Biomedical subjects

M J Dorta

Publications and source records attributed to M J Dorta.

3 recordsLinked to original sources

PubMed2004

Stability indicating method for SPf66 antimalarial peptide in solution.

Stability studies on the SPf66 antimalarial peptide with different pH and temperature conditions were carried out. The degradation mechanism was elucidated by the size-exclusion chromatography (SEC) technique and the experimental data obtained at 37 degrees C and different pH were fitted to a kinetic degradation model that could explain the loss of its immunogenic capacity. At 5, 25, 37, and 70 degrees C and pH 2, changes were detected in the areas of the different species, although the values obtained could not be fitted to any known degradation kinetics.

Chromatography, Gel↗

PubMed2000

Kinetic model for 5-fluorouridine degradation. Catalytic effect of 5-fluorouracil.

The effects of 5-fluorouridine (5-FUR, CAS 316-46-1) degradation products, 5-fluorouracil (5-FU, CAS 51-21-8) and D-ribose (CAS 50-69-1), on its degradation rate was investigated following a 2(3) factorial design. The experimental data fitted to the proposed mathematical model which includes two parallel degradation mechanisms: the first one, a second order bimolecular reaction involving both 5-FUR and 5-FU, and the second, a first order one. Experimental data obtained show a high variability. Both graphic and statistical analysis of the experiments for which a full kinetic model was applied manifested that the degradation mechanism included an autocatalytic route and confirmed the role of the 5-FU on the hydrolysis of 5-FUR.

Algorithms↗

PubMed1997

Stability indicating high performance liquid chromatography methods for 5-fluorouridine in aqueous solution.

Two methods of reversed-phase high performance liquid chromatography (RP-HPLC) were used to detect and quantify the degradation of 5-fluorouridine (CAS 316-46-1, 5-FUR) in aqueous solution. The 1H-NMR technique was used for identifying the degradation products. Several assays were performed from different aqueous solutions of 5-FUR. The best results (optimal resolution, reproducibility and rapidity) were achieved by using Resolve C-18 as stationary phase and a mix (96:4) of 50 mmol/l ammonium dihydrogen phosphate (adjusted to pH 3.5 with phosphoric acid) and acetonitrile as mobile phase. Despite the 5-FUR hydrolysis to 5-fluorouracil (5-FU) and D-ribose under moderate conditions in unlikely, due to high stability of the nucleoside, these were the identified degradation products in assays carried out.

Chromatography, High Pressure Liquid↗