1 research outputs found
Isolation, Structure, and Biological Activity of Phaeofungin, a Cyclic Lipodepsipeptide from a <i>Phaeosphaeria</i> sp. Using the Genome-Wide <i>Candida albicans</i> Fitness Test
Phaeofungin (<b>1</b>), a new cyclic depsipeptide
isolated
from <i>Phaeosphaeria</i> sp., was discovered by application
of reverse genetics technology, using the <i>Candida albicans</i> fitness test (<i>Ca</i>FT). Phaeofungin is comprised of
seven amino acids and a β,γ-dihydroxy-γ-methylhexadecanoic
acid arranged in a 25-membered cyclic depsipeptide. Five of the amino
acids were assigned with d-configurations. The structure
was elucidated by 2D-NMR and HRMS-MS analysis of the natural product
and its hydrolyzed linear peptide. The absolute configuration of the
amino acids was determined by Marfey’s method by complete and
partial hydrolysis of <b>1</b>. The <i>Ca</i>FT profile
of the phaeofungin-containing extract overlapped with that of phomafungin
(<b>3</b>), another structurally different cyclic lipodepsipeptide
isolated from a <i>Phoma</i> sp. using the same approach.
Comparative biological characterization further demonstrated that
these two fungal lipodepsipeptides are functionally distinct. While
phomafungin was potentiated by cyclosporin A (an inhibitor of the
calcineurin pathway), phaeofungin was synergized with aureobasidin
A (2) (an inhibitor of the sphingolipid biosynthesis) and to some
extent caspofungin (an inhibitor of glucan synthase). Furthermore,
phaeofungin caused ATP release in wild-type <i>C. albicans</i> strains but phomafungin did not. It showed modest antifungal activity
against <i>C. albicans</i> (MIC 16–32 μg/mL)
and better activity against <i>Aspergillus fumigatus</i> (MIC 8–16 μg/mL) and <i>Trichophyton mentagrophytes</i> (MIC 4 μg/mL). The linear peptide was inactive, suggesting
that the macrocyclic depsipeptide ring is essential for target engagement
and antifungal activity