Crystal structures of the flavonoid Oroxylin A and the regioisomers Negletein and Wogonin

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.

Benzo[b]tellurophenes as a Potential Histone H3 Lysine 9 Demethylase (KDM4) Inhibitor

Gene expression and tumor growth can be regulated by methylation levels of lysine residues on histones, which are controlled by histone lysine demethylases (KDMs). Series of benzo[b]tellurophene and benzo[b]selenophene compounds were designed and synthesized and they were evaluated for histone H3 lysine 9 demethylase (KDM4) inhibitory activity. Among the carbamates, alcohol and aromatic derivatives, tert-butyl benzo[b]tellurophen-2-ylmethylcarbamate (compound 1c) revealed KDM4 specific inhibitory activity in cervical cancer HeLa cells, whereas the corresponding selenium or oxygen substitute compounds did not display any inhibitory activity toward KDM4. Compound 1c also induced cell death in cervical and colon cancer but not in normal cells. Thus, compound 1c, a novel inhibitor of KDM4, constitutes a potential therapeutic and research tool against cancer.

Efficient synthesis of polymethoxyselenoflavones via regioselective direct C-H arylation of selenochromones

Substantial research has suggested that the configuration and the total number of functional groups on flavones influence their bioactivity. To investigate the changes in the biological activities of selenoflavones in relationship to structural changes, the development of a generally applicable synthetic method was a key. Until now, an efficient pathway for palladium-catalyzed direct arylation with the selenocyclic enone systems is not known in the literature. We herein introduce a simple direct C-H arylation of two difficult coupling partners, selenochromones and electron-rich aryl bromide, affording diverse polymethoxyselenoflavones with great efficiency and high selectivity.

Synthesis and Evaluation of Neuroprotective Selenoflavanones

The physicochemical properties and antioxidant activity of a molecule could be improved by the substitution of an oxygen atom in a molecule with selenium. We synthesized selenoflavanones and flavanones to evaluate their neuroprotective effects. The selenoflavanones showed improved physicochemical properties, suggestive of the ability to pass through the blood-brain barrier (BBB). They showed in vitro antioxidant effects against hydrogen peroxide, and did not result in severe cytotoxicity. Moreover, infarction volumes in a transient ischemia mouse model were significantly reduced by the selenoflavanone treatments.