1
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Timmers M, Weterings J, van Geijn M, Bell R, Lenting PE, Rijcken CJF, Vermonden T, Hennink WE, Liskamp RMJ. A New Class of Tunable Acid-Sensitive Linkers for Native Drug Release Based on the Trityl Protecting Group. Bioconjug Chem 2022; 33:1707-1715. [PMID: 35979909 PMCID: PMC9501768 DOI: 10.1021/acs.bioconjchem.2c00310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
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Core-cross-linked polymeric micelles (CCPMs) are a promising
nanoparticle
platform due to favorable properties such as their long circulation
and tumor disposition exploiting the enhanced permeability and retention
(EPR) effect. Sustained release of covalently linked drugs from the
hydrophobic core of the CCPM can be achieved by a biodegradable linker
that connects the drug and the core. This study investigates the suitability
of trityl-based linkers for the design of acid-triggered native active
pharmaceutical ingredient (API) release from CCPMs. Trityl linker
derivatives with different substituent patterns were synthesized and
conjugated to model API compounds such as DMXAA-amine, doxorubicin,
and gemcitabine, and their release kinetics were studied. Hereafter,
API release from CCPMs based on mPEG-b-pHPMAmLac block copolymers
was investigated. Variation of the trityl substitution pattern showed
tunability of the API release rate from the trityl-based linker with t1/2 varying from <1.0 to 5.0 h at pH 5.0
and t1/2 from 6.5 to >24 h at pH 7.4,
all at 37 °C. A clear difference in release kinetics was found
between gemcitabine and doxorubicin, with gemcitabine showing no detectable
release for 72 h at pH 5.0 and doxorubicin showing a t1/2 of less than 1 h. Based on these findings, we show
that the reaction mechanism of trityl deprotection plays an important
role in the API release kinetics. The first step in this mechanism,
which is protonation of the trityl-bound amine, is pKa-dependent,
which explains the difference in release rate. In conclusion, acid-sensitive
and tunable trityl linkers are highly promising for the design of
linker–API conjugates and for their use in CCPMs.
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Affiliation(s)
- Matt Timmers
- Cristal Therapeutics, Maastricht 6229 EV, The Netherlands.,Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht 3584 CG, The Netherlands
| | | | | | - Roel Bell
- Symeres, Nijmegen 6546 BB, The Netherlands
| | - Peter E Lenting
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K
| | | | - Tina Vermonden
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht 3584 CG, The Netherlands
| | - Wim E Hennink
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht 3584 CG, The Netherlands
| | - Rob M J Liskamp
- Cristal Therapeutics, Maastricht 6229 EV, The Netherlands.,School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.,Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht 6229 ER, The Netherlands
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2
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Le TN, Neralla VR. Evaluation of the best pH-sensitive linker using norbornene-derived polymers. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2020. [DOI: 10.1080/10601325.2020.1858717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Trong-Nghia Le
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan
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3
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Controlled release of silyl ether camptothecin from thiol-ene click chemistry-functionalized mesoporous silica nanoparticles. Acta Biomater 2017; 51:471-478. [PMID: 28131940 DOI: 10.1016/j.actbio.2017.01.062] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/12/2016] [Accepted: 01/23/2017] [Indexed: 01/31/2023]
Abstract
As efficient drug carriers, stimuli-responsive mesoporous silica nanoparticles are at the forefront of research on drug delivery systems. An acid-responsive system based on silyl ether has been applied to deliver a hybrid prodrug. Thiol-ene click chemistry has been successfully utilized for tethering this prodrug to mesoporous silica nanoparticles. Here, by altering the steric bulk of the substituent on the silicon atom, the release rate of a model drug, camptothecin, was controlled. The synthesized drug delivery system was investigated by analytical methods to confirm the functionalization and conjugation of the mesoporous silica nanoparticles. Herein, trimethyl silyl ether and triethyl silyl ether were selected to regulate the release rate. Under normal plasma conditions (pH 7.4), both types of camptothecin-loaded mesoporous silica nanoparticles (i.e., MSN-Me-CPT and MSN-Et-CPT) did not release the model drug. However, under in vitro acidic conditions (pH 4.0), based on a comparison of the release rates, camptothecin was released from MSN-Me-CPT more rapidly than from MSN-Et-CPT. To determine the biocompatibility of the modified mesoporous silica nanoparticles and the in vivo camptothecin uptake behavior, MTT assays with cancer cells and confocal microscopy observations were conducted, with positive results. These functionalized nanoparticles could be useful in clinical treatments requiring controlled drug release. STATEMENT OF SIGNIFICANCE As the release rate of drug from drug-carrier plays important role in therapy effects, trimethyl silyl ether (TMS) and triethyl silyl ether (TES) were selected as acid-sensitive silanes to control the release rates of model drugs conjugated from MSNs by thiol-ene click chemistry. The kinetic profiles of TMS and TES materials have been studied. At pH 4.0, the release of camptothecin from MSN-Et-CPT occurred after 2h, whereas MSN-Me-CPT showed immediate drug release. The results showed that silyl ether could be used to control release rates of drugs from MSNs under acid environment, which could be useful in clinical treatments requiring controlled drug release.
