% CI: 0.89-1.41; p = 0.33), whereas transfusions with M-PC showed an increase in clinically significant bleeding (OR, 1.34; 95% CI: 1.03-1.75; p = 0.03). The OR of severe bleeding did not increase with either I-PC or M-PC (OR 0.88; 95% CI: 0.59-1.31; p = 0.52 for I-PC; OR 1.25; 95% CI: 0.66-2.37; p = 0.49 for M-PC). In the case of all-cause mortality, compared to non-treated PC, I-PC showed an OR of 0.61 (95% CI: 0.36-1.04; p = 0.07), and M-PC showed an OR of 3.04 (95% CI: 0.81-11.47; p = 0.1). CONCLUSION: No differences were observed concerning the clinical efficacy and safety of overall PR-PCs when compared to non-treated PCs. However, differences are evident when analysing platelets prepared with the two PR technologies independently.

Development of a functional outcome measure for riboflavin transporter deficiency.

BACKGROUND AND AIMS: Riboflavin transporter deficiency (RTD) is a progressive inherited neuropathy of childhood onset, characterised clinically by pontobulbar palsy, sensory ataxia, sensorineural deafness, muscle weakness, optic atrophy and respiratory failure. A robust and responsive functional outcome measure is essential for future clinical trials of disease-modifying therapies including genetic therapies. The Charcot-Marie-Tooth disease Pediatric Scale (CMTPedS) is a well-validated outcome measure for CMT and related neuropathies, and might have utility for measuring disease progression in individuals with RTD. However, the CMTPedS requires modifications to account for phenotypic differences between children with CMT and RTD. The aim of this study was to develop a functional outcome measure based on the CMTPedS for specific use in individuals with RTD. METHODS: The CMTPedS data collected over the last 10 years in individuals with RTD attending the Peripheral Neuropathy Management Clinic at the Children's Hospital at Westmead (Sydney, Australia) were reviewed to evaluate each item within the CMTPedS. A literature review of articles published until September 2021 for functional outcome measures generated an item pool for pilot testing. The results of this pilot testing, alongside analysis of existing CMTPedS item scores in the RTD cohort, informed the modification of the CMTPedS. RESULTS: CMTPedS data were reviewed for eight individuals over the past 10 years. Two items were identified as requiring modification or removal and additional items of proximal strength and function needed to be considered. Six studies were identified in the literature review, and five items were selected for pilot testing. 'Shoulder internal rotation' and the '30-s sit to stand test' were added as proximal measures of strength and function. The composite balance item comprising nine tasks in the CMTPedS showed a ceiling effect and was replaced with the single 'Feet apart on a line eyes open' balance item. 'Pinprick sensation' was removed due to a floor effect. INTERPRETATION: This study provides preliminary evidence that the Riboflavin Transporter Deficiency Pediatric Scale (RTDPedS) is a functional outcome measure covering strength, upper and lower limb function, balance and mobility for individuals with RTD to assess disease severity and progression in clinical trials and cohort studies.

Riboflavin protects against pancreatic cancer metastasis by targeting TGF-ß receptor 1.

The inhibition of transforming growth factor-ß1 (TGF-ß1) signaling by targeting TGF-ß receptor 1 (TßR1) has been considered as an ideal approach for the prevention of pancreatic cancer metastasis. Utilizing a pharmacophore model for TßR1 inhibitors, candidate compounds with the potential TßR1 binding ability were screened from the U.S. Food and Drug Administration (FDA) database, and riboflavin (RF) with a highest fit value was chosen to investigate its binding ability to TßR1 and effect on TGF-ß1 signaling in pancreatic cancer cells. Molecular docking and cellular thermal shift assay (CETSA) proved that RF at pharmacological concentrations could directly bind to TßR1. Further studies showed that pharmacological concentrations of RF in vitro could block TGF-ß1 signaling, suppress the migration and invasion, and prevent epithelial-mesenchymal transition (EMT) process of pancreatic cancer cells in the absence or presence of TGF-ß1 stimulation, indicating that RF presented anti-metastatic effect in pancreatic cancer cells. Knockdown of TßR1 could significantly attenuate the effects of RF on the migration and EMT process in pancreatic cancer cells, further confirming that the anti-metastatic effect of RF was achieved by blocking TGF-ß1 signaling after binding to TßR1. Moreover, in a mouse model of pancreatic cancer metastasis, it was certified that RF administration could block lung and liver metastases, TGF-ß1 signaling and EMT process of pancreatic cancer in vivo. In summary, our findings showed that RF could block TGF-ß1 signaling by directly binding to TßR1, thereby suppressing the metastasis of pancreatic cancer cells by inhibiting EMT process both in vitro and in vivo.

Riboflavin-loaded carbon cloth aids the anaerobic digestion of cow dung by promoting direct interspecies electron transfer.

