Antifungal activity of carrageenan extracts from the red alga Chondracanthus teedei var. lusitanicus
2016
Soares, Fabiana | Fernandes, Chantal | Silva, Paulo | Pereira, Leonel | Gonçalves, Teresa
Carrageenans extracted from Chondracanthus teedei var. lusitanicus were studied in order to determine their potential antifungal activity. FTIR-ATR and FT-Raman spectroscopic analysis confirmed the presence of a hybrid kappa/iota carrageenan belonging to the gametophyte phase and a hybrid xi/theta carrageenan in the tetrasporophyte phase. Kappa/iota and xi/theta carrageenan induced the formation of swollen hyphal segments in Alternaria infectoria, upon exposure to 125 and 60 μg mL⁻¹, respectively. The observed phenotype was similar to those induced by antifungals targeting the fungal cell wall. When exposed to 87.5 μg mL⁻¹ of kappa/iota carrageenan, Aspergillus fumigatus hyphae became shortened and highly branched, a phenotype commonly observed in response to antifungals. These morphological alterations were associated with a decrease of the β-glucan content in A. infectoria after exposure to 150 μg mL⁻¹ of kappa/iota and to 100 μg mL⁻¹ of xi/theta carrageenan. On the other hand, the chitin cell wall content of A. fumigatus decreased significantly upon exposure to 150 μg mL⁻¹ of both extracts, which triggered an increase in the content of β-glucan. Overall, the present work shows that carrageenans extracted from C. teedei var. lusitanicus cause alterations on the A. fumigatus and A. infectoria cell walls, indicating a marked antifungal activity.
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