Chemically sulfated galactomannan from Dimorphandra gardneriana seed: characterization and toxicity evaluation

Abstract

Dimorphandra gardneriana galactomannan (DG) was sulfated in pyridine:formamide using chlorosulfonic acid as the sulfation agent. The degree of substitution was 0.32, determined from the sulfur percentage. Confirmation of sulfation was obtained by FTIR spectroscopy through the presence of an asymmetrical SO stretching vibration at 1,259 cm(-1). NMR data showed that the sulfation occurred on primary hydroxyl groups. NMR and GPC data indicate degradation during reaction with elimination of galactose. At the maximum tested concentration of 1,000 μg/mL, unmodified DG polysaccharide did not show a statistically significant cytotoxicity in Vero cells by the MTT method. Therefore, the CC50>1,000 μg/mL obtained for the sulfated polysaccharides from D. gardneriana in Vero cells point to its lower cytotoxicity than the sulfated galactomannan from Mimosa scabrella.

Keywords: Cytotoxicity; Dimorphandra gardneriana; Galactomannan; NMR; Sulfation.