Structure and the Anticancer Activity of Vitamin D Receptor Agonists.

Vitamin D is a group of seco-steroidal fat-soluble compounds. The two basic forms, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), do not have biological activity. They are converted in the body by a two-step enzymatic hydroxylation into biologically active forms, 1α,25-dihydroxyvitamin D2 [ercalcitriol, 1,25(OH)2D2] and 1α,25-dihydroxyvitamin D3 [calcitriol, 1,25(OH)2D3], which act as classical steroid hormones. 1,25(OH)2D3 exerts most of its physiological functions by binding to the nuclear vitamin D receptor (VDR), which is present in most body tissues to provide support to a broad range of physiological processes. Vitamin D-liganded VDR controls the expression of many genes. High levels of 1,25(OH)2D3 cause an increase in calcium in the blood, which can lead to harmful hypercalcemia. Several analogs of 1,25(OH)2D3 and 1,25(OH)2D2 have been designed and synthesized with the aim of developing compounds that have a specific therapeutic function, for example, with potent anticancer activity and a reduced toxic calcemic effect. Particular structural modifications to vitamin D analogs have led to increased anticancer activity and reduced calcemic action with the prospect of extending work to provide future innovative therapies.

4-Hydroxy-1α,25-Dihydroxyvitamin D3: Synthesis and Structure-Function Study.

The active vitamin D metabolites, 25-hydroxyvitamin D3 (25D3) and 1,25-dihydroxyvitamin D3 (1,25D3), are produced by successive hydroxylation steps and play key roles in several cellular processes. However, alternative metabolic pathways exist, and among them, the 4-hydroxylation of 25D3 is a major one. This study aims to investigate the structure-activity relationships of 4-hydroxy derivatives of 1,25D3. Structural analysis indicates that 1,4α,25(OH)3D3 and 1,4ß,25(OH)3D3 maintain the anchoring hydrogen bonds of 1,25D3 and form additional interactions, stabilizing the active conformation of VDR. In addition, 1,4α,25D3 and 1,4ß,25D3 are as potent as 1,25D3 in regulating the expression of VDR target genes in rat intestinal epithelial cells and in the mouse kidney. Moreover, these two 4-hydroxy derivatives promote hypercalcemia in mice at a dose similar to that of the parent compound.

Unraveling the Catalytic Mechanism of ß-Cyclodextrin in the Vitamin D Formation.

Previous experimental studies have shown that the isomerization reaction of previtamin D3 (PreD3) to vitamin D3 (VitD3) is accelerated 40-fold when it takes place within a ß-cyclodextrin dimer, in comparison to the reaction occurring in conventional isotropic solutions. In this study, we employ quantum mechanics-based molecular dynamics (MD) simulations and statistical multistructural variational transition state theory to unveil the origin of this acceleration. We find that the conformational landscape in the PreD3 isomerization is highly dependent on whether the system is encapsulated. In isotropic media, the triene moiety of the PreD3 exhibits a rich torsional flexibility. However, when encapsulated, such a flexibility is limited to a more confined conformational space. In both scenarios, our calculated rate constants are in close agreement with experimental results and allow us to identify the PreD3 flexibility restriction as the primary catalytic factor. These findings enhance our understanding of VitD3 isomerization and underscore the significance of MD and environmental factors in biochemical modeling.

Vitamin D receptor gene polymorphism and serum vitamin D level as risk factors for acquiring Type II diabetes mellitus.

The studies on the relationship between type 2 diabetes mellitus (T2DM) risk and vitamin D receptor (VDR) gene polymorphisms are still inconclusive. Therefore, the objective of the study was to assess possible risks of acquiring T2DM due to polymorphisms in the VDR gene or abnormal serum levels of VD. 362 participants (181 T2DM patients and 181 healthy controls) from the Diabetic Center, Sulaimaniyah/Iraq, from December 2020 to May 2021 were volumtarily enrolled in the study. For each participant, HbA1c, fasting blood sugar (FBS), serum cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG), markers of calcium homeostasis, alkaline phosphatase (ALP), phosphorus, VD and insulin were measured. In addition, FokI, TaqI, ApaI, and BsmI genotypes were also performed using Polymerase Chain Reaction (PCR). The results showed that VD level was significantly lower in T2DM compared to the control group. While, HbA1c was significantly higher in T2DM than in the control group. In contrast to  AA (P=0.034) and CC (P=0.011) genotype of ApaI (rs7975232) gene polymorphism, which were dominant among the control group, AC-genotype was significantly (P=0.0001) dominat among T2DM group. Meanwhile, TT-genotype of TaqI (rs731236) was  significantly (P=0.05) dominant among control group. While there were not any significant differences between other genotypes among T2DM and control groups. In conclusion, low VD-level is a possible risk factor for developing T2DM, and an association was found, especially between ApaI genotypes and T2DM.

