Influence of ascorbic acid on the stability of chitosan solutions

Radiochemical and biological evaluation of novel 153Sm/166Ho‐amino acid–chitosan complexes

“…As can be seen in Figure 2, the radical scavenger has slightly improved the stability of 153 Sm-CHICO, in agreement with the results previously described by Zoldners et al 24 The stability of this compound seems to be relatively dependent on the nature of the solution components. In acetic acid solutions, for example, Zoldners et al described that chitosan degrades with the formation of more water-soluble fragments along the time, as a result of oxidative and hydrolytic splitting of the polymer chains.…”

“…23 The increase stability of 153 Sm-CHICO in the presence of AA may be due to the effect of AA as a scavenger of possible radicalar species and/ or to the additional coordination capability of AA. 23,24 Regarding the 153 Sm/ 166 Ho-CHICO-amino acid complexes, the addition of AA (2% AA solution) has significantly affected its radiochemical behaviour. For compound 153 Sm/ 166 Ho-CHICO-val its stability enhanced significantly up to 24 h. In contrast, the addition of AA to 153 Sm/ 166 Ho-CHICO-asp resulted in a high degree of degradation of the initial complexes, with formation of several species.…”

“…Considering that ascorbic acid (AA), an antioxidant radical scavenger, is often used as a food additive or as a stabilizer in radiopharmaceutical compositions, 24,25 we have decided to evaluate the effect of this compound on the radiochemical stability of 153 Sm/ 166 Ho-chitosan derivatives and at the same time on 153 Sm/ 166 Ho-chitosan. As can be seen in Figure 2, the radical scavenger has slightly improved the stability of 153 Sm-CHICO, in agreement with the results previously described by Zoldners et al 24 The stability of this compound seems to be relatively dependent on the nature of the solution components.…”

“…In CHICO-val the structure is more compact and stable so another oxygen donor co-ligand may lead to a mixed-ligand complex, which will be anchored on the donor groups of the amino acids as well as on the AA, leading to the stabilization of the radiometal by a synergic effect. 24,26 Biodistribution of the 153 Sm-labelled complexes in mice…”

Is Chitosan a New Panacea? Areas of Application

“…Enzymatically, chitosan can be degraded by enzymes able to hydrolyse glucosamine-glucosamine, glucosamine-N-acetyl-glucosamine and N-acetyl-glucosamine-N-acetyl-glucosamine linkages [83]. Even though depolymerisation through oxidationreduction reaction [84] and free radical degradation [85] of chitosan have been reported these are unlikely to play a significant role in the in vivo degradation.…”