- An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone
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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.
- Hemantha, Hosahalli P.,Ramanujam, Rajendran,Majeed, Muhammed,Nagabhushanam, Kalyanam
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p. 1413 - 1420
(2019/08/22)
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- PROCESS FOR SYNTHESIS OF OROXYLIN A
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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
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Page/Page column 7-9
(2020/03/02)
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- New alkoxy flavone derivatives targeting caspases: Synthesis and antitumor activity evaluation
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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.
- Moreira, Joana,Ribeiro, Diana,Silva, Patrícia M. A.,Nazareth, Nair,Monteiro, Madalena,Palmeira, Andreia,Saraiva, Lucília,Pinto, Madalena,Bousbaa, Hassan,Cidade, Honorina
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- Process for synthesis of Oroxylin A
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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.
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Page/Page column 4; 7; 8
(2019/09/23)
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- Role of some food-grade synthesized flavonoids on the control of ochratoxin a in aspergillus carbonarius
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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.
- Ricelli, Alessandra,De Angelis, Martina,Primitivo, Ludovica,Righi, Giuliana,Sappino, Carla,Antonioletti, Roberto
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- 2-substituted benzopyran-4-one compounds and application thereof
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The invention relates to the technical field of medicine and discloses 2-substituted benzopyran-4-one compounds with a structure shown in general formula I and an application of the compounds in preparation of antifungal drugs and synergistic antifungal drugs. The compounds can be jointly used with azole antifungal drugs, can improve sensibility of drug-resistance bacteria to the azole drugs, reverses drug resistance and produces a synergistic antifungal function.
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Paragraph 0146; 0147; 0148; 0155; 0156; 0157
(2016/10/08)
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- Synthesis and evaluation of selenoflavones that have potential neuroprotective effects
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We synthesized selenoflavones and evaluated their physicochemical properties and antioxidant effects. When oxygen was substituted with selenium, the compounds exhibited improved polarity and lipophilicity, implying that this change could lead to better BBB penetration. Selenoflavones revealed more potent antioxidant activity in our in-vitro assay. This suggests that selenoflavones would be more druggable than flavones and have a better potential as a neuroprotective agent.
- Choi, Yong-Sung,Kim, Yoon-Jung,Lee, Ju Yeun,Lee, Jinu,Jeong, Jin-Hyun
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p. 2794 - 2805
(2015/03/04)
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- Synthesis of ring A-modified baicalein derivatives
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Baicalein, an important active constituent of the traditional Chinese herb Scutellaria baicalensis, exhibited antitumor activity and inhibitory activity against P-gp 170. The syntheses of 25 baicalein derivatives, 2-26 (Table), are described here (Scheme
- Wang, Jun-Fei,Ding, Ning,Zhang, Wei,Wang, Peng,Li, Ying-Xia
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experimental part
p. 2221 - 2230
(2012/01/14)
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- Convergent synthesis of mosloflavone, negletein and baicalein from crysin
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An expeditious synthesis of three polyoxygenated flavones: mosloflavone, negletein and baicalein, starting from crysin, an easily available flavone, by a bromination/methoxylation procedure is reported. The convergent synthesis exploits a base induced Wesley-Moser type rearrangement.
- Righi, Giuliana,Antonioletti, Roberto,Silvestri, Ilaria Proietti,D'Antona, Nicola,Lambusta, Daniela,Bovicelli, Paolo
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experimental part
p. 1294 - 1298
(2010/04/02)
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- Synthesis and in vitro study of novel 7-O-acyl derivatives of Oroxylin a as antibacterial agents
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A series of Oroxylin A derivatives, prepared by alkylation and condensation, were fully characterized by spectroscopic methods. All the derivatives were screened for antibacterial activity against a panel of susceptible and resistant Gram-positive and Gram-negative organisms. It was observed that acylation of 7-OH group in Oroxylin A significantly enhanced the activity as compared to their parent compound (Oroxylin A).
- Suresh Babu,Hari Babu,Srinivas,Sastry,Hara Kishore,Murty,Madhusudana Rao
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p. 3953 - 3956
(2007/10/03)
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- COMPOUNDS AND METHODS TO INCREASE ANTI-P-GLYCOPROTEIN ACTIVITY OF BAICALEIN BY ALKYLATION ON THE A RING
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The present invention is directed to analogs of baicalein according to formula (I): where R5 is H, (CI-C12)alkyl, (C2-C13)acyl, or an optionally substituted phenyl or benzyl group, an acyl group, a C1-C20 alkyl or ether group, a phosphate, diphosphate, triphosphate or phosphodiester group; R6 and R7 are each independently H, (C1-C12)alkyl, (C2-C13)acyl, or an optionally substituted phenyl or benzyl or together form a -OCR1R20- group wherein each of R1 and R2 is independently H, a C1-C3 alkyl group or an optionally substituted phenyl or benzyl group; and R8 is H, OH, an O-acyl group, a C1,-C4 alkyl or alkoxy group, F, Cl, Br or I, or a pharmaceutically acceptable salt thereof, which exhibit anti-P-glycoprotein activity and methods of enhancing the bioavailability of active compounds, especially orally administered compounds, by inhibition of P-glycoprotein 170 (P-gp 170) and/or CYP450 enzyme, especially CYP450 3A4 enzyme. Pharmaceutical compositions based upon these novel derivatives according to the present invention are also described herein.