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4
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Abstract
This review summarizes pH-responsive monomers, polymers and their derivative nano- and micro-structures including micelles, cross-linked micelles, microgels and hydrogels.
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Affiliation(s)
- G. Kocak
- Department of Chemistry
- Faculty of Arts and Science
- Eskisehir Osmangazi University
- Eskisehir
- Turkey
| | - C. Tuncer
- Department of Chemistry
- Faculty of Arts and Science
- Eskisehir Osmangazi University
- Eskisehir
- Turkey
| | - V. Bütün
- Department of Chemistry
- Faculty of Arts and Science
- Eskisehir Osmangazi University
- Eskisehir
- Turkey
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5
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pH-responsive polymer–drug conjugates: Design and progress. J Control Release 2016; 222:116-29. [DOI: 10.1016/j.jconrel.2015.12.024] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 01/31/2023]
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6
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Jacques SA, Leriche G, Mosser M, Nothisen M, Muller CD, Remy JS, Wagner A. From solution to in-cell study of the chemical reactivity of acid sensitive functional groups: a rational approach towards improved cleavable linkers for biospecific endosomal release. Org Biomol Chem 2016; 14:4794-803. [DOI: 10.1039/c6ob00846a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
pH-Sensitive linkers designed to undergo selective hydrolysis at acidic pH compared to physiological pH can be used for the selective release of therapeutics at their site of action.
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Affiliation(s)
- Sylvain A. Jacques
- LFCS Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
| | - Geoffray Leriche
- LFCS Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
| | - Michel Mosser
- LFCS Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
| | - Marc Nothisen
- V-SAT Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
| | - Christian D. Muller
- Laboraroire d'Innovation Thérapeutique
- UMR 7200
- CNRS University of Strasbourg
- Faculty of Pharmacy
- 67400 Illkirch
| | - Jean-Serge Remy
- V-SAT Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
| | - Alain Wagner
- LFCS Laboratory
- CAMB UMR 7199 CNRS University of Strasbourg
- LabEx Medalis
- icFRC
- Faculty of Pharmacy
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7
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el Bahhaj F, Dekker FJ, Martinet N, Bertrand P. Delivery of epidrugs. Drug Discov Today 2014; 19:1337-52. [DOI: 10.1016/j.drudis.2014.03.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 02/28/2014] [Accepted: 03/19/2014] [Indexed: 12/22/2022]
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8
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Tong R, Tang L, Ma L, Tu C, Baumgartner R, Cheng J. Smart chemistry in polymeric nanomedicine. Chem Soc Rev 2014; 43:6982-7012. [DOI: 10.1039/c4cs00133h] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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9
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Delatouche R, Denis I, Grinda M, Bahhaj FE, Baucher E, Collette F, Héroguez V, Grégoire M, Blanquart C, Bertrand P. Design of pH responsive clickable prodrugs applied to histone deacetylase inhibitors: A new strategy for anticancer therapy. Eur J Pharm Biopharm 2013; 85:862-72. [DOI: 10.1016/j.ejpb.2013.03.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/21/2013] [Accepted: 03/01/2013] [Indexed: 12/31/2022]
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10
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Kim HK, Van den Bossche J, Hyun SH, Thompson DH. Acid-triggered release via dePEGylation of fusogenic liposomes mediated by heterobifunctional phenyl-substituted vinyl ethers with tunable pH-sensitivity. Bioconjug Chem 2012; 23:2071-7. [PMID: 22988941 DOI: 10.1021/bc300266y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A new family of heterobifunctional phenyl-substituted vinyl ether (PIVE) coupling agents with tunable acid-sensitivity has been developed. The PIVE compounds are designed to hydrolyze under acidic conditions with hydrolysis rates that can be varied by rational selection of the phenyl ring substituent. These reagents were incorporated within 2-methoxypoly(ethylene glycol) PEG-conjugated 1,3-dioctadecyl-rac-glycerol