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Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats.

Lakshminarayanan R, Sridhar R, Loh XJ, Nandhakumar M, Barathi VA, Kalaipriya M, Kwan JL, Liu SP, Beuerman RW, Ramakrishna S - Int J Nanomedicine (2014)

Bottom Line: Terbinafine-loaded mats were effective against three filamentous fungal species.Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains.As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes.

View Article: PubMed Central - PubMed

Affiliation: Singapore Eye Research Institute, Singapore ; Signature Research Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore.

ABSTRACT
Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections.

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Interaction between polyene antifungals and gelatin probed by circular dichroism spectropolarimetry and rheological studies. (A) Far ultraviolet circular dichroism spectropolarimetry of gelatin and gelatin incubated with polyene antifungals at 30°C. Thermal denaturation of gelatin in the presence of (B) amphotericin B and (C) natamycin. The concentration of antifungals was 0.25 wt% with respect to gelatin. (D) Frequency sweep of storage modulus (G′) of gelatin and antifungal-loaded gelatin.Abbreviation: AmpB, amphotericin B.
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f8-ijn-9-2439: Interaction between polyene antifungals and gelatin probed by circular dichroism spectropolarimetry and rheological studies. (A) Far ultraviolet circular dichroism spectropolarimetry of gelatin and gelatin incubated with polyene antifungals at 30°C. Thermal denaturation of gelatin in the presence of (B) amphotericin B and (C) natamycin. The concentration of antifungals was 0.25 wt% with respect to gelatin. (D) Frequency sweep of storage modulus (G′) of gelatin and antifungal-loaded gelatin.Abbreviation: AmpB, amphotericin B.

Mentions: Since the fiber diameter of gelatin mats was doubled in the presence of polyene-loaded antifungals, the interaction between antifungals and gelatin was investigated using spectroscopy and rheometry. First, the changes in secondary structure of gelatin were monitored by CD spectropolarimetry. Figure 8A depicts the changes in the secondary structure of the gelatin solution and gelatin upon incubation with 0.25 wt% amphotericin B and natamycin. The CD spectra of gelatin showed a strong negative trough around 197 nm and no broad positive band in the n-π* region (Figure 8A). However, gelatin incubated with natamycin and amphotericin B displayed a strong maximum in the n-π* region (Figure 8A). The positive maximum was more pronounced for natamycin compared to amphotericin B. The presence of a positive band around 225 nm is a hallmark for triple helical structure associated with collagen.39,40 Using the equation reported by Fujitsu et al, the relative helical content ([C]rel) of gelatin in the presence of polyenes was estimated.41 Positive or negative (C)rel indicates increased or decreased triple helical content, respectively. (C)rel at 10°C for amphotericin B- and natamycin-loaded gelatin was 0.8 and 2.4, respectively, indicating greater stability of triple helix structure in the presence of natamycin.


Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats.

Lakshminarayanan R, Sridhar R, Loh XJ, Nandhakumar M, Barathi VA, Kalaipriya M, Kwan JL, Liu SP, Beuerman RW, Ramakrishna S - Int J Nanomedicine (2014)

Interaction between polyene antifungals and gelatin probed by circular dichroism spectropolarimetry and rheological studies. (A) Far ultraviolet circular dichroism spectropolarimetry of gelatin and gelatin incubated with polyene antifungals at 30°C. Thermal denaturation of gelatin in the presence of (B) amphotericin B and (C) natamycin. The concentration of antifungals was 0.25 wt% with respect to gelatin. (D) Frequency sweep of storage modulus (G′) of gelatin and antifungal-loaded gelatin.Abbreviation: AmpB, amphotericin B.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043707&req=5

f8-ijn-9-2439: Interaction between polyene antifungals and gelatin probed by circular dichroism spectropolarimetry and rheological studies. (A) Far ultraviolet circular dichroism spectropolarimetry of gelatin and gelatin incubated with polyene antifungals at 30°C. Thermal denaturation of gelatin in the presence of (B) amphotericin B and (C) natamycin. The concentration of antifungals was 0.25 wt% with respect to gelatin. (D) Frequency sweep of storage modulus (G′) of gelatin and antifungal-loaded gelatin.Abbreviation: AmpB, amphotericin B.
Mentions: Since the fiber diameter of gelatin mats was doubled in the presence of polyene-loaded antifungals, the interaction between antifungals and gelatin was investigated using spectroscopy and rheometry. First, the changes in secondary structure of gelatin were monitored by CD spectropolarimetry. Figure 8A depicts the changes in the secondary structure of the gelatin solution and gelatin upon incubation with 0.25 wt% amphotericin B and natamycin. The CD spectra of gelatin showed a strong negative trough around 197 nm and no broad positive band in the n-π* region (Figure 8A). However, gelatin incubated with natamycin and amphotericin B displayed a strong maximum in the n-π* region (Figure 8A). The positive maximum was more pronounced for natamycin compared to amphotericin B. The presence of a positive band around 225 nm is a hallmark for triple helical structure associated with collagen.39,40 Using the equation reported by Fujitsu et al, the relative helical content ([C]rel) of gelatin in the presence of polyenes was estimated.41 Positive or negative (C)rel indicates increased or decreased triple helical content, respectively. (C)rel at 10°C for amphotericin B- and natamycin-loaded gelatin was 0.8 and 2.4, respectively, indicating greater stability of triple helix structure in the presence of natamycin.

Bottom Line: Terbinafine-loaded mats were effective against three filamentous fungal species.Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains.As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes.

View Article: PubMed Central - PubMed

Affiliation: Singapore Eye Research Institute, Singapore ; Signature Research Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore.

ABSTRACT
Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections.

Show MeSH
Related in: MedlinePlus