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Lorand Farkas

Bio: Lorand Farkas is an academic researcher from Ludwig Maximilian University of Munich. The author has contributed to research in topics: Citrus paradisi & Isosakuranetin. The author has an hindex of 13, co-authored 61 publications receiving 573 citations. Previous affiliations of Lorand Farkas include Jawaharlal Institute of Postgraduate Medical Education and Research.


Papers
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Journal ArticleDOI
TL;DR: Fur ein new, bisher noch nicht bekanntes Flavon aus den oberirdischen Sprosteilen von Centaurea jacea L. (Jacein) wurde die Struktur eines 5.7.3′-Trihydroxy-3.6.
Abstract: Fur ein neues, bisher noch nicht bekanntes Flavon aus den oberirdischen Sprosteilen von Centaurea jacea L. (Jacein) wurde die Struktur eines 5.7.4′-Trihydroxy-3.6.3′-trimethoxy-flavon-7-β-D-monoglucosids ermittelt und durch Synthese seines Triathylderivates sichergestellt. Das Jacein ist isomer mit einem bereits fruher isolierten Flavonglykosid aus der Wurzel (Centaurein), dem bereits fruher isolierten Flavonglykosid aus der Wurzel (Centaurein), dem nunmehr die Konstitution eines 5.7.3′-Trihydroxy-3.6.4′-trimethoxy-flavon-7-β-D-monoglucosids zukommt.

24 citations

Journal ArticleDOI
TL;DR: In this paper, a flavone-glycoside was identified as 5.7.4′-trihydroxyflavone(apigenin)-7-β-D-glucuronide (3).
Abstract: Aus den gelben Knospen von Ruellia tuberosa L. (Acanthaceae) wurde ein Flavonglykosid isoliert und als 5.7.4′-Trihydroxy-flavon(Apigenin)-7-β-D-glucuronid (3) identifiziert. Der Strukturbeweis gelang durch Kupplung von 4′-O-Benzyl-apigenin mit α-Acetobromglucuronsaure-methylester, Darstellung des Vollacetats, Entbenzylierung und Verseifung zu 3. Synthesis of Glucuronides in the Flavonoid-Series, III Isolation of Apigenin-7-β-D-glucuronide from Ruellia tuberosa L. and its Synthesis From the yellow buds of Ruelliae tuberosa L. (Acanthaceae) a flavone-glycoside was isolated which could be identified as 5.7.4′-trihydroxyflavone(apigenin)-7-β-D-glucuronide (3). Its structure was confirmed by coupling 4′-O-benzylapigenin with methyl(tri-O-acetyl-α-D-glucopyranosyl bromide)uronate, followed by total acetylation, debenzylation and saponification to 3.

23 citations

Journal ArticleDOI
TL;DR: The first synthesis of a naturally occurring flavonoid glucuronide, quercetin-3-β-D -glucuronide (3) is achieved by coupling of 7,4′ -dibenzylquercetIN with methyl(tri-O-acetyl-α-D-glucopyranosyl bromide)-uronate, followed by total acetylation of the product and subsequent removal of the protecting groups.
Abstract: Durch Kupplung von 7.4′-Dibenzyl-quercetin mit α-Acetobromglucuronsaure-methylester, Darstellung des Vollacetats, Entbenzylierung und Verseifung wurde das aus zahlreichen Pflanzen isolierte Quercetin-3-β-D-glucopyranosuronid (3) als erstes naturlich vorkommendes Glucuronid des Pflanzenreiches synthetisiert und in seiner Struktur bewiesen. Synthesis of Glucuronides in the Flavonoid-Series, I. The First Synthesis of a Naturally Occurring Flavonoid Glucuronide(Quercetin-3-β-D-glucuronide) The first synthesis, and thereby confirmation of its structure, of a naturally occurring flavonoid glucuronide, quercetin-3-β-D -glucuronide (3) is achieved by coupling of 7,4′ -dibenzylquercetin with methyl(tri-O-acetyl-α-D-glucopyranosyl bromide)-uronate, followed by total acetylation of the product and subsequent removal of the protecting groups.

