Determination of free and bound riboflavin in cow’s milk using a novel flavin-binding protein

Biogenic synthesis of CuO/ZnO nanocomposite from Bauhinia variegate flower extract for highly sensitive electrochemical detection of vitamin B2

In this study, we report the preparation of bio-inspired binary CuO/ZnO nanocomposite (bb-CuO/ZnO nanocomposite) via the biological route using Bauhinia variegata flower extract following hydrothermal treatment. The prepared bb-CuO/ZnO nanocomposite was electrophoretically deposited (EPD) on indium tin oxide (ITO) substrate to develop bb-CuO/ZnO/ITO biosensing electrode which is employed for the determination of vitamin B2 (Riboflavin) through electrochemical techniques. Physicochemical assets of the prepared bb-CuO/ZnO nanocomposite have been extensively evaluated and make use of different characterization techniques including powder XRD, FT-IR, AFM, SEM, TEM, EDX, XPS, Raman, and TGA. Electrochemical characteristics of the bb-CuO/ZnO/ITO biosensing electrode have been studied towards vitamin B2 determination. Furthermore, different biosensing parameters such as response time, reusability, stability, interference, and real sample analysis were also estimated. From the linear plot of scan rate, charge transfer rate constant (Ks), surface concentration of electrode (γ), and diffusion coefficient (D) have been calculated, and these are found to be 6.56 × 10-1 s-1, 1.21 × 10-7 mol cm-2, and 6.99 × 10-3 cm2 s-1, respectively. This biosensor exhibits the linear range of vitamin B2 detection from 1 to 40 μM, including sensitivity and limit of detection (LOD) of 1.37 × 10-3 mA/μM cm2 and 0.254 μM, respectively. For higher concentration range detection linearity is 50-100 μM, with sensitivity and the LOD of 1.26 × 10-3 mA/μM cm2 and 0.145 μM, respectively. The results indicate that the bio-inspired nanomaterials are promising sustainable biosensing platforms for various food and health-based biosensing devices.

Magnetic field-driven biochemical landscape of browning abatement in goat milk using spatial-omics uncovers

Influence of magnetic field (MF) treatment on the glycation of goat milk proteins is yet to be elucidated. Proteomic and metabolomic analyses of brown goat milk samples with and without MF treatment were performed. Assessed glycation degree and structural modification of proteins explained that MF treatment dramatically down-regulated the glycation of brown goat milk protein, possibly due to the aggregation behavior induced by MF treatment, which consumed additional glycation sites as well as altered their accessibility and preference. Integrated datasets uncovered that the energy metabolism-related biological events including carbohydrate metabolism, glycerophospholipid metabolism, TCA cycle may mainly account for the browning abatement mechanism of MF. In addition, MF treatment enhanced both the quality and flavor of brown goat milk. This study suggests the feasibility of MF treatment to reduce glycation in brown goat milk for producing high-quality dairy ingredients and products.

Two Rare Cases of Long Surviving Riboflavin Transporter Deficiency with Co-Existing Adenosine Monophosphate Deaminase (AMP) Deficiency

(1) Background: Riboflavin transporter deficiency (RTD), formerly known as Brown−Vialetto−Van Laere syndrome, is a rare condition that causes a progressive neurological syndrome in early life with features of auditory and optic neuropathy, weakness of bulbar muscles and the diaphragm and sensorimotor neuropathy. Pathologic mutations in the genes that code for riboflavin transporters have been identified as the genetic basis of RTD, and the majority of the genetically confirmed cases are caused by mutations of SLC52A3, a riboflavin transporter 2 coding gene or compound mutations in SLC52A2, encoding riboflavin transporter 3. Fatality in childhood is common if the condition is left untreated, but survival into adulthood has been reported in cases treated with high-dose oral riboflavin. (2) Case summary: We report two long-term survivors of RTD type 2 due to compound heterozygous 185T> G and 1258G>A mutations in gene SLC2A2. They are two brothers in a family in which two female siblings died in childhood from a similar neurological disorder. Brother one, the older RTD survivor, is aged 71, and brother two is aged 58. Both have significant visual impairment from optic nerve atrophy and sensory ataxia. Their muscle biopsies showed decreased muscle adenosine monophosphate (AMP) deaminase activity. No AMPD1 mutation was detected through whole-genome sequencing. (3) Conclusion: Co-existing riboflavin transporter deficiency (RTD) type 2 and muscle AMP deaminase deficiency has not been previously reported. Apart from the possibility that there is a milder phenotype associated with these mutations in SLC2A2, AMP deaminase deficiency might have contributed to a survival benefit by preserving muscle function through accumulating intracellular AMP.

