Isolation and chemical characteristics of rhamnose enriched polysaccharide from Grateloupia lithophila.

The crude polysaccharide was extracted from Grateloupia lithophila through hot-water extraction and deproteinization. Further, fractionated by anion-exchange column using Q-Sepharose and purified by gel-permeation chromatography using Sepharose 4-LB column. The crude and purified polysaccharide contains high carbohydrate (75.7 and 89.7%), ash (18.2 and 3.2%) and moisture (14.8 and 1.3%); the protein and uronic acid were absent. The molecular weight of crude, fractionated and purified polysaccharide was found to be 37 kDa, 29 kDa and 24 kDa. The monosaccharide composition of the crude polysaccharide was found to be having rhamnose (79.82%), fructose (8.38%), galactose (3.95%), xylose (3.31%) and glucose (1.48%); whereas the purified polysaccharide reported higher amount of rhamnose (95.88%), 1.13% of xylose and 2.21% of fructose. The structural elucidation of the purified polysaccharide was conformed as α-l-rhamnose through polarimetry, FT-IR and 1H NMR spectroscopy.

Characterization, antimicrobial and antioxidant property of exopolysaccharide mediated silver nanoparticles synthesized by Streptomyces violaceus MM72.

Green synthesis of silver nanoparticle (SNPs) has gained considerable attention in nano-biotechnology and nano-medicine owing their potency and eco-friendliness. In this, we account the exopolysaccharide and its mediated synthesis of SNPs and their biological activities. Exopolysaccharide of the Streptomyces violaceus composed of total carbohydrate (61.4%), ash (16.1%), moisture content (1.8%) and NMR confirmed their structural composition. SNPs synthesized by the exopolysaccharide, confirmed using UV-vis spectral analysis and characterized by TEM and XRD analyses. Further, the SNPs evaluated for its antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis using disc diffusion method. The SNPs has shown promising antibacterial activity were evaluated for MIC. Furthermore, the SNPs were tested for antioxidant activities and was found to have promising antioxidant activity over the standards. The above results prove that SNPs can be considered as a potent antibacterial and antioxidant drug in future.