David A Vasselin

University of Nottingham, Nottingham, ENG, United Kingdom

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Publications (2)9.18 Total impact

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    ABSTRACT: A new series of fluoro-, methoxyl-, and amino-substituted isoflavones have been synthesized as potential antitumor agents based on structural similarities to known flavones and isoflavones (quercetin and genistein respectively) and antitumor 2-phenylbenzothiazoles. Target compounds were synthesized using palladium-catalyzed coupling methodologies to construct the central aryl carbon-carbon single bond. The new isoflavone derivatives were tested for in vitro activity in human breast (MDA-MB-468 and MCF-7) and colon (HT29 and HCT-116) cancer cell lines. Low micromolar GI50 values were obtained in a number of cases, with the MDA-MB-468 cell line being the most sensitive overall. Notably, significant potentiation of growth inhibitory activity (GI50<1 microM for 12d, 12f, 12h, 12k, 12l, 12o but not the methylene-bridged derivative 12i) was observed when MDA-MB-468 cells were co-incubated with TBDD, a powerful inducer of cytochrome P450 (CYP)-1A1 activity, suggesting that isoflavone derivatives can act as substrates for CYP1A1 bioactivation.
    Journal of Medicinal Chemistry 07/2006; 49(13):3973-81. · 5.61 Impact Factor
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    ABSTRACT: Novel reaction pathways for the hypervalent iodine-mediated oxidation of bioactive phenols containing extended conjugated pi-systems are described. Oxidation of 4-hydroxystilbenes in methanol using a hypervalent iodine-based oxidant led to the formal 1,2-addition of methoxy groups across the central stilbene double bond. Treatment of the structurally related 4-hydroxyisoflavone with di(trifluoroacetoxy)iodobenzene leads to the surprising formation of 2,4'-dihydroxybenzil. Potential mechanisms for these new reaction pathways are discussed, and the X-ray crystal structure of 2,4'-dihydroxybenzil is presented. In contrast, oxidation of the corresponding 3-hydroxystilbenes and 3-hydroxyisoflavone led to conventional dienone oxidation products. The antitumour implications of these oxidation processes are briefly highlighted; the novel 4-substituted phenolic oxidation products were found to be inactive in terms of in vitro antitumour cellular activity, whereas the 3-substituted phenol products gave novel agents with potent and enhanced antitumour activity in the HCT 116 cancer cell line.
    Organic & Biomolecular Chemistry 12/2005; 3(21):3996-4001. · 3.57 Impact Factor