Association Between Circulating 25-Hydroxy Vitamin D Receptor and Molecular Response in Multiple Myeloma.

<b>Background and Objective:</b> Vitamin D Receptor (VDR) regulate several body processes related to metabolism, immunological function and oncogenesis. Low vitamin D levels are recognized as associated with a higher incidence of hematologic malignancies and poor outcomes. This study aims to determine whether vitamin D levels and VDR contribute to multiple myeloma (MM). <b>Materials and Methods:</b> This study enrolled twenty-five patients diagnosed with MM. Ages and gender were matched between patients and healthy groups. Serum Protein Electrophoresis (SPEP) was detected for all patients. Also, serum 25-hydroxy vitamin D levels were recorded. The PCR products were submitted to Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and Sanger sequencing to detect VDR gene polymorphism including (FokI, ApaI and Tru9I). <b>Results:</b> This study revealed that an M spike was detected in five patients newly diagnosed with MM. According to vitamin D levels 84% of patients had a vitamin D deficiency. In the RFLP technique, FokI CT, ApaI AA and Tru9I GG genotypes were highly distributed in patients. Additionally, the MM group had a significant frequency of the T allele in the FokI (44.0%), the A allele in the ApaI (68.0%) and the A allele in the Tru9I (30.0%). <b>Conclusion:</b> The SPEP is an easy-to-perform laboratory test that can be used to detect and quantify monoclonal proteins. Low vitamin D level of less than 20 ng mL¹ is associated with an increased prevalence of MM and a worse response to treatment. In addition, VDR gene polymorphisms may be a molecular marker of MM risk.

Association between the genetic variant in the vitamin D pathway (rs2282679), circulating 25-hydroxyvitamin D levels, insulin resistance and metabolic syndrome criteria.

Introduction: Background and aims: some studies have reported links between 25-hydroxyvitamin D levels and the presence of metabolic syndrome. The aim of the present study was to evaluate whether an association exists among 25-hydroxyvitamin D, rs2282679 of the GC gene and metabolic syndrome (MS). Methods: the study involved a population of 134 postmenopausal obese females. Measurements of anthropometric parameters, blood pressure, bone turnover markers, fasting blood glucose, insulin resistance (HOMA-IR), lipid profile, C-reactive protein and prevalence of MS were recorded. Genotype of CG gene polymorphism (rs2282679) was evaluated. Results: insulin (delta: 4.6 ± 0.9 mUI/l; p = 0.02), triglycerides (delta: 21.6 ± 2.9 mg/dl; p = 0.04) and HOMA-IR (delta: 1.1 ± 0.9 unit; p = 0.02) were lower in TT subjects than TG + GG patients. The percentages of individuals who had MS (OR = 2.80, 95 % CI = 1.39-5.65; p = 0.02), hypertriglyceridemia (OR = 2.39, 95 % CI = 1.44-5.96; p = 0.01), and hyperglycemia (OR = 2.72, 95 % CI = 1.23-6.00; p = 0.43) were higher in G allele carriers. Logistic regression analysis showed an increased risk of MS in G allele carriers (OR = 2.36, 95 % CI = 1.11-5.91, p = 0.02) and an increased risk of 25-hydroxyvitamin D deficiency (< 20 ng/ml) (OR = 2.43, 95 % CI = 1.13-6.69, p = 0.02), too. Conclusions: a negative association among G allele and insulin resistance, hypertriglyceridemia, deficiency of 25 hydroxyvitamin D levels and MS was reported in this population.