23 citations

Journal ArticleDOI
TL;DR: In this article, a 3.5,7,4′-tetrahydroxyflavone(kaempferol)-3-β-D-glucuronide was isolated from the aerial parts of Euphorbia esula L. (Euphorbiaceae) and its structure was confirmed by coupling of 7.4′ -dibenzylkampferol with methyl(tri-O-acetyl-α-Dglucopyranosyl bromide)-uronate, followed by total acetylation, debenzyl
Abstract: Aus den oberirdischen Teilen von Euphorbia esula L. (Euphorbiaceae) wurde ein Flavonglykosid isoliert und als 3.5.7.4′-Tetrahydroxy-flavon(Kampferol)-3-β-D-glucuronid (8) identifiziert. Seine Struktur wurde durch Kupplung von 7.4′-Dibenzyl-Kampferol mit α-Acetobromglucuronsaure-methylester, Darstellung des Vollacetats, Entbenzylierung und Verseifung zu 8 bewiesen. Synthesis of Glucuronides in the Flavonoid-Series, II. Isolation of Kaempferol-3-β-D-glucuronide from Euphorbia esula L. From the aerial parts of Euphorbia esula L. (Euphorbiaceae) a flavone-glycoside was isolated and identified as 3,5,7,4′-tetrahydroxyflavone(kaempferol)-3-β-D-glucuronide (8). Its structure was confirmed by coupling of 7,4′ -dibenzylkaempferol with methyl(tri-O-acetyl-α-D-glucopyranosyl bromide)-uronate, followed by total acetylation, debenzylation and saponification to 8.

23 citations

Journal ArticleDOI
TL;DR: In this paper, Isoquercitrin (Quercetin-3-β-d-glucosid), Hyperosid, Quercitin-α-l-rhamnosid and Quercithin synthetisch dargestellt.
Abstract: Durch Umsetzung von 7.4′-Dibenzyl-quercetin mit den entsprechenden Acetobromzuckern, anschliesende Verseifung und katalytische Entbenzylierung wurden Isoquercitrin (Quercetin-3-β-d-glucosid), Hyperosid (Quercetin-3-β-d-galaktosid) und Quercitrin (Quercetin-3-α-l-rhamnosid) synthetisch dargestellt.

21 citations


Cited by
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Journal ArticleDOI
TL;DR: The tribal, subtribal and generic distribution of sesquiterpene lactones is examined, the compounds’ utility as taxonomic characters discussed and the biogenetically based methodology shows the efficacy of this analytical methodology.
Abstract: The Asteraceae is characterized by structurally diverse sesquiterpene lactones and furanosesquiterpenes. In this review the tribal, subtribal and generic distribution of sesquiterpene lactones is examined and the compounds’ utility as taxonomic characters discussed. Sesquiterpene lactones fulfill the major requirements for good analytic and synthetic characters. Studies of infraspecific sesquiterpene lactone variation indicate that different elements within complex taxa are often defined by distinct chemistries, termed chemotypes. Chemotypes have been identified within many of the thoroughly investigated taxa:Ambrosia camphorata, A. chamissonis, A. confertiflora, theA. cumanensis-A. psilostachya-A. artemisiifolia complex,A. dumosa, Artemisia tridentata, Gaillardia pulchella andMelampodium leucanthum. Such an analytic usage is mostly restricted to the infraspecific level. Synthetic usage at the interspecific level and above profits from the application of a biogenetically based methodology for sorting out the complex molecules’ carbon-skeletal and substitutional features into unit characters. Cladistics or Hennigian phylogenetic systematics provides a useful framework for such an analysis. Preliminary surveys indicate that sesquiterpene lactones are especially good characters for differentiating subtribes within several major tribes: the Vernonieae, Heliantheae and Mutisieae. As yet, too few data are available for other tribes to discern such patterns. Species surveys inVernonia, Ambrosia, Iva, Parthenium,Tetragonotheca andArtemisia demonstrate that sesquiterpene lactones are useful in discerning infrageneric groups. The biogenetic cladistic analysis of the interspecific sesquiterpene lactone variation inIva shows the efficacy of this analytical methodology. At present, such biogenetically based approaches are impeded by limited biosynthetic evidence and the erratic distribution of sesquiterpene lactones within the family. Instances of apparent displacement of sesquiterpene lactones by other terpenoids (i.e. sesquiterpene furans, alcohols and acids, diterpenes, diterpene acids, etc.) at various taxonomic levels suggest that ultimately sesquiterpene lactones must be interpreted as taxonomic characters in the context of the family’s total terpene chemistry. All taxa from which sesquiterpene lactones have been reported are listed together with the compound names, major structural features and the literature cited. A less-complete listing is provided for taxa producing furanosesquiterpenes. Structures for all reported compounds are included. Two appendices listing alphabetically taxa and compounds and relevant text page numbers permit cross-indexing of plants and compounds.

350 citations

Journal ArticleDOI
TL;DR: Evaluation of data reveals a correlation in most cases between the occurrence of flavonoid aglycones, the presence of secretory structures and the production of other lipophilic plant products.

