- Anti‐melanogenic properties of velutin and its analogs?
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Velutin, one of the flavones contained in natural plants, has various beneficial activities, such as skin whitening, as well as anti‐inflammatory, anti‐allergic, antioxidant, and antimicrobial activities. However, the relationship between the structure of velutin and its anti‐melanogenesis activity is not yet investigated. In this study, we obtained 12 velutin derivatives substituted at C5, C7, C3′, and C4′ of the flavone backbone with hydrogen, hydroxyl, and methoxy functionalities by chemical synthesis, to perform SAR analysis of velutin structural analogues. The SAR study revealed that the substitution of functional groups at C5, C7, C3′, and C4′ of the flavone backbone affects biological activities related to melanin synthesis. The coexistence of hydroxyl and methoxy at the C5 and C7 position is essential for inhibiting tyrosinase activity. However, 1,2‐diol compounds substituted at C3′ and C4′ of flavone backbone induce apoptosis of melanoma cells. Further, substitution at C3′ and C4′ with methoxy or hydrogen is essential for inhibiting melanogenesis. Thus, this study would be helpful for the development of natural‐derived functional materials to regulate melanin synthesis.
- Choe, Jung-Won,Heo, Hee-Young,Jung, Se-Hui,Kim, Jaehyun,Lee, Kooyeon
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- New C,O-Glycosylflavones from the Genus Silene
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Chromatographic separation of extracts from the aerial parts of three Silene species (Caryophyllaceae) isolated 26 flavonoids including the four new C,O-glycosylflavones acacetin-6-C-(2″-O-β-D-glucopyranosyl)-β-D-glucopyranoside-7-O-β-D-glucopyranoside (s
- Olennikov,Kashchenko
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p. 1026 - 1034
(2020/11/05)
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- Site-selective synthesis of acacetin and genkwanin through lipase-catalyzed deacetylation of apigenin 5,7-diacetate and subsequent methylation
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Candida antarctica lipase B-catalyzed deacetylation proceeded with high site-selectivity on the C-4′ acetyl group in apigenin triacetate to give apigenin 5,7-diacetate. Methylation of the liberated hydroxy group with the combination of trimethyloxonium tetrafluoroborate (Meerwein reagent) and 1,8-bis(dimethylamino)naphthalene (proton sponge) in CH2Cl2 proceeded in a quantitative manner to give the product methylated at the C-4′ hydroxy group (acacetin 5,7-diacetate). Even with the same precursor, a different methylation product at the C-7 hydroxy group (genkwanin 4′,5-diacetate) was obtained in 86% yield by applying iodomethane and Cs2CO3 in dimethyl sulfoxide (DMSO). The methylated products were deprotected to form acacetin and genkwanin. We inferred that the latter unexpected methylation was ascribable to the intermolecular migration of an acetyl group from C-7 to C-4′. DFT calculations indicated that the C-7 phenoxide ion was 12.6 kJ/mol more stable than the initially formed C-4′ phenoxide ion.