Introducción: Antecedentes y objetivos: algunos estudios han demostrado una relación entre los niveles de 25-hidroxivitamina D y la presencia del síndrome metabólico. El objetivo de este estudio fue evaluar si existe una asociación entre la 25-hidroxivitamina D, la variante rs2282679 del gen GC y el síndrome metabólico (SM). Métodos: el estudio involucró a una población de 134 mujeres obesas posmenopáusicas. Se registraron parámetros antropométricos, presión arterial, marcadores de recambio óseo, glucemia en ayunas, resistencia a la insulina (HOMA-IR), perfil lipídico, proteína C reactiva y prevalencia de SM. Se evaluó el genotipo del polimorfismo del gen CG (rs2282679). Resultados: los niveles de insulina (delta: 4,6 ± 0,9 mUI/l; p = 0.02), triglicéridos (delta: 21,6 ± 2,9 mg/dl; p = 0,04) y HOMA-IR (delta: 1,1 ± 0,9 unidades; p = 0,02) fueron menores en los sujetos TT que en los pacientes TG + GG. Los porcentajes de individuos que tenían SM (OR = 2,80, IC 95 % = 1,39-5,65; p = 0,02), hipertrigliceridemia (OR = 2,39, IC 95 % = 1,44-5,96; p = 0,01) e hiperglucemia (OR = 2,72, IC 95 % = 1,23-6,00; p = 0,43) fueron mayores en los portadores del alelo G. El análisis de regresión logística mostró un mayor riesgo de SM en los portadores del alelo G (OR = 2,36, IC 95 % = 1,11-5,91; p = 0,02) y un mayor riesgo de deficiencia de 25-hidroxivitamina D (< 20 ng/ml) (OR = 2,43, IC 95 % = 1,13-6,69; p = 0,02). Conclusiones: en esta población hemos detectado una asociación negativa entre el alelo G y la resistencia a la insulina, hipertrigliceridemia, deficiencia niveles de 25-hidroxivitamina D y SM.

Rational Design of Trident Aptamer Scaffold for Rapid and Accurate Monitoring of 25-Hydroxyvitamin D3 Metabolism in Living Cells.

The level of 25-hydroxyvitamin D3 [25(OH)VD3] in human blood is considered as the best indicator of vitamin D status, and its deficiency or excess can lead to various health problems. Current methods for monitoring 25(OH)VD3 metabolism in living cells have limitations in terms of sensitivity and specificity and are often expensive and time-consuming. To address these issues, an innovative trident scaffold-assisted aptasensor (TSA) system has been developed for the online quantitative monitoring of 25(OH)VD3 in complex biological environments. Through the computer-aided design, the TSA system includes an aptamer molecule recognition layer that is uniformly oriented, maximizing binding site availability, and enhancing sensitivity. The TSA system achieved the direct, highly sensitive, and selective detection of 25(OH)VD3 over a wide concentration range (17.4-12,800 nM), with a limit of detection of 17.4 nM. Moreover, we evaluated the efficacy of the system in monitoring the biotransformation of 25(OH)VD3 in human liver cancer cells (HepG2) and normal liver cells (L-02), demonstrating its potential as a platform for drug-drug interaction studies and candidate drug screening.

Separation and identification of monoglucuronides of vitamin D3 metabolites in urine by derivatization-assisted LC/ESI-MS/MS using a new Cookson-type reagent.

A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method was developed using a new Cookson-type reagent, 4-[4-(1-pipelidinyl)phenyl]-1,2,4-triazoline-3,5-dione (PIPTAD), to analyze the monoglucuronides (Gs) of vitamin D3 metabolites in human urine. The G of 23S,25-dihydroxyvitamin D3 [23,25(OH)2D3] was previously found as a major metabolite of vitamin D3 in the urine, but its conjugation position remained undetermined. Determination of the position was an important research issue to clarify the whole picture of the excretion of surplus 25-hydroxyvitamin D3 [25(OH)D3, the circulating form of vitamin D3] in humans. After the pretreated urine sample was derivatized with PIPTAD, the peak corresponding to the G of 23,25(OH)2D3 was satisfactorily separated from the urine-derived interfering substances on reversed-phase LC, which could not be achieved by using the previous analogous reagent, DAPTAD. The PIPTAD-derivatized Gs of the vitamin D3 metabolites provided characteristic product ions useful for identifying the conjugation positions during the MS/MS. Accordingly, we successfully determined the glucuronidated position of 23,25(OH)2D3 to be the C23-hydroxy group. The developed method also enabled the simultaneous detection of Gs of 25(OH)D3 and 24R,25-dihydroxyvitamin D3 as well as 23,25(OH)2D3-23-G without interference from the urine components.

