Effects of vitamins on hepatic nuclear binding of L-tryptophan

Summary. This study investigated the in vitro effects of selected vitamins on nuclear L-tryptophan receptor binding of rat liver. Our results revealed that some fat-soluble vitamins, β-carotene, retinyl acetate, calciferol, α-tocopherol, and Trolox, as well as some water-soluble vitamins, thiamine and riboflavin, acted to inhibit in vitro ³H-tryptophan binding to hepatic nuclei. On the other hand, pyridoxine had little or no effect. The addition of dithiothreitol, a protective agent for sulfhydryl groups, along with each vitamin decreased the vitamin's inhibitory effect on in vitro ³H-tryptophan binding to nuclei, with the exception of riboflavin and calciferol. The addition of L-leucine, which alone had no inhibitory effect on in vitro ³H-tryptophan binding to hepatic nuclei but when added with unlabeled L-tryptophan negated the effect of unlabeled L-tryptophan, caused a markedly diminished inhibitory binding effect due to each of the following vitamins, thiamine, β-carotene, retinyl acetate, and α-tocopherol and Trolox, but no effect on riboflavin and calciferol. Received December 29, 1999 Accepted March 8, 2000     

Determination of potential role of antioxidative status and circulating biochemical markers in the pathogenesis of ethambutol induced toxic optic neuropathy among diabetic and non-diabetic patients

The present study was designed to explore the antioxidative status and circulating biochemical markers having a potential role in the pathogenesis of ethambutol (EMB) induced toxic optic neuropathy (TON) among diabetic and non-diabetic patients.Fifty patients under complete therapy of EMB for tuberculosis were included in the present study. Inclusion criteria for patients were to receive EMB everyday during treatment, a dose of 25 mg/kg for initial 2 months and 15 mg/kg during the rest of therapy period. We conducted color vision and visual acuity test for all patients.Fifteen out of fifty EMB induced TON patients, were found to be diabetic. Color vision and visual acuity test results were evaluated for diabetic and non-diabetic as well as twenty age matched controls. The results demonstrated a significant pattern of circulating biochemical markers between the studied groups. Data regarding hematological (RBC, p value = 0.02; Hemoglobin, p value = 0.02), hepatic (total bilirubin, p value = 0.01), renal (urea, p value = 0.03; creatinine, p value = 0.007), lipid (total cholesterol, p value = 0.01; total triglycerides, p value = 0.03) and antioxidative (superoxide dismutase, p value = 0.005; glutathione, p value = 0.02; catalase, p value = 0.02) profile showed a highly significant difference among the studied groups specially patients with diabetes. Malondialdehyde (MDA) level had gone significantly up in diabetic TON patients (p value = 0.02), in comparison to other antioxidants and vitamins (Vit). Vit-A, E, B₁, B₁₂ and Zinc seem to be playing a major role in the pathogenesis of TON, specially Vit-E and B₁ surpassed all the antioxidants as having highly significant inverse relationships with MDA (MDA vs Vit-E, r = −0.676^** and MDA vs Vit-B₁, r = −0.724^** respectively).We conclude that during the ethambutol therapy the decreased levels of Vit-E and Vit-B₁ possibly play a role in the development of TON and may be used as therapeutic agents to lessen the deleterious effects of ethambutol.     

Inhibition of human tumor cell proliferation by novel anthraquinones from daylilies

Daylilies (Hemerocallis) are used medicinally in eastern Asia and extracts of the plant had been shown to inhibit cell proliferation and induce cancer cells to undergo differentiation. In our studies of the constituents of Hemerocallis fulva var. 'Kwanzo' roots, we isolated a series of new [kwanzoquinones A (1), B (2), C (4), D (5), E (6), F (7), G (9)] and known [2-hydroxychrysophanol (3) and rhein (8)] anthraquinones. These compounds were tested in order to determine their potential roles as cancer cell growth inhibitors. Kwanzoquinones A-C and E, kwanzoquinone A and B monoacetates (1a and 2a), 2-hydroxychrysophanol, and rhein inhibited the proliferation of human breast, CNS, colon, and lung cancer cells with GI50 values between 1.8 to 21.1 microg/mL. However, upon exposure of the cancer cells to the GI50 concentrations of the bioactive anthraquinones, most of the cancer cell lines exhibited higher than anticipated levels of cell viability. Co-incubation of the anthraquinones with vitamins C and E increased the viability of breast cancer cells. In contrast, vitamins C and E potentiated the cytotoxic effects of the anthraquinones against the colon cancer cells. None of the anthraquinones inhibited the activity of topoisomerase.     

