Pyrocatechol borates: Synthesis, reaction with formaldehyde, and solvent effect on polycondensation process

Lenskiy, Maxim A.; Шульц, Э. Э.; Корабельников, Д. В.; Ozhogin, A.V.; Novitskiy, Alexey N.

doi:10.1016/j.polymer.2020.122162

Cited by 3 publications

(10 citation statements)

References 20 publications

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“…This physiological feature accounts for the likely occurrence of non-ionized borate esters of eumelanin within melanosomes. Considering the well-known stereochemical aspects of the formation of catechol-borate esters (Gerrard et al, 1959;Lang et al, 1997;Yan et al, 2005;Lenskiy et al, 2020) and the use of molecular modeling methods in studies on the chemistry of eumelanin Stockert and Felix-Pozzi, 2023), the DABO and DHIBO precursors, as well as the catecholporphycene proposed for eumelanin were modeled. The characteristic trigonal configuration of neutral borate group in the catechol-5,6-borate ester was found in both DABO and DHIBO models, in agreement with geometric features of boric acid and its neutral esters (Gerrard et al, 1959;Yoshino et al, 1979;Lang et al, 1997;Schubert et al, 2003;Tsuyumoto et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

“…Catechols, flavonols, anthraquinones, β-diketones, etc., are known to give stable borate complexes (Frohne, 1974;Yoshino et al, 1979;Yang et al, 2003;Lenskiy et al, 2020). Borax is widely used as a cross-linking agent between hydroxyl groups (Frasconi et al, 2009), and fluorescent boronic acid (C-B[OH] 2 ) derivatives are applied for the detection of specific carbohydrates by forming stable boratecis diol 1:1 esters with mannose, gulose, allose, talose, rhamnose, ribose, etc.…”

Section: Introductionmentioning

confidence: 99%

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In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Stockert¹,

ROMERO²,

Felix-Pozzi³

et al. 2023

Biocell

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The 10 boron neutron-capture therapy (BNCT) is an emerging antitumoral method that shows increasing biomedical interest. BNCT is based on the selective accumulation of the 10 boron isotope within the tumor, which is then irradiated with low-energy thermal neutrons, generating nuclear fission that produces 7 lithium, 4 helium, and γ rays. Simple catechol-borate esters have been rather overlooked as precursors of melanin biosynthesis, and therefore, a proof-of-concept approach for using dopamine-borate (DABO) as a suitable boron-containing candidate for potential BNCT is presented here. DABO can spontaneously oxidize and autopolymerize in vitro, giving a soluble, eumelaninlike brown-black poly-DABO product. Melanotic melanoma cell cultures treated with 1 mM DABO for 24 and 48 h were viable and showed no signs of damage or cell death. The stability and possible trans-esterification of DABO is shortly discussed. Chemical calculations and quantitative structure-activity relationships (QSAR) analysis of DABO and the BNCT agent BPA indicated that they should be cell permeant and accumulate within lysosomes and melanosomes. Molecular modeling allows visualization of both the DABO precursor and the structure of a borate derivative of the proposed catechol-porphycene model for eumelanin, showing interesting features from molecular orbital calculations. The main difference between DABO and other agents, such as BPA, is that it is not a boronic acid nor a boron cluster. This simple catechol-borate ester (protected from oxidation and blackening) could be administrated to living cells and organisms, in which biosynthesis of boron-melanin in melanoma melanocytes can lead to improved BNCT.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Stockert¹,

ROMERO²,

Felix-Pozzi³

et al. 2023

Biocell

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“…The geometry of PBA and CBE, shown as space-filling (atomic volume) models, offers a more realistic representation of the molecular structure, as is clearly observed in Figure 2. Considering the stereochemistry of boronic acids and the formation of catechol-borate esters [25,26,40,41], molecular modeling methods are very suitable to illustrate their molecular shape and orbitals. The characteristic trigonal or tetrahedral configuration of neutral borate or borate anion in PBA or CBE, respectively, was found in atomic volume models (Figure 2), in agreement with chemical features of boric acid and anionic esters.…”

Section: Resultsmentioning

confidence: 99%

“…Vicinal aliphatic and aromatic cis-diols such as catechols, flavonols, β-diketones, anthraquinones, etc., form stable borate complexes [20][21][22][23][24][25]. Boronic acid (C-B[OH] 2 ) derivatives are applied for detection of glycols and catechols [23].…”

