Design and synthesis of chronic wound healing collagen peptide mimics
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Witwatersrand, Johannesburg
Abstract
The South African wound care management market is expecting a compound annual growth rate (CAGR) of 6.75%. The numbers are expected to further increase because South Africa has the highest number (4.6 million) of people living with diabetes in Africa. Annually approximately 2% of patients with diabetes develop diabetic foot ulcers and hence chronic wounds. Many chronic wound patients must deal with the financial burden, as many current wound treatment options are expensive, ineffective, and inconvenient.
Intervention in the form of synthetic collagen mimetic peptides has been limited due to cytotoxicity and susceptibility to protease degradation. These challenges have, for an ardent time affected the clinical and commercial development of synthetic wound healing peptides. The aim of the current study is to develop novel wound healing peptides by derivatizing bioactive peptides into selective and protease stable peptidomimetics. All the synthesized peptides are meant to mimic the function of collagen type I. Thus, the designed peptides comprise of the retro- integrin binding type I collagen motif, -GFOGER-, the DGD tripeptide for attraction of growth factors, the retro- tripeptides Thr-Thr-Lys (TTK), Gly-His-Lys (GHK), Gln-Pro-Arg (QPR) and Glu-Glu-Met (EEM) to stimulate collagen production.
The importance of collagen is evidenced by the fact that it features in all four stages of wound healing. This therefore means, its inclusion in any biomaterial meant to curb chronicity in wound healing is indispensable. With this approach, the biomaterial would overcome the challenge of excess matrix metalloproteinases (MMPs), which degrade both viable and nonviable collagen used in the wound healing process. It would further provide a collagen-based wound scaffold that compensates for the loss of collagen required for proper tissue regeneration. The applications of collagens in wound healing are immense. Due to its material
properties, and apparent effectiveness, collagen has the potential to be utilized as an unprecedented treatment protocol for chronic, slow-healing wounds.
Sixteen palmitate and adamantane collagen mimetic peptides were designed and successfully synthesized using the solid-phase peptide synthesis strategy. Eight of the sixteen peptidescomprise of lipophilic moieties (adamantane and palmitic acid) for improved membrane permeability and different collagen inducing retro-tripeptides namely, TTK, GHK, QPR and EEM (retro-DGD-GG-GFOGER-GG-TTK-Adamantane (NL010)/palmitate (NL009), retro-DGD- GG-GFOGER-GG-GHK-Adamantane/palmitate, retro-DGD-GG-GFOGER-GG-QPR- Adamantane/palmitate and retro-DGD-GG-GFOGER-GG-EEM-Adamantane/palmitate). Another eight are control peptides without the retro-tripeptides (retro-DGRGOF- Adamantane/palmitate, retro-GOP-GFOGER-GOP-Adamantane/palmitate, retro-GG- GFOGER-GG-Adamantane/palmitate and retro-DGD-GG-GFOGER-GG-Adamantane (NL008)/palmitate).
The tertiary structure and secondary features (folding patterns) of the peptides were determined using the Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD). From NMR experiments, medium-range couplings were detected for NL010 and NL009, suggesting a possibility of alpha helices. Temperature 1H NMR experiment for the peptide DGRGOF- Adamantane proved the presence of cis and trans geometric isomers. CD experiments revealed that NL009 mainly has α-helix while NL010 mainly consists of a parallel conformation.
Synthesis of adamantane and palmitate peptides with enhanced integrin binding was accomplished by incorporation of para-fluorophenylalanine in place of phenylalanine in the peptide retro-GG-GFOGER-GG-Adamantane/palmitate. The peptides were obtained in low yields but with increased hydrophobicity. Structural features for the improvement of the stability of the peptides against protease degradation were accomplished by the synthesis of peptoids and N-methylated peptides. The peptoids were synthesized in low yields but with increased hydrophobicity. The efficacy of NL009 and NL010 in wound healing was tested both in vitro and in vivo. In the former, the efficiency of both NL009 and NL010 in inducing migration of cells in a scratch wound was accentuated by hyaluronic acid. In in vivo studies, NL010 performed better than NL009. However, NL010 was outperformed by a comparator, Puramatrix® The peptides have the ability to induce migration of cells and therefore have an ability to create an environment needed for proper wound healing. The peptides could be used in place of native collagen and bring about proper healing of wounds
Description
A research report submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy to the Faculty of Science, School of Chemistry, University of the Witwatersrand, Johannesburg, 2024
Keywords
Collagen, Wound-healing, Peptides, Integrin, Amino acids, UCTD
Citation
Lesotho, Ntlama Francis. (2024). Design and synthesis of chronic wound healing collagen peptide mimics [Master’s dissertation, University of the Witwatersrand, Johannesburg]. WireDSpace.