lipids to produce the acid-cleavable lipopolymers mPEG-[H-PIVE]-DOG, mPEG-[F-PIVE]-DOG, mPEG-[Me-PIVE]-DOG, and mPEG-[MeO-PIVE]-DOG. These lipopolymers were hydrolyzed under acidic conditions (pH 3.5 or 4.5) at rates that were dependent on the electron donating or withdrawing character of the α-phenyl vinyl ether substituent, while remaining stable at pH 7.4. Blending of these compounds with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in a 10:90 mPEG-PIVE-Lipid:DOPE ratio produced stable liposomes at neutral pH; however, acidification of the solution led to dePEGylation and release of the liposomal cargo in a manner that correlated with the PIVE proton affinity. Specifically, we observed 70% calcein release within 12 h from mPEG-[MeO-PIVE]-DOG-containing liposomes at pH 4.5, whereas only 22% calcein release was observed from mPEG-[F-PIVE]-DOG:DOPE liposomes over this same time scale and pH. These results indicate that dePEGylation following acidification is a triggering mechanism that can be rationally designed and controlled through the appropriate selection of PIVE moieties.
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Affiliation(s)
- Hee-Kwon Kim
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
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11
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Wang Y, Byrne JD, Napier ME, DeSimone JM. Engineering nanomedicines using stimuli-responsive biomaterials. Adv Drug Deliv Rev 2012; 64:1021-30. [PMID: 22266128 PMCID: PMC3422739 DOI: 10.1016/j.addr.2012.01.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 12/24/2011] [Accepted: 01/09/2012] [Indexed: 12/22/2022]
Abstract
The ability to engineer particles has the potential to shift the paradigm in the creation of new medicines and diagnostics. Complete control over particle characteristics, such as size, shape, mechanical property, and surface chemistry, can enable rapid translation and facilitate the US Food and Drug Administration (FDA) approval of particle technologies for the treatment of cancer, infectious diseases, diabetes, and a host of other major illnesses. The incorporation of natural and artificial external stimuli to trigger the release of drugs enables exquisite control over the release profiles of drugs in a given environment. In this article, we examine several readily scalable top-down methods for the fabrication of shape-specific particles that utilize stimuli-responsive biomaterials for controlled drug delivery. Special attention is given to Particle Replication In Nonwetting Templates (PRINT®) technology and the application of novel triggered-release synthetic and natural polymers.
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Affiliation(s)
- Yapei Wang
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - James D. Byrne
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Mary E. Napier
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Joseph M. DeSimone
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Institute for Nanomedicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Eschelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Institute for Advanced Materials, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
- Sloan-Kettering Institute for Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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12
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Parrott MC, Finniss M, Luft JC, Pandya A, Gullapalli A, Napier ME, DeSimone JM. Incorporation and controlled release of silyl ether prodrugs from PRINT nanoparticles. J Am Chem Soc 2012; 134:7978-82. [PMID: 22545784 PMCID: PMC3362319 DOI: 10.1021/ja301710z] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Asymmetric bifunctional silyl ether (ABS) prodrugs of chemotherapeutics were synthesized and incorporated within 200 nm × 200 nm particles. ABS prodrugs of gemcitabine were selected as model compounds because of the difficulty to encapsulate a water-soluble drug within a hydrogel. The resulting drug delivery systems were degraded under acidic conditions and were found to release only the parent or active drug. Furthermore, changing the steric bulk of the alkyl substituents on the silicon atom could regulate the rate of drug release and, therefore, the intracellular toxicity of the gemcitabine-loaded particles. This yielded a family of novel nanoparticles that could be tuned to release drug over the course of hours, days, or months.
