Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• corresponding flavanones hesperetin and naringenin and the flavonol quercetin, respectively. These compounds have a disaccharide moiety connected to the aglycones through an ether linkage with the hydroxy groups in the 7 and 3 positions (Figure 1a). On the other hand, silibinins (the main components of

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

• curcumin or (iso)quercetin, not to mention hydroxychloroquine. Past these rather scathing comments which could lead to a long-delayed but healthy debate in the concerned countries, the last four decades saw several “revolutions” in medicinal chemistry which were triggered by the following major advance in

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0013, Japan 10.3762/bjoc.14.291 Abstract Among the five hydroxy (OH) groups of quercetin (3,5,7,3',4'-pentahydroxyflavone), the OH group at 5 position is the most resistant to methylation due to its strong intramolecular hydrogen bonding with the

• carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature

• for about 2 hours, affording quercetin pentamethyl ether (QPE) quantitatively as a single product. When methyl iodide was used in place of dimethyl sulfate, the C-methylation product 6-methylquercetin pentamethyl ether was also formed. A computational study provided a rationale for the experimental

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• composites loaded with quercetin may show improved cytotoxic activity towards some human breast cancer cell lines [32], likely due to a synergistic action between the polyphenol nutraceutic guest molecule and triazole derivatives coming from the progressive disgregation of the co-polymer carrier. From the

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• cancer cells towards apoptosis through the mitochondrial pathway. Mitrasinovic has reported sequence-dependent binding of various structurally different flavonoids (quercetin (QUE) and flavopiridol (FLP)), a family of prospective anticancer agents, to duplex DNAs [104]. The five hydroxy groups in QUE

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

• Paweł Chmielarz,
• Tomasz Pacześniak,
• Katarzyna Rydel-Ciszek,
• Izabela Zaborniak,
• Paulina Biedka and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2017, 13, 2466–2472, doi:10.3762/bjoc.13.243

• macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the “grafting from” strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate

• naturally-derived macromolecules showed narrow MWDs (Đ = 1.08–1.11). 1H NMR spectral results confirm the formation of quercetin-based polymers. These new flavonoid-based polymer materials may find applications as antifouling coatings and drug delivery systems. Keywords: flavonoids; on-demand seATRP

• ; quercetin-based macromolecules; Introduction In the last decade, there have been increasing research activities in the use of atom transfer radical polymerization (ATRP) to prepare naturally-derived star-like polymers [1][2][3][4]. Considering this method, naturally-occurring polymers can be synthesized

Biomimetic synthesis and HPLC–ECD analysis of the isomers of dracocephins A and B

• Viktor Ilkei,
• András Spaits,
• Anita Prechl,
• Áron Szigetvári,
• Zoltán Béni,
• Miklós Dékány,
• Csaba Szántay Jr,
• Judit Müller,
• Árpád Könczöl,
• Ádám Szappanos,
• Attila Mándi,
• Sándor Antus,
• Ana Martins,
• Attila Hunyadi,
• György Tibor Balogh,
• György Kalaus (†),
• Hedvig Bölcskei,
• László Hazai and
• Tibor Kurtán

Beilstein J. Org. Chem. 2016, 12, 2523–2534, doi:10.3762/bjoc.12.247

• measured, but these compounds, along with naringenin were virtually inactive in the DPPH radical scavenging test (IC50 > 200 µg/mL), compared to the positive control quercetin (IC50 = 9.4 ± 0.6 µg/mL). Conclusion An efficient one pot synthesis of dracocephins A (2a–d) and B (3a–d) was achieved starting

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• of hydrophilic products and to obtain safe and stable pro-drugs. Results: A totally green, solvent-free and catalyst-free microwave (MW)-assisted method for peracetylation of natural products such as oleuropein, alpha-hederin, quercetin and rutin is presented. By simply tuning the MW heating program

• ester (8), uridine (12) and methyl-α-D-glucopyranoside (11)) and natural antioxidant compounds in their simple (hydroxytyrosol (4), homovanillic alcohol (5), quercetin (13)) or glycosylated forms (oleuropein (14), rutin (17), alpha-hederin (16)). Because of their heterogeneity in terms of

• cases more than one reaction cycle was necessary for complete conversion (entries 11, 12, 15, 16 and 17, Table 2). The only exception was the natural product quercetin (13) that, despite a quantitative conversion after the first acetylation run, surprisingly gave a complex mixture of differently

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• natural antioxidants are flavonoids, anthocyanins and their glycosides. Huber and collaborators [18] revealed the inhibition of PUFA oxidation by quercetin and its 3-O-glucoside. They were as effective as butylated hydroxytoluene (BHT, a synthetic antioxidant) against the oxidation of DHA and methylated

Genicunolide A, B and C: three new triterpenoids from Euphorbia geniculata

• Alia Farozi,
• Javid A. Banday and
• Shakeel A. Shah

Beilstein J. Org. Chem. 2015, 11, 2707–2712, doi:10.3762/bjoc.11.291

• inflammations. Previous phytochemical investigations have demonstrated that this plant contains flavonoids: kaempferol, quercetin and 3-rhamnosyl quercetin [28] and triterpenes β-amyrin acetate [29] and geniculatin [30]. Reinvestigation of chemistry of the plant led to isolation of three new triterpenoids

