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Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products
Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome(®)), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O(2...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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MDPI
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7587531/ https://www.ncbi.nlm.nih.gov/pubmed/33080948 http://dx.doi.org/10.3390/molecules25204778 |
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author | Mishchenko, Natalia P. Vasileva, Elena A. Gerasimenko, Andrey V. Grigorchuk, Valeriya P. Dmitrenok, Pavel S. Fedoreyev, Sergey A. |
author_facet | Mishchenko, Natalia P. Vasileva, Elena A. Gerasimenko, Andrey V. Grigorchuk, Valeriya P. Dmitrenok, Pavel S. Fedoreyev, Sergey A. |
author_sort | Mishchenko, Natalia P. |
collection | PubMed |
description | Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome(®)), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O(2) in air-equilibrated aqueous solutions were identified, isolated, and structurally characterized. An HPLC method coupled with diode-array detection (DAD) and mass spectrometry (MS) was developed and validated to monitor the Ech A degradation process and identify the appearing compounds. Five primary oxidation products were detected and their structures were proposed on the basis of high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 7-ethyl-2,2,3,3,5,7,8-heptahydroxy-2,3-dihydro-1,4-naphthoquinone (2), 6-ethyl-5,7,8-trihydroxy-1,2,3,4-tetrahydronaphthalene-1,2,3,4-tetraone (3), 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (4), 2,3,4,5,7-pentahydroxy-6-ethylinden-1-one (5), and 2,2,4,5,7-pentahydroxy-6-ethylindane-1,3-dione (6). Three novel oxidation products were isolated, and NMR and HR-ESI-MS methods were used to establish their structures as 4-ethyl-3,5,6-trihydroxy-2-oxalobenzoic acid (7), 4-ethyl-2-formyl-3,5,6-trihydroxybenzoic acid (8), and 4-ethyl-2,3,5-trihydroxybenzoic acid (9). The known compound 3-ethyl-2,5-dihydroxy-1,4-benzoquinone (10) was isolated along with products 7–9. Compound 7 turned out to be unstable; its anhydro derivative 11 was obtained in two crystal forms, the structure of which was elucidated using X-ray crystallography as 7-ethyl-5,6-dihydroxy-2,3-dioxo-2,3-dihydrobenzofuran-4-carboxylic acid and named echinolactone. The chemical mechanism of Ech A oxidative degradation is proposed. The in silico toxicity of Ech A and its degradation products 2 and 7–10 were predicted using the ProTox-II webserver. The predicted median lethal dose (LD(50)) value for product 2 was 221 mg/kg, and, for products 7–10, it appeared to be much lower (≥2000 mg/kg). For Ech A, the predicted toxicity and mutagenicity differed from our experimental data. |
format | Online Article Text |
id | pubmed-7587531 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-75875312020-10-29 Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products Mishchenko, Natalia P. Vasileva, Elena A. Gerasimenko, Andrey V. Grigorchuk, Valeriya P. Dmitrenok, Pavel S. Fedoreyev, Sergey A. Molecules Article Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome(®)), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O(2) in air-equilibrated aqueous solutions were identified, isolated, and structurally characterized. An HPLC method coupled with diode-array detection (DAD) and mass spectrometry (MS) was developed and validated to monitor the Ech A degradation process and identify the appearing compounds. Five primary oxidation products were detected and their structures were proposed on the basis of high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 7-ethyl-2,2,3,3,5,7,8-heptahydroxy-2,3-dihydro-1,4-naphthoquinone (2), 6-ethyl-5,7,8-trihydroxy-1,2,3,4-tetrahydronaphthalene-1,2,3,4-tetraone (3), 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (4), 2,3,4,5,7-pentahydroxy-6-ethylinden-1-one (5), and 2,2,4,5,7-pentahydroxy-6-ethylindane-1,3-dione (6). Three novel oxidation products were isolated, and NMR and HR-ESI-MS methods were used to establish their structures as 4-ethyl-3,5,6-trihydroxy-2-oxalobenzoic acid (7), 4-ethyl-2-formyl-3,5,6-trihydroxybenzoic acid (8), and 4-ethyl-2,3,5-trihydroxybenzoic acid (9). The known compound 3-ethyl-2,5-dihydroxy-1,4-benzoquinone (10) was isolated along with products 7–9. Compound 7 turned out to be unstable; its anhydro derivative 11 was obtained in two crystal forms, the structure of which was elucidated using X-ray crystallography as 7-ethyl-5,6-dihydroxy-2,3-dioxo-2,3-dihydrobenzofuran-4-carboxylic acid and named echinolactone. The chemical mechanism of Ech A oxidative degradation is proposed. The in silico toxicity of Ech A and its degradation products 2 and 7–10 were predicted using the ProTox-II webserver. The predicted median lethal dose (LD(50)) value for product 2 was 221 mg/kg, and, for products 7–10, it appeared to be much lower (≥2000 mg/kg). For Ech A, the predicted toxicity and mutagenicity differed from our experimental data. MDPI 2020-10-18 /pmc/articles/PMC7587531/ /pubmed/33080948 http://dx.doi.org/10.3390/molecules25204778 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Mishchenko, Natalia P. Vasileva, Elena A. Gerasimenko, Andrey V. Grigorchuk, Valeriya P. Dmitrenok, Pavel S. Fedoreyev, Sergey A. Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title | Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title_full | Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title_fullStr | Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title_full_unstemmed | Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title_short | Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products |
title_sort | isolation and structure determination of echinochrome a oxidative degradation products |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7587531/ https://www.ncbi.nlm.nih.gov/pubmed/33080948 http://dx.doi.org/10.3390/molecules25204778 |
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