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Affiliation(s)
- Matthew C Parrott
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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13
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Cleavable linkers in chemical biology. Bioorg Med Chem 2012; 20:571-82. [DOI: 10.1016/j.bmc.2011.07.048] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 07/08/2011] [Accepted: 07/23/2011] [Indexed: 01/11/2023]
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14
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Mondon M, Delatouche R, Bachmann C, Frapper G, Len C, Bertrand P. Triazolyl Derivatives for Acidic Release of Alcohols. European J Org Chem 2011. [DOI: 10.1002/ejoc.201001677] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Delatouche R, Mondon M, Gil A, Frapper G, Bachmann C, Bertrand P. Novel triazolyl derivatives for acidic release of amines. Tetrahedron 2011. [DOI: 10.1016/j.tet.2010.11.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Parrott MC, Luft JC, Byrne JD, Fain JH, Napier ME, Desimone JM. Tunable bifunctional silyl ether cross-linkers for the design of acid-sensitive biomaterials. J Am Chem Soc 2010; 132:17928-32. [PMID: 21105720 DOI: 10.1021/ja108568g] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Responsive polymeric biomaterials can be triggered to degrade using localized environments found in vivo. A limited number of biomaterials provide precise control over the rate of degradation and the release rate of entrapped cargo and yield a material that is intrinsically nontoxic. In this work, we designed nontoxic acid-sensitive biomaterials based on silyl ether chemistry. A host of silyl ether cross-linkers were synthesized and molded into relevant medical devices, including Trojan horse particles, sutures, and stents. The resulting devices were engineered to degrade under acidic conditions known to exist in tumor tissue, inflammatory tissue, and diseased cells. The implementation of silyl ether chemistry gave precise control over the rate of degradation and afforded devices that could degrade over the course of hours, days, weeks, or months, depending upon the steric bulk around the silicon atom. These novel materials could be useful for numerous biomedical applications, including drug delivery, tissue repair, and general surgery.
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Affiliation(s)
- Matthew C Parrott
- Departments of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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17
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Luong A, Issarapanichkit T, Kong SD, Fong R, Yang J. pH-Sensitive, N-ethoxybenzylimidazole (NEBI) bifunctional crosslinkers enable triggered release of therapeutics from drug delivery carriers. Org Biomol Chem 2010; 8:5105-9. [PMID: 20820656 DOI: 10.1039/c0ob00228c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This paper presents a pH-sensitive bifunctional crosslinker that enables facile conjugation of small molecule therapeutics to macromolecular carriers for use in drug delivery systems. This N-ethoxybenzylimidazole (NEBI) bifunctional crosslinker was designed to exploit mildly acidic, subcellular environments to trigger the release of therapeutics upon internalization in cells. We demonstrate that an analog of doxorubicin (a representative example of an anticancer therapeutic) conjugated to human serum albumin (HSA, a representative example of a macromolecular carrier) via this NEBI crosslinker can internalize and localize into acidic lysosomes of ovarian cancer cells. Fluorescence imaging and cell viability studies demonstrate that the HSA-NEBI-doxorubicin conjugate exhibited improved uptake and cytotoxic activity compared to the unconjugated doxorubicin analog. The pH-sensitive NEBI group was also shown to be relatively stable to biologically-relevant metal Lewis acids and to serum proteins, supporting that these bifunctional crosslinkers may be useful for constructing drug delivery systems that will be stable in biological fluids such as blood.
