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Synthesis and Immunological Evaluation of Mannosylated Desmuramyl Dipeptides Modified by Lipophilic Triazole Substituents. Int J Mol Sci 2022; 23:ijms23158628. [PMID: 35955759 PMCID: PMC9368957 DOI: 10.3390/ijms23158628] [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] [Received: 07/12/2022] [Revised: 07/30/2022] [Accepted: 08/01/2022] [Indexed: 02/05/2023] Open
Abstract
Muramyl dipeptide (N-acetylmuramyl-L-alanyl-D-isoglutamine, MDP) is the smallest peptidoglycan fragment able to trigger an immune response by activating the NOD2 receptor. Structural modification of MDP can lead to analogues with improved immunostimulating properties. The aim of this work was to prepare mannosylated desmuramyl peptides (ManDMP) containing lipophilic triazole substituents to study their immunomodulating activities in vivo. The adjuvant activity of the prepared compounds was evaluated in the mouse model using ovalbumin as an antigen and compared to the MDP and referent adjuvant ManDMPTAd. The obtained results confirm that the α-position of D-isoGln is the best position for the attachment of lipophilic substituents, especially adamantylethyl triazole. Compound 6c exhibited the strongest adjuvant activity, comparable to the MDP and better than referent ManDMPTAd.
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Khan F, Khanam R, Wasim Qasim M, Wang Y, Jiang Z. Improved Synthesis of D‐Isoglutamine: Rapid Access to Desmuramyl Analogues of Muramyl Dipeptide for the Activation of Intracellular NOD2 Receptor and Vaccine Adjuvant Applications. European J Org Chem 2021. [DOI: 10.1002/ejoc.202101170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Farooq‐Ahmad Khan
- Third World Center (TWC) for Chemical Sciences International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
- H.E.J. Research Institute of Chemistry International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
| | - Rahila Khanam
- Third World Center (TWC) for Chemical Sciences International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
- H.E.J. Research Institute of Chemistry International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
| | - Muhammad Wasim Qasim
- Third World Center (TWC) for Chemical Sciences International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
- H.E.J. Research Institute of Chemistry International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
| | - Yan Wang
- H.E.J. Research Institute of Chemistry International Center for Chemical & Biological Sciences University of Karachi-75270 Pakistan
| | - Zi‐Hua Jiang
- Department of Chemistry Lakehead University 955 Oliver Rd Thunder Bay Ontario P7B 5E1 Canada
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Design, Synthesis, and Biological Evaluation of Desmuramyl Dipeptides Modified by Adamantyl-1,2,3-triazole. Molecules 2021; 26:molecules26216352. [PMID: 34770761 PMCID: PMC8587862 DOI: 10.3390/molecules26216352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/16/2021] [Accepted: 10/18/2021] [Indexed: 11/17/2022] Open
Abstract
Muramyl dipeptide (MDP) is the smallest peptidoglycan fragment able to trigger the immune response. Structural modification of MDP can lead to the preparation of analogs with improved immunostimulant properties, including desmuramyl peptides (DMPs). The aim of this work was to prepare the desmuramyl peptide (L-Ala-D-Glu)-containing adamantyl-triazole moiety and its mannosylated derivative in order to study their immunomodulatory activities in vivo. The adjuvant activity of the prepared compounds was evaluated in a murine model using ovalbumin as an antigen, and compared to the reference adjuvant ManAdDMP. The results showed that the introduction of the lipophilic adamantyl-triazole moiety at the C-terminus of L-Ala-D-Glu contributes to the immunostimulant activity of DMP, and that mannosylation of DMP modified with adamantyl-triazole causes the amplification of its immunostimulant activity.