- Fujita, Rie,Hanaya, Kengo,Higashibayashi, Shuhei,Mandal, Susanta,Shoji, Mitsuru,Sugai, Takeshi
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p. 638 - 648
(2019/07/31)
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- Scope and Mechanism of the Ruthenium-Catalyzed Dehydrative C-H Coupling of Phenols with α,β-Unsaturated Carbonyl Compounds: Expedient Synthesis of Chromene and Benzoxacyclic Derivatives
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Chromene and benzoxacyclic derivatives were efficiently synthesized from the ruthenium-catalyzed dehydrative C-H coupling reaction of phenols with α,β-unsaturated carbonyl compounds. The cationic ruthenium-hydride complex was found to be an effective catalyst for the coupling and annulation of phenols with enals to form chromene products. The coupling of phenols with linear enones afforded 2,4-disubstituted chromene derivatives, whereas the analogous coupling with cyclic enones yielded 9-hydroxybenzoxazole products. The reaction of 3,5-dimethoxyphenol with PhCH=CHCDO resulted in the chromene product with a significant H/D exchange to both benzylic and vinyl positions. The most significant carbon isotope effect from the coupling of 3,5-dimethoxyphenol with 4-methoxycinnamaldehyde was observed on the α-olefinic carbon of the chromene product (C(2) = 1.067). A Hammett plot from the coupling of 3,5-dimethoxyphenol with para-substituted p-X-C6H4CH=CHCHO displayed a linear correlation, with a strong promotional effect by an electron-withdrawing group (ρ = +1.5; X = OCH3, CH3, H, F, Cl). Several biologically active chromenone derivatives were synthesized by using the catalytic coupling method. The catalytic method provides an expedient synthetic protocol for the coupling of phenols with α,β-unsaturated carbonyl compounds without employing reactive reagents or forming any wasteful byproducts.
- Mokar, Bhanudas Dattatray,Yi, Chae S.
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p. 4625 - 4632
(2019/12/24)
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- Activities of Wogonin Analogs and Other Flavones against Flavobacterium columnare
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In our on-going pursuit to discover natural products and natural product-based compounds to control the bacterial species Flavobacterium columnare, which causes columnaris disease in channel catfish (Ictalurus punctatus), we synthesized flavone and chalcone analogs, and evaluated these compounds, along with flavonoids from natural sources, for their antibacterial activities against two isolates of F. columnare (ALM-00-173 and BioMed) using a rapid bioassay. The flavonoids chrysin (1a), 5,7-dihydroxy-4′-methoxyflavone (11), isorhamnetin (26), luteolin (27), and biochanin A (29), and chalcone derivative 8b showed strong antibacterial activities against F. columnare ALM-00-173 based on minimum inhibition concentration (MIC) results. Flavonoids 1a, 8, 11, 13 (5,4′-dihydroxy-7-methoxyflavone), 26, and 29 exhibited strong antibacterial activities against F. columnare BioMed based upon MIC results. The 24-h 50% inhibition concentration (IC50) results revealed that 27 and 29 were the most active compounds against F. columnare ALM-00-173 (IC50 of 7.5 and 8.5 mg/l, resp.), while 26 and 29 were the most toxic compound against F. columnare BioMed (IC50 of 9.2 and 3.5 mg/l, resp.). These IC50 results were lower than those obtained for wogonin against F. columnare ALM-00-173 and F. columnare BioMed (28.4 and 5.4 mg/l, resp.). However, based on MIC results, none of the compounds evaluated in this study were as active as wogonin (MIC 0.3 mg/l for each F. columnare isolate). Further modification of the wogonin structure to enhance antibacterial is of interest.
- Tan, Cheng-Xia,Schrader, Kevin K.,Khan, Ikhlas A.,Rimando, Agnes M.
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p. 259 - 272
(2015/10/19)
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- Structure-activity relationship study of biflavonoids on the dengue virus polymerase DENV-NS5 RdRp
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Dengue virus is the worlds most prevalent human pathogenic arbovirus. There is currently no treatment or vaccine, and solutions are urgently needed. We previously demonstrated that biflavonoids from Dacrydium balansae, an endemic gymnosperm from New Caledonia, are potent inhibitors of the Dengue virus NS5 RNA-dependent RNA polymerase. Herein we describe the structure-activity relationship study of 23 compounds: biflavonoids from D. balansae (1-4) and from D. araucarioides (5-10), hexamethyl-amentoflavone (11), cupressuflavone (12), and apigenin derivatives (13-23). We conclude that 1) over the four different biflavonoid skeletons tested, amentoflavone (1) and robustaflavone (5) are the most promising ones for antidengue drug development, 2) the number and position of methyl groups on the biflavonoid moiety modulate their inhibition of Dengue virus NS5 RNA-dependent RNA polymerase, and 3) the degree of oxygenation of flavonoid monomers influences their antidengue potential. Sotetsuflavone (8), with an IC50 = 0.16 μM, is the most active compound of this series and is the strongest inhibitor of the Dengue virus NS5 RNA-dependent RNA polymerase described in the literature. Georg Thieme Verlag KG Stuttgart New York.
