Extraction and bioautographic-guided separation of antibacterial compounds from Ulva lactuca

Tan, Shiau Pin and O'Sullivan, Laurie and Prieto, Maria Luz and Gardiner, Gillian E. and Lawlor, Peadar G. and Leonard, Frank and Duggan, Patrick and McLoughlin, Peter and Hughes, Helen (2012) Extraction and bioautographic-guided separation of antibacterial compounds from Ulva lactuca. Journal of Applied Phycology, 24 (3). pp. 513-523. ISSN 0921-8971

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Abstract

This study aimed to optimize an extraction and separation procedure to obtain a concentrated fraction with antibacterial activity from the macroalga Ulva lactuca. Antibacterial compounds were extracted using eight solvents, and consistent activity against Staphylococcus aureus, Bacillus subtilis and methicillin-resistant (MR) S. aureus was observed from a dilute (1:100, w/v) ethyl acetate extract. Seasonal analysis revealed that antibacterial activity was the lowest in spring/summer and the highest in autumn/winter. Bioautography was found to be a more appropriate assay compared to disc diffusion when screening crude extracts, as it separates the masking compounds from the antibacterial compounds and a direct assessment of the bands responsible for the antibacterial effect could be made. The antibacterial compounds were first separated from the crude extract using preparative thin-layer chromatography, followed by column chromatography to obtain a semi-pure sub-fraction. Using this approach, the antibacterial compounds were successfully concentrated from a crude extract (300 μg) to semi-pure fractions (6 μg) in which antibacterial activities were greatly enhanced. This study also revealed that prolonged storage (9 months) under a nitrogen atmosphere at -20°C resulted in a considerable increase in antibacterial activity. This is the first report of seasonal assessment of antibacterial compounds from seaweeds collected in Ireland. In addition, an antibacterial fraction was successfully isolated from U. lactuca which exhibited potent anti-MR S. aureus activity.

Item Type:	Article
Additional Information:	Funding Information: Acknowledgements The authors would like to thank the Higher Education Authority/Institutes of Technology Ireland Technological Sector Research Strand III Programme for funding this research.
Uncontrolled Keywords:	/dk/atira/pure/subjectarea/asjc/1100/1104
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Depositing User:	Admin SSL
Date Deposited:	19 Oct 2022 23:11
Last Modified:	07 Aug 2023 01:40
URI:	http://repository-testing.wit.ie/id/eprint/4539

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