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Ledvina M, Turský M, Veselý J, Tišlerová I, Trnka T. Synthesis of a New Type ofd-Mannosamine Glycosyl Donor and Acceptor and their Use for the Preparation of Oligosaccharides Consisting ofd-Mannosamine Units Linked by α(1→4)-Glycosidic Bonds. SYNTHESIS-STUTTGART 2008. [DOI: 10.1055/s-2008-1067197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Wang XF, Birringer M, Dong LF, Veprek P, Low P, Swettenham E, Stantic M, Yuan LH, Zobalova R, Wu K, Ledvina M, Ralph SJ, Neuzil J. A peptide conjugate of vitamin E succinate targets breast cancer cells with high ErbB2 expression. Cancer Res 2007; 67:3337-44. [PMID: 17409443 DOI: 10.1158/0008-5472.can-06-2480] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Overexpression of erbB2 is associated with resistance to apoptosis. We explored whether high level of erbB2 expression by cancer cells allows their targeting using an erbB2-binding peptide (LTVSPWY) attached to the proapoptotic alpha-tocopheryl succinate (alpha-TOS). Treating erbB2-low or erbB2-high cells with alpha-TOS induced similar levels of apoptosis, whereas alpha-TOS-LTVSPWY induced greater levels of apoptosis in erbB2-high cells. alpha-TOS rapidly accumulated in erbB2-high cells exposed to alpha-TOS-LTVSPWY. The extent of apoptosis induced in erbB2-high cells by alpha-TOS-LTVSPWY was suppressed by erbB2 RNA interference as well as by inhibition of either endocytotic or lysosomal function. alpha-TOS-LTVSPWY reduced erbB2-high breast carcinomas in FVB/N c-neu transgenic mice. We conclude that a conjugate of a peptide targeting alpha-TOS to erbB2-overexpressing cancer cells induces rapid apoptosis and efficiently suppresses erbB2-positive breast tumors.
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Turánek J, Ledvina M, Kasná A, Vacek A, Hríbalova V, Krejcí J, Miller AD. Liposomal preparations of muramyl glycopeptides as immunomodulators and adjuvants. Vaccine 2006; 24 Suppl 2:S2-90-1. [PMID: 16823942 DOI: 10.1016/j.vaccine.2005.01.137] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The need for safe and structurally defined immunomodulators and adjuvants is increasing in connection with the recently observed marked increase in the prevalence of pathological conditions characterized by immunodeficiency. Important groups of such compounds are muramyl glycopeptides, analogs of muramyl dipeptide (MDP), glucosaminyl-muramyl dipeptide (GMDP), and desmuramylpeptides. We have designed and synthesized new types of analogs with changes in both the sugar and the peptide parts of the molecule that show a high immunostimulating and adjuvant activity and suppressed adverse side effects. The introduction of lipophilic residues has also improved their incorporation into liposomes, which represent a suitable drug carrier. The proliposome-liposome method is based on the conversion of the initial proliposome preparation into liposome dispersion by dilution with the aqueous phase. The description of a home-made stirred thermostated cell and its link-up with a liquid delivery system for a rapid and automated preparation of multilamellar liposomes at strictly controlled conditions (sterility, temperature, dilution rate and schedule) is presented. The cell has been designed for laboratory-scale preparation of liposomes (300-1000 mg of phospholipid per run) in a procedure taking less than 90 min. The method can be readily scaled up. Examples of adjuvant and immunostimulatory effect of liposomal preparation in mice model will be presented.