Selective methylation of kaempferol via benzylation and deacetylation of kaempferol acetates

• Qinggang Mei,
• Chun Wang,
• Weicheng Yuan and
• Guolin Zhang

Beilstein J. Org. Chem. 2015, 11, 288–293, doi:10.3762/bjoc.11.33

• some have been used for the preparation of natural and therapeutic products of biological significance. To date, however, the regioselective direct O-alkylation of polyhydroxy favonoids is still of challenge. Until recently, selective O-methylation of quercetin was carried out by the protection of

• phenolic functions with benzyl or diphenylmethylene ketal [19]. Quercetin was converted to pentabenzylquercetin and thereby four mono-methylated isomers were synthesized through selective deprotection [20]. The regioselective O-methylation of kaempferol, to the best of our knowledge, has not been reported

• . The major strategy depends on the selective benzylation and controllable deacetylation of kaempferol acetates. Results and Discussion Selectivity of direct methylation of kaempferol Kaempferol is both significantly similar to and different from quercetin. Rao et al. found that the methylation of the

Natural phenolic metabolites with anti-angiogenic properties – a review from the chemical point of view

• Qiu Sun,
• Jörg Heilmann and
• Burkhard König

Beilstein J. Org. Chem. 2015, 11, 249–264, doi:10.3762/bjoc.11.28

• cells (HMEC-1) have been given special attention. In contrast, compounds showing in vitro anti-angiogenic activity but also signs of strong unspecific cytotoxic effects in vitro have been excluded. The secondary metabolites discussed include six flavonoids from different subclasses: quercetin, fisetin

• ·Et2O gave genistein (60) in good yield. In the Friedel–Crafts acylation, BF3·Et2O was used as the catalyst and solvent. The following formation of the pyrone was also catalyzed by BF3·Et2O, and a convenient one-pot synthesis of 60 was achieved without isolation of 59 [85]. Fisetin and quercetin The

• flavonoids fisetin (67) and quercetin (68) belong to the flavonol subgroup that exhibit a double bond between C-2/C-3 and a hydroxy group at C-3. Flavonols are the most abundant flavonoid subtype in plants and commonly occur as glycosides. Nevertheless, pharmacological testing was historically concentrated

Binding mode and free energy prediction of fisetin/β-cyclodextrin inclusion complexes

• Bodee Nutho,
• Wasinee Khuntawee,
• Chompoonut Rungnim,
• Piamsook Pongsawasdi,
• Peter Wolschann,
• Alfred Karpfen,
• Nawee Kungwan and
• Thanyada Rungrotmongkol

Beilstein J. Org. Chem. 2014, 10, 2789–2799, doi:10.3762/bjoc.10.296

• were used to describe the molecular mechanisms of inclusion complexation between the flavonoids quercetin/myricetin and cyclodextrin in comparison with the experimental results from 1H NMR spectroscopy [30]. Choi and coworkers [31] also reported a theoretical study based on MD simulations in order to

Computational evidence for intramolecular hydrogen bonding and nonbonding X···O interactions in 2'-haloflavonols

• Tânia A. O. Fonseca,
• Matheus P. Freitas,
• Rodrigo A. Cormanich,
• Teodorico C. Ramalho,
• Cláudio F. Tormena and
• Roberto Rittner

Beilstein J. Org. Chem. 2012, 8, 112–117, doi:10.3762/bjoc.8.12

• carbonyl oxygen (conformer A), establishing an intramolecular HB as the stabilizing interaction of this conformation, in agreement with the crystal structure of 2'-methoxyflavonol [19] and with the bioactive conformation of fisetin [20] and quercetin [21]. Moreover, a weak (H)O···H–C HB also takes place in

An efficient partial synthesis of 4′-O-methylquercetin via regioselective protection and alkylation of quercetin

• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang,
• Jian-Ping Yang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2009, 5, No. 60, doi:10.3762/bjoc.5.60

• Medicine, Nanjing, Jiangsu 210046, P.R. China Division of Organic Chemistry, China Pharmaceutical University, Nanjing, Jiangsu 211198, China 10.3762/bjoc.5.60 Abstract An efficient partial 5-step synthesis of 4′-O-methylquercetin from quercetin in 63% yield is reported. This strategy relies on the

• ; Introduction Flavonoids, such as flavones and flavonols, are secondary plant metabolites found in many foods, especially in fruits and vegetables [1][2]. Quercetin (1) (Figure 1), the major individual non-polymeric molecule among the polyphenols represents 60–75% of the flavonoid intake [3]. Quercetin is a

• very efficient antioxidant [4] and appears to be active against many diseases related to ageing such as cancer [5], cardiovascular [6] and neurodegenerative [7] diseases. In blood, quercetin is found mainly in metabolized forms. The non-degradative metabolism of quercetin involves three main