Vitamin D and inflammatory cytokines association in mild cognitive impaired subjects.

BACKGROUND: Mild cognitive impairment (MCI) is a prodromal stage of Alzheimer's disease (AD). The association of low Vitamin D and chronic inflammation in the onset of cognitive decline in the elderly population has been established but the variable population-based study is still lacking. METHODOLOGY: The present study aims to investigate the level of plasma Vitamin D, pro-inflammatory cytokines IL-1ß, IL-6, TNF-α, cognitive performance, and white matter changes in the elderly population in the North-Eastern part of Uttar Pradesh, India. RESULTS: 70 participants with (Mean age- 75.14 ± 1.24, Male/Female- 50/20) with an Mini Mental State Examination (MMSE) score of (24.82 ± 1.82) and Montreal Cognitive Assessment Test (MOCA) score (21.83 ± 1.75), were cognitive decline, against the 70 healthy controls (Mean Age-73.18 ± 1.43; Male/Female- 50/20) with MMSE score (28.1 ± 1.5) and MOCA (28.5 ± 1.65), White matter variable Fractional Anisotropy (FA) and Apparent Diffusion Coefficient (ADC) values in MCI subject was found significantly altered in Right temporal lobe, Corpus Callosum (Right) and Hippocampus body (Right), Hippocampus body (left), Hippocampus head (Right) and Hippocampus head (Left)as compared with healthy controls. The level of cytokines IL-1ß, IL-6, TNF-α, was significantly high in MCI subjects as compared with controls. Further lower Vitamin D level in plasma was detected in MCI as compared with healthy controls. CONCLUSION: The result from the present study depicts that chronic inflammation and lower Vitamin D level influences neurodegeneration and decline in cognitive performance in the elderly population. These variables can be used as biomarkers for early identification of AD and interventional strategies can be designed for prevention at the prodromal stage of AD.

Evaluation of interleukins 37 and 38 and vitamin D status in the serum of women with Graves' disease.

BACKGROUND: Graves' disease (GD) is an autoimmune thyroid disorder and recent studies have proposed a role for interleukin (IL)-37, IL-38, and vitamin D (VitD) in the pathophysiology of disease. Therefore, this study investigated the expression of IL-37, IL-38, and VitD in the serum of GD patients and correlations of their levels with some demographic and clinical characteristics. METHODS: Serum IL-37, IL-38, and VitD levels were evaluated in 90 women with GD and 93 control women using enzyme-linked immunosorbent assay kits. Depending on therapy, six patients were newly diagnosed (ND; untreated), and 50 patients were receiving only carbimazole (CMZ), while 34 patients were also on CMZ but also received one (31 patients), two (one patient), or three (two patients) doses of radioactive iodine (RAI). RESULTS: IL-37 levels were significantly higher in GD patients than in controls, while IL-38 and VitD levels were significantly decreased. As indicated by the area under the curve (AUC), receiver operating characteristic curve analysis demonstrated the potential of IL-37, IL-38, and VitD as biomarkers to distinguish GD patients from controls (AUC = 0.953, 0.959, and 0.793, respectively). Multinomial logistic regression analysis showed that altered levels of IL-37, IL-38, and VitD were most likely associated with the pathogenesis of GD. IL-37 was negatively correlated with IL-38 and VitD, while IL-38 and VitD were positively correlated. CONCLUSION: Serum Il-37 levels were upregulated in women with GD, while IL-38 and VitD levels showed downregulated levels. The latter two were positively correlated while they showed a negative correlation with IL-37.

Medium and long-chain structured triacylglycerol enhances vitamin D bioavailability in an emulsion-based delivery system: combination of in vitro and in vivo studies.

