Basidiomycetous yeasts
Cryptococcus humicola and
Pseudozyma fusiformata secrete cellobiose lipids into the culture broth. In the case of
Cr.
humicola, 16-(tetra-O-acetyl-β-cellobiosyloxy)-2-hydroxyhexadecanoic acid was defined as major product and 16-(tetra-O-acetyl-β-cellobiosyloxy)-2,15-dihydrohexadecanoic acid was defined as minor product, while
Ps.
fusiformata secreted mainly 16-[6-O-acetyl-2’-O-(3-hydroxyhexanoyl)-β-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid. These compounds exhibit similar fungicidal activities against different yeasts including pathogenic
Cryptococcus and
Candida species. The cells of
Filobasidiella neoformans causing systemic cryptococcosis completely died after 30-min incubation with 0.02 mg mL
-1 of cellobiose lipids. The same effect on ascomycetous yeast, including pathogenic
Candida species, is achieved at 0.1-0.3 mg mL
-1 of cellobiose lipids depending on the test culture used. Cellobiose lipid of
Ps.
fusiformata inhibits the growth of phytopathogenic fungi
Sclerotinia sclerotiorum and
Phomopsis helianthi more efficiently than cellobiose lipids from
Cr.
humicola. Fully O-deacylated analogue, namely16-(β-cellobiosyloxy)-2-hydroxyhexadecanoic acid, and totally synthetic compound, 16-(β-cellobiosyloxy)-hexadecanoic acid, do not inhibit the growth of
F.
neoformans and
Saccharomyces cerevisiae, while 16-(β-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid inhibits the growth of both test cultures but at higher concentrations than cellobiose lipids of
Cr.
humicola and
Ps.
fusiformata. The amide of 16-(β-cellobiosyloxy)-2,15-dihydroxyhexadecanoic acid possessed no fungicide activity. Thus, the structures of both the carbohydrate part and fatty acid aglycon moiety are important for the fungicidal activity of cellobiose lipids.
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