Synthesis and receptor binding assay of indolin-2-one derivatives as dopamine D4 receptor ligands.

Five indolin-2-one derivatives bearing piperazinylbutyl side chains attached to the amide nitrogen were synthesized from 2-indolinone. 1-(4-Bromobutyl)-indolin-2-one was reacted with 1-piperazinecarboxaldehyde to form 1-(4-(4-formyl-1-piperazinyl)butyl)indolin-2-one (2). In the presence of H2SO4, the aldehyde moiety was removed from 1-(4-(4-formyl-1-piperazinyl)butyl)indolin-2-one and then 1-(4-(1-piperazinyl)butyl)indolin-2-one (3) was obtained, this compound was reacted with benzaldehyde derivatives to give the target compounds 4 a-e by N-alkylation reaction. The structures of the intermediates and the target compounds were characterized by 1H NMR, ESI-MS spectra and elemental analyses. In vitro receptor binding assays at D2, D3, D4 receptor subtypes of the target compounds were performed and the five compounds showed selectivity towards D2-like receptors. Among them, 1-(4-(4-(4-hydroxybenzy)-1-piperazinyl)butyl) indolin-2-one (4c) exhibited a remarkable affinity and selectivity to D4 receptor with K(i) value of 0.5 nM. The results indicated that 1-(4-(4-(4-hydroxybenzy)-1-piperazinyl)butyl)indolin-2-one might be a potential dopamine D4 receptor ligand.

Enhancement of ginsenoside Rg(1) in Panax ginseng hairy root by overexpressing the α-L-rhamnosidase gene from Bifidobacterium breve.

OBJECTIVES: To improve the production of ginsenoside Rg1 in Panax ginseng. RESULTS: The α-L-rhamnosidase gene from Bifidobacterium breve (BbRha) was overexpressed into hairy root culture system using Agrobacterium rhizogenes A4. Ginsenoside Rg1 in hairy roots was obtained following transformation via overexpressed gene representing 2.2-fold higher than those of control lines. Several overexpression transgenic hairy root lines were obtained exhibiting markedly increased levels of the corresponding α-L-rhamnosidase enzymatic activity relative to control. Ginsenoside Rg1 levels in the transgenic lines were higher (2.2-fold) than those of control after following 30 days culturing, while ginsenoside Re contents in tested transgenic lines were found to be lower. The transgenic hairy roots harboring α-L-rhamnosidase gene improved the accumulation of ginsenoside Rg1 up to 3.6 mg g(-1) dry weight. CONCLUSION: BbRha gene selectively enhances the production of ginsenoside Rg1 in P. ginseng hairy roots.

Biotransformation of rutin to isoquercitrin using recombinant α-L-rhamnosidase from Bifidobacterium breve.

OBJECTIVES: To biotransform rutin into isoquercitrin. RESULTS: A α-L-rhamnosidase from Bifidobacterium breve was produced by using Escherichia coli BL21 for biotransformation of rutin to isoquercitrin. The enzyme was purified by Ni(2+)-NTA chromatography to yield a soluble protein with a specific activity of 56 U protein mg(-1). The maximum enzyme activities were at pH 6.5, 55 °C, 20 mM rutin, and 1.2 U enzyme ml(-1). Under optimal conditions, the half-life of the enzyme was 96 h. The K m and V max values were 2.2 mM, 56.4 µmol mg(-1) min(-1) and 2.1 mM, 57.5 µmol mg(-1) min(-1) using pNP-Rha and rutin as substrates, respectively. The kinetic behavior indicated that the recombinant α-L-rhamnosidase has good catalytic performance for producing isoquercitrin. 20 mM rutin was biotransformed into 18.25 and 19.87 mM isoquercitrin after 60 and 240 min. CONCLUSION: The specific biotransformation of rutin to isoquercitrin using recombinant α-L-rhamnosidase from B. breve is a feasible method for use in industrial processes.