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Affiliation(s)
- Alice Luong
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, CA 92093-0358, USA
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18
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Abstract
Liposomal nanocarriers anchored with a cell-penetrating peptide and a pH-sensitive PEG-shield where later has ability to provide simultaneously better systemic circulation and site-specific exposure of cell penetrating peptide. PEG chains were incorporated into the liposome membrane via the PEG-attached phosphatidylethanolamine (PE) residue with PEG and PE being conjugated with the lowered pH-degradable hydrazone bond (PEG-HZ-PE), while cell-penetrating peptide (TATp) was added as TATp-PEG-PE conjugate. Under normal conditions, liposome-grafted PEG "shielded" liposome-attached TATp moieties, since the PEG spacer for TATp attachment (PEG(1000)) was shorter than protective PEG(2000). PEGylated liposomes accumulate in targets via the EPR effect, but inside the "acidified" tumor or ischemic tissues lose their PEG coating because of the lowered pH-induced hydrolysis of HZ and penetrate inside cells via the now-exposed TATp moieties. pH-responsive behavior of these constructs is successfully tested in cell cultures in vitro as well as in tumors in experimental mice in vivo. These nanocarriers also showed enhanced pGFP transfection efficiency upon intratumoral administration in mice, compared to control pH nonsensitive counterpart. These results can be considered as an important step in the development of tumor-specific stimuli-sensitive drug and gene delivery systems.
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Affiliation(s)
- Amit A Kale
- Department of Pharmaceutical Sciences, Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, MA, USA
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19
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Kale AA, Torchilin VP. Environment-Responsive Polymers for Coating of Pharmaceutical Nanocarriers(,). POLYMER SCIENCE SERIES A 2009; 51:730-737. [PMID: 23150741 DOI: 10.1134/s0965545x09060182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Polyethylene glycol derivatives, such as block copolymers of polyethylene glycol and diacyllipids (for example, phosphatidylethanolamine) are widely used for surface modification of various pharmaceutical carriers in order to impart them longevity in the body. To make polyethylene glycol detachable from the surface of pharmaceutical carrier and facilitate the interaction of the carrier with target cells when in pathological zone, we have prepared a set of polyethylene glycol-phosphatidylethanolamine block copolymers with the pH sensitive hydrazone bond between polyethylene glycol and phosphatidylethanolamine, which destabilizes at lowered pH values typical for tumors and inflammation zones. We have demonstrated that the stability of the hydrazone bond at normal physiological pH (7.4) as well as the rate of its hydrolysis at pH 6 and below strongly depend on the type of substitutions at this bond. Using aliphatic and aromatic aldehydes and ketones, polyethylene glycol-phosphatidylethanolamine block copolymers were prepared with different stabilities and degradation rates, which can be useful in constructing stimuli-sensitive pharmaceutical carriers.
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Affiliation(s)
- A A Kale
- Department of Pharmaceutical Sciences and Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, MA 02115, USA
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20
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Tang X, Pan C. Double hydrophilic block copolymers PEO‐b‐PGA: Synthesis, application as potential drug carrier and drug release via pH‐sensitive linkage. J Biomed Mater Res A 2008; 86:428-38. [DOI: 10.1002/jbm.a.31515] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Arimitsu S, Hammond GB. Selective Synthesis of Fluorinated Furan Derivatives via AgNO3-Catalyzed Activation of an Electronically Deficient Triple Bond. J Org Chem 2007; 72:8559-61. [PMID: 17910507 DOI: 10.1021/jo701616c] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transition metal-catalyzed direct activation of electron deficient triple bonds was investigated by using the combined electron withdrawing effects of two fluorine atoms to modulate the electronic density of the triple bond. With use of catalytic amounts of AgNO3 (10 mol %) the synthesis of substituted 3,3-difluoro-4,5-dihydrofurans from gem-difluorohomopropargyl alcohols occurred in excellent NMR yields. Treatment of these dihydrofurans with SiO2 or Pd/H2 yielded the corresponding 3-fluorinated furans and 3,3-difluorotetrahydrofurans.
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Affiliation(s)
- Satoru Arimitsu
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA
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22
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Kale AA, Torchilin VP. Design, synthesis, and characterization of pH-sensitive PEG-PE conjugates for stimuli-sensitive pharmaceutical nanocarriers: the effect of substitutes at the hydrazone linkage on the ph stability of PEG-PE conjugates. Bioconjug Chem 2007; 18:363-70. [PMID: 17309227 PMCID: PMC2538438 DOI: 10.1021/bc060228x] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A set of aliphatic and aromatic aldehyde-derived hydrazone (HZ)-based acid-sensitive polyethylene glycol-phosphatidylethanolamine (PEG-PE) conjugates was synthesized and evaluated for their hydrolytic stability at neutral and slightly acidic pH values. The micelles formed by aliphatic aldehyde-based PEG-HZ-PE conjugates were found to be highly sensitive to mildly acidic pH and reasonably stable at physiologic pH, while those derived from aromatic aldehydes were highly stable at both pH values. The pH-sensitive PEG-PE conjugates with controlled pH sensitivity may find applications in biological stimuli-mediated drug targeting for building pharmaceutical nanocarriers capable of specific release of their cargo at certain pathological sites in the body (tumors, infarcts) or intracellular compartments (endosomes, cytoplasm) demonstrating decreased pH.