- Coulerie, Paul,Nour, Mohammed,Maciuk, Alexandre,Eydoux, Cecilia,Guillemot, Jean-Claude,Lebouvier, Nicolas,Hnawia, Edouard,Leblanc, Karine,Lewin, Guy,Canard, Bruno,Figadere, Bruno
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p. 1313 - 1318
(2013/10/22)
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- Synthesis of oriented anti-virus 7-O-substituted apigenins
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7-O-Substituted apigenins were synthesized for searching anti-virus active compound. Using a commercially available naringenin as a starting material, 7-O-methylapigenin (1) and seven unnatural 7-0-substituted apigenin derivatives (13-19) were prepared via 4'-O-methoxymethylapigenin (5) as an intermediate.
- Oyama, Kin-ichi,Kondo, Tadao,Yoshida, Kumi
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experimental part
p. 1607 - 1615
(2009/07/19)
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- Flavonoid glycosides from Salvia moorcroftiana Wall
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Phytochemical analysis of the whole plant of Salvia moorcroftiana Wall. (Lamiaceae) resulted in the isolation of two new flavonoid glycosides, together with three known compounds. The structures of the new compounds were established as genkwanin 4′-O-α-L-arabinopyranosyl-(1→6)-β-D-galactopyranoside (1) and genkwanin 4′-O-{α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl- (1→6)]-β-D-galactopyranoside} (2). The structures of all compounds were elucidated by spectroscopic methods, including 2D NMR techniques.
- Zahid, Muhammad,Ishrud, Omar,Pan, Yuanjiang,Asim, Muhammad,Riaz, Muhammad,Uddin Ahmad, Viqar
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p. 403 - 407
(2007/10/03)
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- Synthesis of genkwanin
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Genkwanin (3) isolated from a Chinese drug Yuen Hua has been synthesized. 2,6-Dihydroxy-4-methoxyacetophenone (1) is condensed with p-hydroxybenzaldehyde to give the chalcone 2 which on DDQ oxidation afford the genkwanin (3). All the compounds have been characterized on the basis of spectral data and microanalysis.
- Hossain, M. Amzad
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p. 927 - 928
(2007/10/03)
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- Synthesis of Flavones via Application of the Nitrile Oxide and the Stille Reactions
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Hydroxylated and methoxylated benzaldehyde oximes have been chlorinated, dehydrohalogenated and cycloadded to tributylstannylacetylene to give 3-aryl-5-tributylstannylisoxazoles in good to excellent yields.The palladium-catalyzed coupling reaction, the so-called Stille reaction, of hindered and electron-rich 2-iodophenols and a 2-iodo-1,4-benzoquinone with 3-aryl-5-tributylstannyl-isoxazoles gave 3-aryl-5-(2-hydroxyaryl)isoxazoles in moderate to excellent yields.The coupling reaction was studied under various conditions and with various Pd(II) and Pd(0) complexes.Reduction of the 3,5-diarylisoxazoles with H2/Raney-Ni, hydrolysis and acid-catalyzed cyclisation gave flavones.The synthesis of 2-iodo-3,5-dimethoxy-1,4-benzoquinone is described.
- Gothelf, Kurt V.,Torssell, Kurt B. G.
