Isotope-labeled Vitamins

Introduction

A vitamin is an organic molecule that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism. Vitamins have diverse biochemical functions. Therefore, it is very necessary to track the vitamin level and its action path and mechanism in the biological body. And stable isotope-labeled vitamins provide such a safe and efficiency tool. They can act as tracers to follow micronutrients in a quantitative manner, because the absorption, distribution, metabolism, and excretion of the labeled vitamin tracer are assumed to be similar to the unlabeled vitamin. Nowadays, numerous labeled vitamins are used in clinical chemistry, bioavailability research and others.

Fig. 1 The various vitamins.

Classification

Vitamins are classified as either water-soluble or fat-soluble. There are 13 common vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Similarly, stable isotope-labeled vitamins include labeled vitamin A, labeled vitamin B, labeled vitamin C, labeled vitamin D, labeled vitamin E and labeled vitamin K.

Fig. 2 The structures of 4 most common stable isotope-labeled vitamin A.

Applications

The main applications of stable isotope-labeled vitamins are as internal standard used in various fields. Some examples are as follows.

Life science: Factors affecting absorption of physiological doses of vitamin C in man have not been widely studied, partly because few suitable tools exist to distinguish recently absorbed vitamin C from endogenous vitamin C. Stable isotope-labeled vitamin C provides such a tool. For example, Christopher J. et al studied the detailed information about the efficiency and kinetics of vitamin C absorption and distribution by using stable isotope-labeled vitamin C ^[1]. Assays for vitamin D are widely used by those interested in studies of the mechanism of calcium and phosphate homeostasis in humans and animals. Based on isotope dilution method using the appropriate stable isotope-labeled vitamin D as an internal standard in mass fragmentographic assays can clearly reveal that the vitamin D metabolites in human body fluids ^[2]. These studies proved that stable isotope-labeled vitamins play an important role in life science research.

Public health: Vitamin A has multiple functions that is essential for embryo development and growth, maintenance of the immune system, and vision. However, vitamin A deficiency (VAD) is second to iron deficiency anemia as being the nutritional health problem of highest public health significance in developing countries. Therefore, the evaluation of vitamin A is very important. Stable isotope methods use stable isotope-labeled vitamin A as internal standard are the most powerful techniques available to scientists for evaluating vitamin A status. For example, total body retinol stores were estimated by using ¹³C₂-retinol isotope internal standard before and after feeding Zambian children maize biofortified with β-carotene to determine if vitamin A reserves were improved by the intervention ^[3].

Fig. 3 The principles of stable isotope methods for evaluating vitamin A status. Where A is the vitamin A in the entire body, A^* is the stable isotope-labeled vitamin A.

Nutrition: Vitamins are essential to human health, and dietary supplements containing vitamins are widely used by individuals hoping to ensure they have adequate intake of these important nutrients. Measurement of vitamins in nutritional formulations is necessary to monitor regulatory compliance and in studies examining the nutrient intake of specific populations. Stable isotope-labeled vitamin internal standards can be used in LC-MS methods for quantification analysis of the analytes of both fat and water-soluble vitamins, even in complex matrices, which is generally considered to represent the most ideal approach to quantification of vitamins.

Oceanography: Vitamin B12 is an essential nutrient for more than half of surveyed marine algae species, but methods for directly measuring this important cofactor in seawater are limited. Katherine R et al presented a method to measure vitamin B1, B2, B6, B7 and four forms of B12 dissolved in seawater by using stable-isotope-labeled vitamin internal standards in the liquid chromatography/mass spectrometry to understand the cycling of this important nutrient in the marine environment ^[4].

What can we offer?

As a professional supplier of stable isotope-labeled compounds, Alfa Chemistry has always shown great interest in the latest developments in stable isotope-labeled vitamins. Alfa Chemistry has excellent R&D staffs with rich experience who aim to provide high quality and cost-effective stable isotope-labeled vitamins timely. We can offer you with various stable isotope-labeled vitamins such as ²H, ¹³C, ¹⁵N, ¹³C ¹⁵N labeled vitamins. You can click on our product list for a detailed view. If you do not find the product you want, we also provide you with custom synthesis service. Please contact us, if you are in need of assistance.

References

• Bates, C. J., et al. Stable isotope-labelled vitamin C as a probe for vitamin C absorption by human subjects[J]. British Journal of Nutrition, 2004, 91(05):699-705.
• Coldwell, R. D., et al. Stable isotope-labeled vitamin D, metabolites and chemical analogs: synthesis and use in mass spectrometric studies[J]. Steroids, 1990, 55(10):418-432.
• Sheftel, J., et al. Use of Stable Isotopes to Evaluate Bioefficacy of Provitamin A Carotenoids, Vitamin A Status, and Bioavailability of Iron and Zinc[J]. Advances in Nutrition An International Review Journal, 2018, 9(5): 625-636.
• Heal, K. R., et al. Determination of four forms of vitamin B12 and other B vitamins in seawater by liquid chromatography/tandem mass spectrometry[J]. Rapid Communications in Mass Spectrometry Rcm, 2015, 28(22):2398-2404.