Synthesis of benzopyrano[3,4-c]pyridin-5-ones as dopamine D4 receptor ligands.

The dopamine D4 receptor is highly expressed in prefrontal cortex, hippocampus, amygdala, hypothalamus and is hypothesized to relate with the pathophysiology and pharmacotherapy of schizophrenia while its level in brain regions is much lower. To date, no specific ligand is available for the study of D4 receptor in vivo. In this study, we report the synthesis and in vitro receptor binding assay of three benzopyrano[3,4-c]pyridin-5-ones as potential dopamine D4 receptor ligands. These new compounds have higher affinity and selectivity toward dopamine D4 receptor and their K(i) values for D4 receptor are in the nanomolar (nM) range.

Development of high-performance liquid chromatographic for quality and authenticity control of Chinese propolis.

A RP-high-performance liquid chromatography (HPLC) method was developed for quality control of Chinese propolis by simultaneous analysis of 12 flavonoids and 8 phenolic acids. The results showed that vanillic acid, rutin, myricetin, and luteolin were not detected in all of the analyzed propolis and poplar tree gum samples. The caffeic acid, ferulic acid and p-coumaric acid were not detected in poplar tree gum but were detected in propolis, which suggest that they are practical indexes of distinguishing propolis from poplar tree gum. The flavonoid profiles of poplar tree gum were found to be similar to those of propolis, which are dominated by pinobanksin, pinocembrin, 3-O-acetylpinobanksin, chrysin, and galangin. Therefore, the proposed method could be applied to exclude poplar tree gum from propolis with cafferic acid, ferulic acid, and p-coumaric acid as qualitative markers, and distinguish poplar source resin from other illegal substances, and evaluate the quality grading of poplar-type propolis with pinobanksin, pinocembrin, 3-O-acetylpinobanksin, chrysin, and galangin as qualitative and quantitative markers.