29550-13-8Relevant academic research and scientific papers
A convenient and efficient approach to synthesize negletein from baicalin
He, Guihua,Gao, Yu,Li, Cailong,Wu, Guolin,Li, Yazhen,Dong, Longrong,Huang, Changcang,Chen, Haijun
, p. 2001 - 2005 (2016)
A simple two-step/one-pot and highly efficient strategy for the synthesis of negletein from naturally abundant and inexpensive baicalin has been developed. In this one-pot sequence, esterification of baicalin catalyzed by concentrated H2SO
An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone
Hemantha, Hosahalli P.,Ramanujam, Rajendran,Majeed, Muhammed,Nagabhushanam, Kalyanam
, p. 1413 - 1420 (2019/08/22)
Oroxylin A, a major flavonoid in the extracts of Oroxylum indicum as well as Scutellaria baicalensis possesses useful medicinal properties. Many of the published routes claiming the synthesis of Oroxylin A (1) have in fact led to a regioisomer Negletein that was misinterpreted as Oroxylin A. In the present work, we describe a novel, straight-forward and scalable semi-synthetic approach for rapid access to the title compound, the structure of which is unambiguously secured by NMR and X-ray crystallographic analysis of a derivative. This work also encompasses the synthesis of a glycosylated derivative of Oroxylin A viz OAGME (2), which has marked pharmacological importance.
Characterization of a Flavonoid 3’/5’/7-O-Methyltransferase from Citrus reticulata and Evaluation of the in Vitro Cytotoxicity of Its Methylated Products
Liu, Xiaojuan,Wang, Yue,Chen, Yezhi,Xu, Shuting,Gong, Qin,Zhao, Chenning,Cao, Jinping,Sun, Chongde
, (2020/02/25)
O-methylation of flavonoids is an important modification reaction that occurs in plants. O-methylation contributes to the structural diversity of flavonoids, which have several biological and pharmacological functions. In this study, an O-methyltransferase gene (CrOMT2) was isolated from the fruit peel of Citrus reticulata, which encoding a multifunctional O-methyltransferase and could effectively catalyze the methylation of 3’-, 5’-, and 7-OH of flavonoids with vicinal hydroxyl substitutions. Substrate preference assays indicated that this recombinant enzyme favored polymethoxylated flavones (PMF)-type substrates in vitro, thereby providing biochemical evidence for the potential role of the enzyme in plants. Additionally, the cytotoxicity of the methylated products from the enzymatic catalytic reaction was evaluated in vitro using human gastric cell lines SGC-7901 and BGC-823. The results showed that the in vitro cytotoxicity of the flavonoids with the unsaturated C2-C3 bond was increased after being methylated at position 3’. These combined results provide biochemical insight regarding CrOMT2 in vitro and indicate the in vitro cytotoxicity of the products methylated by its catalytic reaction.
PROCESS FOR SYNTHESIS OF OROXYLIN A
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Page/Page column 7-9, (2020/03/02)
Disclosed is a novel, simple, scalable and environment friendly process for the synthesis of Oroxylin A from Baicalin. Baicalm is esterified to obtain a methyl ester which is further selectively methylated to provide Oroxylin A gluciironide methyl ester w
Crystal structures of the flavonoid Oroxylin A and the regioisomers Negletein and Wogonin
Grano, Ruel Valerio Robles De,Nisar, Madiha,Sung, Herman H.-Y.,Vashchenko, Elena V.,Vashchenko, Valerii V.,Williams, Ian D.
, p. 490 - 499 (2020/05/18)
The flavonoid Oroxylin A (6-methoxychrysin or 5,7-dihydroxy-6-methoxy-2- phenyl-4H-chromen-4-one, C16H12O5) and its regioisomers are of increasing interest for a variety of bioactive functions and their pharmaceutical formulation is of importance. Previous difficulties in the separation and misidentification of Oroxylin A from its regioisomers Wogonin (8-methoxychrysin or 5,7-dihydroxy-8-methoxy-2-phenyl-4H-chromen-4-one) and Negletein (5,6- dihydroxy-7-methoxyflavone or 5,6-dihydroxy-7-methoxy-2-phenyl-4H-chromen- 4-one) render its full structural and powder X-ray characterization highly desirable. The low-temperature (100 K) crystal structures of Oroxylin A, Negletein and Wogonin sesquihydrate are reported for the first time. Wogonin crystallizes in two related but distinct hydrated forms. These have very similar powder diffractograms, indicating that such issues need to be addressed for its pharmaceutical formulation.