Rapid and sensitive high-performance liquid chromatographic method for simultaneous determination of retinol, α-tocopherol, 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in human plasma with photodiode-array ultraviolet detection

A new rapid and sensitive high-performance liquid chromatographic method using 0.5 ml of plasma has been developed for the simultaneous determination of retinol (vitamin A), α-tocopherol (vitamin E), 25-hydroxyvitamin D₂ and 25-hydroxyvitamin D₃. The eluate was monitored with a photodiode-array detector with two fixed wavelengths (267 nm for vitamin D, 292 nm for α-tocopherol and retinol). For all compounds, including internal standards, the method provides extraction recoveries greater than 81%. Detection limits were equal to or lower than 1.5 μg/l for the 4 vitamins. Linearity of standards was excellent (r>0.999 in all cases). Intra-day and inter-day precision were generally acceptable; the intra-day-assay C.V. was 7.7 for all compounds and the inter-day-assay C.V. was <9.2% except for the lower concentrations of 25-hydroxyvitamin D₃, 25-hydroxyvitamin D₂ and α-tocopherol (10.8, 11.8 and 11.9, respectively). The important properties of the present method are its ease of use, its rapidity, since sample preparation was achieved in 15 min and all the compounds were eluted in less than 15 min, and its small sample volume required (=0.5 ml), which enables it to be used in pediatric practice.     

Simultaneous determination of retinol, β-carotene and α-tocopherol in adipose tissue by high-performance liquid chromatography

A method is described for evaluation of fat-soluble vitamin in human adipose tissue with the aim to obtain, accurately and within the shortest analysis time, a time-integrated measure of exposure to vitamins from the diet. Fat tissue was deproteinized with ethanol and extracted with n-hexane. Normal-phase HPLC was performed in a Lichrosorb Si60 column with a gradient of n-hexane–2-propanol at 1 ml/min. Detection was accomplished using a diode-array system (for retinol and β-carotene) in series with a fluorescence detector (α-tocopherol). The method was validated and applied to human adipose tissue in a total of 140 subjects. The mean contents found were 0.43, 0.84, 240.3 μg/g for retinol, β-carotene and α-tocopherol, respectively. The method is sensitive enough for detecting the compounds in 1.6 mg of adipose tissue considering the lowest concentration found.     

Alteration of plankton communities and biogeochemical cycles by harmful Cochlodinium polykrikoides (Dinophyceae) blooms

Cochlodinium polykrikoides is a globally distributed, ichthyotoxic, bloom-forming dinoflagellate. Blooms of C. polykrikoides manifest themselves as large (many km²) and distinct patches with cell densities exceeding 10³ ml⁻¹ while water adjacent to these patches can have low cell densities (<100 cells ml⁻¹). While the effect of these blooms on fish and shellfish is well-known, their impacts on microbial communities and biogeochemical cycles are poorly understood. Here, we investigated plankton communities and the cycling of carbon, nitrogen, and B-vitamins within blooms of C. polykrikoides and compared them to areas in close proximity (<100 m) with low C. polykrikoides densities. Within blooms, C. polykrikoides represented more than 90% of microplankton (>20 μm) cells, and there were significantly more heterotrophic bacteria and picoeukaryotic phytoplankton but fewer Synechococcus. Terminal restriction fragment length polymorphism analysis of 16S and 18S rRNA genes revealed significant differences in community composition between bloom and non-bloom samples. Inside the bloom patches, concentrations of vitamin B₁₂ were significantly lower while concentrations of dissolved oxygen were significantly higher. Carbon fixation and nitrogen uptake rates were up to ten times higher within C. polykrikoides bloom patches. Ammonium was a more important source of nitrogen, relative to nitrate and urea, for microplankton within bloom patches compared to non-bloom communities. While uptake rates of vitamin B₁ were similar in bloom and non-bloom samples, vitamin B₁₂ was taken up at rates five-fold higher (>100 pmol⁻¹ L⁻¹ d⁻¹) in bloom samples, resulting in turn-over times of hours during blooms. This high vitamin demand likely led to the vitamin B₁₂ limitation of C. polykrikoides observed during nutrient amendment experiments conducted with bloom water. Collectively, this study revealed that C. polykrikoides blooms fundamentally change microbial communities and accelerate the cycling of carbon, some nutrients, and vitamin B₁₂.     

