Antibacterial and Antifungal Activities of Linear and Cyclic Peptides Containing Arginine, Tryptophan, and Diphenylalanine
<b>Background.</b> We have previously reported peptides composed of sequential arginine (R) residues paired with tryptophan (W) or 3,3-diphenyl-L-alanine residues (Dip), such as cyclic peptides [R<sub>4</sub>W<sub>4</sub>] and [R<sub>4</sub>(Dip)<su...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Antibiotics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-6382/14/1/82 |
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| Summary: | <b>Background.</b> We have previously reported peptides composed of sequential arginine (R) residues paired with tryptophan (W) or 3,3-diphenyl-L-alanine residues (Dip), such as cyclic peptides [R<sub>4</sub>W<sub>4</sub>] and [R<sub>4</sub>(Dip)<sub>3</sub>], as antibacterial agents. <b>Results.</b> Herein, we report antibacterial and antifungal activities of five linear peptides, namely ((DipR)<sub>4</sub>(WR)), ((DipR)<sub>3</sub>(WR)<sub>2</sub>), ((DipR)<sub>2</sub>(WR)<sub>3</sub>), ((DipR)(WR)<sub>4</sub>), and (DipR)<sub>4</sub>R, and five cyclic peptides [(DipR)<sub>4</sub>(WR)], [(DipR)<sub>3</sub>(WR)<sub>2</sub>], [(DipR)<sub>2</sub>(WR)<sub>3</sub>], [(DipR)(WR)<sub>4</sub>], and [DipR]<sub>5</sub>, containing alternate positively charged R and hydrophobic W and Dip residues against fungal, Gram-positive, and Gram-negative bacterial pathogens. The minimum inhibitory concentrations (MICs) of all peptides were determined by the micro-broth dilution method against <i>Methicillin-Resistant Staphylococcus aureus</i>, <i>Klebsiella pneumoniae</i>, <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli</i>, <i>Staphylococcus aureus</i>, <i>Enterococcus faecium</i>, <i>Enterococcus faecalis</i>, <i>Streptococcus pneumoniae</i>, and <i>Bacillus subtilis</i>. Fungal organisms were <i>Candida albicans</i>, <i>Candida parapsilosis</i>, and <i>Aspergillus fumigatus.</i> [DipR]<sub>5</sub> and ((DipR)<sub>2</sub>(WR)<sub>3</sub>) showed MIC values of 0.39–25 µM and 0.78–12.5 µM against Gram-positive and Gram-negative bacteria strains, respectively. The highest activity was observed against <i>S. pneumoniae</i> with MIC values of 0.39–0.78 µM among tested compounds. [DipR]<sub>5</sub> demonstrated MIC values of 6.6 µM against <i>C. parapsilosis</i> and 1.6 µM against <i>A. fumigatus</i>, whereas fluconazole showed MIC values of 3.3 µM and >209 µM, respectively. <b>Conclusions.</b> These findings highlight the potential of these peptides as broad-spectrum antimicrobial agents. |
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| ISSN: | 2079-6382 |