Geunhyeong Jo

Synthesis and complete assignment of NMR data of 20 chalcones

Chalcones, intermediates in flavonoid biosynthesis, can exhibit antibacterial, antiproliferative, and anti‐inflammatory properties. Chalcones contain two benzene rings and both hydroxylated and methoxylated analogs are frequently produced by hydroxylases and O‐methyltransferases in plant biosynthetic pathways. Assignments of NMR peaks in the spectra of hydroxylated and/or methoxylated chalcones can help in identifying novel chalcone derivatives isolated from natural sources by referencing these data against NMR spectra obtained from known chalcones. We report here the syntheses of 20 chalcones and complete assignments of 1H and 13C NMR spectra. Copyright

Synthesis of methoxybenzoflavones and assignments of their NMR data

A phytotoxic root exudate from Acroptilon repens was identified as 7,8‐benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6‐benzoflavone also is a potent phytotoxin. Six 7,8‐benzoflavones and eight 5,6‐benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described. Copyright

1H and 13C NMR spectral assignments of 2′-hydroxychalcones

Chalcones are of interest to medicinal chemists because their structures can be easily modified with various functional groups. The syntheses and biological activities of chalcones from natural sources are well known. In this study, 24 2′‐hydroxychalcones bearing methoxy substituents were synthesized, among which five are new. The NMR data for all synthesized chalcones are described for the first time. The complete assignments of the 1H and 13C NMR data can be used for the identification of newly discovered and widely isolated, synthesized chalcones. Copyright

1H and 13C NMR spectral assignments of novel chromenylchalcones.

Several types of chalcones containing 2H‐chromen group were synthesized. Claisen–Schmidt condensation of 2H‐chromen‐3‐carbaldehydes (I) with methoxy substituted acetophenones afforded (E)‐3‐(2H‐chromen‐3‐yl)‐1‐(methoxyphenyl)prop‐2‐en‐1‐ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)‐1‐(6‐methoxy‐2H‐chromen‐3‐yl)‐3‐(methoxyphenyl)prop‐2‐en‐1‐ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1‐(6‐methoxy‐2H‐chromen‐3‐yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete 1H‐NMR and 13C‐NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright

Chromenylchalcones with inhibitory effects on monoamine oxidase B

Structure-activity relationship (SAR) calculations were used to find monoamine oxidase-B (MAO-B) inhibitors by identifying pharmacophores exhibiting high inhibitory activities. Several such chromenylchalcones were designed and synthesized accordingly. Their inhibitory effects on MAO-B were determined using an HPLC-based method and an MAO-B enzyme assay kit. (E)-3-(6-Methoxy-2H-chromen-3-yl)-1-(2-methoxyphenyl)prop-2-en-1-one exhibited a half-maximal inhibitory concentration of 320 nM. Its molecular-level binding mode with the three-dimensional structure of MAO-B was elucidated using an in silico docking study. The chromenylchalcone scaffold, which is derived from natural products including isoflavonoids and chalcones, had not been previously reported as an MAO-B inhibitor.

Complete NMR data of methoxylated cis- and trans-stilbenes as well as 1,2-diphenylethanes

Resveratrol is a polyphenol isolated from many natural sources including grapes, mulberries, eucalyptus, spruce, lilies, and peanuts. The hydroxyl groups in polyphenols can be substituted with various functional groups, allowing production of multiple derivatives. NMR spectroscopy is used to identify new derivatives. Since the complete NMR data of the known derivatives can be useful for identification of the newly isolated derivatives, here, we report the synthesis of 14 methoxylated stilbenes and four 1,2‐diphenylethanes and their NMR data. Copyright

Cell growth inhibitory effects of polyphenols with naphthalene skeleton against cisplatin-resistant ovarian cancer cells

Cisplatin often shows the drug resistance which could limit the chemotherapeutic efficacy. Thus, it is necessary to develop anticancer agents against cisplatin-resistant cancer cells. To identify pharmacophores exhibiting the cell growth inhibitory effect against cisplatin-resistant A2780/Cis ovarian cancer cells, we prepared 35 synthetic polyphenols bearing naphthalene skeleton including naphthalenyl chalcones, naphthalenyl flavones, naphthalenyl flavanones, 4,5-dihydro-1H-pyrazol-3-yl)naphthalen-2-ols, naphthalen-1-yl-N-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamides, and 4,5-dihydro-1H-pyrazol-3-yl)naphthalen-1-ol. The correlation between their inhibitory effects and structural properties was evaluated using hologram quantitative structure activity relationship and comparative molecular field analysis. The pharmacophores derived here can lead us to design new polyphenols against the growth of cisplatin-resistant cells.