Vitamin B12 Enables Consecutive Generation of Acyl and Alkyl Radicals from One Reagent

2019 ◽  
Vol 2020 (10) ◽  
pp. 1567-1571 ◽  
Author(s):  
Aleksandra Potrząsaj ◽  
Michał Ociepa ◽  
Oskar Baka ◽  
Grzegorz Spólnik ◽  
Dorota Gryko
Keyword(s):  
Vitamin B12 ◽  
Consecutive Generation ◽  
Alkyl Radicals

Studies on Vitamin B12 and Related Compounds, 51 [1] Direct Syntheses of Alkylcobalamins from Alkanes and Vitamin B12r under "Oxidizing-Reducing" Conditions

1980 ◽  
Vol 35 (11) ◽  
pp. 1435-1438 ◽  
Author(s):  
Abdussalam Maihub ◽  
Hui Bi Xu ◽  
Gerhard N. Schrauzer
Keyword(s):  
Vitamin B12 ◽  
Oxygen Radicals ◽  
Room Temperature ◽  
High Efficiency ◽  
Vitamin B ◽  
Methyl Radicals ◽  
Alkyl Radicals ◽  
Acidic Solutions ◽  
Reducing Conditions ◽  
Related Compounds

AbstractSyntheses of methylcobalamin from methane, and of n-alkylcobalamins from n-alkanes (C2→C10) and vitamin B12r are described. The compounds are formed under "oxidizing-reducing" conditions: Oxygen radicals (O2-, HOO·, and HO·) are generated from the reaction of O2 with reducing metal ions, notably V+3 (aq) and abstract hydrogen from the alkane substrates. The resulting alkyl radicals are captured by vitamin Bj2r with high efficiency to yield alkylcobalamins. The reactions take place at room temperature in mildly alkaline or acidic solutions. In addition to n-alkylcobalamins, the preparation of neopentylcobalamin from neopentane, of isobutylcobalamin from isobutane, and of several cycloalkylcobalamins from cycloalkanes, is also reported. Methyl radicals generated in D2O from CH4 under "oxidizing-reducing" conditions are reduced to yield CH3D.

Vitamin B12 Content of Liver and Serum in Malignant Neoplasia

1962 ◽  
Vol 42 (4) ◽  
pp. 414-418 ◽  
Author(s):  
Robert S. Nelson ◽  
Vasant M. Doctor
Keyword(s):  
Vitamin B12 ◽  
Malignant Neoplasia

55: The Risk of Vitamin B12 Deficiency is Low after Ileal Orthotopic Bladder Substitution

2004 ◽  
Vol 171 (4S) ◽  
pp. 15-15
Author(s):  
Urs E. Studer ◽  
Richard Aebischer ◽  
Katharina Ochsner ◽  
Werner W. Hochreiter
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
B12 Deficiency ◽  
Bladder Substitution

Switching to Oral Vitamin B12 Replacement

2006 ◽  
Vol 39 (18) ◽  
pp. 30
Author(s):  
JON O. EBBERT ◽  
ERIC G. TANGALOS
Keyword(s):  
Vitamin B12 ◽  
Oral Vitamin

Vitamin B12-based elimination of alkyl halides

2020 ◽  
Author(s):  
Julian West ◽  
Alexandros S Pollatos ◽  
Radha Bam
Keyword(s):  
Vitamin B12 ◽  
Alkyl Halides

Bioavailability of Vitamin B12

2010 ◽  
Vol 80 (45) ◽  
pp. 330-335 ◽  
Author(s):  
Lindsay Helen Allen
Keyword(s):  
Vitamin B12 ◽  
Vitamin B12 Deficiency ◽  
The Elderly ◽  
Radioactive Isotopes ◽  
Animal Source Foods ◽  
Dietary Requirements ◽  
In Vivo Labeling ◽  
B12 Deficiency ◽  
Vitamin B12 Malabsorption

Vitamin B12 deficiency is common in people of all ages who consume a low intake of animal-source foods, including populations in developing countries. It is also prevalent among the elderly, even in wealthier countries, due to their malabsorption of B12 from food. Several methods have been applied to diagnose vitamin B12 malabsorption, including Schilling’s test, which is now used rarely, but these do not quantify percent bioavailability. Most of the information on B12 bioavailability from foods was collected 40 to 50 years ago, using radioactive isotopes of cobalt to label the corrinoid ring. The data are sparse, and the level of radioactivity required for in vivo labeling of animal tissues can be prohibitive. A newer method under development uses a low dose of radioactivity as 14C-labeled B12, with measurement of the isotope excreted in urine and feces by accelerator mass spectrometry. This test has revealed that the unabsorbed vitamin is degraded in the intestine. The percent bioavailability is inversely proportional to the dose consumed due to saturation of the active absorption process, even within the range of usual intake from foods. This has important implications for the assessment and interpretation of bioavailability values, setting dietary requirements, and interpreting relationships between intake and status of the vitamin.

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