Atividades de Iota-Carragenana hidrolisada: influência da massa molecular

Abstract

Carbohydrates have many applications in several areas, such as food and medical. Sulfated polysaccharides, due to their chemical structure, can be recognized by enzymes or receptors of animal and plant cells to trigger responses such as anticoagulant activity or plant growth and defense. The objective of this work was to demonstrate that the activity of the sulfated polysaccharide ι-carrageenan in animal or vegetable models is directly related to its molecular mass. For this, the acid hydrolysis of this polysaccharide was carried out at a concentration of 3% (m / v) in a reaction cell under shaking and with controlled temperature. A design was elaborated using the Software Statistica with 11 independent hydrolysis experiments for the study of two factors (HCl concentration - 40 to 90 ° C - and reaction temperature - 1 to 100 mM); two response (molecular mass and viscosity) were analyzed. The 11 hydrolysates and the intact polysaccharide were analyzed by Gel Permeation Chromatography and Rheometer. Tables with result ANOVA tables, mathematical models, response surfaces and contour curves for responses were generated. After analysis, two hydrolysates and the intact polysaccharide were selected for further assays. The selected samples were subjected to characterization tests: Fourier Transform Infrared Spectroscopy and Determination of soluble proteins. They were also analyzed for their activities: Cell cytotoxicity, Antioxidant activity in vitro, Anticoagulant activity in vitro (by the methods of activated partial thromboplastin time - APTT - and prothrombin time - PT), Tail bleeding time, Plant growth and defense. After analyzing the molecular masses and viscosity, samples with 123 and 14.1 KDa and the intact ι- carrageenan (1,700 KDa) were selected for subsequent assays. This selection was made due to test ι- carrageenan activities in different order of molecule sizes. The hydrolysis process did not generate changes in the products. The samples had good purity and were considered non-toxic. The hydrolysis of ι- carrageenan promoted a reduction in the antioxidant capacity of the hydrolyzate (64.05 ± 6.11%) in comparison with a whole ι- carrageenan (78.44 ± 8.95%). For the anticoagulant activity ATPP, the longest time of activity of the hydrolysates was 257.5 ± 8.1 s for the sample with 123 KDa at the concentration of 4.0 mg / mL while the intact ι- carrageenan presenting a time of 126,6 ± 19.6 s. An increase of 7.5 times in the normal clotting time was promoted in relation to intact ι- carrageenan, which promoted an increase of 3.7 s. All sources had no PT anticoagulant activity. The sample with 123 KDa was tested at the time of tail bleeding and showed bleeding tendency at 1.0 and 2.0 mg / kg. In the experiments with Vigna unguiculata plants, the sample with 123 KDa promoted an increase in leaf area (71.12 ± 9.31 cm2) compared to the control (57.22 ± 9.62 cm2). It was observed an increase in the height of plants treated with a sample with 14.1 KDa. The sample with 123 KDa promoted an increase in the fresh weight and moisture of the the plants (22.9 ± 3.73 and 20.7 ± 3.37 g, respectively) and did not change the dry mass in relation to the control. None of the samples was able to activate the defense system of V. unguiculata against the Cowpea severe mosaic virus.