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Affiliation(s)
| | - Vladimir P. Torchilin
- * Corresponding author: Northeastern University, Mugar Building 312, 360 Huntington Ave, Boston, MA 02115, USA, Tel: 617 373 3206, Fax: 617 373 8886, E-mail:
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23
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Kong SD, Luong A, Manorek G, Howell SB, Yang J. Acidic hydrolysis of N-Ethoxybenzylimidazoles (NEBIs): potential applications as pH-sensitive linkers for drug delivery. Bioconjug Chem 2007; 18:293-6. [PMID: 17261055 PMCID: PMC3260555 DOI: 10.1021/bc060224s] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes the development of a new class of N-linked imidazoles as potential pH-sensitive, cleavable linkers for use in cancer drug delivery systems. Kinetic analysis of eight derivatives of N-ethoxybenzylimidazoles (NEBIs) showed that their rates of hydrolysis are accelerated in mild aqueous acidic solutions compared to in solutions at normal, physiological pH. Incorporation of electron donating or electron withdrawing substituents on the phenyl ring of the NEBI resulted in the ability to tune the rates of hydrolysis under mild acidic conditions with half-lives ranging from minutes to months. A derivative of NEBI carrying doxorubicin, a widely used anticancer agent, also showed an increased rate of hydrolysis under mild acid compared to that at normal physiological pH. The doxorubicin analogue resulting from hydrolysis from the NEBI exhibited good cytotoxic activity when exposed to human ovarian cancer cells. These results demonstrate a potentially useful, general strategy for conjugating a wide range of drugs to imidazole-containing delivery vessels via NEBI functionalities for controlled release of therapeutics for drug delivery applications.
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Affiliation(s)
- Seong Deok Kong
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla CA 92093-0358
| | - Alice Luong
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla CA 92093-0358
| | - Gerald Manorek
- Department of Medicine and the Rebecca and John Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, MC 0819, La Jolla, 92093
| | - Stephen B. Howell
- Department of Medicine and the Rebecca and John Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, MC 0819, La Jolla, 92093
| | - Jerry Yang
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla CA 92093-0358
- CORRESPONDING AUTHOR: Tel: 858-534-6006; Fax: 858-534-4554,
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24
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Abstract
An immunoconjugate of doxorubicin (adriamycin) and a tumor-specific monoclonal antibody, BR96-DOX (now SGN-15) targets chemotherapy to cells that express the LewisY antigen. This immunoconjugate is internalized into lysosomes in antigen-expressing cells, with release of free doxorubicin after hydrolysis of the acid-labile linker. We review our studies using BR96-DOX in a human small-cell lung carcinoma intracerebral xenograft model in nude rats. We have found that the immunoconjugate is effective against intracerebral tumors when delivery is enhanced with osmotic disruption of the blood-brain barrier (BBB). Enhanced delivery of BR96-DOX with BBB opening can work together with radiotherapy to increase antitumor efficacy, which is maximally effective if immunoconjugate is administered prior to radiotherapy. In heterogeneous brain tumors, enhanced delivery of BR96-DOX significantly reduced tumor volumes, but local release of doxorubicin by targeting antigen expressing cells shows modest cytotoxicity against adjacent non-expressor cells. Although BR96-DOX is not effective against glioma cells tested, it does provide a model for drug-immunoconjugate therapy of gliomas. Our studies in a rat brain tumor model point out the importance of optimized delivery, antigenic heterogeneity, and bystander effect for brain tumor therapy. We review additional studies of drug-mAb immunoconjugates pertinent to the treatment of gliomas.
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Affiliation(s)
- Leslie L Muldoon
- Department of Neurology, Oregon Health & Sciences University, Portland, OR 97201, USA.