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- FLAVONOID 5-GLUCOSIDES FROM PRUNUS CERASUS BARK AND THEIR CHARACTERISTIC WEAK GLYCOSIDIC BONDING
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Pinostrobin 5-glucoside, a novel flavanone glycoside, was isolated from the bark of Prunus cerasus.As it was not found in P. avium, the substance is useful to distinguish these two species.Apigenin 5-glucoside, genkwanin 5-glucoside and neosakuranin were also isolated from the bark of P. cerasus.They occur in both species as minor components.These 5-glucosides together with genistein 5-glucoside, prunetin 5-glucoside, sakuranin, tectochrysin 5-glucoside and luteolin 5-glucoside were hydrolysed in malic acid.The isoflavone and flavone 5-glucosides were shown to be hydrolysed more rapidly than the flavanone 5-glucosides, whereas no hydrolysis was observed with the corresponding 7-glucosides under the same conditions.The chalcone 2'-glucoside neosakuranin was transformed at first to the corresponding flavanone 5-glucoside, which was hydrolysed thereafter. Key Word Index - Prunus cerasus; Prunus avium; Rosaceae; bark; pinostrobin 5-glucoside; flavonoid 5-glucosides; hydrolysis.
- Geibel, Martin,Feucht, Walter
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p. 1519 - 1521
(2007/10/02)
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- Chemical and Chemotaxonomical Studies of Ferns. LXXIII. New Flavonoids with Modified B-Ring from the Genus Pseudophegopteris (Thelypteridaceae)
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Chemical studies of three representatives of the genius Pseudophegopteris (Thelypteridaceae) revealed that the genus is characterized by the occurrence of unusual flavonoids with a modifield B-ring related to protogenkwain (VII).From P. hirtirachis HOLTT., three novel compounds, protogenkwanone(1), tetrahydroprotogen wanone (II) and tetrahydroprotogen wanin (III), were isolated, along with protogenkwanin 4-O-β-D-glucoside (VI)from P.subaurita CHING, two new acylated glucosides of protogenkwanin 4-O-(2-O-acetyl)-β-D-glucoside (IV) and 4'-O-(6-O-acetyl)-β-D-glucoside (V), were obtained, together with I, II and VI.From P. bukoensis HOLTT., IV, V and VI were isolated, in addition to apigenin 7-O-α-L-rhamnoside and kaempferol.The structures of the new compounds were determined by means of spectroscopic methods and chemical transformations.Keywords----Pseudophegopteris hirtirachis; Pseudophegopteris subaurita; Pseudophegopteris bukoensis; Thelypteridaceae; protogenkwanin-type flavonoid; protogenkwanin; acylated glycoside; fern; chemotaxonomy; 13C-NMR
- Wada, Hiroshi,Fujita, Hiroyuki,Murakami, Takao,Saiki, Yasuhisa,Chen, Chiu-Ming
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p. 4757 - 4762
(2007/10/02)
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- Structure of Phegopolin
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The structure of a rare flavonoid glycoside phegopolin has been established as 4'-α-D-glucopyranosyloxy-5-hydroxy-7-methoxyflavone (I) on the basis of chemical and spectroscopic evidences.This is the first report of its isolation from a member of Leguminosae family.
- Jain, Raka,Gupta, R. K.
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p. 999 - 1000
(2007/10/02)
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- PROTOGENKWANIN, A NEW FLAVONOID FROM EQUISETUM ARVENSE L.
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From the fertile sprouts of Equisetum arvense L. have been isolated protogenkwanin-4'-glucoside and gossypitrin.The structure of protogenkwanin as 5-hydroxy-2-(1,4-dihydroxy-2,5-cyclohexadienyl)-7-methoxy-4-chromenon is proved on the basis of chemical and physical evidence.It is demonstrated that articulatin, a thiamine decomposing substance, from E. arvense, is identical with the known flavonol glycoside gossypitrine (=gossypetin-7-glucoside).The synthesis of 2,5-dihydroxy-2-(4-hydroxyphenyl)-7-methoxy-4-chromanon is reported.
- Hauteville, Marcelle,Chopin, Jean,Geiger, Hans,Schuler, Lothar
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p. 377 - 381
(2007/10/02)
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