Riboflavin as an internal marker for spoilage and adulteration detection in milk

Milk is a common consumable in daily life due to its nutritional values. Ensuring milk's integrity and authenticity is a prime task for researchers and food industries by providing solutions to prevent spoilage and adulteration. We present a robust and reliable optical method to ensure milk quality through its constituent riboflavin as an internal biomarker. Riboflavin is a widely present constituent in several food matrices. This research demonstrates the characteristic fluorescence of riboflavin for checking spoilage and urea adulteration in real-time. The proposed method can even detect and quantify high urea adulteration levels up to 80 mM (i.e., eight times permissible standard value) with a LOD value of 9.3 mM. The linearity (0-80 mM) and high R2 value (0.98, 0.93) of riboflavin's fluorescence in pure and milk solutions, respectively present this strategy closely associated with fate of milk samples in terms of spoilage and adulteration. Thus, this optical method of riboflavin biosensing in real-time is intuitive and conclusive for determining milk quality.

Vitamin B2 concentration in cow milk: Quantification by a new UHPLC method and prediction by visible and near-infrared spectral analysis

Until now, there are few information on vitamin B₂ concentration variability in milk. In this study, a novel analytical method to quantify total vitamin B₂ in milk was developed and applied on 676 samples. In parallel, spectral analysis (colorimetry and near infrared spectroscopy) were performed to develop prediction models of vitamin B₂ concentration in milk. The analytical method includes an acid and enzymatic extraction followed by vitamin B₂ quantification by Ultra High Performance Liquid Chromatography coupled with fluorimetry. Samples analysis showed a wide range of concentration from 0.78 to 4.58 mg/L with a mean of 2.09 ± 0.48 mg/L. Two prediction models based on colorimetric analysis allow estimation of vitamin B₂ concentration in milk. Thus, this work shows an analytical method and, for the first time, a prediction method to enable enhancement of researches on vitamin B₂ content of milk and its variation factors.

Rapid determination of the various native forms of vitamin B6 and B2 in cow's milk using ultra-high performance liquid chromatography

As the formation of pyridoxal phosphate, the active cofactor of vitamin B₆, is dependent on riboflavin 5-phosphate, we propose a fast and simple ultra-high performance liquid chromatography method for the simultaneous determination of the native B₆ vitamers pyridoxal, pyridoxine, pyridoxamine, their mono phosphorus esters and 4-pyridoxic acid as well as vitamin B₂ as riboflavin and its phosphorus ester riboflavin 5-phosphate in milk. Separation was achieved under 6.0min by reversed-phase and pH gradient elution. Sample preparation was optimized regarding various acids and pH levels. Changes in those parameters led to significant deviations of sample matrix breakdown efficiency. The optimized method was then validated regarding specificity, accuracy, precision, linearity, range, detection and quantification limits. As the method performed satisfactory, is was used to study commercial liquid cow's milk (n=31), regarding effects of the employed preservation technique (pasteurization, extended shelf-life, ultra-high temperature) on the composition and content of B₆ and B₂ vitamers. In cow's milk, vitamin B₆ mostly consists of pyridoxal and its phosphate ester, with pyridoxal phosphate being the bulk component. The catabolite of the vitamin B₆ metabolism, 4-pyridoxic acid was present in significant amounts in all studied samples, with up to 2.69μmolL^-1. Vitamin B₂ was present as riboflavin and its phosphate ester up to 12.86μmolL^-1.

Riboflavin uptake transporter Slc52a2 (RFVT2) is upregulated in the mouse mammary gland during lactation

While it is well recognized that riboflavin accumulates in breast milk as an essential vitamin for neonates, transport mechanisms for its milk excretion are not well characterized. The multidrug efflux transporter ABCG2 in the apical membrane of milk-producing mammary epithelial cells (MECs) is involved with riboflavin excretion. However, it is not clear whether MECs possess other riboflavin transport systems, which may facilitate its basolateral uptake into MECs. We report here that transcripts encoding the second (SLC52A2) and third (SLC52A3) member of the recently discovered family of SLC52A riboflavin uptake transporters are expressed in milk fat globules from human breast milk. Furthermore, Slc52a2 and Slc52a3 mRNA are upregulated in the mouse mammary gland during lactation. Importantly, the induction ofSlc52a2, which was the major Slc52a riboflavin transporter in the lactating mammary gland, was also observed at the protein level. Subcellular localization studies showed that green fluorescent protein-tagged mouse SLC52A2 mainly localized to the cell membrane, with no preferential distribution to the apical or basolateral membrane in polarized kidney MDCK cells. These results strongly implicate a potential role for SLC52A2 in riboflavin uptake by milk-producing MECs, a critical step in the transfer of riboflavin into breast milk.