Estudo químico estrutural e avaliação da toxicidade in vivo dos polissacarídeos sulfatados da rodofícea Cryptonemia crenulata (J. Agardh)

Abstract

Red seaweeds (rhodophytes) are natural sources of sulfated polysaccharides that have been attracting the interest of the pharmaceutical industry due to their various biological effects, many of them already described in the literature, such as antioxidant, anticoagulant, antiinflammatory, antidiarrheal and gastroprotective. This study aimed to isolate sulfated polysaccharides from the rhodophyte Cryptonemia crenulata (PS-Cc), characterize the chemical structure, and investigate acute toxicity in vivo and antioxidant activity in vitro. The PS-Cc obtained by enzymatic digestion with papain showed a degree of sulfation of 1.44 with an estimated molar mass of 3.18 x 105 g/mol. In addition, PS-Cc showed total carbohydrate content of 71.43% and levels of carbon (25.31%), sulfur (5.48%), and hydrogen (8.08%) through microanalysis. Structural characterization was performed by Fourier transform infrared spectroscopy (IVTF) and by Nuclear Magnetic Resonance (NMR) of proton ( 1H) and 13CDEPT 135, allowing to identify PS-Cc by hybrid D/L type galactanas. Acute toxicity assessment was performed in mice according to OECD (Organization for Economic Cooperation and Development) guideline 423 and through Hippocratic screening. In both tests, the animals were divided into a treated group, which received a single dose of 2000 mg/kg of PS-Cc, and a control group, which was monitored for 14 days. The animals did not show toxic signs related to the administration of the treatment, nor did they show important changes in body and organ weights. The treated group did not show significant changes in parameters related to liver function; albumin, ALT (alanine aminotransferase), AST (aspartate aminotransferase), and ALP (alkaline phosphatase), renal function (creatinine and urea), and glucose/lipid profile. Furthermore, the PS-Cc dosage did not induce any apparent adverse signs in autonomy, behavior, or general neurological profiles, nor did it cause death in any animal. The in vitro antioxidant activity of PS-Cc was evaluated through the 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging assay, ferrous ion chelating activity, and total antioxidant capacity, with respective results of 52.6%, 51.03% and 58.97%, which demonstrated a considerable antioxidant effect. The results suggest that PS-Cc had a non-toxic character and maybe a potential candidate to exert some type of biological activity.