Structural characterizations and bioactivities of fucoidans from Dyctyopteris membranaceae and Padina pavonica with in silico investigations

Abstract

Fucoidans, a complex water-soluble sulfated polysaccharide is regarded as a valuable source of new drug development. The aim of this study was to characterize the chemical properties of fucoidans isolated from two brown algae Dyctyopteris membranaceae and Padina pavonica and to evaluate their anti-inflammatory, gastroprotective, antioxidant and immunomodulatory activities. The characterization of fucoidans was investigated with colorimetric techniques and Fourier transform infrared spectroscopy. The different macromolecular characteristics of fucoidans were determined by size exclusion chromatography. The immunomodulatory activity was evaluated using cytometric bead array technology to follow up the secretion of TNF-α in lipopolysaccharide activated THP-1 cells. The antioxidant effect was determined using the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The anti-inflammatory activity was evaluated using the carrageenan-induced rat paw edema model. The gastroprotective activity was determined using HCl/EtOH induced gastric ulcers in rats. Pharmacokinetic and molecular docking analysis was conducted. As a result, only fucoidan from D. membranaceae showed an effect on the synthesis of TNF-α in THP-1 cells induced by LPS with IC₅₀ of 77 μg/mL. Fucoidans from both algae showed antioxidant properties with EC₅₀ of 0.2 mg/mL for fucoidan from D. membranaceae, and 0.21 mg/mL for fucoidan from P. pavonica. Furthermore, isolated fucoidans from D. membranaceae and P. pavonica showed important anti-inflammatory activity with percentages of inhibition of oedema of 75 % and 57 %, respectively, at dose of 50 mg/kg, associated with significant gastroprotective activity with percentages of ulcer inhibition of 97 % and 88 %, respectively, at the same dose. Docking study showed the reactivity of this fucoidans. The study highlights the potential pharmacological importance of D. membranaceae and P. pavonica as sources of natural compounds with biological activities.

Keywords: Anti-inflammatory; Antioxidant; Fucoidans; Immunomodulatory; Molecular docking.