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Molecules 2018, 23(7), 1536;

Efficient Intracellular Delivery of Cell-Impermeable Cargo Molecules by Peptides Containing Tryptophan and Histidine

Center for Targeted Drug Delivery, Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Harry and Diane Rinker Health Science Campus, Irvine, CA 92618, USA
Authors to whom correspondence should be addressed.
Received: 29 May 2018 / Revised: 21 June 2018 / Accepted: 25 June 2018 / Published: 26 June 2018
(This article belongs to the Special Issue Cell-Penetrating Peptides (CPPs))
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We have previously evaluated and reported numerous classes of linear and cyclic peptides containing hydrophobic and hydrophilic segments for intracellular delivery of multiple molecular cargos. Herein, a combination of histidine and tryptophan amino acids were designed and evaluated for their efficiency in intracellular delivery of cell-impermeable phosphopeptides and the anti-HIV drug, emtricitabine. Two new decapeptides, with linear and cyclic natures, both containing alternate tryptophan and histidine residues, were synthesized using Fmoc/tBu solid-phase chemistry. The peptides were characterized and purified by using matrix-assisted laser desorption/ionization (MALDI) spectroscopy and high-performance liquid chromatography (HPLC), respectively. These peptides did not show significant toxicity up to 100 µM in ovarian cancer (SK-OV-3) and leukemia cancer (CCRF-CEM) cells. Furthermore, the cellular uptake of a fluorescence (F’)-labeled cell-impermeable phosphopeptide (F’-GpYEEI) was enhanced in the presence of linear (WH)5 and cyclic [WH]5 by 2- and 8-fold, respectively, compared to the uptake of the phosphopeptide alone. The cellular uptake was not significantly changed in the presence of endocytosis inhibitors. Furthermore, the intracellular uptake of the fluorescently-labeled anti-HIV drug, emtricitabine (F’-FTC), by linear (WH)5 and cyclic [WH]5 in SK-OV-3 cancer cell lines was found to be enhanced by 3.5- and 9-fold, respectively, compared to that of the drug alone. Fluorescent uptake experiments confirmed the localization of F’-GpYEEI-loaded cyclic [WH]5 intracellularly in the SK-OV-3 cancer cell line after 3 h of incubation. Thus, these data demonstrated that [WH]5 containing tryptophan and histidine enhanced the cellular uptake of F’-GpYEEI and emtricitabine. View Full-Text
Keywords: histidine; Peptide-based Drug Delivery Systems; phosphopeptides; tryptophan histidine; Peptide-based Drug Delivery Systems; phosphopeptides; tryptophan

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Shirazi, A.N.; Mozaffari, S.; Sherpa, R.T.; Tiwari, R.; Parang, K. Efficient Intracellular Delivery of Cell-Impermeable Cargo Molecules by Peptides Containing Tryptophan and Histidine. Molecules 2018, 23, 1536.

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