3 research outputs found
Hydrophobicity and Helicity Regulate the Antifungal Activity of 14-Helical β‑Peptides
<i>Candida albicans</i> is one of the most prevalent
fungal pathogens, causing both mucosal candidiasis and invasive candidemia.
Antimicrobial peptides (AMPs), part of the human innate immune system,
have been shown to exhibit antifungal activity but have not been effective
as pharmaceuticals because of low activity and selectivity in physiologically
relevant environments. Nevertheless, studies on α-peptide AMPs
have revealed key features that can be designed into more stable structures,
such as the 14-helix of β-peptide-based oligomers. Here, we
report on the ways in which two of those features, hydrophobicity
and helicity, govern the activity and selectivity of 14-helical β-peptides
against <i>C. albicans</i> and human red blood cells. Our
results reveal both antifungal activity and hemolysis to correlate
to hydrophobicity, with intermediate levels of hydrophobicity leading
to high antifungal activity and high selectivity toward <i>C.
albicans</i>. Helical structure-forming propensity further influenced
this window of selective antifungal activity, with more stable helical
structures eliciting specificity for <i>C. albicans</i> over
a broader range of hydrophobicity. Our findings also reveal cooperativity
between hydrophobicity and helicity in regulating antifungal activity
and specificity. The results of this study provide critical insight
into the ways in which hydrophobicity and helicity govern the activity
and specificity of AMPs and identify criteria that may be useful for
the design of potent and selective antifungal agents
Incorporation of β‑Amino Acids Enhances the Antifungal Activity and Selectivity of the Helical Antimicrobial Peptide Aurein 1.2
Antimicrobial
peptides (AMPs) are attractive antifungal drug candidates
because they kill microbes <i>via</i> membrane disruption
and are thus unlikely to provoke development of resistance. Low selectivity
for fungal vs human cells and instability in physiological environments
have limited the development of AMPs as therapeutics, but peptidomimetic
AMPs can overcome these obstacles and also provide useful insight
into AMP structure–function relationships. Here, we describe
antifungal peptidomimetic α/β-peptides templated on the
natural α-peptidic AMP aurein 1.2. These α/β-aurein
analogs fold into <i>i</i> → <i>i</i> +
4 H-bonded helices that present arrays of side chain functionality
in a manner virtually identical to that of aurein 1.2. By varying
charge, hydrophobicity, conformational stability, and α/β-amino
acid organization, we designed active and selective α/β-peptide
aurein analogs that exhibit minimum inhibitory concentrations (MIC)
against the opportunistic pathogen <i>Candida albicans</i> that are 4-fold lower than that of aurein 1.2 and elicit less than
5% hemolysis at the MIC. These α/β-aurein analogs are
promising candidates for development as antifungal therapeutics and
as tools to elucidate mechanisms of AMP activity and specificity
Intraluminal Release of an Antifungal β‑Peptide Enhances the Antifungal and Anti-Biofilm Activities of Multilayer-Coated Catheters in a Rat Model of Venous Catheter Infection
Candida albicans is the most prevalent
cause of hospital-acquired fungal infections and forms biofilms on
indwelling medical devices that are notoriously difficult to treat
or remove. We recently demonstrated that the colonization of C. albicans on the surfaces of catheter tube segments
can be reduced in vitro by coating them with polyelectrolyte multilayers
(PEMs) that release a potent antifungal β-peptide. Here, we
report on the impact of polymer structure and film composition on
both the inherent and β-peptide-mediated ability of PEM-coated
catheters to prevent or reduce the formation of C.
albicans biofilms in vitro and in vivo using a rat
model of central venous catheter infection. Coatings fabricated using
polysaccharide-based components [hyaluronic acid (HA) and chitosan
(CH)] and coatings fabricated using polypeptide-based components [poly-l-lysine (PLL) and poly-l-glutamic acid (PGA)] both
served as reservoirs for the loading and sustained release of β-peptide,
but differed substantially in loading and release profiles and in
their inherent antifungal properties (e.g., the ability to prevent
colonization and biofilm growth in the absence of β-peptide).
In particular, CH/HA films exhibited inherent antifungal and antibiofilm
behaviors in vitro and in vivo, a result we attribute to the incorporation
of CH, a weak polycation demonstrated to exhibit antimicrobial properties
in other contexts. The antifungal properties of both types of films
were improved substantially when β-peptide was incorporated.
Catheter segments coated with β-peptide-loaded CH/HA and PLL/PGA
films were both strongly antifungal against planktonic C. albicans and the formation of surface-associated
biofilms in vitro and in vivo. Our results demonstrate that PEM coatings
provide a useful platform for the design of new antifungal materials,
and suggest opportunities to design multifunctional or dual-action
platforms to prevent or reduce the severity of fungal infections in
applied biomedical contexts or other areas in which fungal biofilms
are endemic