Abstract
The chemical composition and some biological properties of four algae (Ulva rigida, Codium bursa, Cystoseira barbata, and Ceramium diaphanum) collected from the Gabes Gulf area (Tunisia) were examined. Ash (11.35–29.08% weight/dry weight [w/dw]) and total sugar (13.20–18.70% w/dw) were the most abundant contents in these algae. Protein contents were moderate (5.03–14.00% w/dw), with the red alga (C. diaphanum) having the highest value. Lipid contents were within the range mentioned for seaweeds (less than 3% w/dw). Saturated fatty acids occurring at the highest proportions were C16:0 (24.53–41.37%) and C12:0 (10.37–24.44%). The most abundant monounsaturated fatty acid was C18:1n-9 (21.74–54.22%), whereas the most abundant polyunsaturated fatty acid was C18:2n-6 (9.57–11.71%). Variations in chemical composition can be attributed to both environmental and genetic differences among species. All algal extracts displayed antibacterial activity against Escherichia coli and Staphylococcus simulans (inhibition diameter: 10–25 mm), antioxidant activity (radical scavenging activity: 0.8–23%), and anti-inflammatory activity (48–61% inhibition of the phospholipase A2 activity); therefore, the marine algae examined can be considered abundant resources of bioactive molecules.