7245-02-5Relevant articles and documents
Mechanism of Intramolecular Excited-State Porton Transfer and Relaxation Processes in the Ground and Excited States of 3-Hidroxyflavone and Related Compounds
Itoh, Michiya,Fujiwara, Yoshihisa,Sumitani, Minoru,Yoshihara, Keitaro
, p. 5672 - 5678 (1986)
Two components of flueroscence rise dou tho the phototautomer generated in the excited-state proton transfer were observed in 3-methylpentane solutions of 3-hydroxyflavone (3-HF) and its derivatives, while only a fast rise was observed in 3-hidroxychromone (3-HC) which lacks a 2-phenyl group.The shorter rise times are independent of temperature and substituent at hte para position in the 2-phenyl group of 3-HF, whereas the longer riese times ared dependent on each of them.As a result, the former and latter were ascribed to excited-state proton transfer in the Franck-Condon state (probably a twisted from of the phenyl group th the γ-pyrone ring), respectively.The transient absorption of these compounds exhibts absorption bands at 430-530 nm with lifetimes of 7-30 μs at room temperature, which were attributable to the ground-state tautomers of these compounds.The two-step laser excitations (TSLE) of these transient absorption bands show TSLE fluorescence intensity afford lifetimes of the ground-state fluorescence spectra.Further, variable delay polts of TSLE fluorescence intensity afford lifetimes of the ground-state toutomers.From the temperature dependence of these lifetimes, the activation free-energy changes for the reverse proton transfer in the ground state were determined.Taking into account the reaction constant (?) of Hammett's plots of the activation free-energy change vs. substituent constants (?), it was concluded that the electron-attracting group at the phenyl para postion nay assist the reverse proton tarnsfer to the parent molecluses and that the phenyl group in 3-HF may act as an electron-donating group to the γ-pyrone ring to decrease the reaction rate of the reverse proton transfer in comparison with 3-HC.
Synthesis and biological evaluation of flavones and benzoflavones as inhibitors of BCRP/ABCG2
Juvale, Kapil,Stefan, Katja,Wiese, Michael
, p. 115 - 126 (2013/10/01)
Multidrug resistance (MDR) often leads to a failure of cancer chemotherapy. Breast Cancer Resistance Protein (BCRP/ABCG2), a member of the superfamily of ATP binding cassette proteins has been found to confer MDR in cancer cells by transporting molecules with amphiphilic character out of the cells using energy from ATP hydrolysis. Inhibiting BCRP can be a solution to overcome MDR.We synthesized a series of flavones, 7,8-benzofl avones and 5,6-benzo flavones with varying substituents at positions 3, 3′ and 4′ of the (benzo)fl avone structure. All synthesized compounds were tested for BCRP inhibition in Hoechst 33342 and pheophorbide A accumulation assays using MDCK cells expressing BCRP. All the compounds were further screened for their P-glycoprotein (P-gp) and Multidrug resistance-associated protein 1 (MRP1) inhibitory activity by calcein AM accumulation assay to check the selectivity towards BCRP. In addition most active compounds were investigated for their cytotoxicity. It was observed that in most cases 7,8-benzoflavones are more potent in comparison to the 5,6-benzoflavones. In general it was found that presence of a 3-OCH3 substituent leads to increase in activity in comparison to presence of OH or no substitution at position 3. Also, it was found that presence of 3′,4′-OCH3 on phenyl ring lead to increase in activity as compared to other substituents. Compound 24, a 7,8-benzoflavone derivative was found to be most potent being 50 times selective for BCRP and showing very low cytotoxicity at higher concentrations.
Enantioselective synthesis of 3,4-chromanediones via asymmetric rearrangement of 3-allyloxyflavones
Marie, Jean-Charles,Xiong, Yuan,Min, Geanna K.,Yeager, Adam R.,Taniguchi, Tohru,Berova, Nina,Schaus, Scott E.,Porco, John A.
experimental part, p. 4584 - 4590 (2010/10/01)
(Figure presented) Asymmetric scandium(III)-catalyzed rearrangement of 3-allyloxyflavones was utilized to prepare chiral, nonracemic 3,4-chromanediones in high yields and enantioselectivities. These synthetic intermediates have been further elaborated to novel heterocyclic frameworks including angular pyrazines and dihydropyrazines. The absolute configuration of rearrangement products was initially determined by a nonempirical analysis of circular dichroism (CD) using time-dependent density functional theory (TDDFT) calculations and verified by X-ray crystallography of a hydrazone derivative. Initial studies of the mechanism support an intramolecular rearrangement pathway that may proceed through a benzopyrylium intermediate.
