Spectrofluorimetric approach for determination of citicoline in the presence of co-formulated piracetam through fluorescence quenching of eosin Y

A simple, sensitive, and precise spectrofluorimetric method has been developed and validated for quantitation of citicoline in its pharmaceutical formulations. The proposed method based on quantitative quenching effect of citicoline on the native fluorescence of Eosin Y via developing of a binary complex reaction between the cited drug and Eosin Y in acidic medium using acetate buffer pH = 3.6. The quenching of the fluorescence of eosin was measured at 540 nm after excitation at 518 nm. Calibration graph was achieved in the range of 300-3000 ng/mL with 0.9996 as correlation coefficient and 291.0 and 93.86 ng/mL as quantitation and detection limits, respectively. The developed method considered as the first developed spectrofluorimetric one for quantitation of citicoline with high sensitivity and validated according to ICH guidelines. The selectivity of the proposed method was investigated by studying the interference of piracetam as co-formulated drug with CIT in pharmaceutical formulation, therefore the developed method could be used for routine quality control of citicoline in its pharmaceutical formulations either alone or in combination with piracetam.

Novel Validated Analytical Method Based on Potentiometric Transduction for the Determination of Citicoline Psychostimulant/Nootropic Agent

Herein, a novel validated potentiometric method is presented for the first time for citicoline determination. The method is based on measuring the potential using new constructed citicoline electrodes. The electrodes are based on the use of citicolinium/phosphomolybdate [Cit]₂[PM] (sensor I) and citicolinium/tetraphenylborate [Cit][TPB] (sensor II) ion association complexes. These sensory materials were dispersed in plasticized polyvinyl chloride (PVC) polymeric membranes. The sensors revealed a Nernstian response with the slopes 55.9 ± 1.8(r² = 0.9994) and 51.8 ± 0.9 (r² = 0.9991) mV/decade over a linearity range of 6.3 × 10⁻⁶–1.0 × 10⁻³ and 1.0 × 10⁻⁵–1.0 × 10⁻³ M and detection limits of 3.16 × 10⁻⁶ and 7.1 × 10⁻⁶ M for sensors I and II, respectively. To ensure the existence of monovalent citicoline, all measurements were performed in 50 mM acetate buffer at pH 3.5. All presented electrodes showed good performance characteristics such as rapid response, good selectivity, high potential-stability and long life-span. Method verification and validation in terms of response linearity, quantification limit, accuracy, bias, trueness, robustness, within-day variability and between-days variability were evaluated. The method was introduced for citicoline determination in different pharmaceutical formulations and compared with the standard high performance liquid chromatography (HPLC) method.

Cytidine and uridine increase striatal CDP-choline levels without decreasing acetylcholine synthesis or release

AIMS

Treatments that increase acetylcholine release from brain slices decrease the synthesis of phosphatidylcholine by, and its levels in, the slices. We examined whether adding cytidine or uridine to the slice medium, which increases the utilization of choline to form phospholipids, also decreases acetylcholine levels and release.

METHODS

We incubated rat brain slices with or without cytidine or uridine (both 25-400 microM), and with or without choline (20-40 microM), and measured the spontaneous and potassium-evoked release of acetylcholine.

RESULTS

Striatal slices stimulated for 2 h released 2650+/-365 pmol of acetylcholine per mg protein when incubated without choline, or 4600+/-450 pmol/mg protein acetylcholine when incubated with choline (20 microM). Adding cytidine or uridine (both 25-400 microM) to the media failed to affect acetylcholine release whether or not choline was also added, even though the pyrimidines (400 microM) did enhance choline;s utilization to form CDP-choline by 89 or 61%, respectively. The pyrimidines also had no effect on acetylcholine release from hippocampal and cortical slices. Cytidine or uridine also failed to affect acetylcholine levels in striatal slices, nor choline transport into striatal synaptosomes.

CONCLUSION

These data show that cytidine and uridine can stimulate brain phosphatide synthesis without diminishing acetylcholine synthesis or release.

31P-NMR analysis of Entamoeba histolytica. Occurrence of high amounts of two inositol phosphates

Perchloric-acid extracts of axenic Entamoeba histolytica were investigated by 31P-NMR spectroscopy. All major 31P resonances observed were assigned to specific compounds. The cells contained inorganic phosphate (1039 nmol/g wet cells), pyrophosphate (16 nmol/g wet cells), nucleoside diphosphates (91 nmol/g wet cells), nucleoside triphosphates (275 nmol/g wet cells), NAD(P) (60 nmol/g wet cells), phosphocholine (184 nmol/g wet cells), phosphoethanolamine (214 nmol/g wet cells), cytidine 5'-diphosphocholine (41 nmol/g wet cells) and cytidine 5'-diphosphoethanolamine (55 nmol/g wet cells). The latter four compounds may act as intermediates in the salvage pathway for the synthesis of phosphatidylethanolamine and phosphatidylcholine. E. histolytica trophozoites also contained two inositol phosphates in large quantities, InsP3 (0.26 mumol/g wet cells) and InsP7 (0.11 mumol/g wet cells). These components were identified by 31P-NMR, using homonuclear J-resolved and two-dimensional 1H-31P correlative, analyses as myo-inositol trisphosphate, Ins(2,4,6)P3, and pentakisphospho-myo-inositol diphosphate, Ins(1,2,3,4,6)P5(5)P2.