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Page/Page column 30
(2010/02/13)
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- Structure-activity relationships for α-glucosidase inhibition of baicalein, 5,6,7-trihydroxyflavone: The effect of A-ring substitution
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In order to estimate the effects of the A-ring hydroxyl group of baicalein (5,6,7-trihydroxyflavone, 1) on rat intestinal α-glucosidase inhibition, flavone, monohydroxyflavones, dihydroxyflavones, and methylated derivatives of 5,6,7-trihydroxyflavone were used for the structure-activity relationship (SAR) study. The importance of the 6-hydroxyl group of baicalein was validated for an exertion of the activity. And also, the tested flavones which lacked a hydroxyl substituent on any of positions 5, 6, or 7, showed no activity. Hence, the 5,6,7-trihydroxyflavone structure was concluded to be crucial for the potent inhibitory activity. In addition, an introduction of electron-withdrawing or electron-donating groups at position 8 of baicalein led to a dramatic decrease for activity, except for 8-fluoro-5,6,7-trihydroxyflavone, which carried a less bulky substituent on position 8. Hence, this result suggested that a sterically bulky substituent on C-8 of baicalein was detrimental for the activity regardless of its electronic nature. Through examining the inhibitory mechanism of baicalein against rat intestinal α-glucosidase, it was suggested to be a mixed type inhibition.
- Gao, Hong,Nishioka, Tetsuo,Kawabata, Jun,Kasai, Takanori
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p. 369 - 375
(2007/10/03)
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- Increased anti-P-glycoprotein activity of baicalein by alkylation on the A ring
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The aqueous extract of Scutellariae baicalensis Georgi has inhibitory activity against P-gp 170, a multiple drug resistant gene product. Baicalein, one of the major flavones, was found to be responsible for this activity. The hydroxyl groups of the A ring
- Lee, Yashang,Yeo, Hosup,Liu, Shwu-Huey,Jiang, Zaoli,Savizky, Ruben M.,Austin, David J.,Cheng, Yung-Chi
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p. 5555 - 5566
(2007/10/03)
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- A new 2-hydroxyflavanone from Mosla soochouensis
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A new antifungal and radical scavenging 2-hydroxyflavanone, named mosloflavanone, was isolated from the dichloromethane extract of Mosla soochouensis together with the known mosloflavone and moslosooflavone. Structures were established by spectroscopic and chemical methods, as well as X-ray crystallography.
- Wang, Qi,Terreaux, Christian,Marston, Andrew,Tan, Ren Xiang,Stoeckli-Evans, Helen,Hostettmann, Kurt
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p. 729 - 731
(2007/10/03)
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- Synthesis of some commonly occurring 2-phenyl-4H-1-benzopyran-4-ones: Revised structures for three natural products
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5-Hydroxy-6,7-dimethoxyflavone, 5-hydroxy-7,8-dimethoxyflavone, 5-hydroxy-3,7-dimethoxyflavone, 3-hydroxy-5,7-dimethoxyflavone, 5-hydroxy-7,8-dimethoxyisoflavone and 5,7-dihydroxy-3-methoxyflavone and their derivatives have been synthesised to confirm the
- Parmar, Virinder S.,Gupta, Sandhya,Sinha, Rita,Sharma, Sunil K.
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p. 244 - 256
(2007/10/02)
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- O-methylation of flavonoids by cell-free extracts of calamondin orange
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Cell-free extracts of calamondin orange (Citrus mitis) catalysed the O-methylation of almost all hydroxyls of a number of flavonoids, indicating the existence in citrus tissues of ortho, meta, para and 3-O-methyltransferases. The latter, hitherto unreported enzyme, catalysed the formation of 3-O-methyl ethers of galangin and quercetin. The stepwise O-methylation of a number of compounds, especially quercetin and quercetagetin, tends to suggest a coordinated sequence of O-methylations on the surface of a multienzyme complex. The methyl acceptor abilities of the flavonoid substrates used are discussed in relation to their hydroxyl substitution patterns and their negative electron density distribution.
- Brunet, Gunter,Ibrahim, Ragai K.
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p. 741 - 746
(2007/10/02)
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