Vitamin D (VitD) is an essential fat-soluble micronutrient required for maintaining and regulating calcium homeostasis. Although sunlight can provide VitD, epidemiological studies indicate that the occurrence of VitD deficiency and insufficiency is widespread. Lipids are required at all stages of VitD digestion and absorption. In this research two different medium and long-chain triacylglycerol structures, possessing identical fatty acid composition lipids, namely structured triacylglycerol (STG), and physical mixtures of medium/long-chain triacylglycerol (MCT/LCT), were selected. Our results demonstrated that STG had a significant VitD bioavailability compared to MCT/LCT. In terms of the lipid digestion and absorption, the extent of the higher free fatty acid released (69.42%, p < 0.05), extent of lipolysis (89.28%, p < 0.05), lipolysis rate (0.06 s-1, p < 0.05), and the ratio of the long-chain fatty acid to medium-chain fatty acid of STG (4.8, p < 0.05), result in a higher capacity for accommodating VitD when forming mixed micelles (61.31%, p < 0.05). An in vivo animal study also demonstrated that STG significantly increases the delivery ability of VitD (18.75 ng mL-1, p < 0.05). The findings of this work may have unique applications for designing novel interesterified lipids with an effective delivery capacity for fat-soluble nutrients.

Characterization of a Cleavable Fusion of Human CYP24A1 with Adrenodoxin Reveals the Variable Role of Hydrophobics in Redox Partner Binding.

The improper maintenance of the bioactivated form of vitamin-D (1α,25(OH)2D) may result in vitamin-D insufficiency and therefore compromise the absorption of dietary calcium. A significant regulator of vitamin-D metabolism is the inactivating function of the mitochondrial enzyme cytochrome P450 24A1 (CYP24A1). In humans, CYP24A1 carries out hydroxylation of carbon-23 (C23) or carbon-24 (C24) of the 1α,25(OH)2D side chain, eventually resulting in production of either an antagonist of the vitamin-D receptor (C23 pathway) or calcitroic acid (C24 pathway). Despite its importance to human health, the human isoform (hCYP24A1) remains largely uncharacterized due in part to the difficulty in producing the enzyme using recombinant means. In this study, we utilize a cleavable fusion with the cognate redox partner, human Adx (hAdx), to stabilize hCYP24A1 during production. The subsequent cleavage and isolation of active hCYP24A1 allowed for an investigation of substrate and analog binding, enzymatic activity, and redox partner recognition. We demonstrate involvement of a nonpolar contact involving Leu-80 of hAdx and a nonconserved proximal surface of hCYP24A1. Interestingly, shortening the length of this residue (L80V) results in enhanced binding between the CYP-Adx complex and 1α,25(OH)2D yet unexpectedly results in decreased catalysis. The same mutation has a negligible effect on rat CYP24A1 (a C24-hydroxylase), indicating the presence of a species-specific requirement that may correlate with differences in regioselectivity of the reaction. Taken together, this work presents an example of production of a challenging human CYP as well as providing details regarding hydrophobic modulation of a CYP-Adx complex that is critical to human vitamin-D metabolism.

Vitamin D levels in Greek patients with systemic lupus erythematosus.

OBJECTIVES: Vitamin D deficiency has been observed in autoimmune rheumatic diseases, such as rheumatoid arthritis. The aim was to study vitamin D in patients with systemic lupus erythematosus (SLE) and its relationship with disease activity. METHODS: In a cohort of 45 patients with SLE, 41 females and 4 males, aged 47.07 ± 2.17 years (mean ± SEM), and range = 21-79 years, 25(OH)D3 levels were determined by electrochemiluminescence. C3 and C4 levels were also analyzed. SLE disease activity was estimated by SLEDAI-2K. Observations were also performed in a control group matched for age and sex. RESULTS: In this cohort of SLE patients, 25(OH)D3 levels were 40.36 ± 2.41 nmol/L (mean ± SEM) as opposed to 60.98 ± 4.28 nmol/L in the control group (p < 0.001, Student's t test). Vitamin D levels were related to C3 (p < 0.001, linear regression analysis), correlation coefficient 0.106, r2 = 0.011, and C4 (p < 0.001); correlation coefficient 0.316 and r2 = 0.100; and inversely related to disease activity (p < 0.001), correlation coefficient -0.572 and r2 = 0.327. 25(OH)D3 levels were 17.73 ± 1.20 nmol/L and 12.24 ± 0.93 nmol/L, in the groups without and with renal involvement, respectively (p = 0.001, Student's t test). CONCLUSIONS: Vitamin D levels are low in SLE patients and are inversely related to disease activity. Routine screening for vitamin D levels should be performed in SLE patients.

Vitamin D Inhibits the Early Aggregation of α-Synuclein and Modulates Exocytosis Revealed by Electrochemical Measurements.

