A novel chemical uncoupler ameliorates obesity and related phenotypes in mice with diet-induced obesity by modulating energy expenditure and food intake.

AIMS/HYPOTHESIS: Decreasing mitochondrial coupling efficiency has been shown to be an effective therapy for obesity and related metabolic symptoms. Here we identified a novel mitochondrial uncoupler that promoted uncoupled respiration in a cell type-specific manner and investigated its effects on modulation of energy metabolism in vivo and in vitro. METHODS: We screened a collection of mitochondrial membrane potential depolarising compounds for a novel chemical uncoupler on isolated skeletal muscle mitochondria using a channel oxygen system. The effect on respiration of metabolic cells (L6 myotubes, 3T3-L1 adipocytes and rat primary hepatocytes) was examined and metabolic pathways sensitive to cellular ATP content were also evaluated. The chronic metabolic effects were investigated in high-fat diet-induced obese mice and standard diet-fed (SD) lean mice. RESULTS: The novel uncoupler, CZ5, promoted uncoupled respiration in a cell type-specific manner. It stimulated fuel oxidation in L6 myotubes and reduced lipid accumulation in 3T3-L1 adipocytes but did not affect gluconeogenesis or the triacylglycerol content in hepatocytes. The administration of CZ5 to SD mice increased energy expenditure (EE) but did not affect body weight or adiposity. Chronic studies in mice on high-fat diet showed that CZ5 reduced body weight and improved glucose and lipid metabolism via both increased EE and suppressed energy intake. The reduced adiposity was associated with the restoration of expression of key metabolic genes in visceral adipose tissue. CONCLUSIONS/INTERPRETATION: This work demonstrates that a cell type-specific mitochondrial chemical uncoupler may have therapeutic potential for treating high-fat diet-induced metabolic diseases.

O-methyl nakafuran-8 lactone, a new sesquiterpenoid from a hainan marine sponge Dysidea sp.

A new sesquiterpenoid, O-methyl nakafuran-8 lactone (1) has been isolated from a Hainan sponge Dysidea sp. and the structure of the new compound proposed by spectral data, was confirmed by X-ray diffraction analysis. The complete 1H- and 13C-NMR assignments were made on the basis of detailed 2D NMR spectral analysis. Compound 1 showed strong inhibitory bioactivity against PTP1B with IC50 value of 1.58 microM.

Development of a K562 cell-based assay for screening anticancer agents.

AIM: To develop a leukemia cell line K562-based assay for high-throughput screening. METHODS: The screening was carried out on 96-well plates with monitoring cell proliferation by a combined 3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium (MTS)/phenazine methosulfate (PMS) method. Conditions for evaluating effects on the proliferation of K562 cells by individual compounds on the 96-well plates were optimized. RESULTS: A set of 800 small organic compounds was screened for anticancer activity by this cell-based assay, with consumption of each compound at 500 ng. Eleven compounds were identified with >80 % inhibitory activity at 5 mg/L, among which 9 compounds were confirmed by subsequent testing at multiple concentrations. The most potent compound showed an IC50 at 170 nmol/L, and there were total of 7 compounds showed IC50 less than 10 micromol/L. CONCLUSION: The high-throughput method using K562 cell line is fast, economical, effective, and practical in identifying inhibitors as potential therapeutic agents for cancer.

High-throughput screening for human collagenase 1 inhibitors.

AIM: To establish a high-throughput method for inhibitor screening using a recombinant collagenase catalytic domain. METHODS: Human collagenase 1 catalytic domain protein was expressed in E coli and used for screening a set of 2720 compounds in a high-throughput fashion. RESULTS: The screening was accomplished within 2 h and 10 min with consumption of each compound at 4 micrograms. Sixty-six compounds were identified with > 60% inhibitory activity at 20 mg/L, among which 44 compounds were confirmed by subsequent testing at multiple concentrations. The most potent compound showed an IC50 at 4.3 mumol/L, and there were total 15 compounds with IC50 less than 20 mumol/L. CONCLUSION: The high-throughput method using the recombinant collagenase is fast, effective and practical in identifying inhibitors.