Understanding CAS Numbers for Chemical Identification
A Chemical Abstracts Service (CAS) Registry Number is a unique numerical identifier assigned by the American Chemical Society's Chemical Abstracts Service. This number acts as a universal, unambiguous code for a specific chemical substance, distinguishing it from potentially confusing synonyms or regional names. For example, water and its formula (H₂O) have one CAS number: 7732-18-5. This system is critical for scientific research, international trade, and regulatory compliance.
The Multiple Forms of Vitamin B3
Unlike simpler vitamins, 'vitamin B3' is a generic name for a group of compounds that exhibit biological activity, a detail that is key to understanding its CAS numbers. The two primary forms that fulfill the role of vitamin B3 in the body are niacin and niacinamide, but there are other derivatives as well. Each of these distinct chemical structures receives its own unique CAS number.
The CAS Number for Niacin (Nicotinic Acid)
Niacin, also known by its chemical name nicotinic acid, is one of the main forms of vitamin B3. It is a pyridine derivative with a carboxylic acid group, which gives it distinct chemical properties. The CAS number for niacin is 59-67-6. This form is known for causing a temporary skin flushing reaction, and in high doses, it can influence cholesterol levels.
The CAS Number for Niacinamide (Nicotinamide)
Niacinamide, also called nicotinamide, is the amide version of nicotinic acid. This slight chemical difference in its structure—the replacement of the carboxylic acid group with an amide group—changes how the body processes it, notably eliminating the flushing side effect. The CAS number for niacinamide is 98-92-0. It is commonly used in supplements and is a popular ingredient in topical skincare products.
Another Vitamin B3 Precursor: Nicotinamide Riboside
Another compound that acts as a precursor to the coenzyme NAD+, a function of vitamin B3, is nicotinamide riboside. While not marketed as niacin, it is sometimes included in the broader vitamin B3 discussion. Its specific CAS number is 1341-23-7.
Comparison of Vitamin B3 Forms
To clarify the differences, here is a comparison of niacin and niacinamide:
| Feature | Niacin (Nicotinic Acid) | Niacinamide (Nicotinamide) |
|---|---|---|
| CAS Number | 59-67-6 | 98-92-0 |
| Chemical Structure | Pyridine-3-carboxylic acid | 3-Pyridinecarboxamide |
| Flushing Effect | Yes, can cause noticeable flushing, especially at higher doses | No, it does not cause skin flushing |
| Effect on Cholesterol | High doses can help lower LDL ('bad') cholesterol and raise HDL ('good') cholesterol | Does not typically impact cholesterol levels |
| Common Uses | Prescription medication for dyslipidemia, pellagra treatment | Dietary supplements, topical skincare, pellagra treatment |
Why Does a Vitamin Have Multiple CAS Numbers?
The reason for multiple CAS numbers stems from the chemical definitions. The CAS Registry assigns a unique identifier based on a substance's precise molecular structure. Since 'vitamin B3' is a functional description rather than a single chemical compound, each molecule that fits this description (like niacin and niacinamide) is a distinct substance from a chemical standpoint and therefore receives its own CAS number.
Common Sources of Vitamin B3
Both niacin and niacinamide are available in various foods, which are converted into the essential coenzymes NAD and NADP in the body. These coenzymes are vital for metabolic processes, nervous system function, and DNA repair.
Some common dietary sources of vitamin B3 include:
- Meat: Red meat, poultry, and fish are particularly rich sources.
- Nuts and Legumes: Peanuts and legumes offer a good plant-based source.
- Fortified Grains: Many breads and breakfast cereals are enriched with niacin.
- Mushrooms: Certain types of mushrooms contain vitamin B3.
The Importance of Understanding the Correct Form
Knowing the specific chemical form, and thus the correct CAS number, is crucial for both clinical and industrial applications. For instance, a physician prescribing a high-dose vitamin B3 to manage cholesterol must use niacin (nicotinic acid), while a dermatologist formulating a skincare product will choose niacinamide to avoid the flushing side effect. This precision is a key benefit of the universally recognized CAS numbering system.
Conclusion
In summary, there is no single CAS number for vitamin B3 because it refers to a group of compounds, not a single chemical substance. For accurate identification, the specific CAS numbers for niacin (59-67-6) and niacinamide (98-92-0) must be used. Understanding this distinction is vital for researchers, healthcare professionals, and consumers to ensure the correct compound is being identified and used for its intended purpose. The CAS system's precision eliminates potential confusion and errors, highlighting its importance in chemical and health-related fields.
For more information on chemical nomenclature and identification, consult the resources provided by the American Chemical Society, such as the CAS Common Chemistry database.
