Production and characterization of antimicrobial active substance from some macroalgae collected from Abu- Qir bay (Alexandria) Egypt

Abstract

The antimicrobial activity of three different macroalgal species [Jania rubens (Linnaeus) Lamouroux; Ulva fasciata Delile and Sargassum vulgare C. Agardh] belonging to Rhodophyta, Chlorophyta and Phaeophyceae, respectively, were collected seasonally in 2007 to 2008 from Abu-Qir bay (Alexandria, Egypt). The different macroalgal species were tested against pathogenic microbes such as Bacillus subtilis, Staphylococcus aureus and Streptococcus aureus as gram-positive bacteria, Escherichia coli, Salmonella typhi and Klebsiella pneumoniae as gram-negative bacteria and one yeast strain, Candida albicans. The influence of sampling season on the antimicrobial activity of the collected seaweeds showed strong activity in spring followed by winter, summer and autumn, respectively. However, the strongest antimicrobial activity was recorded in 70% acetone extract of U. fasciata collected during winter against all the tested microorganisms. This extract was purified using column chromatography (CC) and thin layer chromatography (TLC). The nature of this purified antimicrobial material was detected using different chemical analysis (UV, IR,¹H NMR and MS) which indicated that it is an aromatic compound and has different active groups (-NH₂, -C=O, -NO₂, phenyl ring and -CH₃). The molecular weight of the compound was determined (662) and its structure was characterized as a derivative of phthalate ester [(E)-1-(10-acetamido-2-nitrodec-9-enyl) 2-(10-acetamido-2-nitrodecyl) 4-methylphthalate]. This is the first evidence of the isolation of phthalate esters derivative from green seaweeds (U. fasciata) that has broad antimicrobial activity.

Key words: Antimicrobial, pathogenic microbes, season, seaweeds.