Characterization of exopolysaccharide produced from marine-derived Aspergillus terreus SEI with prominent biological activities

Abstract

Four fungal isolates were obtained from marine sediments collected from El-Max shore of Alexandria City, Egypt. The four isolates were screened for exopolysaccharide (EPS) production. The most promising isolate SEI that provided the highest EPS yield (4.98 g/L) was identified morphologically and genetically using 18S rRNA gene sequence analysis as Aspergillus terreus (A. terreus). Physio-chemical analysis using UV–Vis estimated the carbohydrate contents to be ~ 70.7%. As well, HPLC analysis indicated that it composed of O-glucosamine 59.2%, D-fucose 1.27%, D-glucose 0.88% and D-galactose 0.56%. Further, NMR showed the abundance of α-type monosaccharides over β-anomers, existed mainly in the pyranose form. The SEC estimated the molar mass (Mw-) to be ~ 5.0 x 104 g/mol. The SEM revealed irregular blocks-like structure with smooth surface. The anticoagulant activity of SEI-EPS was investigated for the first time using activated partial thromboplastin time (APTT) assay. The current results displayed that the SEI-EPS had successfully increased the APTT from 33 s to 56 s and 251 s at concentrations of 10 and 100 mg/mL, respectively. Moreover, SEI-EPS showed cytotoxic effects against breast cancer and human skin fibroblast cell lines (IC50 > 100 µg/mL and IC50 ~ 47 µg/mL, respectively). To the best of our knowledge, this is the first time to report the anticoagulant and cytotoxic activities of A. terreus EPS.