Physicochemical properties, preliminary characterization, and assessment of potential bioactivities of polysaccharide purified from the leaves of Avicennia marina

A low molecular weight polysaccharide, the AMLP was isolated from the leaves of Avicennia marina and sequentially purified using DEAE-Sepharose fast flow and size exclusion chromatography. Monosaccharide analysis suggested that AMLP is mainly composed of fucose (38.34 %), galactose (30.16 %), mannose (13.32 %), and rhamnose (18.18 %). IR spectroscopy and High-performance size-exclusion chromatography (HPSEC) analysis revealed that AMLP was a sulfated homogenous heteropolysaccharide, and their molecular weight observed was 1.31 kDa. The Spectroscopic analysis of AMLP comprised of (1,2)- alpha-L-Fucp, (1,6)-beta-D-linked galactan, alpha-rhamnose, and (1,4)-beta-D mannose residues. AMLP has a loosely arranged granular bead-like appearance present on the surface and also with the presence of some porous structures. The rheological properties of AMLP exhibited pseudoplastic properties with shear-thinning flow behavior. Congo red test and X-ray diffraction (XRD) results indicated the semi-crystalline nature of AMLP with a triple-helical structure. Thermogravimetric and Differential scanning calorimetry (TGA-DSC) analysis of AMLP found was thermally stable and its degradation temperature observed was 280 degrees C. Furthermore, AMLP exhibited potential antibacterial and antibiofilm properties against bacterial pathogens such as Listeria monocytogenes, Escherichia coli, Klebsiella pneumonia, Salmonella typhimurium, and Staphylococcus aureus. The In vitro antioxidant activities such as DPPH scavenging, Superoxide radical scavenging, OH radical scavenging, and reducing power activities of AMLP were evaluated and the results revealed that the tested antioxidant activities of AMLP were significantly (P < 0.05) increased with increasing the concentrations. Overall, these findings suggested that AMLP could be used as a potential candidate in pharmaceutical, cosmetics, and food industry applications.

Automated summary

AMLP, a low molecular weight polysaccharide isolated from Avicennia marina leaves, exhibits potential antibacterial and antioxidant properties, making it a promising candidate for applications in pharmaceutical, cosmetics, and food industries.