Synthesis of 4-Tetrazolyl-Substituted 3,4-Dihydroquinazoline Derivatives with Anticancer Activity via a One-Pot Sequential Ugi-Azide/Palladium-Catalyzed Azide-Isocyanide Cross-Coupling/Cyclization Reaction.

A new one-pot preparation of 4-tetrazolyl-3,4-dihydroquinazolines has been reported. The Ugi-azide reactions of 2-azidobenzaldehydes, amines, trimethylsilyl azide, and isocyanides produced azide intermediates without separation, which were treated with isocyanides to give 4-tetrazolyl-3,4-dihydroquinazoline derivatives through a sequential Palladium-catalyzed azide-isocyanide cross-coupling/cyclization reaction in moderate to good yields. The biological evaluation demonstrated that compound 6c inhibited breast cancer cells well and displayed broad applications for synthesis and medicinal chemistry.

The determination of monosaccharide in different years Qingzhuan Dark Tea polysaccharide by liquid chromatography-mass spectrometry.

AIM: To establish a fast, sensitive and accurate high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for determining the monosaccharide content of Qingzhuan Dark Tea polysaccharides in different years (2 years, 5 years and 11 years). METHODS: The optimised chromatographic conditions were achieved on a C18 column (5.0 µm, 250 mm × 4.6 mm inner diameter). The mobile phase flow rate was 0.9 mL/min and the column temperature was set to 27°C. The aqueous phase A (5 mM aqueous ammonium acetate) and organic phase B (acetonitrile) were used to elute the target analyses isocratically (0-60 min: 18% B). The mass spectrometer detector was equipped with an electron spray ionisation (ESI)source, and multiple reaction monitoring (MRM) mode was used for the determination of 1-phenyl-3-methyl-5-pyrazolone (PMP) derived monosaccharides. RESULTS: We carried out a comprehensive methodological validation of PMP derived monosaccharides, including linearity, precision, stability and repeatability. Nine monosaccharides (rhamnose, mannose, ribose, glucose, galacturonic acid, xylose, galactose, fucose and arabinose) of Qingzhuan Dark Tea polysaccharides were identified, in which ribose and fucose were reported for the first time. The results showed the contents of these nine monosaccharides differed significantly among different years. CONCLUSIONS: The validated method is reliable, accurate, repeatable and can be applied to quality assessment of these monosaccharides.

[Degradation kinetics of chlorogenic acid, cryptochlorogenic acid, and neochlorogenic acid at neutral and alkaline pH values].

The degradation kinetics of chlorogenic acid (5-CQA), cryptochlorogenic acid (4-CQA), and neochlorogenic acid (3-CQA) in aqueous solution at 37 degrees C and different pH values (7.05, 7.96, 9.25) were investigated in the present work. The results indicated that 3-, 4- and 5-CQA tended to remain stable in acidic pH circumstance, and unstable in neutral and alkaline pH circumstance. With the increase of the alkalinity, the degradation of 3-, 4- and 5-CQA was increased leading to a less amount of total CQA and was satisfactorily described by the Weibull equation. Meanwhile, caffeic acid was not detected after the degradation of CQA. Moreover, the degradation of 3-CQA and 5-CQA tended to be converted to 4-CQA, and the degradation of 4-CQA tended to be converted to 3-CQA rather than 5-CQA. The comparison of the degradation kinetics parameters of 3-, 4- and 5-CQA at neutral and alkaline pH values showed that the orders of the rate constant (k) values were 4-CQA > 3-CQA > 5-CQA, while the orders of the degradation half life (t½) values were 4-CQA < 3-CQA < 5-CQA, indicating the orders of the stabilities of 3-, 4- and 5-CQA at 37 degrees C and neutral and alkaline pH values were 4-CQA < 3-CQA < 5-CQA.

Mild Hypothermia Combined with Hydrogen Sulfide Treatment During Resuscitation Reduces Hippocampal Neuron Apoptosis Via NR2A, NR2B, and PI3K-Akt Signaling in a Rat Model of Cerebral Ischemia-Reperfusion Injury.

