Convergent synthesis of mosloflavone, negletein and baicalein from crysin

Righi, Giuliana; Antonioletti, Roberto; Silvestri, Ilaria Proietti; D’Antona, Nicola; Lambusta, Daniela; Bovicelli, Paolo

doi:10.1016/j.tet.2009.12.021

Cited by 31 publications

(28 citation statements)

References 27 publications

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“…The synthesis of these compounds by a bromination/methoxylation procedure was recently published by some of the authors of the present paper [14]; the structures differ only by the presence of hydroxy or methoxy groups at the positions 5, 6, and 7 of the A ring (Fig. 1).…”

Section: Introductionmentioning

confidence: 80%

“…Mosloflavone (6,7-dimethoxy-5-hydroxyflavone), negletein (5,6-dihydroxy-7-methoxyflavone), 5,6-dihydroxyflavone (no trivial name) and baicalein (5,6,7-trihydroxyflavone) were synthesized through convergent synthesis starting from chrysin as previously reported [14]. Galvinoxyl, 2,2-diphenyl-1-picrylhydrazyl (DPPH), cumene hydroperoxide, quercetin, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and phorbol 12-myristate 13-acetate (PMA) were purchased from Sigma-Aldrich (St. Louis, MO).…”

Section: Methodsmentioning

confidence: 99%

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Protection of Cells against Oxidative Stress by Nanomolar Levels of Hydroxyflavones Indicates a New Type of Intracellular Antioxidant Mechanism

et al. 2013

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Natural polyphenol compounds are often good antioxidants, but they also cause damage to cells through more or less specific interactions with proteins. To distinguish antioxidant activity from cytotoxic effects we have tested four structurally related hydroxyflavones (baicalein, mosloflavone, negletein, and 5,6-dihydroxyflavone) at very low and physiologically relevant levels, using two different cell lines, L-6 myoblasts and THP-1 monocytes. Measurements using intracellular fluorescent probes and electron paramagnetic resonance spectroscopy in combination with cytotoxicity assays showed strong antioxidant activities for baicalein and 5,6-dihydroxyflavone at picomolar concentrations, while 10 nM partially protected monocytes against the strong oxidative stress induced by 200 µM cumene hydroperoxide. Wide range dose-dependence curves were introduced to characterize and distinguish the mechanism and targets of different flavone antioxidants, and identify cytotoxic effects which only became detectable at micromolar concentrations. Analysis of these dose-dependence curves made it possible to exclude a protein-mediated antioxidant response, as well as a mechanism based on the simple stoichiometric scavenging of radicals. The results demonstrate that these flavones do not act on the same radicals as the flavonol quercetin. Considering the normal concentrations of all the endogenous antioxidants in cells, the addition of picomolar or nanomolar levels of these flavones should not be expected to produce any detectable increase in the total cellular antioxidant capacity. The significant intracellular antioxidant activity observed with 1 pM baicalein means that it must be scavenging radicals that for some reason are not eliminated by the endogenous antioxidants. The strong antioxidant effects found suggest these flavones, as well as quercetin and similar polyphenolic antioxidants, at physiologically relevant concentrations act as redox mediators to enable endogenous antioxidants to reach and scavenge different pools of otherwise inaccessible radicals.

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Section: Introductionmentioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

Protection of Cells against Oxidative Stress by Nanomolar Levels of Hydroxyflavones Indicates a New Type of Intracellular Antioxidant Mechanism

et al. 2013

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“…findings, where methylation in basic media of baicalein occurs firstly on hydroxyl group on C-7, then on hydroxyl group on C-6 and finally on hydroxyl group on C-5. In analogy, demethylation in acidic media occurs in reverse order [17]. Therefore, baicalein with 6,7-dihydroxychelation site has higher potency than negletein with 5,6-dihydroxy groups and both agents are more potent than 5-hydroxyflavone.…”

Section: Discussionmentioning

confidence: 99%

“…2), with exception of negletein and mosloflavone, were purchased from SigmaAldrich (Germany), deferoxamine from Novartis (Switzerland). Negletein and mosloflavone were synthesized through a convergent synthesis starting from chrysin as previously reported [17].…”

Section: Reagentsmentioning

confidence: 99%

In vitro analysis of iron chelating activity of flavonoids

Mladěnka

Macáková

Filipský

et al. 2011

Journal of Inorganic Biochemistry

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209

169

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“…S1), with exception of negletein and mosloflavone, were purchased from Sigma-Aldrich (Steinheim, Germany). Negletein and mosloflavone were synthesised through a convergent synthesis starting from chrysin, as was previously reported (Righi et al, 2010). Deferoxamine was purchased from Novartis (Basle, Switzerland) and methanol for HPLC was from JT Baker (Phillipsburg, NJ).…”

Section: Reagentsmentioning

confidence: 99%