Version 4: Characterization, and in vitro antibacterial activity of sulfated polysaccharides from freshwater algae Cladophora crispata

Barada River is characterized by an abundant growth of freshwater algae. Cladophora sp have been emerged as a new source of bioactive compounds, in this research Cladophora crispata was cultivated with the outdoor method, and algal Sulfated polysaccharides (SPs) were extracted by ultrasonic-assisted extraction method. After extraction, Gel filtration was used to purify the  crude SPs; SPs compounds were determined and selected, and the effect of purified SPs as antibacterial agents was investigated. the purified extract gave two fractions (F1 and F2). The chemical components of both crude and purified SPs were then determined. The highest carbohydrate content (74.12%) and protein content (4.02%) was found in the crude extract, while the highest sulfate content (12.17%) was found in purified fraction instead of F2, and the highest uronic acid content (18.46%) was found in purified fraction instead of F1. Fourier transforms infrared spectroscopy (FT-IR) was used to confirm that the crude extact and fractions consist of sugar, uronic acids, protein unite, and sulfate groups. Both F1 and F2 were consist of rhamnose, galactose, xylose, and ribose based on the High Performance Liquid Chromatography (HPLC) separation. Each fraction showed an inhibitory effect on the gram-positive and gram-negative bacteria. F2 has the lowest minimum Inhibition concentration (MIC) value against Staphylococcus aureus, Bacillus anthracis, Enterobacter aerogenes, and Pseudomonas aeroginosa; where its MIC values were 6,13,25 and 30 (mg/ml) respectively. Algae polysaccharides had the most important interest due to their antibacterial properties, which making them included in pharmaceutics and food applications.