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Ledvina M, Veselý J, Rohlenová A, Džoganová M, Trnka T, Tišlerová I, Šaman D. Preparation of Ethyl 2-Azido-2-deoxy-1-thio-β-d-mannopyranosides, and their Rearrangement to 2-S-Ethyl-2-thio-β-d-mannopyranosylamines. SYNTHESIS-STUTTGART 2006. [DOI: 10.1055/s-2006-926297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Turánek J, Kasná A, Koudela B, Ledvina M, Miller AD. Stimulation of innate immunity in newborn kids againstCryptosporidium parvuminfection-challenge by intranasal/per-oral administration of liposomal formulation of N-L18-norAbu-GMDP adjuvant. Parasitology 2005; 131:601-8. [PMID: 16255818 DOI: 10.1017/s0031182005007924] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 12/21/2004] [Accepted: 03/15/2005] [Indexed: 11/07/2022]
Abstract
The effects of a liposomal preparation of lipophilic immunomodulator β-D-GlcNstearoyl-(1-4)-norMurNAc-L-Abu-D-isoGln (N-L18-norAbu-GMDP) were investigated on resistance toCryptosporidium parvuminfection in neonatal kids. The liposomal preparation was administered subcutaneously or intranasally/orally (i.n./p.o.) twice at doses of 100 μg, 200 μg, or 1000 μg per kid pre-infection challenge. The treatment schemes were (i) 72 and 24 h pre-infection challenge, (ii) 24 h pre-infection challenge and 24 h post-infection challenge (oral inoculation with 1×107oocysts ofC. parvumin 5 ml of PBS). Administration of liposomal N-L18-norAbu-GMDP by i.n./p.o. route at the cumulative dose of 2000 μg per kid 72 and 24 h pre-infection challenge, lead to substantially increased clearance of coccidian parasites from various parts of the intestine. On the basis of histological examination, the distribution of cryptosporidia in the intestine and the severity of the infection, treated kids were classified on day 5 as having a strong reduction in infection in comparison to the control group (P<0·05). No cryptosporidia were found on the mucosal surface of treated kids by day 10, while the intestines of the control kids were still infected. All doses and routes of administration were judged effective with respect to suppression of cryptosporidia infections.
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Veselý J, Ledvina M, Jindřich J, Trnka T, Šaman D. Synthesis of 2-Amino-2-deoxy-β-D-galactopyranosyl-(1→4)-2-amino-2-deoxy-β-D-galactopyranosides: Using Various 2-Deoxy-2-phthalimido-D-galactopyranosyl Donors and Acceptors. ACTA ACUST UNITED AC 2004. [DOI: 10.1135/cccc20041914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A systematic study is presented of the efficiency of the most common glycosylation methods using standard 2-deoxy-2-phthalimidogalactopyranosyl donors ethyl 4-O-acetyl-3,6-di-O- benzyl-2-deoxy-2-phthalimido-1-thio-β-D-galactopyranoside (3a), 4-O-Acetyl-3,6-di-O-benzyl- 2-deoxy-2-phthalimido-β-D-galactopyranosyl bromide (4), 4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-D-galactopyranosyl fluoride (5b), O-(4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-D-galactopyranosyl) trichloroacetimidate (7) and ethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-galactopyranoside (8), pent-4-enyl 3,6-di-O-benzyl- and 3-O-allyl-6-O-benzyl-2-deoxy-2-phthalimido-β-D-galactopyranoside (10a) and (10b) and pent-4-enyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-4-O-(trimethylsilyl)-β-D-galactopyranoside (11) as glycosyl acceptors in the synthesis of 2-amino-2-deoxy-β-D-galactopyranosyl-(1→4)-2-amino-2-deoxy-β-D-galactopyranosides 12, 16a and 17a. It was found that due to a low reactivity of the axial OH(4) group of glycosyl acceptors, disaccharides 16b and 17b with α(1→4) bond were also formed. The unexpected intermolecular migration of ethylsufanyl group from the reducing end of glycosyl acceptor 8 the reducing end of the activated form of glycosyl donor 4 in the glycosylation step to give ethylsulfanyl derivative 3a was proved. For preparation of the glycosyl donors and glycosyl acceptors with galacto configuration an approach based on epimerization of 4-O-mesyl derivatives of appropriate synthons with gluco configuration 2a and 2b was employed.