A literature review on beneficial role of vitamins and trace elements: Evidence from published clinical studies

COVID-19 is a kind of SARS-CoV-2 viral infectious pneumonia. This research aims to perform a bibliometric analysis of the published studies of vitamins and trace elements in the Scopus database with a special focus on COVID-19 disease. To achieve the goal of the study, network and density visualizations were used to introduce an overall picture of the published literature. Following the bibliometric analysis, we discuss the potential benefits of vitamins and trace elements on immune system function and COVID-19, supporting the discussion with evidence from published clinical studies. The previous studies show that D and A vitamins demonstrated a higher potential benefit, while Selenium, Copper, and Zinc were found to have favorable effects on immune modulation in viral respiratory infections among trace elements. The principles of nutrition from the findings of this research could be useful in preventing and treating COVID-19.     

Identification of a Bis-molybdopterin Intermediate in Molybdenum Cofactor Biosynthesis in Escherichia coli

The molybdenum cofactor is an important cofactor, and its biosynthesis is essential for many organisms, including humans. Its basic form comprises a single molybdopterin (MPT) unit, which binds a molybdenum ion bearing three oxygen ligands via a dithiolene function, thus forming Mo-MPT. In bacteria, this form is modified to form the bis-MPT guanine dinucleotide cofactor with two MPT units coordinated at one molybdenum atom, which additionally contains GMPs bound to the terminal phosphate group of the MPTs (bis-MGD). The MobA protein catalyzes the nucleotide addition to MPT, but the mechanism of the biosynthesis of the bis-MGD cofactor has remained enigmatic. We have established an in vitro system for studying bis-MGD assembly using purified compounds. Quantification of the MPT/molybdenum and molybdenum/phosphorus ratios, time-dependent assays for MPT and MGD detection, and determination of the numbers and lengths of Mo–S and Mo–O bonds by X-ray absorption spectroscopy enabled identification of a novel bis-Mo-MPT intermediate on MobA prior to nucleotide attachment. The addition of Mg-GTP to MobA loaded with bis-Mo-MPT resulted in formation and release of the final bis-MGD product. This cofactor was fully functional and reconstituted the catalytic activity of apo-TMAO reductase (TorA). We propose a reaction sequence for bis-MGD formation, which involves 1) the formation of bis-Mo-MPT, 2) the addition of two GMP units to form bis-MGD on MobA, and 3) the release and transfer of the mature cofactor to the target protein TorA, in a reaction that is supported by the specific chaperone TorD, resulting in an active molybdoenzyme.     

Plasmodium gallinaceum: effects of various compounds on immunity of susceptible Aedes aegypti and refractory Culex pipiens pipiens

Para-aminobenzoic acid (PABA) administered in the diet in 0.01, 0.1, 0.2, 0.3, 0.4, and 1.0% concentrations to Aedes aegypti was found to enhance oocyst production. The most significant increase in oocyst production was in groups receiving 0.3 and 0.1% solutions. A combination of 0.01% PABA + 0.1 M NaOH, and 0.02 M HCL, 0.1 M KOH, 0.1 M NaOH, and 0.2 M MgCl₂ likewise increased the susceptibility of A. aegypti to Plasmodium gallinaceum with 0.1 M NaOH being the most effective.Culex pipiens pipiens was found to exhibit a low degree of susceptibility to P. gallinaceum. This is the first report of oocyst development by P. gallinaceum in this species. PABA in 0.1, 0.2, 0.3, 0.4, and 1.0% concentrations was tested and all concentrations increased the susceptibility of this refractory host. This compound was most effective in a 0.4% concentration.The susceptibility of C. pipiens pipiens to P. gallinaceum was also increased by inorganic materials. NaOH and KOH in 0.1 M concentrations yielded the greatest increase. A slight increase in susceptibility was effected by 0.2 M MgCl₂ and 0.02 M HCL. Culex receiving the combination of 0.01% PABA and 0.01 M NaOH had the highest infection of those receiving inorganic compounds.Most of the oocysts produced in these experimental Culex were fairly typical of those found in A. aegypti; however, some were quite small and others showed evidence of deterioration, distortion, and shrinkage.     

Rapid mass spectrometric analysis for ascorbate and related organic acids in small volumes of plasma for use in pediatric subjects

A gas chromatographic–mass spectrometric isotope dilution method was developed for analysis of ascorbate on 10 μl samples of plasma. This assay was reproducible (standard deviation of less than 4%) and gave values for plasma ascorbate content within 8% of our previously published gas chromatographic–mass spectrometric method. Non-specific sample preparation allowed other analytes to be determined on the same sample by adjusting data acquisition parameters and adding the appropriate internal standard. Analysis on 28 subjects fell within the expected range for plasma ascorbate 68±29 μm (11.9±5.0 μg/ml) and established a normal range for plasma threonate of 28.1±2.4 μm (3.8±0.4 μg/ml).