Section: Annals Of Reviews and Researchmentioning

confidence: 99%

“…Borate complexes formed at alkaline pH (higher than ~8), lose the hydroxyls at acid pH (lower than ~7) and become neutral (non-ionized) trigonal borate (BO 3 ) esters [20]. Boric acid, borates, and boronic acids react easily with catechols [25][26][27]. Therefore, simple compounds such as BPA and catechol-borate ester (CBE) could form specific complexes directly with catechols from an already formed melanin, and work then as melanin-reactive drugs, and not as melanin precursors.…”

Section: Annals Of Reviews and Researchmentioning

confidence: 99%

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Molecular Modeling of Phenyl-Boronic Acids and Catechol-Borate Esters: A Mechanistic Rationale for Boron Binding to Melanin Catechols, Regarding the 10Boron Neutron-Capture Therapy of Melanoma

Stockert

2022

ARR

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The 10 boron neutron-capture therapy (BNCT) is an emerging anti-tumor therapy based on the accumulation of a 10 B isotope within the tumor followed by irradiation with low-energy neutrons. The nuclear fission process produces 7 lithium, 4 helium, and λ rays within the tumor tissue, inducing specific tumor cell damage and death. 10 B can be delivered either as simple B-containing agents or as B clusters. In the first case, boronic acid derivatives such as 4-borono-phenylalanine (BPA) are currently applied for BNCT of melanoma and other tumors. Although it can be assumed that BPA would act as a precursor metabolite for melanin biosynthesis, the precise action mechanism is not yet clear. Direct binding of this boronic acid to a target substrate, namely the catechol groups from already synthesized melanin, could be an alternative mechanism. In keeping with this, high affinity for melanin would explain the action mode of boronic acids as melanoma seekers. DOPA-and dopamine-borate esters are also potential B-carrier candidates for BNCT, and they could be incorporated as melanin precursors or binding reagents. In this work, molecular modeling methods have been applied to analyze the structure of boronic acid and borate ester derivatives, as well as their interaction and binding mode with the recently proposed catechol-porphycene model for the melanin polymer. Interestingly, remarkable structural features drawn from chemical geometry, and also molecular orbital calculations, support the possibility that boronic acids and borate esters could be reactive agents for direct binding to melanin catechols.

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Reinforced Epoxy Binder Modified with Borpolymer

et al. 2023

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Polymer binders based on epoxy resins have unique properties that contribute to their use in many composite industries. The potential of using epoxy binders is due to their high elasticity and strength characteristics, thermal and chemical resistance, and resistance to climatic aging. This is the reason for the existing practical interest in modifying the composition of epoxy binders and understanding the strengthening mechanisms in order to form reinforced composite materials with a required set of properties based on them. This article presents the results of a study of the process of dissolving the modifying additive of polymethylene-p-triphenyl ether of boric acid in the components of an epoxyanhydride binder applicable to the production of fibrous composite materials. The temperature and time conditions for the dissolution of polymethylene-p-triphenyl ether of boric acid in anhydride-type isomethyltetrahydrophthalic anhydride hardeners are presented. It has been established that the complete dissolution of the borpolymer-modifying additive in iso-MTHPA occurs at a temperature of 55 ± 2 °C for 20 h. The effect of the modifying additive of polymethylene-p-triphenyl ether of boric acid on the strength properties and structure of the epoxyanhydride binder has been studied. Increases in transverse bending strength up to 190 MPa, elastic modulus up to 3200 MPa, tensile strength up to 0.8 MPa, and impact strength (Charpy) up to 5.1 5.1 kJ/m2 are observed when the content of the borpolymer-modifying additive in the composition of the epoxy binder is 0.50 mass. %.

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Pyrocatechol borates: Synthesis, reaction with formaldehyde, and solvent effect on polycondensation process

Cited by 3 publications

References 20 publications

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Molecular Modeling of Phenyl-Boronic Acids and Catechol-Borate Esters: A Mechanistic Rationale for Boron Binding to Melanin Catechols, Regarding the 10Boron Neutron-Capture Therapy of Melanoma

Reinforced Epoxy Binder Modified with Borpolymer

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