Cow dung generates globally due to increased beef and milk consumption, but its treatment efficiency remains low. Previous studies have shown that riboflavin-loaded conductive materials can improve anaerobic digestion through enhance direct interspecies electron transfer (DIET). However, its effect on the practical anaerobic digestion of cow dung remained unclear. In this study, carbon cloth loaded with riboflavin (carbon cloth-riboflavin) was added into an anaerobic digester treating cow dung. The carbon cloth-riboflavin reactor showed a better performance than other two reactors. The metagenomic analysis revealed that Methanothrix on the surface of the carbon cloth predominantly utilized the CO2 reduction for methane production, further enhanced after riboflavin addition, while Methanothrix in bulk sludge were using the acetate decarboxylation pathway. Furthermore, the carbon cloth-riboflavin enriched various major methanogenic pathways and activated a large number of enzymes associated with DIET. Riboflavin's presence altered the microbial communities and the abundance of functional genes relate to DIET, ultimately leading to a better performance of anaerobic digestion for cow dung.

Association between dietary riboflavin intake and cognitive decline in older adults: a cross-sectional analysis.

BACKGROUND: Research exploring the link between dietary riboflavin intake and cognitive decline in this demographic is limited. Our aim was to examine the association between riboflavin intake levels and cognitive decline. METHODS: The National Health and Nutrition Examination Survey (NHANES) data from 2011 to 2014 were utilized in this cross-sectional analysis. The Consortium to Establish a Registry for Alzheimer's Disease test Word Learning delayed recall trial (DR), Digit Symbol Substitution Test (DSST), Animal Fluency Test(AFT) and Z test were used to evaluate cognitive performance. Multivariate logistic regression, restricted cubic spline and subgroup analysis were performed to evaluate the associations between riboflavin intake and cognitive decline. RESULTS: The study included a total of 2255 patients, with 47.9% being male. The incidence of cognitive decline was 23.8%. After adjusting for all selected covariates, we found that high riboflavin intake was associated with a lower risk of cognitive impairment in adults in the United States. When riboflavin intake was used as a Categorical variable, compared to those with the lowest intake, the odds ratio (OR) of individuals with the highest riboflavin intake for DR test, AFT test, DSST test and Z test were 0.73 (95% CI: 0.53~1), 0.68(95% CI: 0.49-0.96),0.53(95% CI: 0.37-0.77) and 0.56(95% CI: 0.39-0.8). The study also found an L-shaped association between riboflavin intake and cognitive decline, with an inflection point at approximately 2.984 mg/d. CONCLUSIONS: Our cross-sectional study in a nationwide sample of American old adults suggests that dietary riboflavin intake was negative associated with cognitive decline.

High fatty acid accumulation and coloration molecular mechanism of the elm mushroom (Pleurotus citrinopileatus).

Pleurotus citrinopileatus is a low-cholesterol, protein-rich, and high-nutrient food. The molecular mechanisms of the compounds and coloration have not been reported. Metabolome and transcriptome were used to clarify the molecular mechanisms of key compounds biosynthesis. K-means analysis identified 19 compounds in P. citrinopileatus, mainly lipids and alkaloids in class 8. In addition, 84 lipids were higher and that the different compounds were mainly enriched in linoleic acid metabolism. A total of 14 compounds detected in the linoleic acid metabolism pathway were significantly up-regulated, while 3 sterol regulatory element binding protein (SREBP) transcription factors were screened. Tryptophan metabolism and riboflavin biosynthesis pathway analysis indicated that 3 Unigenes had tryptophan decarboxylase similar elements, which belonged to tyrosine decarboxylase 1. Moreover, CL15618.Contig5_All had high homology with MFS. In conclusion, the expression of 3 SREBP, the synthesis of isobavachalcone D, and the regulation of riboflavin transport by MCH5 were the reasons for fatty acid accumulation and yellow cap formation in the P. citrinopileatus.

Real-time monitoring of riboflavin concentration using different clinically available ophthalmic formulations for epi-off and epi-on corneal cross-linking.

PURPOSE: To assess the feasibility of theranostics to determine the riboflavin concentration in the cornea using clinically available ophthalmic formulations during epithelium-off (epi-off) and transepithelial (epi-on) corneal cross-linking procedures. METHODS: Thirty-two eye bank human donor corneas were equally randomized in eight groups; groups 1 to 3 and groups 4 to 8 underwent epi-off and epi-on delivery of riboflavin respectively. Riboflavin ophthalmic solutions were applied onto the cornea according to the manufacturers' instructions. The amount of riboflavin into the cornea was estimated, at preset time intervals during imbibition time, using theranostic UV-A device (C4V CHROMO4VIS, Regensight srl, Italy) and expressed as riboflavin score (d.u.). Measurements of corneal riboflavin concentration (expressed as µg/cm3) were also performed by spectroscopy absorbance technique (AvaLight-DH-S-BAL, Avantes) for external validation of theranostic measurements. RESULTS: At the end of imbibition time in epi-off delivery protocols, the average riboflavin score ranged from 0.77 ± 0.38 (the average corneal riboflavin concentration was 213 ± 190 µg/cm3) to 1.79 ± 0.07 (554 ± 103 µg/cm3). In epi-on delivery protocols, the average riboflavin score ranged from 0.17 ± 0.01 to 0.67 ± 0.19 (corneal riboflavin concentration ranged from 6 ± 5 µg/cm3 to 122 ± 39 µg/cm3) at the end of imbibition time. A statistically significant linear correlation (P ≤ 0.05) was found between the theranostic and spectrophotometry measurements in all groups. CONCLUSIONS: Real-time theranostic imaging provided an accurate strategy for assessing permeation of riboflavin into the human cornea during the imbibition phase of corneal cross-linking, regardless of delivery protocol. A large variability in corneal riboflavin concentration exists between clinically available ophthalmic formulations both in epi-off and epi-on delivery protocols.