Role of some food-grade synthesized flavonoids on the control of ochratoxin a in aspergillus carbonarius
Ricelli, Alessandra,De Angelis, Martina,Primitivo, Ludovica,Righi, Giuliana,Sappino, Carla,Antonioletti, Roberto
, (2019/07/18)
Ochratoxin A (OTA) is a mycotoxin with a serious impact on human health. In Mediterranean countries, the black Aspergilli group, in particular Aspergillus carbonarius, causes the highest OTA contamination. Here we describe the synthesis of three polyphenolic flavonoids: 5-hydroxy-6,7-dimethoxy-flavone (MOS), 5,6-dihydroxy-7-methoxy-flavone (NEG), and 5,6 dihydroxy-flavone (DHF), as well as their effect on the prevention of OTA biosynthesis and lipoxygenase (LOX) activity in A. carbonarius cultured in a conducive liquid medium. The best control effect on OTA biosynthesis was achieved using NEG and DHF. In fungal cultures treated with these compounds at 5, 25, and 50 μg/mL, OTA biosynthesis significantly decreased throughout the 8-day experiment. NEG and DHF appear to have an inhibiting effect also on the activity of LOX, whereas MOS, which did not significantly inhibit OTA production, had no effect on LOX activity. The presence of free hydroxyls in catecholic position in the molecule appears to be a determining factor for significantly inhibiting OTA biosynthesis. However, the presence of a methoxy group in C-7 in NEG could slightly lower the molecule’s reactivity increasing OTA inhibition by this molecule at 5 μg/mL. Polyphenolic flavonoids present in edible plants may be easily synthesized and used to control OTA biosynthesis.
Process for synthesis of Oroxylin A
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Page/Page column 4; 7-10, (2019/09/23)
Disclosed is a novel, simple, scalable and environment friendly process for the synthesis of Oroxylin A from Baicalin. Baicalin is esterified to obtain a methyl ester which is further selectively methylated to provide Oroxylin A glucuronide methyl ester which on de-glycosylation results in the formation of Oroxylin A.
New alkoxy flavone derivatives targeting caspases: Synthesis and antitumor activity evaluation
Moreira, Joana,Ribeiro, Diana,Silva, Patrícia M. A.,Nazareth, Nair,Monteiro, Madalena,Palmeira, Andreia,Saraiva, Lucília,Pinto, Madalena,Bousbaa, Hassan,Cidade, Honorina
, (2019/01/14)
The antitumor activity of natural flavonoids has been exhaustively reported. Previously it has been demonstrated that prenylation of flavonoids allows the discovery of new compounds with improved antitumor activity through the activation of caspase-7 activity. The synthesis of twenty-five flavonoids (4-28) with one or more alkyl side chains was carried out. The synthetic approach was based on the reaction with alkyl halide in alkaline medium by microwave (MW) irradiation. The in vitro cell growth inhibitory activity of synthesized compounds was investigated in three human tumor cell lines. Among the tested compounds, derivatives 6, 7, 9, 11, 13, 15, 17, and 18 revealed potent growth inhibitory activity (GI50 10 μM), being the growth inhibitory effect of compound 13 related with a pronounced caspase-7 activation on MCF-7 breast cancer cells and yeasts expressing human caspase-7. A quantitative structure-activity relationship (QSAR) model predicted that hydrophilicity, pattern of ring substitution/shape, and presence of partial negative charged atoms were the descriptors implied in the growth inhibitory effect of synthesized compounds. Docking studies on procaspase-7 allowed predicting the binding of compound 13 to the allosteric site of procaspase-7.
Discovery of novel negletein derivatives as potent anticancer agents for acute myeloid leukemia
Wu, Jianlei,Chen, Yingyu,Liu, Xuanping,Gao, Yu,Hu, Jianda,Chen, Haijun
, p. 924 - 932 (2018/01/27)
Baicalin and its aglycone baicalein derived from Scutellaria baicalensis exhibited potent anticancer effects in various types of cancer cell lines. However, the unfavorable pharmaceutical properties became the main obstacle for their potential clinical de
A new domino oxidation—rearrangement of 2,3-dihydrowogonin to negletein
Spoerlein-Guettler, Cornelia,Milius, Wolfgang,Obenauf, Johannes,Schobert, Rainer
, p. 1560 - 1562 (2018/03/29)
We report an expeditious, iodine-catalysed oxidation of 2,3-dihydrowogonin to negletein which comprises a Wessely–Moser rearrangement (WMR), associated not with an O-demethylation, as usual, but with an oxygen to oxygen methyl shift. In contrast, DDQ in 1
