Determination of Hydrolytically-Stable Boron Hydrides in Biological Materials.

Soloway, Albert H.; Messer, J. R.

doi:10.1021/ac60208a061

Cited by 20 publications

(8 citation statements)

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“…Boron compounds have already been introduced in certain organs and tissues of animals [4], antibodies [5] and viruses [6] for basic studies of this technique and for autoradiographic purposes [7]. Treatment of neoplastic diseases with boron compounds and slow neutrons have also been attempted on humans [8]. Our early studies to demonstrate the structural similarity between Phe and Car were carried out on the enzyme a-chymotrypsin using the tripeptide inhibitor Z-Ala-Ala-P", where P" is the amino acid containing an aromatic nucleus in the side-chain and Z the benzyloxycarbonyl group.…”

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Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin

Leukart

Escher

Regoli

et al. 1979

Helvetica Chimica Acta

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SummaryThirteen peptides, analogues of bradykinin (BK), enkephalin, Substance P (SP) and [Sar'l-angiotensin I1 ([Sari]-ATII) have been synthesized by the solid-phase method. In all these peptides the residue Phe and Tyr were substituted with the boron-containing amino-acid L-o-carboranylalanine (Car). The purity and identity of the peptides were established by TLC., cellulose-electrophoresis and amino acid analysis.Introduction. -The synthesis of the new amino-acid L-o-carboranylalanine (Car) was primarily intended to develop an analogue of phenylalanine (Phe), containing in its side-chain a maximal concentration of the boron isotope loB i1-31. This amino acid (Car) could perhaps be inserted in the sequence of peptide hormones or of antibodies in order to enable l"B to be carried and accumulated specifically in tumoral tissues. Capture of a slow neutron by the loB isotope will disintegrate with 2.3 MeV

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Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin

Leukart

Escher

Regoli

et al. 1979

Helvetica Chimica Acta

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“…Very pure [loB]-decaborane, the starting material for [10B]-o-carboranylalariine, has been prepared in this laboratory (E. Escher). From the above data it would appear that o-carboranylalanine with -on the average -two or more 10R nuclei would be an excellent molecule for producing ionizing radiation in biological materials.Boron, introduced into certain parts of the animal or plant body, has been used for auto-radiographic purposes [3], and for the treatment of neoplastic diseases (cancer) [4]. o-Carboranylalanine, as a component of peptides such as peptide hormones, might offer an especially attractive means of transporting via the blood…”

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confidence: 99%

“…Boron, introduced into certain parts of the animal or plant body, has been used for auto-radiographic purposes [3], and for the treatment of neoplastic diseases (cancer) [4]. o-Carboranylalanine, as a component of peptides such as peptide hormones, might offer an especially attractive means of transporting via the blood…”