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Rohlenová A, Ledvina M, Šaman D, Bezouška K. Synthesis of Linear and Branched Regioisomeric Chitooligosaccharides as Potential Mimetics of Natural Oligosaccharide Ligands of Natural Killer Cells NKR-P1 and CD69 Lectin Receptors. ACTA ACUST UNITED AC 2004. [DOI: 10.1135/cccc20041781] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Regioisomer of chitobiose13with β(1→3) glycosidic bond and branched analog of chitotriose25having β(1→4) and β(1→3) glycosidic bonds, were prepared and tested as potential mimetics of natural oligosaccharide ligands for activating lectin receptors NKR-P1A and CD69 of natural killer (NK) cells. The structural requirements of NKR-P1 lectin receptor on effective mimetics of its natural ligands has been discussed. A significant binding activity of the branched trisaccharide25to the receptor CD69 was observed.
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Veselý J, Ledvina M, Jindřich J, Šaman D, Trnka T. Improved Synthesis of 1,2-trans-Acetates and 1,2-trans Ethyl 1-Thioglycosides Derived from 3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-D-hexopyranosides. ACTA ACUST UNITED AC 2003. [DOI: 10.1135/cccc20031264] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Effective one-pot synthesis of 1,2-trans-acetates 4b, 5b and 6a derived from N-phthaloyl-protected D-glucosamine, D-galactosamine and D-mannosamine, respectively, is presented. Anomerisation of the corresponding 1,2-cis-acetates 4a, 5a and 6b and direct conversion of all of them to 1,2-trans ethyl 1-thioglycosides 7, 8 and 9 are also described and discussed.
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Ježek J, Velek J, Vepřek P, Velková V, Trnka T, Pecka J, Ledvina M, Vondrášek J, Písačka M. Solid phase synthesis of glycopeptide dendrimers with Tn antigenic structure and their biological activities. Part I. J Pept Sci 1999. [DOI: 10.1002/(sici)1099-1387(199901)5:1<46::aid-psc179>3.0.co;2-c] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ledvina M, Rigney ED. The thin electrolyte layer approach to corrosion testing of dental materials--characterization of the technique. Biomaterials 1998; 19:2201-7. [PMID: 9884061 DOI: 10.1016/s0142-9612(98)00129-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
An innovative technique for corrosion testing of metallic dental materials is introduced. The thin electrolyte layer technique (TET) simulates the physical characteristics of the oral environment by employing a still, thin layer of an electrolyte, in contrast to bulk electrolyte techniques (BET) which utilize relatively large quantities of fluid. Limiting current density tests on a platinum electrode revealed a lower surface oxygen content for TET. Borate buffer (pH 6.8) was employed as an electrolyte. The effect of lower oxygen content in TET on passivation and polarization characteristics of 316L SS in 0.9% saline was investigated. The results revealed differences in the polarization resistance and open circuit potential development with time, as well as in anodic and cathodic polarization behavior. Lower O2 concentration in TET was attributed to different electrolyte convection characteristics under both testing conditions. Additionally, use of the TET resulted in better data reproducibility. Overall, this investigation led to a deeper understanding of the electrochemical processes inherent in thin electrolytes such as those found in the oral environment.
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Ledvina M, Zyka D, Ježek J, Trnka T, Šaman D. New Effective Synthesis of (N-Acetyl- and N-Stearoyl-2-amino-2-deoxy-β-D-glucopyranosyl)-(1→4)-N-acetylnormuramoyl-L-2-aminobutanoyl-D-isoglutamine, Analogs of GMDP with Immunopotentiating Activity. ACTA ACUST UNITED AC 1998. [DOI: 10.1135/cccc19980577] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Ethyl 3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (5), prepared by benzylation of ethyl 2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (4), was transformed by reaction with bromine into 3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl bromide (6). Thioglycoside 5 in the presence of methyl triflate and glycosylbromide 6 in the presence of silver triflate were used as glycosyl donors for condensation with benzyl 2-acetamido-3-O-allyl-6-O-benzyl-2-deoxy-α-D-glucopyranoside (7), to give benzyl 2-acetamido-3-O-allyl-6-O-benzyl-4-O-(3,4,6-tri-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl)-2-deoxy-α-D-glucopyranoside (8). Its reductive dephthaloylation with NaBH4/AcOH afforded benzyl 2-acetamido-3-O-allyl-4-O-(2-amino-3,4,6-tri-O-benzyl-2-deoxy-β-D-glucopyranosyl)- 6-O-benzyl-2-deoxy-α-D-glucopyranoside (11). Compound 11 was N-acylated to give benzyl 2-acetamido-4-O-(2-acylamino-3,4,6-tri-O-benzyl-2-deoxy-β-D-glucopyranosyl)-3-O-allyl-6-O-benzyl-2-deoxy-α-D-glucopyranosides (12a) or (12b). These compounds were converted into corresponding benzyl 2-acetamido-4-O-(2-acylamino-3,4,6-tri-O-benzyl-2-deoxy-β-D-glucopyranosyl)-6-O-benzyl-3-O-carboxymethyl-2-deoxy-α-D-glucopyranosides which, by condensation with H-L-Abu-D-isoGln(OBzl) followed by hydrogenolysis of protective benzyl groups, furnished glycopeptides 16a and 16b. Intramolecular O→N migration of the allyl protecting group followed by its reduction to the propyl residue by reaction of compound 8 with hydrazine or hydrazinium acetate, to give benzyl 2-acetamido-4-O-(3,4,6-tri-O-benzyl-2-deoxy-2-propylamino-β-D-glucopyranosyl)-6-O-benzyl-2-deoxy-α-D-glucopyranoside (9), is also described.
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Ledvina M, Ježek J, Šaman D, Hříbalová V. Synthesis and Immunomodulating Activity of Lipophilic Analogs of N-Acetylnormuramoyl-L-2-aminobutanoyl-D-isoglutamine. ACTA ACUST UNITED AC 1998. [DOI: 10.1135/cccc19980590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
N-Acetylnormuramoyl-L-2-aminobutanoyl-D-isoglutamine (7) and its lipophilic 6-O-octadecanoyl (8) and 6-O-(2-tetradecylhexadecanoyl) (9) derivatives were prepared and their immunoadjuvant activity and pyrogenicity were tested. Compounds 8 and 9 are less pyrogenic than muramoyl-dipeptide (MDP) and norMDP analog 7. Both lipophilic derivatives 8 and 9 are better adjuvants than MDP in cell mediated immunity.
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Turánek J, Záluská D, Hofer M, Vacek A, Ledvina M, Jezek J. Stimulation of haemopoiesis and protection of mice against radiation injury by synthetic analogues of muramyldipeptide incorporated in liposomes. INTERNATIONAL JOURNAL OF IMMUNOPHARMACOLOGY 1997; 19:611-7. [PMID: 9637362 DOI: 10.1016/s0192-0561(98)00003-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Protection from undesirable effects of radiotherapy or chemotherapy, primarily from myelosuppression, remains still a crucial problem to be studied. Attention has been therefore paid to various immunomodulatory agents that through the monocyte/macrophage system induced production of cytokines, which can induce and operate restoration of haemopoiesis and thus act radioprotectively. Some synthetic analogues of MDP free of undesirable side-effects, were synthesized in the Czech Republic. Lipophilic beta-D-GlcNstearoyl-(1- > 4)-norMurNAc-L-Abu-D-isoGln (DDD-St) was designed to be easily entrapped into liposomes and this liposomal DDD-St protected efficiently mice against irradiation, when administered i.p., i.v. or s.c. 24 h prior to lethal irradiation (survival rate in the range of 30-80% compared with 0% in control). Especially the subcutaneous application of liposomal DDD-St was very efficient. The parameters characteristic of recovery of haemopoiesis in bone marrow on day 10 after 6.5 Gy irradiation were significantly improved in comparison with the controls. Very high radioprotective effect of s.c. administered liposomal DDD-St can be explained (together with induction of haemopoiesis) by an effective and long-lasting activation of nonspecific immunity, which is able to withhold an onset of septicemia in early days after irradiation. In conclusion, the liposomal DDD-St should be therapeutically beneficial in moderating the haemopoietic damage, which is an undesirable effect of radiotherapy or chemotherapy.
