Attila Agócs

University of Pecs

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New methods for the synthesis of carotenoid glycosides

Tetrahedron Letters (2014)

Miki Hanaura Attila Agócs Katalin Böddi József Deli Véronika Nagy

10.1016/j.tetlet.2014.04.114

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Citations (6)

Natural Apocarotenoids and Their Synthetic Glycopeptide Conjugates Inhibit SARS-CoV-2 Replication

Pharmaceuticals (2021)

Ilona Bereczki Henrietta Papp Anett Kuczmog Mónika Madai Véronika Nagy

The protracted global COVID-19 pandemic urges the development of new drugs against the causative agent SARS-CoV-2. The clinically used glycopeptide antibiotic, teicoplanin, emerged as a potential antiviral, and its efficacy was improved with lipophilic modifications. This prompted us to prepare new lipophilic apocarotenoid conjugates of teicoplanin, its pseudoaglycone and the related ristocetin aglycone. Their antiviral effect was tested against SARS-CoV-2 in Vero E6 cells, using a cell viability assay and quantitative PCR of the viral RNA, confirming their micromolar inhibitory activity against viral replication. Interestingly, two of the parent apocarotenoids, bixin and β-apo-8'carotenoic acid, exerted remarkable anti-SARS-CoV-2 activity. Mechanistic studies involved cathepsin L and B, as well as the main protease 3CLPro, and the results were rationalized by computational studies. Glycopeptide conjugates show dual inhibitory action, while apocarotenoids have mostly cathepsin B and L affinity. Since teicoplanin is a marketed antibiotic and the natural bixin is an approved, cheap and widely used red colorant food additive, these readily available compounds and their conjugates as potential antivirals are worthy of further exploration.

Teicoplanin

Vero cell

10.3390/ph14111111

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Citations (10)

Total Synthesis of Angucyclines. XVII. First Synthesis of Antibiotic 100‐1, a Deoxydisaccharide Angucycline Antibiotic of the Urdamycinone B‐Type

Journal of Carbohydrate Chemistry (2003)

Karsten Krohn Attila Agócs Christiane Bäuerlein

Abstract Two routes to the deoxydisaccharide angucycline antibiotic 100‐1 (3) are described. Key steps comprise the regioselective oxidation/bromination of the 1,5‐diacetoxyolivose C‐saccharide 7 to the bromoquinone 8. Diels–Alder reaction of the bromoquinone with the diene 9 followed by HBr elimination afforded the urdamycinone B precursor 11 as a diastereomeric mixture. Selective protection as the TBDMS ether 13, acetylation and deprotection of the silyl ether afforded the alcohol 15 which was selectively glycosylated to the α‐rhamnal glycoside 17 in 72% yield (at 70% conversion) using benzoyl rhamnal (16) as the glycoside donor and scandium triflate as the promotor. The silyl group at C‐3 of the aglycone was then transformed into a hydroxyl group. Zemplén deacylation and photooxidation of the benzylic position at C‐1 then converted the two diastereoisomers into the natural product 3 and the C‐3 diastereoisomer 20. At this stage the diastereomers 3 and 20 were separated. Alternatively and more easily, the diastereomers were separated at the stage of the urdamycinone B analogues 21a and 21b, followed by a similar reaction sequence to the natural disaccharide 3. †This paper is dedicated to Prof. Gérard Descotes on the occasion of his 70th birthday. Keywords: DeoxydisaccharidesAngucycline antibiotics C‐glycosidesScandium triflate Acknowledgment We thank Prof. Dr. J. Rohr, University of Kentucky, USA, for a sample of authentic antibiotic 100‐1. Notes †This paper is dedicated to Prof. Gérard Descotes on the occasion of his 70th birthday.

Diastereomer

Trifluoromethanesulfonate

Silyl ether

Aglycone

10.1081/car-120026460

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Citations (27)

Dicarotenoid esters of bivalent acids

Tetrahedron Letters (2008)

Magdolna Háda Véronika Nagy Anikó Takátsy József Deli Attila Agócs

Bivalent (engine)

10.1016/j.tetlet.2008.03.137

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Citations (8)

Total Synthesis of Angucyclines. Part 17. First Synthesis of Antibiotic 100‐1, a Deoxydisaccharide Angucycline Antibiotic of the Urdamycinone B‐Type.

ChemInform (2004)

Karsten Krohn Attila Agócs Christiane Baeuerlein

Abstract For Abstract see ChemInform Abstract in Full Text.