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confidence: 99%

L‐o‐Carboranylalanine, a Boron Analogue of Phenylalanine

Leukart¹,

Caviezel²,

Eberlé³

et al. 1976

Helvetica Chimica Acta

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Summary. The synthesis of a new, boron-containing analogue of phenylalanine is described. Carboranylala.nine (Car) carries a 1,2-carborane cage in place of the benzene ring of phenylalanine. It is obtained by the reaction of derivatives of propargylglycine with decaborane. Possibilities of practical application derive from the facile neutron activation of boron nuclei with mass number 10.o-Carborane (1, 2-C~BloH12) and its C-derivatives [ 21 display icosahedral geometry. The dimensions of the cage are only slightly larger than the space occupied by a benzene ring rotating about its C(l)-C(4) axis, and the two carbon atoms participate in the delocalized bonding. It thus appears that o-carboranylalanine (1; Car) would be sufficiently similar to phenylalanitie in order to be an interesting analogue for probing the role of this amino acid in certain biologically active peptides. The likeness becomes apparent from the Figure.The possible role of 1 as a probe becomes even more intriguing if one considers the interaction of boron with thermal neutrons, having v N 2,220 m/s at 0.025 eV '31 : Natural boron is composed of 18.45% 1% and 81.5Sy0 IlB; the former has a large capture cross section for thermal neutrons of 3,900 barns (= 10--2* 1112). Very pure [loB]-decaborane, the starting material for [10B]-o-carboranylalariine, has been prepared in this laboratory (E. Escher). From the above data it would appear that o-carboranylalanine with -on the average -two or more 10R nuclei would be an excellent molecule for producing ionizing radiation in biological materials.Boron, introduced into certain parts of the animal or plant body, has been used for auto-radiographic purposes [3], and for the treatment of neoplastic diseases (cancer) [4]. o-Carboranylalanine, as a component of peptides such as peptide hormones, might offer an especially attractive means of transporting via the blood )This work was supported by the Schweizerischer Nationalfonds zur Forderung der wissenschaftlichen Fovschung, and is part of the doctoral thesis of 0. L. Abbreviations according to [l] and [Z]. For the new amino acid, o-carboranylalanine, the abbreviation Car is proposed.HELVETICA CHIMICA ACTA -Vol. 59, Fasc. 6 (1976) -Nr. 225 2185 CarFhe stream rather high concentrations of boron to specifically defined areas (target cells and target organs). Starting materials for the synthesis of 1 (Scheme) were the bis(acetonitri1e)-decaborane complex [5], and L-phthalyl-propargylglycine methyl ester [6] : (4Condensation (c) was carried out according to the general procedure of Heying [7], and immediately and stereospecifically gave pure, crystalline 2 in a moderate yield (50-60%). Concentrated boiling HC1 solution removed both protecting groups (reaction (d)) ; the free amino acid 1 was readily obtained, although in a small yield (22%). More diluted HC1-solution in acetic acid, according to the general procedure of Sheehan et al. [8], selectively hydrolysed the methoxycarbonyl group to give the N-phthalyl-L-amino-acid 3 (Ieaction (e)) . 86HELVETICA CHIMI...

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“…Between 6 and 24 animals are used in such a study and they are sacrificed in groups at time intervals such as 6,12,24,48,96, and 192 h after injection. At the time of sacrifice, samples of various organs including tumor, blood, and brain are taken and analyzed for boron content by the method of Soloway and Messer (61). Figure 1 shows the results of an uptake study of the B|2H nSH 2-anion and presents the boron concentration in the tumor and in the blood versus time.…”

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confidence: 99%

Boron Neutron Capture Therapy of Cerebral Gliomas

et al. 1975

Oncology

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The use of the blood-brain barrier and of tumor-specific antibodies to concentrate boron selectively in gliomas for neutron capture therapy is considered experimentally and theoretically. The time-dependent concentration of two anionic boranes, B₁₂H₁₁SH^2––and B₁₂H₁₁ SOSB₁₂H₁₁^4––, in the blood, brain, and tumor of rats bearing a tumor of gliomatous origin is reported. The rate of clearance of each anionic borane from the blood is correlated with the fraction of non-protein bound anion in the plasma. The use of antibodies to carry therapeutically useful amounts of boron to tumor-specific or tumor-associated antigens on the tumor cell surface will require different numbers of boron atoms bound per antibody depending on several immunological and physical parameters. Calculations using published values of antibody-antigen association constants and of cell surface antigen densities predict that in order to obtain 10 μg ¹⁰B/g tumor from 10 to over 10,000 boron-10 atoms will have to be bound per tumor antigenic site.

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Determination of Hydrolytically-Stable Boron Hydrides in Biological Materials.

Cited by 20 publications

References 6 publications

Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin

Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin

L‐o‐Carboranylalanine, a Boron Analogue of Phenylalanine

Boron Neutron Capture Therapy of Cerebral Gliomas

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Determination of Hydrolytically-Stable Boron Hydrides in Biological Materials.

Cited by 20 publications

References 6 publications

Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car1, Leu5]‐enkephalin

Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car1, Leu5]‐enkephalin

L‐o‐Carboranylalanine, a Boron Analogue of Phenylalanine

Boron Neutron Capture Therapy of Cerebral Gliomas

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Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin

Synthesis of angiotensins, bradykinins and substance P octapeptides in which the residues Phe and Tyr have been replaced with car and of [Car¹, Leu⁵]‐enkephalin