Avaliação do Potencial da Galactomanana de Caesalpinia pulcherrima Sulfatada no Controle da Antracnose em Mangas

Abstract

The present work aims at the sulfation of Caesalpinia pulcherrima galactomannan (GCP). Two methods were used for sulfation, one with the use of pyridine (Py), generating GCPS-O derivatives, and the another with use of N,N-dimethylformamide (DMF), generating derivatives (GCPS- P). Different amounts of chlorosulfonic acid (7 and 13 mL) were used seeking for an increase in the content of sulfate groups on the polysaccharide structure. The sulfation was confirmed by the appearance of an intense band at 1250 cm-1 in the absorption spectrum in the infrared region. The gel permeation chromatography revealed that GCPS-O7 preserved the same order magnitude of peak molar mass of the GCP. The others had masses reduced up to 100 times. After sulfation, zeta potential becomes more negative, indicating an increase of sulfate groups. The 1H NMR spectra show that the ratio mannose: galactose increased to sulfated derivatives, indicating that during sulfation reaction occurred output galactose units of polysaccharide structure. The sulphation performed with Py resulted in a degree of sulfation greater than 1.7 times that occurred in DMF. However it is reasonable to search for improving the reaction with DMF, because pyridine as well as being more toxic has very unpleasant odor. Antimicrobial tests showed that the sulfated galactomannan presented no antifungal activity, but the unmodified galactomannan expressed fungistatic effect against Colletotrichum sp. In view of these results a more detailed investigation of the antifungal activity of galactomannan Caesalpinia pulcherrima is necessary, because this effect was unusual.