The full quaternisation of DEAE-dextran was successfully attempted and an application of the quaternised product was suggested. Commercial DEAE-dextran was reacted with iodomethane at 60°C in the presence of NaOH. The raw product was purified by dialysis, during which the iodide ion was replaced by chloride. N-methylation and O-methylation resulted from the 1H NMR spectrum. A second methylation step produced no further changes in the molecule. Alkalimetry indicated the absence of amino groups in the methylated polymer molecule, thus testifying to a complete quaternisation. N-acetylcysteine (AcCy) was neutralised with the polymer in the hydroxide form, thus obtaining the methyl DEAE-dextran salt of AcCy (Me-DEAE-dextran/AcCy), whereby an ophthalmic formulation for the treatment of the Dry Eye Syndrome was prepared. For comparison, the neutral AcCy salt of commercial DEAE-dextran (DEAE-dextran/AcCy) was prepared. The AcCy content in Me-DEAE-dextran/AcCy was higher than in DEAE-dextran/AcCy (23 vs 13%), while the viscosity of a solution containing the salt concentration corresponding to the therapeutic AcCy concentration (4% w/v) was lower with the former compared to the latter salt (20.5 vs 23.9 mPa s). Both solutions were ipotonic (245 mOsm/kg) and nonirritant in rabbit eyes, whereas the commercial Tirocular is strongly hypertonic (900 mOsm/kg) and irritant.
Methyl-DEAE-dextran: a candidate biomaterial
ZAMBITO, YLENIA;CARELLI, VERA;SERAFINI, MARIA FRANCESCA;DI COLO, GIACOMO
2004-01-01
Abstract
The full quaternisation of DEAE-dextran was successfully attempted and an application of the quaternised product was suggested. Commercial DEAE-dextran was reacted with iodomethane at 60°C in the presence of NaOH. The raw product was purified by dialysis, during which the iodide ion was replaced by chloride. N-methylation and O-methylation resulted from the 1H NMR spectrum. A second methylation step produced no further changes in the molecule. Alkalimetry indicated the absence of amino groups in the methylated polymer molecule, thus testifying to a complete quaternisation. N-acetylcysteine (AcCy) was neutralised with the polymer in the hydroxide form, thus obtaining the methyl DEAE-dextran salt of AcCy (Me-DEAE-dextran/AcCy), whereby an ophthalmic formulation for the treatment of the Dry Eye Syndrome was prepared. For comparison, the neutral AcCy salt of commercial DEAE-dextran (DEAE-dextran/AcCy) was prepared. The AcCy content in Me-DEAE-dextran/AcCy was higher than in DEAE-dextran/AcCy (23 vs 13%), while the viscosity of a solution containing the salt concentration corresponding to the therapeutic AcCy concentration (4% w/v) was lower with the former compared to the latter salt (20.5 vs 23.9 mPa s). Both solutions were ipotonic (245 mOsm/kg) and nonirritant in rabbit eyes, whereas the commercial Tirocular is strongly hypertonic (900 mOsm/kg) and irritant.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
