Carboximetilação de (1→6)-β-D-glucana: influência da concentração do agente derivatizante sobre o grau de substituição da molécula

Abstract

The world market for polysaccharides has attracted large industrial companies interested in gaining new and profitable fields of activity. Polysaccharides with technological and biological properties can be obtained from plants, algae and microorganisms. Among the polysaccharides for industrial applications there are the β-glucans, which are polysaccharides that exhibit biological properties as antitumor, antioxidant, anticoagulant, antiviral and antithrombotic activities. The bioactivity of polysaccharides is related to the molecular weight and the chemical and conformational structure of the molecule. Changes in the molecule structure, such as the introduction of chemical groups, can affect the biological activity and their intensity. In this context, in the present work lasiodiplodan, a (1→6)-β-D-glucan, was produced by submerged fermentation and obtained carboxymethylated derivatives. Three carboxymethylated derivatives were obtained through controlled reaction using three massic relationship between lasiodiplodan and monochloroacetic acid (1: 5, 1: 6.5 and 1: 8). FTIR analysis showed typical signs of polysaccharides in the region between 4000 cm-1 and 400 cm-1. The β-glycosidic linkage was confirmed by weak absorption bands in the region of 890 cm-1. Strong absorption band in the region 1604 cm-1 (COO) and 1421 cm-1 (-COO-) resulting from the asymmetric and symmetric stretching vibrations of COO-, respectively, indicated carboxymethylation of the biopolymer. The obtained products showed substitution degree of 0.47, 0.51 and 0.58, respectively. The carboxymethylation contributes to the increased solubility of the biopolymer, being obtained derived with solubility between 9 to 10 mg / mL.