Cyclic and Linear Peptides Containing Tryptophan and Arginine Residues as Cell-Penetrating Peptides and Antifungal Agents

Author

Khushbu Bhakta, Chapman UniversityFollow

Date of Award

Spring 5-2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Pharmaceutical Sciences

First Advisor

Dr. Keykavous Parang

Second Advisor

Dr. Rakeshkumar Tiwari

Third Advisor

Dr. Aftab Ahmed

Abstract

Here, we synthesized a novel group of linear and cyclic amphiphilic peptides containing different sequences of arginine (R) and tryptophan (W) residues. The peptides included a class of cyclic peptides, [R3W3]2, [R3WRW]2, [RWW]4, [WRR]4, [RWRW3]2, and the corresponding linear peptides, (R3WRW)2, (RWW)4, (WRR)4, (RWRW3)2. The peptides were examined as potential molecular transporters and cell-penetrating peptides (CPPs), and their efficiency in delivering cell-impermeable compounds was compared with [WR]5. The peptides showed no significant cytotoxicity in different cell lines (MDA-MB-231, SK-OV-3, and HEK-293) at a concentration of 1 µM and after 3 h of incubation time. The uptake of fluorescence-labeled cargo molecules (F′-GpYEEI, F′-AMpYSSV, F′-siRNA, and F′-d4T) in the presence of the peptides was monitored in different cell lines (MDA-MB-231and SK-OV-3) with FACS. Among all the peptides, (RWRW3)2 showed the highest cellular uptake of F′-GpYEEI, indicating it can act as an effective molecular transporter. Confocal microscopy in MDA-MB-231 and SK-OV-3 cells showed the cellular uptake of F′-GpYEEI in the presence of (RWRW3)2 and the intercellular localization of fluorescence-labeled (RWRW3)2 [F′-(RWRW3)2] in the cytosol. The F′- (RWRW3)2 cellular uptake was found to be concentration- and time- dependent, as shown by flow cytometry in SK-OV-3 cells. Confocal microscopy and flow cytometry of F′-(RWRW3)2 in SK-OV-3 cells were examined alone and in the presence of different endocytosis inhibitors. The data showed that the cellular uptake of F′-(RWRW3)2 in the presence of chlorpromazine and methyl- β-cyclodextrin was reduced but not eliminated, indicating that both energy-dependent VI and energy-independent pathways contributed to the cellular uptake of F′-(RWRW3)2. This data indicates that (RWRW3)2 can be used as a cell-penetrating peptide and cargo transporter. Furthermore, the peptides were also evaluated against the fungi Candida albicans and Aspergillus fumigatus to determine the optimal sequence for antifungal activity. Linear and cyclic peptides showed minimum inhibitory concentrations (MIC) ranging from 6.25 to 50 µg/mL. Minimum Fungicidal concentration (MFC) values were 25 to 50 µg/ml against C. albicans and C. pararpsilosis. Among linear peptides, (WRR)4 showed the lowest MIC of 6.25 µg/ml against C. parapsilosis and 12.5 µg/mL against C. Albicans and A. fumigatus, respectively. Cyclic [R3WRW]2 showed a MIC of 12.5 µg/mL in three isolates, and cyclic [WRR]4 showed MIC values of 12.5, 6.25, and 25 µg/mL against C. Albicans, C. parapilosis, and A. fumigatus, respectively. These data indicate the potential of these peptides for further optimization as antifungal agents.

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Recommended Citation

Bhakta, K. Cyclic and Linear Peptides Containing Tryptophan and Arginine Residues as Cell-Penetrating Peptides and Antifungal Agents. [master’s thesis]. Irvine, CA: Chapman University; 2023. https://doi.org/10.36837/chapman.000466