Abstract
Biofilm formation and hyphal growth are considered to be the most serious virulence factors of Candida species in blood causing candidemia infections, which are difficult to treat due to the spread of resistant Candida isolates to most antifungal drugs. Therefore, in this study, we investigated the effect of different types and concentrations of selected macroalgal extracts from Cladostephus spongiosus (Phaeophyta), Laurencia papillosa (Rhodophyta), and Codium arabicum (Chlorophyta) in inhibiting those virulence factors of the isolated Candida. Acetone extract of C. spongiosus (AECS) showed a stronger anticandidal activity against the selected strains than ethanol extract. Candida krusei was the highest biofilm producer among the selected isolates. AECS showed an inhibition of C. krusei biofilm formation as well as a reduction in the viability of preformed biofilms. Also, AECS reduced various sugars in the candidal exo-polysaccaride layer (EPS). Scanning electron microscopy (SEM) and light microscopic images revealed an absence of hyphae and an alteration in the morphology of biofilm cells when treated with AECS. Moreover, AECS downregulated the expression of hyphal specific genes, hyphal wall protein 1 (HWP1), Agglutinin-like protein 1 (ALS1) and fourth secreted aspartyl proteinase (SAP4), which confirmed the inhibitory effect of AECS on hyphal growth and biofilm formation. Gas chromatography-mass spectrophotometer (GC-MS) analysis of AECS showed three major compounds, which were non-existent in the ethanol extract, and might be responsible for the anticandidal activity; these revealed compounds were 4-hydroxy-4-methyl-2-pentanone, n-hexadecenoic acid, and phenol, 2-methoxy-4-(2-propenyl). These active compounds of AECS may be promising for future pharmaceutical applications in the treatment of candidemia.
Highlights
Biofilm formation and hyphal growth are considered to be the most serious virulence factors of Candida species in blood causing candidemia infections, which are difficult to treat due to the spread of resistant Candida isolates to most antifungal drugs
Among different species of algae collected from the Red sea along the coastal region of Hurghada in Egypt, three species, namely, Cladostephus spongiosus, Laurencia papillosa, and Codium arabicum, were evaluated for their potential anticandidal activities
Further from the results obtained, it was observed that all the algal extracts prepared with acetone and ethanol could record higher inhibitory activities against the tested Candida compared to fluconazole, which did not show inhibitory activity at the same concentration of extracts (10 μg/ml)
Summary
Biofilm formation and hyphal growth are considered to be the most serious virulence factors of Candida species in blood causing candidemia infections, which are difficult to treat due to the spread of resistant Candida isolates to most antifungal drugs. Gas chromatography-mass spectrophotometer (GC-MS) analysis of AECS showed three major compounds, which were non-existent in the ethanol extract, and might be responsible for the anticandidal activity; these revealed compounds were 4-hydroxy-4-methyl-2-pentanone, n-hexadecenoic acid, and phenol, 2-methoxy-4-(2-propenyl). These active compounds of AECS may be promising for future pharmaceutical applications in the treatment of candidemia. Past screens have successfully identified compounds from some plant extracts that exhibit antifungal and antibiofilm activities against C. albicans such as purpurin, chyrsophanol and rhein[13,14,15,16]
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