Product Name: Xanthosine Dihydrate
CAS Number: 5968-90-1
Molecular Formula: C₁₀H₁₂N₄O₆·2H₂O
Molecular Weight: 320.26 g/mol
Appearance: White to off-white crystalline powder
Description: Xanthosine dihydrate is a naturally occurring purine nucleoside composed of xanthine covalently linked to D-ribose through a β-N9-glycosidic bond, existing as a dihydrate. It appears as a white to off-white crystalline powder and is soluble in water, particularly under warm conditions, and in aqueous buffers, but less soluble in nonpolar organic solvents. It is stable under normal laboratory conditions when protected from moisture, heat, and light. Functionally, xanthosine dihydrate serves as an important biochemical intermediate and research reagent. It is widely used as a substrate for enzymes such as xanthosine phosphorylase, purine nucleoside phosphorylase, and nucleoside hydrolases, aiding studies of purine salvage and catabolic pathways. In plant biochemistry, xanthosine is a key precursor in the biosynthesis of caffeine and related methylxanthines, making it valuable in investigations of secondary metabolism. It is also employed as a reference standard in chromatographic and mass spectrometric analysis of nucleosides and purine metabolites. Additionally, xanthosine dihydrate is used in the synthesis of nucleotide derivatives, pharmaceutical intermediates, and potential nucleoside-based therapeutic agents. Its ribose moiety allows incorporation into nucleic acid-related pathways, supporting cell culture and metabolic labeling studies. It is handled as a laboratory chemical, with standard precautions for dust avoidance and personal protection.
ITEMS | STANDARDS | RESULTS |
Description | White to almost white powder | White powder |
UV absorbance ratio | A250/A260 A280/A260 | 0.41-0.49 2.03-2.71 | 0.45 2.14 |
PH | 2.0-4.0 | 2.68 |
Loss on drying | ≤5.0% | 2.64% |
Assay (UV) | ≥98.0% | 99.17% |
Transmittance | ≥98.5% | 99.1% |
Heavy metals | ≤10ppm | ＜10ppm |
Purity (HPLC) | ≥98.0% | 99.6% |
Conclusion | It complies to the standard |
For regulatory compliance (e.g., USP, EP, JP), raw material Vidarabine must meet several rigorous standards:
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Assay (by HPLC): 98.0% – 102.0% on an anhydrous basis.
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Related Substances: Limits for specific impurities, notably Ara-Hx (NMT 2.0%), as well as any unspecified individual impurity (NMT 0.1%) and total impurities (NMT 2.0%).
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Residual Solvents: Must comply with ICH Q3C guidelines (Class 1 and 2 solvents limited or absent).
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Heavy Metals: NMT 20 ppm (typically lower for injectable grades).
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Water Content (Karl Fischer): NMT 6.0% (the material is hygroscopic to a degree).
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Microbial Limits: Total aerobic microbial count (TAMC) ≤ 1000 CFU/g, absence of S. aureus, P. aeruginosa, and Candida albicans.
As a high-purity pharmaceutical intermediate, L-Tyrosine Ethyl Ester Hydrochloride is predominantly utilized in the chemical synthesis of bioactive peptides, dopamine analogs, and melanin precursors. Its excellent solubility profile makes it an ideal chiral building block for asymmetric synthesis and a critical substrate in enzymatic reactions. Available in purity grades of ≥98% (HPLC), it meets stringent requirements for R&D and cGMP manufacturing processes. Reliable supply ensures batch-to-batch consistency for long-term project scalability.
Vidarabine is classified as a potential reproductive hazard and an irritant. Safety Data Sheets (SDS) mandate the following:
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Hazard Statements (H360): May damage fertility or the unborn child (Category 1B).
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Precautionary Measures: Use fume hoods and wear impermeable gloves (e.g., nitrile), lab coats, and safety goggles. Avoid generating airborne dust.
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First Aid: In case of skin contact, wash immediately with copious soap and water. If inhaled, move to fresh air.
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Storage: Store in tightly sealed, light-resistant containers at 2°C to 8°C (refrigerated) for long-term stability. Avoid freezing.
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While superseded by newer nucleoside analogs (Acyclovir, Ganciclovir) for systemic use due to better bioavailability and lower toxicity, Vidarabine retains niche value. Its primary current application is ophthalmic ointment (3%) . Pharmacokinetically, the raw material has poor oral bioavailability (<10%) and is rapidly deaminated in the gastrointestinal tract, necessitating parenteral or topical administration.
Vidarabine API is a well-characterized, stable crystalline nucleoside analog. While its systemic use has declined, it remains a critical raw material for topical antiviral ophthalmic preparations, particularly where resistance to other agents occurs. Manufacturers must strictly control impurities (especially Ara-Hx) and water content to ensure final drug product efficacy.
ECHEMI Editorial Reference
white crystalline powder
Xanthosine comprises xanthine ring. It is derived from a purine metabolite and is a caffeine biosynthesis intermediate.
It crystallises from EtOH (anhydrous) or water (as dihydrate). [Howard et al. J Chem Soc 232 1949, Beilstein 31 H 28, 26 III/IV 2428.]