We investigated whether mild hypothermia combined with sodium hydrosulfide treatment during resuscitation improves neuron survival following cerebral ischemia-reperfusion injury beyond that observed for the individual treatments. Male Sprague-Dawley rats were divided into seven groups (n = 20 for each group). All rats underwent Pulsinelli 4-vessel occlusion. Ischemia was induced for 15 min using ligatures around the common carotid arteries, except for the sham group. Immediately after initiating reperfusion, the mild hypothermia (MH), sodium hydrosulfide (NaHS), hydroxylamine (HA), MH + NaHS, MH + HA, and ischemia-reperfusion (I/R) control groups received an intraperitoneal injection of saline, sodium hydrosulfide, hydroxylamine, sodium hydrosulfide, hydroxylamine, and saline, respectively, and mild hypothermia (32 to 33 °C) was induced in the MH, MH + NaHS, and MH + HA groups for 6 h. The levels of NR2A, NR2B, p-Akt, and p-Gsk-3ß in the hippocampus of the MH, NaHS, and MH + NaHS groups were higher than those in the I/R control group, with the highest levels observed in the MH + NaHS group (P < 0.05). Treatment with hydroxylamine reduced the levels of these proteins in the HA and MH + HA groups, compared with the I/R control and MH groups, respectively. The apoptotic index of the CA1 region of the hippocampus was 45.2, 66.5, 63.5, and 84.8 % in the MH + NaHS, MH, NaHS, and I/R control groups, respectively (P < 0.05), indicating that the combination treatment shifted the NR2A/NR2B balance in favor of synaptic neuron stimulation and phosphatidylinositol 3'-kinase (PI3K)/Akt signaling. The combination of mild hypothermia and sodium hydrosulfide treatment for resuscitation following ischemia-reperfusion injury was more beneficial for reducing hippocampal apoptosis and pathology than that of mild hypothermia or hydrogen sulfide treatment alone.

Hydrogen sulphide and mild hypothermia activate the CREB signaling pathway and prevent ischemia-reperfusion injury.

BACKGROUND: Both hydrogen sulphide (H2S) and mild hypothermia have been reported to prevent brain damage caused by reperfusion assault through regulating the N-methyl-D-aspartate receptor (NMDAR). However, the relationship between the two treatments and how they exert neuro-protective effects through NMDARs remain to be elucidated. METHODS: Transient cerebral ischemia was induced using the Pulsinelli four-vessel occlusion method. We used sodium hydrosulphide (NaHS) as the H2S donor. We randomly divided 100 Sprague-Dawley rats into five groups of 20: Sham operation group (Sh), normothermic (36-37 °C) ischemia group (NT), mild hypothermic (32-33 °C) ischemia group (mHT), normothermic ischemia combined with NaHS treatment group (NT + NaHS), and mild hypothermic ischemia combined with NaHS treatment group (mHT + NaHS). After 6 hrs of reperfusion, rats were decapitated and hippocampus samples were immediately collected. We measured NR2A (GluN1), NR2B (GluN2) and p-CREB protein levels using western blotting. We further analyzed BDNF mRNA expression by real-time PCR. Hematoxylin and eosin (HE) staining was used to examine pyramidal cell histology at the CA1 region. All statistical analyses were carried out by ANOVA and LSD t-test as implemented by the SPSS 13.0 software. RESULTS: In the four test groups with ischemia-reperfusion, hippocampal H2S concentration increased following treatment, and administration of NaHS further increased H2S levels. Moreover, administration of both NaHS and mild hypothermia resulted in up-regulation of NR2A and NR2B protein expressions, as well as p-CREB protein and BDNF mRNA levels. At the cellular level, NaHS and mild hypothermia groups exhibited lower damage caused by ischemia-reperfusion in the CA1 region of the hippocampus. The strongest protective effect was observed in rats treated with combined NaHS and mild hypothermia, suggesting their effects were additive. CONCLUSION: Our results support previous findings that hydrogen sulphide and mild hypothermia can prevent ischemia-reperfusion injury. Both treatments caused an up-regulation of NMDA receptors, as well as an elevation in p-CREB protein and BDNF mRNA levels. Thus, hydrogen sulphide and mild hypothermia may provide neuro-protective effect through activating the pro-survival CREB signaling pathway.