Presence of cytidine 5'-tetraphosphate in commerical samples of cytidine 5'-triphosphate

Application of a HPLC-Q/TOF method with post-column compensation for separation and identification of polar impurities in Cytidine disodium triphosphate for injection

Background:

Cytidine Disodium Triphosphate (CTP-2Na) for injection is mainly used for treating nervous system diseases. Currently, there are few studies focused on the separation and identification of polar impurities in CTP-2Na for injection, which is important for ensuring drug safety and efficacy.

Objective:

The study aimed to establish an HPLC-Q/TOF method for the separation and identification of polar impurities in CTP-2Na for injection.

Methods:

Chromatographic separation was achieved on a Waters Atlantis T3 column using 5 mM aqueous ammonium acetate solution as the mobile phase in an isocratic elution mode. A postcolumn compensation technology was used to improve the ionization efficiency of impurities in the spray chamber.

Results:

Three polar impurities (disodium cytidine tetraphosphate, disodium cytidine diphosphate, disodium cytidine monophosphate) were detected in CTP-2Na for injection. The former one is probably the overreaction product during the production of CTP-2Na, the latter two were reported as degradation products. The fragmentation patterns of cytidine phosphate compounds in negative ion mode are summarized.

Conclusion:

This study provides a good reference for the separation and identification of polar impurities in nucleotide drugs.

New Insight into Plant Signaling: Extracellular ATP and Uncommon Nucleotides

New players in plant signaling are described in detail in this review: extracellular ATP (eATP) and uncommon nucleotides such as dinucleoside polyphosphates (NpnN's), adenosine 5'-phosphoramidate (NH2-pA), and extracellular NAD+ and NADP+ (eNAD(P)+). Recent molecular, physiological, and biochemical evidence implicating concurrently the signaling role of eATP, NpnN's, and NH2-pA in plant biology and the mechanistic events in which they are involved are discussed. Numerous studies have shown that they are often universal signaling messengers, which trigger a signaling cascade in similar reactions and processes among different kingdoms. We also present here, not described elsewhere, a working model of the NpnN' and NH2-pA signaling network in a plant cell where these nucleotides trigger induction of the phenylpropanoid and the isochorismic acid pathways yielding metabolites protecting the plant against various types of stresses. Through these signals, the plant responds to environmental stimuli by intensifying the production of various compounds, such as anthocyanins, lignin, stilbenes, and salicylic acid. Still, more research needs to be performed to identify signaling networks that involve uncommon nucleotides, followed by omic experiments to define network elements and processes that are controlled by these signals.

Chromatographic separation of cytidine triphosphate from fermentation broth of yeast using anion-exchange cryogel

A novel separation method was developed to isolate directly cytidine triphosphate (CTP) from fermentation broth of yeast using anion-exchange supermacroporous cryogel. The anion-exchange cryogel with tertiary amine groups was prepared by graft polymerization. The breakthrough characteristics and elution performance of pure CTP in the cryogel bed were investigated experimentally and the CTP binding capacity was determined. Then the separation experiments of CTP from crude fermentation broth of yeast using the cryogel column were carried out using deionized water and 0.01 M HCl as washing buffer, respectively. The chromatographic behavior was monitored and analyzed. The purity and concentration of the obtained CTP in these processes were determined quantitatively by HPLC. The maximal purity of CTP obtained at the condition of 0.01 M HCl as washing buffer and 0.5 M NaCl in 0.01 M HCl as elution buffer reached 93%.

Uridine 5'-polyphosphates (p4U and p5U) and uridine(5')polyphospho(5')nucleosides (Up(n)Ns) can be synthesized by UTP:glucose-1-phosphate uridylyltransferase from Saccharomyces cerevisiae

UTP:glucose-1-phosphate uridylyltransferase (EC 2.7.7.9) from Saccharomyces cerevisiae can transfer the uridylyl moiety from UDP-glucose onto tripolyphosphate (P(3)), tetrapolyphosphate (P(4)), nucleoside triphosphates (p(3)Ns) and nucleoside 5'-polyphosphates (p(4)Ns) forming uridine 5'-tetraphosphate (p(4)U), uridine 5'-pentaphosphate (p(5)U) and dinucleotides, such as Ap(4)U, Cp(4)U, Gp(4)U, Up(4)U, Ap(5)U and Gp(5)U. Unlike UDP-glucose, UDP-galactose was not a UMP donor and ADP was not a UMP acceptor. This is the first example of an enzyme that may be responsible for accumulation of dinucleoside tetraphosphates containing two pyrimidine nucleosides in vivo. Occurrence of such dinucleotides in S. cerevisiae and Escherichia coli has been previously reported (Coste et al., J. Biol. Chem. 262 (1987) 12096-12103).

Dinucleoside polyphosphates-friend or foe?

Despite being known for over 30 years, the functions of the dinucleoside polyphosphates, such as diadenosine 5',5"'-P(1), P(4)-tetraphosphate (Ap(4)A) and diadenosine 5',5"'-P(1), P(3)-triphosphate (Ap(3)A), are still unclear. On the one hand, they may have important signalling functions, both inside and outside the cell (friend), while on the other hand, they may simply be the unavoidable by-products of certain biochemical reactions, which, if allowed to accumulate, would be potentially toxic through their structural similarity to ATP and other essential mononucleotides (foe). Here, the occurrence, synthesis, degradation, and proposed functions of these compounds are briefly reviewed, along with some new data and recent evidence supporting roles for Ap(3)A and Ap(4)A in the cellular decision making processes leading to proliferation, quiescence, differentiation, and apoptosis. Hypotheses are forwarded for the involvement of Ap(4)A in the intra-S phase DNA damage checkpoint and for Ap(3)A and the pFhit (fragile histidine triad gene product) protein in tumour suppression. It is concluded that the roles of friend and foe are not incompatible, but are distinguished by the concentration range of nucleotide achieved under different circumstances.