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Manček-Keber M, Ribić R, Chain F, Sinnaeve D, Martins JC, Jerala R, Tomić S, Fehér K. Adamantane Containing Peptidoglycan Fragments Enhance RANTES and IL-6 Production in Lipopolysaccharide-Induced Macrophages. Molecules 2020; 25:molecules25163707. [PMID: 32823878 PMCID: PMC7465286 DOI: 10.3390/molecules25163707] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 07/08/2020] [Accepted: 08/06/2020] [Indexed: 11/24/2022] Open
Abstract
We report the enhancement of the lipopolysaccharide-induced immune response by adamantane containing peptidoglycan fragments in vitro. The immune stimulation was detected by Il-6 (interleukine 6) and RANTES (regulated on activation, normal T cell expressed and secreted) chemokine expression using cell assays on immortalized mouse bone-marrow derived macrophages. The most active compound was a α-D-mannosyl derivative of an adamantylated tripeptide with L-chirality at the adamantyl group attachment, whereby the mannose moiety assumed to target mannose receptors expressed on macrophage cell surfaces. The immune co-stimulatory effect was also influenced by the configuration of the adamantyl center, revealing the importance of specific molecular recognition event taking place with its receptor. The immunostimulating activities of these compounds were further enhanced upon their incorporation into lipid bilayers, which is likely related to the presence of the adamantyl group that helps anchor the peptidoglycan fragment into lipid nanoparticles. We concluded that the proposed adamantane containing peptidoglycan fragments act as co-stimulatory agents and are also suitable for the preparation of lipid nanoparticle-based delivery of peptidoglycan fragments.
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Affiliation(s)
- Mateja Manček-Keber
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia; (M.M.-K.); (R.J.)
- Centre of Excelence EN-FIST, SI-1000 Ljubljana, Slovenia
| | - Rosana Ribić
- University Center Varaždin, University North, Jurja Križanića 31b, HR-42 000 Varaždin, Croatia;
| | - Fernando Chain
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4, 9000 Ghent, Belgium; (F.C.); (D.S.); (J.C.M.)
| | - Davy Sinnaeve
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4, 9000 Ghent, Belgium; (F.C.); (D.S.); (J.C.M.)
- Univ. Lille, Inserm, Institut Pasteur de Lille, CHU Lille, U1167—Labex DISTALZ—RID-AGE—Risk Factors and Molecular Determinants of Aging-Related Diseases, F-59000 Lille, France
- CNRS, ERL9002—Integrative Structural Biology, F-59000 Lille, France
| | - José C. Martins
- Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4, 9000 Ghent, Belgium; (F.C.); (D.S.); (J.C.M.)
| | - Roman Jerala
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia; (M.M.-K.); (R.J.)
- Centre of Excelence EN-FIST, SI-1000 Ljubljana, Slovenia
| | - Srđanka Tomić
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102A, HR-10 000 Zagreb, Croatia;
| | - Krisztina Fehér
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
- Molecular Recognition and Interaction Research Group, Hungarian Academy of Sciences, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
- Correspondence: or ; Tel.: +36-52-512-900; Fax: +36-52-518-660
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Ribić R, Manček-Keber M, Chain F, Sinnaeve D, Martins JC, Jerala R, Tomić S, Fehér K. Targeted Delivery of Adamantylated Peptidoglycan Immunomodulators in Lipid Nanocarriers: NMR Shows That Cargo Fragments Are Available on the Surface. J Phys Chem B 2020; 124:4132-4145. [PMID: 32283934 DOI: 10.1021/acs.jpcb.0c00029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We present an in-depth investigation of the membrane interactions of peptidoglycan (PGN)-based immune adjuvants designed for lipid-based delivery systems using NMR spectroscopy. The derivatives contain a cargo peptidoglycan (PGN) dipeptide fragment and an adamantyl group, which serves as an anchor to the lipid bilayer. Furthermore, derivatives with a mannose group that can actively target cell surface receptors on immune cells are also studied. We showed that the targeting mannose group and the cargo PGN fragment are both available on the lipid bilayer surface, thereby enabling interactions with cognate receptors. We found that the nonmannosylated compounds are incorporated stronger into the lipid assemblies than the mannosylated ones, but the latter compounds penetrate deeper in the bilayer. This might be explained by stronger electrostatic interactions available for zwitterionic nonmannosylated derivatives as opposed to the compounds in which the charged N-terminus is capped by mannose groups. The higher incorporation efficiency of the nonmannosylated compounds correlated with a larger relative enhancement in immune stimulation activities upon lipid incorporation compared to that of the derivatives with the mannose group. The chirality of the adamantyl group also influenced the incorporation efficiency, which in turn correlated with membrane-associated conformations that affect possible intermolecular interactions with lipid molecules. These findings will help in improving the development of PGN-based immune adjuvants suitable for delivery in lipid nanoparticles.