10.1002/chin.200415204

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Citations (0)

Isolation of allene carotenoids from mamey

Journal of Food Composition and Analysis (2017)

Attila Agócs Enrique Murillo Erika Turcsi Szabolcs Béni András Darcsi

The fruit of red mamey (Pouteria sapota) contains a wide variety of carotenoids, generally in high concentration, which makes possible even the isolation of minor components in measurable amounts. Carotenoids were extracted from red mamey with acetone, subsequent saponification resulted a crude extract, which was submitted to column chromatography using aluminium oxide (Al2O3) as adsorbent. By using consecutive chromatographic steps and crystallization allene carotenoids, such as neoxanthin, (9'Z)-neoxanthin and capsoneoxanthin, were isolated from the most polar fractions in milligram amounts and in high purity. The amount of capsoneoxanthin was found sufficient for the complete analysis of this rare carotenoid 15 years after its first isolation. The complete 1H- and 13C NMR assignments of neoxanthin and (9'Z)-neoxanthin using 2D techniques were achieved for the first time, as well. Electronic Circular Dichroism (ECD) spectra for the neoxanthin isomers were in good accordance with literature data, whereas the spectrum of capsoneoxanthin suggested aggregate formation in n-hexane solution.

Neoxanthin

Saponification

Hexane

Allene

10.1016/j.jfca.2017.04.004

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Citations (19)

Cycloaddition reactions of carbohydrate derivatives. Part 8: Intramolecular cycloaddition of nitrilimines derived from sugars

Tetrahedron Asymmetry (2001)

Attila Agócs T. E. GUNDA Gyula Batta Árpád Kovács-Kulyassa Pál Herczegh

10.1016/s0957-4166(01)00050-7

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Citations (9)

CHAPTER 3. Chemical Synthesis of Carotenoid Esters

Food chemistry, function and analysis (2019)

Véronika Nagy József Deli Attila Agócs

Carotenoids can be found in nature mostly as long-chain fatty acid esters; thus, chemical synthesis of these esters may be necessary for the carotenoid analysis of plant samples. From the synthetic point of view, the saponified carotenoids are typically used, and their functional groups are modified. Another field of ester synthesis is the attachment of hydrophilic moieties to hydroxy-carotenoids (i.e. xanthophylls containing hydroxyl functional groups) to improve their bioavailability, as well as their antioxidant and pharmacological properties. Esterification is considered to be a mild method in support of the conjugation of carotenoids with other bioactive compounds.

Saponification

10.1039/9781788015851-00068

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Citations (1)

Synthesis of carotenoid dimers and trimers

Acta Biologica Cracoviensia. Series Zoologia (2011)

Magdolna Háda Véronika Nagy Gergely Gulyás‐Fekete József Deli Attila Agócs

Source

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Citations (0)

Isolation and purification of acid‐labile carotenoid 5,6‐epoxides on modified silica gels

Phytochemical Analysis (2009)

Véronika Nagy Attila Agócs Erika Turcsi József Deli

Abstract Introduction The acid‐labile carotenoid 5,6‐epoxides occur in all green plants and in most fruits, but their isolation or purifica‐tion is complicated and expensive because they decompose on normal silica gels. Alkaline stationary phases in open column chromatography (OCC) have low capacities, which makes them unsuitable for preparative scale. Objective To find a simple high‐capacity stationary phase for OCC that does not induce transformations of acid‐labile compounds. Methodology Commercially available silica gel was treated with aqueous sodium bicarbonate solution to neutralise its slightly acidic character, and was then washed and dried. The effect of the treated gel (named silica‐9) on violaxanthin was studied. The modified gel was also applied to the OCC of different complex natural extracts (maple leaves and fruits of yellow paprika). Carotenoids were examined by HPLC‐PAD both before and after chromatography on the modified gel. Results Violaxanthin decomposed rapidly on normal silica gels but not on the modified gel. Chromatography of plant extracts showed that the modified gel had a similar capacity to the untreated gel but did not effect epoxy‐carotenoids, which could be separated or enriched readily on a large scale. Conclusion The modified gel does not induce any transformation or decomposition of epoxy‐carotenoids but still exhibits a high capacity, suggesting that it can be used in preparative organic chemistry as an additional and convenient tool in the OCC for the separation of other acid‐labile compounds. Copyright © 2009 John Wiley & Sons, Ltd.

Violaxanthin

10.1002/pca.1109

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Citations (14)