Quitooligosacáridos bifuncionales: relación entre características químico-físicas y propiedades biológicas

As the degraded products of chitosan, chitooligosaccharides (COS) have recently been produced by several methods, such as enzymatic an acidic hydrolysis. Chitosans are a family of biocompatible and biodegradable biopolymers obtained by N-deacetylation of chitin, the most abundant natural polymer after cellulose, consisting of two monomeric units, N-acetyl-2- amino-2-deoxi-D-glucose (A units) and 2-amino-2-deoxi-D-glucose (D units) linked by β (1→4) links. The degraded products COS, have a smaller molecular weight and therefore have better solubility and lower viscosity under physiological conditions because of shorter chain lengths and free amino groups in D-glucosamine units. The study of COS has been increasing not only because they come from a natural source, but also because of their biological compatibility and effectiveness. There are numerous reports on the biological activities of COS and their potential applications in food industry, pharmacy, agricultural or biomedicine. Nevertheless, in these studies it is difficult to find well defined COS in terms of physicochemical parametres, because these samples are usually poorly characterized. This makes it difficult to compare the results and to understand their mecanism of action. Degradation of the O-glycosidic linkages of chitosan by different methods, results in COS with different numbers and sequences of A and D units as well as different degrees of polymerisation (DP). Over the past few years, several technological approaches have been taken in preparing COS, including acid hydrolysis or enzymatic methods, among others. Therefore, in order to obtain COS with different physicochemical properties, different preparation methods of COS have been developed in this work. Then, the study of the relationship between physicochemical properties of these COS and their biological activities such as natural antioxidants, antibacterial agents, mucoadhesive and anti-inflammatory effects have been studied...