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Affiliation(s)
- Rosana Ribić
- University Center Varaždin, University North, Jurja Križanića 31b, HR-42 000 Varaždin, Croatia.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Mateja Manček-Keber
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Fernando Chain
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Davy Sinnaeve
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium.,Univ. Lille, Inserm, Institut Pasteur de Lille, CHU Lille, U1167 - Labex DISTALZ - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, F-59000 Lille, France.,CNRS, ERL9002 - Integrative Structural Biology, F-59000 Lille, France
| | - José C Martins
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium
| | - Roman Jerala
- Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia
| | - Srđanka Tomić
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102A, HR-10 000 Zagreb, Croatia
| | - Krisztina Fehér
- Department of Organic and Macromolecular Chemistry, Ghent University, Campus Sterre S4, Krijgslaan 281, 9000 Ghent, Belgium.,Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Molecular Recognition and Interaction Research Group, Hungarian Academy of Sciences, Egyetem tér 1, H-4032 Debrecen, Hungary
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Leko K, Hanževački M, Brkljača Z, Pičuljan K, Ribić R, Požar J. Solvophobically Driven Complexation of Adamantyl Mannoside with β‐Cyclodextrin in Water and Structured Organic Solvents. Chemistry 2020; 26:5208-5219. [DOI: 10.1002/chem.202000282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Indexed: 01/20/2023]
Affiliation(s)
- Katarina Leko
- Department of ChemistryFaculty of ScienceUniversity of Zagreb Horvatovac 102a 10000 Zagreb Croatia
| | - Marko Hanževački
- Division of Physical ChemistryRuđer Bošković Institute Bijenička 54 10000 Zagreb Croatia
- Department of Chemical and Environmental EngineeringThe University of Nottingham University Park Nottingham NG7 2RD UK
| | - Zlatko Brkljača
- Division of Organic Chemistry and BiochemistryRuđer Bošković Institute Bijenička 54 10000 Zagreb Croatia
| | - Katarina Pičuljan
- Department of ChemistryFaculty of ScienceUniversity of Zagreb Horvatovac 102a 10000 Zagreb Croatia
| | - Rosana Ribić
- Department of ChemistryFaculty of ScienceUniversity of Zagreb Horvatovac 102a 10000 Zagreb Croatia
- University Center VaraždinUniversity North Jurja Križanića 31b 42000 Varaždin Croatia
| | - Josip Požar
- Department of ChemistryFaculty of ScienceUniversity of Zagreb Horvatovac 102a 10000 Zagreb Croatia
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7
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Ribić R, Stojković R, Milković L, Antica M, Cigler M, Tomić S. Design, synthesis and biological evaluation of immunostimulating mannosylated desmuramyl peptides. Beilstein J Org Chem 2019; 15:1805-1814. [PMID: 31467600 PMCID: PMC6693374 DOI: 10.3762/bjoc.15.174] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/11/2019] [Indexed: 12/28/2022] Open
Abstract
Muramyl dipeptide is the minimal structure of peptidoglycan with adjuvant properties. Replacement of the N-acetylmuramyl moiety and increase of lipophilicity are important approaches in the preparation of muramyl dipeptide analogues with improved pharmacological properties. Mannose receptors present on immunocompetent cells are pattern-recognition receptors and by mannose ligands binding they affect the immune system. Here we present the design, synthesis and biological evaluation of novel mannosylated desmuramyl peptide derivatives. Mannose was coupled to dipeptides containing a lipophilic adamantane on N- or C-terminus through a glycolyl or hydroxyisobutyryl linker. Adjuvant activities of synthesized compounds were investigated in the mouse model using ovalbumin as an antigen. Their activities were compared to the previously described mannosylated adamantane-containing desmuramyl peptide and peptidoglycan monomer. Tested compounds exhibited adjuvant activity and the strongest enhancement of IgG production was stimulated by compound 21 (Man-OCH2-ᴅ-(1-Ad)Gly-ʟ-Ala-ᴅ-isoGln).
