Abstract
Seaweeds are subject to numerous biological interactions and sometimes to extreme abiotic conditions, so they have developed among other defense mechanisms, the ability to produce biologically active substances. Thus, these organisms produce mainly terpenes and phenols. Among others, the antifungal activity, due to its importance in human and animal health and the production of agricultural products, has been the subject of several studies. In the present work, this activity was investigated in ten seaweeds extracts, by direct bioautography assays, compared to Colletotrichum lagenarium and disk diffusion assay, compared to Aspergillus flavus. The organisms studied were: Stypopodium zonale, Laurencia dendroidea, Ascophyllum nodosum, Sargassum muticum, Pelvetia canaliculata, Fucus spiralis, Sargassum filipendula, Sargassum stenophyllum, Laminaria hyperborea and Gracilaria edulis. S. zonale, L. dendroidea, P. canaliculata, S. muticum, A. nodosum and F. spiralis extracts significantly inhibited the C. lagenarium growth, but not inhibited significantly the A. flavus growth. The presence of terpenes in all of these extracts was confirmed by thin layer chromatography whereas the presence of phenolic compounds was confirmed only in extracts of P. canaliculata, A. nodosum and S. muticum. In chemical study by column chromatography, followed by gas chromatography/mass spectrometry analysis, the terpenes neophytadiene, cartilagineol, obtusol elatol; and the ester ethyl hexadecanoate were identified in the L. dendroidea extract. This is the first report on the activity of seaweed extracts against C. lagenarium, a fungus bearing agricultural importance.
Highlights
Seaweeds are prolific producers of biologically active compounds
The objective of this work was the search of fungicidal activity of Stypopodium zonale, Laurencia dendroidea, Pelvetia canaliculata, Sargassum muticum, Ascophyllum nodosum and Fucus spiralis extracts against C. lagenarium and A. flavus, and at establishing a relationship between this activity and the L. dendroidea terpenes
After removal of the solvent by evaporation under reduced pressure, the crude extracts were submitted to thin layer chromatography (TLC) on AL TLC 20X20 cm, silicagel 60 (Merck), eluted with hexane/ AcOEt (7:3) and evaluated by bioautography assay against C. lagenarium
Summary
Seaweeds are prolific producers of biologically active compounds Such an ability were developed as defense against numerous organisms which coexist and interact in the same complex environment (BLUNT et al, 2006). According to Smit (2004) the discovery of metabolites with biological activity from algae increased substantially in the last three decades These substances exhibit an appreciable number of distinct biological activities such as antitumoral, antiviral, antifungal, insecticidal, cytotoxic, phytotoxic, and antiproliferative actions (MACHADO et al, 2010, 2011; KLADI et al 2006; BHAKUNI; RAWAT, 2005). The majority of these compounds are terpenes and polyphenols (BLUNT et al, 2006). The red macroalgae (Rhodophyta) stands out as the major producer of halogenated compounds above the green and brown macroalgae groups
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