Antimicrobial photodynamic effect of the photosensitizer riboflavin, alone and in combination with colistin, against pandrug-resistant Pseudomonas aeruginosa clinical isolates.

INTRODUCTION: Development of multi-, extensively-, and pandrug-resistant (MDR, XDR, and PDR) strains of Pseudomonas aeruginosa remains a major problem in medical care. The present study evaluated the effect of antimicrobial photodynamic therapy (aPDT) as a monotherapy and in combination with colistin against P. aeruginosa isolates. METHODS: Two P. aeruginosa isolates recovered from patients with respiratory tract infections were examined in this study. Minimum inhibitory concentration (MIC) of colistin was determined by the colistin broth disk elution (CBDE) and the reference broth microdilution (rBMD) methods. aPDT was performed using the photosensitizer (Ps) riboflavin at several concentrations and a light-emitting diode (LED) emitting blue light for different irradiation times with or without colistin at 1/2 × MIC concentration. RESULTS: Both PA1 and PA2 isolates were identified as colistin-resistant P. aeruginosa with a MIC ≥4 µg/mL by the CBDE and MICs of 512 µg/mL and 256 µg/mL, respectively, by the rBMD. In aPDT, neither riboflavin nor LED light alone had antibacterial effects. The values of colony forming units per milliliter (CFU/mL) in both isolates were significantly reduced by LED + Ps treatments in a time-dependent manner (LED irradiation time) and dose-dependent manner (Ps concentration). In comparison with control, treatment with Ps (50 µM) + LED (120 s) and Ps (100 µM) + LED (120 s) resulted in 0.27 log10 CFU/mL and 0.43 log10 CFU/mL reductions in PA1, and 0.28 log10 CFU/mL and 0.34 log10 CFU/mL reductions in PA2, respectively, (P < 0.01). The best results were obtained after the combination of aPDT followed by colistin, which increased bacterial reduction, resulting in a 0.41-0.7 log10 CFU/mL reduction for PA1 and 0.35-0.83 log10 CFU/mL reduction for PA2 (P = 0.001). CONCLUSIONS: This study suggests the potential implications of aPDT in combination with antibiotics, such as colistin for treatment of difficult-to-treat P. aeruginosa infections.

Effect of accelerated high-fluence riboflavin and rose bengal-mediated corneal cross-linking on resistance to enzymatic digestion.

PURPOSE: This study evaluated the effect of high-fluence accelerated corneal cross-linking on the resistance to enzymatic digestion, assessing two chromophore/light combinations: riboflavin/UV-A light (RF/UV-A) and rose bengal/green light (RB/green). METHODS: Freshly prepared ex-vivo porcine corneas (n = 189) were divided into 8 groups groups. Group A corneas were unirradiated controls without chromophore soaking (A0), or soaked with riboflavin (A1) or rose bengal (A2). Group B corneas underwent accelerated epi-off RF/UV-A CXL at fluences of 5.4 J/cm² (B1), 10 J/cm² (B2), or 15 J/cm² (B3). Group C corneas underwent accelerated epi-off RB/green CXL at fluences of either 10 J/cm² (C1) or 15 J/cm² (C2). Following CXL, all corneas were digested in 0.3% collagenase-A solution, and the time until complete dissolution was measured. RESULTS: Non-irradiated controls exposed to RF and RB enhanced corneal resistance to collagenase digestion, with RB having a stronger effect than RF. RF/UV-A-treated corneas showed significantly increased digestion resistance with increasing fluence levels. RB/green-treated corneas displayed enhanced digestion resistance with each increase in fluence up to 10 J/cm²; a 15 J/cm² fluence yielded similar digestion resistance times to a 10 J/cm² fluence, suggesting a plateau effect in accelerated RB/green CXL protocols. CONCLUSIONS: When compared to standard-fluence treatments, high-fluence accelerated epi-off CXL using both riboflavin and rose bengal significantly increases resistance to enzymatic digestion. The optimal settings for clinical protocols might be 15 J/cm² (30 mW/cm² for 8 min 20 s) for RF/UV-A and 10 J/cm² (15 mW/cm² for 11 min 7 s) for RB/Green Light.