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Affiliation(s)
- Rosana Ribić
- University Center Varaždin, University North, Jurja Križanića 31b, HR-42000 Varaždin, Croatia
| | - Ranko Stojković
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia
| | - Lidija Milković
- Ruđer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia
| | | | - Marko Cigler
- Department of Chemistry, Technical University Munich, Lichtenbergstraße 4, D-85748 Garching, Germany
| | - Srđanka Tomić
- Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia
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Petrović Peroković V, Car Ž, Opačak-Bernardi T, Martin-Kleiner I, Kralj M, Tomić S. In vitro antiproliferative study of novel adamantyl pyridin-4-ones. Mol Divers 2017; 21:881-891. [PMID: 28695468 DOI: 10.1007/s11030-017-9763-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/30/2017] [Indexed: 12/23/2022]
Abstract
The preparation of several N-aryl-substituted (phenyl, p-methylphenyl, p-methoxyphenyl, p-nitrophenyl, p-aminophenyl, p-hydroxyphenyl) 3-hydroxy-2-methylpyridin-4-ones as well as their adamantyl derivatives is described, and their in vitro antitumor properties were investigated. The compounds were synthesized in good yields using efficient synthetic routes and methods. Prepared derivatives were evaluated in an antiproliferative in vitro study on 4 cancer cell lines, namely HCT 116 (colon carcinoma), H 460 (lung carcinoma), MCF-7 (breast carcinoma) and K562 (chronic myelogenous leukemia). All tested compounds showed antiproliferative activity ranging from moderate to strong on all inspected cell lines with 4 adamantane containing derivatives being active and selective at low micromolar IC[Formula: see text] concentrations on HCT 116, H 460 and MCF-7. LDH cytotoxicity assay revealed that cytotoxic effects occur after 48 h of exposure. It was shown that there was no change in caspase activity in the treated cells, but there were changes in the cell cycle. All treated samples showed reduced number of cells in the S phase with increased G0/G1 (4b, 5a, 5b) and G2/M (4a) phase.
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Affiliation(s)
- V Petrović Peroković
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia.
| | - Ž Car
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - T Opačak-Bernardi
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, Cara Hadrijana 10/E, 31000, Osijek, Croatia
| | - I Martin-Kleiner
- Laboratory of Experimental Therapy, Division of Molecular Medicine, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - M Kralj
- Laboratory of Experimental Therapy, Division of Molecular Medicine, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - S Tomić
- Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
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Štimac A, Šekutor M, Mlinarić-Majerski K, Frkanec L, Frkanec R. Adamantane in Drug Delivery Systems and Surface Recognition. Molecules 2017; 22:molecules22020297. [PMID: 28212339 PMCID: PMC6155684 DOI: 10.3390/molecules22020297] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 01/19/2017] [Accepted: 02/11/2017] [Indexed: 11/30/2022] Open
Abstract
The adamantane moiety is widely applied in design and synthesis of new drug delivery systems and in surface recognition studies. This review focuses on liposomes, cyclodextrins, and dendrimers based on or incorporating adamantane derivatives. Our recent concept of adamantane as an anchor in the lipid bilayer of liposomes has promising applications in the field of targeted drug delivery and surface recognition. The results reported here encourage the development of novel adamantane-based structures and self-assembled supramolecular systems for basic chemical investigations as well as for biomedical application.