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Sharma M, Li YX, Ledvina M, Bobek M. Synthesis of 5′-Fluoro-5′-deoxy-and 5′-Amino-5′-Deoxytoyocamycin and Sangivamycin and Some Related Derivatives. ACTA ACUST UNITED AC 1995. [DOI: 10.1080/15257779508010707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ledvina M, Jezek J, Saman D, Vaisar T, Hríbalová V. Synthesis of O-[2-acetamido-2-deoxy-6-O-stearoyl- and -6-O-(2-tetradecylhexadecanoyl)-beta-D-glucopyranosyl]-(1-->4)-N- acetylnormuramoyl-L-alpha-aminobutanoyl-D-isoglutamine, lipophilic disaccharide analogues of MDP. Carbohydr Res 1994; 251:269-84. [PMID: 8149375 DOI: 10.1016/0008-6215(94)84291-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Silver triflate-promoted condensation of 3,4,6-tri-O-acetyl-2-deoxy-2- phthalimido-beta-D-glucopyranosyl bromide (1) with benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O- (methoxycarbonyl)methyl-alpha-D-glucopyranoside (4) afforded the key compound, benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O- (methoxy-carbonyl)methyl-4-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b eta-D- glucopyranosyl)-alpha-D-glucopyranoside (5), which after deprotection was transformed into acid 10. Condensation of 10 with the benzyl ester of L-alpha-aminobutanoyl-D-isoglutamine and deisopropylidenation of the product 11 afforded the benzyl ester of N-(2-O-[benzyl 2-acetamido-4-O-(2-acetamido-3-O-benzyloxymethyl-2- deoxy-beta-D-glucopyranosyl)-6-O-benzyl-2,3-dideoxy-alpha-D-glucopyra nosid-3- yl]glycoloyl)-L-alpha-aminobutanoyl-D-isoglutamine (12). Partial O-acylation of 12 and hydrogenolysis of protecting groups gave the 6-O-stearoyl- and 6-O-(2-tetradecylhexadecanoyl)-disaccharide-dipeptides 17 and 18, respectively. Pyrogenicity and adjuvant activity in cell-mediated immunity are reported.
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Ledvina M. [Prof. Jan Horbaczewski. On the 50th anniversary of his death]. CASOPIS LEKARU CESKYCH 1992; 131:347. [PMID: 1638604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Ledvina M, Šaman D, Ježek J. Synthesis of O-(2-Deoxy-2-stearoylamino-β-D-glucopyranosyl)-(1→4)-N-acetylnormuramoyl-L-α-aminobutanoyl-D-isoglutamine, a Lipophilic Disaccharide Analogue of MDP. ACTA ACUST UNITED AC 1992. [DOI: 10.1135/cccc19920579] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Partial N-deacetylation of compound II with barium hydroxide afforded benzyl 2-acetamido-3-O-allyl-4-O-(2-amino-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranosyl)-6-O,-benzyl-2-deoxy-α-D-glucopyranoside (III) in high yield. Compound III was N-acylated with stearic acid in the presence of DCC and the obtained product was converted into benzyl 2-acetamido-6-O-benzyl-3-O-carboxymethyl-2-deoxy-4-O-(3,4,6-tri-O-benzyl-2-deoxy-2-stearoylamino-β-D-glucopyranosyl)-α-D-glucopyranoside (VII). Coupling of compound VII with L-α-aminobutanoyl-D-isoglutamine benzyl ester followed by hydrogenolysis of the product VIII afforded compound IX.
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Ledvina M, Farkaš J, Zajíček J, Ježek J, Zaoral M. An alternative synthesis of O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1→4)-N-acetylnormuramoyl-L-α-aminobutanoyl-D-isoglutamine. ACTA ACUST UNITED AC 1989. [DOI: 10.1135/cccc19892784] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Silver triflate-promoted condensation of 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl bromide (VIII) with benzyl 2-acetamido-6-O-benzoyl-2-deoxy-3-O-(methoxycarbonyl)-methyl-α-D-glucopyranoside (IV) afforded benzyl 2-acetamido-4-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl)-6-O-benzoyl-2-deoxy-3-O-(methoxycarbonyl)methyl-α-D-glucopyranoside (IX) which, after deprotection, was converted into the acid XI. Condensation of acid XI with L-α-aminobutanoyl-D-isoglutamine benzyl ester and subsequent hydrogenolysis of the product XIII furnished compound XIV. Benzyl 2-acetamido-6-O-benzoyl-2-deoxy-3-O-(methoxycarbonyl)methyl-α-D-glucopyranoside (IV) was prepared by partial benzoylation of benzyl 2-acetamido-2-deoxy-3-O-(methoxycarbonyl)methyl-α-D-glucopyranoside (III) with benzoyl cyanide.
