Antioxidant and antibacterial activities of <i>Cladophora glomerata</i> (L.) Kütz. in Caspian Sea Coast, Iran

Abstract

Cladophora is one of the largest filamentous green-algal genus and has a widespread distribution in Caspian Sea Coast. This study aimed at assaying the antimicrobial and antioxidant activities of Cladophora glomerata in South of Caspian sea. The antioxidant activity of the extract was investigated, including the total phenolic contents (3077 ± 105 mg gallic acid equivalent g-1 of extract), total flavonoid contents (595 ± 23 mg quercetin equivalent gl^-1 of extract), scavenging activity of 2,2-diphenyl-1- picrylhydrazyl (DPPH) radicals (920 ± 42 μg ml^-1 as IC₅₀ value), iron chelating activity (IC₅₀ = 971 ± 39 μg ml^-1), scavengers of nitric oxide (0.20 ± 0.01 mg ml-1 as IC₅₀) and reducing power. There were significant differences between the extract and vitamin C (P<0.001). Furthermore, antimicrobial activities of the hydroalcoholic extracts of five different gram negative and positive bacteria including Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhimurium and Proteus mirabilis were investigated. The extract was primarily screened for their possible antimicrobial effects using disc diffusion methods. The potential antibacterial activities at different concentrations of the extract were elucidated. The extract displayed a variable degree of antimicrobial activities on different bacteria. Among the gram positive bacteria, the S. aureus (with wider zones of inhibition) was found to be more sensitive than B. subtilis. Among the gram negative bacteria, Salmonella enteritidis was found to be more resistant than Proteus vulgaris. Our findings suggest the possibility of using the Cladophora glomerata as a novel source of natural antimicrobial and antioxidant agents for pharmaceutical industries.

Key words: Cladophora glomerata, antibacterial activity, antioxidant activity, flavonoid contents, phenolic contents.