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Affiliation(s)
- Adela Štimac
- University of Zagreb, Centre for Research and Knowledge Transfer in Biotechnology, Rockefellerova 10, 10000 Zagreb, Croatia.
| | - Marina Šekutor
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Kata Mlinarić-Majerski
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Leo Frkanec
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Ruža Frkanec
- University of Zagreb, Centre for Research and Knowledge Transfer in Biotechnology, Rockefellerova 10, 10000 Zagreb, Croatia.
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Štimac A, Cvitaš JT, Frkanec L, Vugrek O, Frkanec R. Design and syntheses of mono and multivalent mannosyl-lipoconjugates for targeted liposomal drug delivery. Int J Pharm 2016; 511:44-56. [PMID: 27363934 DOI: 10.1016/j.ijpharm.2016.06.123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/23/2016] [Accepted: 06/26/2016] [Indexed: 12/21/2022]
Abstract
Multivalent mannosyl-lipoconjugates may be of interest for glycosylation of liposomes and targeted drug delivery because the mannose specifically binds to C-type lectin receptors on the particular cells. In this paper syntheses of two types of novel O-mannosides are presented. Conjugates 1 and 2 with a COOH- and NH2-functionalized spacer and the connection to a lysine and FmocNH-PEG-COOH, are described. The coupling reactions of prepared intermediates 6 and 4 with a PEGylated-DSPE or palmitic acid, respectively, are presented. Compounds 5, mono-, 8, di- and 12, tetravalent mannosyl-lipoconjugates, were synthesized. The synthesized compounds were incorporated into liposomes and liposomal preparations featuring exposed mannose units were characterized. Carbohydrate liposomal quartz crystal microbalance based assay has been established for studying carbohydrate-lectin binding. It was demonstrated that liposomes with incorporated mannosyl-lipoconjugates were effectively recognized by Con A and have great potential to be used for targeted liposomal drug delivery systems.
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Affiliation(s)
- Adela Štimac
- University of Zagreb, Centre for Research and Knowledge Transfer in Biotechnology, Rockefellerova 10, 10000 Zagreb, Croatia
| | | | - Leo Frkanec
- Institute Rudjer BoškoviĿ, BijeniĿka cesta 54, 10000 Zagreb, Croatia
| | - Oliver Vugrek
- Institute Rudjer BoškoviĿ, BijeniĿka cesta 54, 10000 Zagreb, Croatia
| | - Ruža Frkanec
- University of Zagreb, Centre for Research and Knowledge Transfer in Biotechnology, Rockefellerova 10, 10000 Zagreb, Croatia.
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Frkanec R, Vranešić B, Tomić S. Adamantoylated biologically active small peptides and glycopeptides structurally related to the bacterial peptidoglycan. Methods Mol Biol 2014; 1081:91-106. [PMID: 24014436 DOI: 10.1007/978-1-62703-652-8_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
A large number of novel synthetic compounds representing smaller parts of original peptidoglycan molecules have been synthesized and found to possess versatile biological activity, particularly immunomodulating properties. A series of compounds containing the adamantyl residues coupled to peptides and glycopeptides characteristic for bacterial peptidoglycan was described. The new adamantylpeptides and adamantylglycopeptides were prepared starting from N-protected racemic adamantylglycine and dipeptide L-Ala-D-isoglutamine. The adamantyl glycopeptides were obtained by coupling the adamantyltripeptides with alpha-D-mannose moiety through spacer molecule of fixed chirality. Since the starting material was D,L-(adamantyl-glycine) the condensation products with the dipeptide were mixtures of diastereoisomers. The obtained diastereoisomers were separated, characterized, and tested for immunostimulating activity. An HPLC method for purity testing was developed and adapted for the particular compounds.
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