319 citations

Journal ArticleDOI
TL;DR: The mutagenicities of 61 flavonoids and those of 11 compounds structurally related to flavonoid compounds were tested with Salmonella typhimurium strains TA100 and TA98 and it was found that quercetin was the strongest mutagen.
Abstract: The mutagenicities of 61 flavonoids (naturally occurring flavonoid aglycones and flavonal glycosides and synthetic flavonoids) and those of 11 compounds structurally related to flavonoids were tested with Salmonella typhimurium strains TA100 and TA98. Among the 22 flavone derivatives tested, only wogonin was strongly mutagenic, while five derivatives, apigenin triacetate, acacetin, chrysoeriol, pedalitin, and pedalitin tetraacetate, were only weakly mutagenic. Two bisflavonyl derivatives, neither of which has a 3-hydroxyl group, were not mutagenic. Of the 16 flavonol derivatives tested, all except 3-hydroxyflavone and the tetra- and penta-methyl ethers of quercetin were mutagenic. Of the five flavanone derivatives tested, only 7,4-dihydroxyflavanone was mutagenic, showing weak activity. Of the four flavanonol derivatives tested, hydrorobinetin and taxifolin were weakly mutagenic. Of the six isoflavone derivatives tested, tectorigenin was weakly mutagenic. Of the 11 compounds in the miscellaneous group structurally related to flavonoids, only iso-liquiritigenin was mutagenic, showing weak activity. For the emergence of strong mutagenicity, the double bond between positions 2 and 3 and the hydroxyl group at position 3 are required, except in wogonin, which does not have a hydroxyl group at position 3 but is strongly mutagenic to TA100. The 3-O-acetyl ester of flavonol, quercetin, was mutagenic with S9 mix, but 3-O-methyl ethers were not. Six flavonol glycosides, three quercetin glycosides and three kaempferol glycosides were mutagenic after preincubation with “hesperidinase,” a crude extract of Aspergillus niger. Of 66 flavonoid agylcones and compounds structurally related to flavonoids, quercetin was the strongest mutagen. The carcinogenicity of this compound should be clarified because it is ubiquitously found in vegetables.

177 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide an overview of approximately 300 secondary metabolites with inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), which were isolated from various natural sources or derived from synthetic process in the last decades.
Abstract: This article provides an overview of approximately 300 secondary metabolites with inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), which were isolated from various natural sources or derived from synthetic process in the last decades. The structure-activity relationship and the selectivity of some compounds against other protein phosphatases were also discussed. Potential pharmaceutical applications of several PTP1B inhibitors were presented.

173 citations

Book
27 Apr 2001
TL;DR: The Flavonoids as Indicators of the Evolutionary Process and Hybridization and Introgression and Flavonoid Relationships with other Families.
Abstract: Section I. Introduction to the Sunflower Family.- 1. Biology and Distribution.- 2. Classification, Phylogeny and Biogeography.- Section II. Introduction to the Flavonoids.- 3. The Use of Flavonoids as Taxonomic Markers.- 4. Structural Variation of the Flavonoids of Asteraceae.- 5. Biosynthesis of Flavonoids.- 6. Biological Functions of Flavonoids.- Section III. Flavonoid Data.- 7. Flavonoids of Anthemideae.- 8. Flavonoids of Astereae.- 9. Flavonoids of Calenduleae and Cardueae.- 10. Flavonoids of Eupatorieae.- 11. Flavonoids of Heliantheae s.l.- 12. Flavonoids of Inuleae s.l.- 13. Flavonoids of Lactuceae.- 14. Flavonoids of Mutisieae and Barnadesioideae.- 15. Flavonoids of Senecioneae.- 16. Flavonoids of Tageteae.- 17. Flavonoids of Vernonieae and Liabeae.- Section IV. Efficacy of Flavonoids at Different Taxonomic Levels.- 18. Flavonoids at the Subfamilial Level.- 19. Flavonoids at the Tribal Level.- 20. Flavonoids at the Subtribal Level.- 21. Flavonoids at the Generic Level.- 22. Flavonoids at the Specific Level.- 23. Flavonoids at Infraspecific Levels.- Section V. Flavonoids as Indicators of the Evolutionary Process.- 24. Flavonoids and Populational Variation.- 25. Flavonoids and Hybridization and Introgression.- Section VI. Flavonoids and Phylogeny.- 26. Flavonoid Relationships with other Families.- 27. Evolution of the Flavonoid System in Asteraceae.- Addendum.- References.- Common Names of Flavonoids Used in This Book and Their Equivalents.- Chemical Index.- Taxon Index.

164 citations