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25
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King HD, Dubowchik GM, Mastalerz H, Willner D, Hofstead SJ, Firestone RA, Lasch SJ, Trail PA. Monoclonal antibody conjugates of doxorubicin prepared with branched peptide linkers: inhibition of aggregation by methoxytriethyleneglycol chains. J Med Chem 2002; 45:4336-43. [PMID: 12213074 DOI: 10.1021/jm020149g] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High mole ratio BR96 immunoconjugates were synthesized using branched peptide-doxorubicin linkers designed to liberate doxorubicin following antigen-specific internalization into lysosomes. However, these immunoconjugates are highly prone to noncovalent, dimeric aggregation. We hypothesize that this is due to (1) the hydrophobic nature of the peptides, (2) the loss of positive charge upon amide formation at the 3'-amino group of doxorubicin, and (3) the proximity of the peptide hydrophobic residues to form efficient intermolecular stacking interactions. By introducing a hydrophilic methoxytriethylene glycol chain onto the doxorubicin portion of the branched peptide linkers, aggregation has been eliminated or greatly reduced in the immunoconjugate products. The methoxytriethylene glycol chain was linked to the doxorubicin moiety of the linker via a hydrazone bond that is stable at pH 7 but hydrolyzes rapidly at pH 5 to release free drug. BR96 immunoconjugates synthesized from methoxytriethylene glycol-modified branched peptide-doxorubicin linkers are highly potent and immunospecific in vitro. The data suggest that the methoxytriethylene glycol chain hydrolyzes as designed upon antigen-specific internalization into tumor lysosomes in vitro, where enzymatic degradation of the peptide linker releases free doxorubicin.
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Affiliation(s)
- H Dalton King
- Bristol Myers Squibb Pharmaceutical Research Institute, 5 Research Parkway, Wallingford, CT 06492, USA.
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26
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Fischer PM, Zheleva DI. Liquid-phase peptide synthesis on polyethylene glycol (PEG) supports using strategies based on the 9-fluorenylmethoxycarbonyl amino protecting group: application of PEGylated peptides in biochemical assays. J Pept Sci 2002; 8:529-42. [PMID: 12371706 DOI: 10.1002/psc.413] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Stepwise synthetic assembly of polypeptide chains reversibly linked to polyethylene glycol represents a hybrid between traditional solution and solid-phase chemistries and combines the inherent advantages of both approaches. The technical simplicity and scalability of the liquid-phase peptide synthesis method renders it particularly attractive for multiple parallel syntheses, combinatorial approaches and the large-scale preparation of peptides. The versatile protection strategy based on the N alpha-fluorenylmethoxycarbonyl group commonly used in solid-phase peptide synthesis was adapted to the liquid-phase approach. Fluoride ions were used rather than the conventional organic base piperidine for the repetitive amino-deprotection step. Using a range of acid- and base-labile linkers between the polymer and the peptide, it was shown that free and fully side-chain protected peptides can be obtained using our version of the liquid-phase peptide synthesis method. Protocols for simultaneous multiple syntheses requiring a minimum of equipment are presented and the use of polyethylene glycol-bound peptides in biochemical binding and functional assay systems is demonstrated.
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27
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28
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Dubowchik GM, Walker MA. Receptor-mediated and enzyme-dependent targeting of cytotoxic anticancer drugs. Pharmacol Ther 1999; 83:67-123. [PMID: 10511457 DOI: 10.1016/s0163-7258(99)00018-2] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
This review is a survey of various approaches to targeting cytotoxic anticancer drugs to tumors primarily through biomolecules expressed by cancer cells or associated vasculature and stroma. These include monoclonal antibody immunoconjugates; enzyme prodrug therapies, such as antibody-directed enzyme prodrug therapy, gene-directed enzyme prodrug therapy, and bacterial-directed enzyme prodrug therapy; and metabolism-based therapies that seek to exploit increased tumor expression of, e.g., proteases, low-density lipoprotein receptors, hormones, and adhesion molecules. Following a discussion of factors that positively and negatively affect drug delivery to solid tumors, we concentrate on a mechanistic understanding of selective drug release or generation at the tumor site.
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Affiliation(s)
- G M Dubowchik
- Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492-7660, USA.
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