Alpha-synuclein (α-Syn) localizes at presynaptic terminal and modulates synaptic functions. Increasing evidence demonstrate that α-Syn oligomers, forming at the early of aggregation, are cytotoxic and is thus related to brain neurodegenerative diseases. Herein, we find that vitamin D (VD) can reduce neurocytotoxicity. The reduced neurocytotoxicity might be attributed to the less amount of large-sized α-Syn oligomers inhibited by VD, measured by electrochemical collision at single particle level, which are not observable with traditionally ensembled method. Single-cell amperometry (SCA) results show that VD can recover the amount of neurotransmitter release during exocytosis induced by α-Syn oligomers, further verifying the neuroprotection of VD. Our study reveals the neuroprotective role of VD through inhibiting α-Syn aggregation, which is envisioned to be of great importance in treatment and prevention of the neurodegenerative diseases.

The Synthesis and Biological Evaluation of D-Ring-Modified Vitamin D Analogues.

The vitamin D3 structure consists of the A-ring, a linker originating from the B-ring, C-ring, D-ring, and side-chain moieties. Each unit has its unique role in expressing the biological activities of vitamin D3. Many efforts have been made to date to assess the possible clinical use of vitamin D. Some organic chemists focused on the D-ring structure of vitamin D and synthesized D-ring-modified vitamin D analogues, and their biological activities were studied. This review summarizes the synthetic methodologies of D-ring-modified vitamin D analogues, except for seco-D, and their preliminary biological profiles.

Ultrasound-Assisted Microencapsulation of Soybean Oil and Vitamin D Using Bare Glycogen Nanoparticles.

Ultrasonically synthesized core-shell microcapsules can be made of synthetic polymers or natural biopolymers, such as proteins and polysaccharides, and have found applications in food, drug delivery and cosmetics. This study reports on the ultrasonic synthesis of microcapsules using unmodified (natural) and biodegradable glycogen nanoparticles derived from various sources, such as rabbit and bovine liver, oyster and sweet corn, for the encapsulation of soybean oil and vitamin D. Depending on their source, glycogen nanoparticles exhibited differences in size and 'bound' proteins. We optimized various synthetic parameters, such as ultrasonic power, time and concentration of glycogens and the oil phase to obtain stable core-shell microcapsules. Particularly, under ultrasound-induced emulsification conditions (sonication time 45 s and sonication power 160 W), native glycogens formed microcapsules with diameter between 0.3 µm and 8 µm. It was found that the size of glycogen as well as the protein component play an important role in stabilizing the Pickering emulsion and the microcapsules shell. This study highlights that native glycogen nanoparticles without any further tedious chemical modification steps can be successfully used for the encapsulation of nutrients.

Detection of Vitamin D Metabolites in Breast Milk: Perspectives and challenges for measurement by Liquid Chromatography Tandem-Mass Spectrometry.

Breast milk is an emerging matrix for vitamin D assessment of breastfed infants and their mothers. It is considered a more reliable indicator of infant intake than the assessment of maternal circulating vitamin D. With the improved sensitivity of mass spectrometry-based technologies, this method principle has been the recent mainstay for the quantitation of various vitamin D metabolites in breast milk for population-based clinical trials. There are still several areas across the total testing process (pre-analytical, analytical and post-analytical) to be defined and harmonised to translate breast milk vitamin D measurement by liquid chromatography-tandem mass spectrometry (LC-MS/MS) from population-based research to routine clinical use and public health applications. Pre-analytically, the determination of the best form of vitamin D to measure in breast milk requires more evidence. Analytically, standardisation of the methods to allow for comparability of results is required. Post analytically, breast milk vitamin D decision limits are needed to turn the individual numerical outputs into clinically meaningful results. This review aims to synthesise the current evidence and utility of measurement of breast milk vitamin D by LC-MS/MS and to lead a future discussion on best practices to allow for its clinical utility beyond its current research-based use.

Identification of kinase inhibitors that rule out the CYP27B1-mediated activation of vitamin D: an integrated machine learning and structure-based drug designing approach.