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Farkaš J, Ledvina M, Brokeš J, Ježek J, Zajíček J, Zaoral M. The synthesis of O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→4)-N-acetylnormuramoyl-l-α-aminobutanoyl-d-isoglutamine. Carbohydr Res 1987. [DOI: 10.1016/0008-6215(87)80165-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Collagen-like structures were formed in solutions of alpha-elastin after heating to 57 degrees C and after treatment with absolute ethanol. A complex between acetyl-alpha-elastin and cetyltrimethylammonium bromide showed a similar structure. Thick fibrils (diameter approximately 100 nm), resembling those described by Volpin, et al.12 revealed transversal banding with periodicity of 39 to 62 nm. A possible mechanism for the formation of these fibers is suggested based on hydrophobic interactions.
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Velebný V, Kádár A, Ledvina M, Lankasová V. Fibrillar structure of alpha-elastin methylester complexes with glycoproteins and proteoglycans. Connect Tissue Res 1984; 12:203-10. [PMID: 6206981 DOI: 10.3109/03008208409013683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
alpha-Elastin methylester forms with proteoglycan subunits and structural glycoproteins water-insoluble complexes which after staining with phosphotungstic acid (pH 7.0), reveal at large magnification bundles of slender smooth fibrils with a diameter from 4 to 5 nm. Similar fibrils can be observed after interaction of alpha-elastin methylester with chondroitin sulfate, but only if fixation with glutaraldehyde is used prior to staining. Phosphotungstic acid alters the organization of the complexes, in particular those formed with ligands of low molecular weight. The possible biological significance of the interactions studied is discussed.
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Ledvina M, Farkaš J. Alternative synthesis of 4-methyl-2H-1,2,6-thiadiazin-3(6H)-one 1,1-dioxide, a structural analogue of thymine. ACTA ACUST UNITED AC 1984. [DOI: 10.1135/cccc19840840] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
N-Alkylsulfamides react with methyl 3-methoxy-2-methyl-2-propenoate (XI) in aqueous hydrochloric acid under formation of methyl 3-(N' -alkylsulfamido)-2-methyl-2-propenoates (VIIa to VIIc). Attempted base-catalyzed cyclization of the ester VIIb was unsuccessful. The 2-benzyl derivative IV and the 6-benzyl derivative V were prepared by reaction of iodotrimethylsilane with the acid VIII and the amide IX, respectively. Hydrogenolytic removal of the benzyl groups in the 2- and 6-benzyl derivatives IV and V afforded the title compound III.
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Benesová-Půlpánová J, Ledvina M. [The efect of ionizing radiation and fasting on the excretion of o-iodobenzoic acid 125I and its conjugates in the urine of rats protected by radioprotective agents]. SBORNIK VEDECKYCH PRACI LEKARSKE FAKULTY KARLOVY UNIVERZITY V HRADCI KRALOVE. SUPPLEMENTUM 1983; 26:201-215. [PMID: 6335783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Krízala J, Stoklasová A, Kovárovă H, Ledvina M. The effect of gamma irradiation and cystamine on superoxide dismutase activity in the bone marrow and erythrocytes of rats. Radiat Res 1982; 91:507-15. [PMID: 6750680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Kr̈íz̆ala J, Stoklasová A, Kovár̆ová H, Ledvina M, Krizala J, Stoklasova A, Kovarova H. The Effect of γ Irradiation and Cystamine on Superoxide Dismutase Activity in the Bone Marrow and Erythrocytes of Rats. Radiat Res 1982. [DOI: 10.2307/3575888] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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