CYP27B1, a cytochrome P450-containing hydroxylase enzyme, converts vitamin D precursor calcidiol (25-hydroxycholecalciferol) to its active form calcitriol (1α,25(OH)2D3). Tyrosine kinase inhibitor such as imatinib is reported to interfere with the activation of vitamin D3 by inhibiting CYP27B1 enzyme. Consequently, there is a decrease in the serum levels of active vitamin D that in turn may increase the relapse risk among the cancer patients treated with imatinib. Within this framework, the current study focuses on identifying other possible kinase inhibitors that may affect the calcitriol level in the body by inhibiting CYP27B1. To achieve this, we explored multiple machine learning approaches including support vector machine (SVM), random forest (RF), and artificial neural network (ANN) to identify possible CYP27B1 inhibitors from a pool of kinase inhibitors database. The most reliable classification model was obtained from the SVM approach with Matthews correlation coefficient of 0.82 for the external test set. This model was further employed for the virtual screening of kinase inhibitors from the binding database (DB), which tend to interfere with the CYP27B1-mediated activation of vitamin D. This screening yielded around 4646 kinase inhibitors that were further subjected to structure-based analyses using the homology model of CYP27B1, as the 3D structure of CYP27B1 complexed with heme was not available. Overall, five kinase inhibitors including two well-known drugs, i.e., AT7867 (Compound-2) and amitriptyline N-oxide (Compound-3), were found to interact with CYP27B1 in such a way that may preclude the conversion of vitamin D to its active form and hence testify the impairment of vitamin D activation pathway.

Assessment of serum total 25-hydroxyvitamin D assay commutability of Standard Reference Materials and College of American Pathologists Accuracy-Based Vitamin D (ABVD) Scheme and Vitamin D External Quality Assessment Scheme (DEQAS) materials: Vitamin D Standardization Program (VDSP) Commutability Study 2.

An interlaboratory study was conducted through the Vitamin D Standardization Program (VDSP) to assess commutability of Standard Reference Materials® (SRMs) and proficiency testing/external quality assessment (PT/EQA) samples for determination of serum total 25-hydroxyvitamin D [25(OH)D] using ligand binding assays and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A set of 50 single-donor serum samples were assigned target values for 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] using reference measurement procedures (RMPs). SRM and PT/EQA samples evaluated included SRM 972a (four levels), SRM 2973, six College of American Pathologists (CAP) Accuracy-Based Vitamin D (ABVD) samples, and nine Vitamin D External Quality Assessment Scheme (DEQAS) samples. Results were received from 28 different laboratories using 20 ligand binding assays and 14 LC-MS/MS methods. Using the test assay results for total serum 25(OH)D (i.e., the sum of 25(OH)D2 and 25(OH)D3) determined for the single-donor samples and the RMP target values, the linear regression and 95% prediction intervals (PIs) were calculated. Using a subset of 42 samples that had concentrations of 25(OH)D2 below 30 nmol/L, one or more of the SRM and PT/EQA samples with high concentrations of 25(OH)D2 were deemed non-commutable using 5 of 11 unique ligand binding assays. SRM 972a (level 4), which has high exogenous concentration of 3-epi-25(OH)D3, was deemed non-commutable for 50% of the LC-MS/MS assays.

Vitamin D and lumisterol novel metabolites can inhibit SARS-CoV-2 replication machinery enzymes.

Vitamin D deficiency significantly correlates with the severity of SARS-CoV-2 infection. Molecular docking-based virtual screening studies predict that novel vitamin D and related lumisterol hydroxymetabolites are able to bind to the active sites of two SARS-CoV-2 transcription machinery enzymes with high affinity. These enzymes are the main protease (Mpro) and RNA-dependent RNA polymerase (RdRP), which play important roles in viral replication and establishing infection. Based on predicted binding affinities and specific interactions, we identified 10 vitamin D3 (D3) and lumisterol (L3) analogs as likely binding partners of SARS-CoV-2 Mpro and RdRP and, therefore, tested their ability to inhibit these enzymes. Activity measurements demonstrated that 25(OH)L3, 24(OH)L3, and 20(OH)7DHC are the most effective of the hydroxymetabolites tested at inhibiting the activity of SARS-CoV-2 Mpro causing 10%-19% inhibition. These same derivatives as well as other hydroxylumisterols and hydroxyvitamin D3 metabolites inhibited RdRP by 50%-60%. Thus, inhibition of these enzymes by vitamin D and lumisterol metabolites may provide a novel approach to hindering the SARS-CoV-2 infection.NEW & NOTEWORTHY Active forms of vitamin D and lumisterol can inhibit SARS-CoV-2 replication machinery enzymes, which indicates that novel vitamin D and lumisterol metabolites are candidates for antiviral drug research.