Daiying Zuo

Effect of MK-801 and ketamine on hydroxyl radical generation in the posterior cingulate and retrosplenial cortex of free-moving mice, as determined by in vivo microdialysis

This study investigated the effect of MK-801 and ketamine, N-methyl-D-aspartate (NMDA) receptor antagonists which can induce schizophrenic symptoms and have neurotoxicity in human and animals, on hydroxyl radical (*OH) generation in the posterior cingulate and retrosplenial (PC/RS) cortex of free-moving mice using the salicylic acid trapping technique. MK-801 (0.6 mg/kg) or ketamine (50 mg/kg) acute administration significantly increased *OH levels in mouse PC/RS cortex. The basal *OH levels after MK-801 and ketamine administrations for 7 consecutive days were significantly increased compared with the naive basal levels. MK-801 (0.6 mg/kg) or ketamine (50 mg/kg) challenge after chronic administration further significantly increased dialysate levels of *OH. Our study also found that the release of *OH was secondary to stereotyped behavior, and the intensity of stereotyped behavior induced by MK-801 was more than that induced by ketamine. The results suggested that NMDA receptor antagonists participate in the generation of *OH in the PC/RS cortex of mouse, and oxidative stress, derived from the formation of free radicals, might play an important role in the pathophysiology of these two models of schizophrenia.

Synthesis and evaluation of benzimidazole carbamates bearing indole moieties for antiproliferative and antitubulin activities

A series of novel benzimidazole carbamates bearing indole moieties with sulphur or selenium atoms connecting the aromatic rings were synthesised and evaluated for their antiproliferative activities against three human cancer cell lines (SGC-7901, A-549 and HT-1080) using an MTT assay. Compounds 10a, 10b, 7a, 7b and 7f showed significant activities against these cell lines. The most potent compound in this series, 10a, was selected to investigate its antitumour mechanism. In addition, molecular docking studies suggested that compound 10a interacts very closely with the nocodazole docking pose through hydrogen bonds at the colchicine binding site of tubulin.

Conditioned fear stress combined with single-prolonged stress: a new PTSD mouse model

There are still some defects in current single-prolonged stress (SPS) model and conditioned fear (CF) stress model of post-traumatic stress disorder (PTSD). The purpose of this study is to evaluate a novel mouse model of PTSD. Male KM mice suffered the double stresses-SPS and CF. After incubation time, the novel model exhibited the PTSD-like behaviors: sensitive fear and conditioned fear, low activities and defects in novel object recognition abilities. The apoptosis in the hippocampus was significantly increased, which was induced by the double stresses and further caused the synaptic structure damages in the hippocampus. The electron microscopy analysis further proved the synaptic losses and neuronal impairments in the hippocampus. Our results indicated this combined stresses mouse model was better than the SPS model and CF model. In addition, in order to further verify this model, paroxetine was administered after the double stresses. The results showed that paroxetine administration reduced PTSD-like behaviors, hippocampal apoptosis and structure damages. We conclude that this mouse model is novel and more predictably mimicked the clinical characteristics of PTSD, and this model can be further used for investigating the mechanisms of PTSD and screening effective therapeutics agents.

3-(3-Hydroxy-4-methoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-1,2,5-selenadiazole (G-1103), a novel combretastatin A-4 analog, induces G2/M arrest and apoptosis by disrupting tubulin polymerization in human cervical HeLa cells and fibrosarcoma HT-1080 cells.

Microtubule is a popular target for anticancer drugs. In this study, we describe the effect 3-(3-hydroxy-4-methoxyphenyl)-4-(3,4,5-trimethoxyphenyl)-1,2,5-selenadiazole (G-1103), a newly synthesized analog of combretastatin A-4 (CA-4), showing a strong time- and dose-dependent anti-proliferative effect on human cervical cancer HeLa cells and human fibrosarcoma HT-1080 cells. We demonstrated that the growth inhibitory effects of G-1103 in HeLa and HT-1080 cells were associated with microtubule depolymerization and proved that G-1103 acted as microtubule destabilizing agent. Furthermore, cell cycle analysis revealed that G-1103 treatment resulted in cell cycle arrest at the G2/M phase in a time-dependent manner with subsequent apoptosis induction. Western blot analysis revealed that down-regulation of cdc25c and up-regulation of cyclin B1 was related with G2/M arrest in HeLa and HT-1080 cells treatment with G-1103. In addition, G-1103 induced HeLa cell apoptosis by up-regulating cleaved caspase-3, Fas, cleaved caspase-8 expression, which indicated that G-1103 induced HeLa cell apoptosis was mainly associated with death receptor pathway. However, G-1103 induced HT-1080 cell apoptosis by up-regulating cleaved caspase-3, Fas, cleaved caspase-8, Bax and cleaved caspase-9 expression and down-regulating anti-apoptotic protein Bcl-2 expression, which indicated that G-1103 induced HT-1080 cell apoptosis was associated with both mitochondrial and death receptor pathway. Taken together, all the data demonstrated that G-1103 exhibited its antitumor activity through disrupting the microtubule assembly, causing cell cycle arrest and consequently inducing apoptosis in HeLa and HT-1080 cells. Therefore, the novel compound G-1103 is a promising microtubule inhibitor that has great potentials for therapeutic treatment of various malignancies.

DAT-230, a novel microtubule inhibitor, exhibits potent anti-tumor activity by inducing G2/M phase arrest, apoptosis in vitro and perfusion decrease in vivo to HT-1080

PurposeThe anti-mitotic agent, combretastatin A-4 (CA-4), is the lead compound of a new class of anti-cancer drugs that target tumor vasculature. 2-Methoxy-5-(2-(3, 4, 5-trimethoxyphenyl) thiophen-3-yl) aniline (DAT-230) is a structurally novel CA-4 analog with more stability. We investigated its anti-tumor activity and mechanisms in vitro and in vivo for the first time.MethodsCytotoxicity was measured by MTT method. Apoptosis, mitochondria membrane potential (ΔΨm) and NO generation were measured by flow cytometry. Intracellular microtubule network was detected by immunofluorescence experiments. Protein expression was analyzed by Western blotting. In vivo, the anti-tumor activity was assessed using fibrosarcoma xenografts subcutaneously established in BALB/c nude mice. Vasculature perfusion was identified using fluorescent DNA-binding compound Hoechst 33342.ResultsDAT-230 exhibited potent anti-proliferative activity against various cancer cells. DAT-230-treatment in HT-1080 cells resulted in microtubule de-polymerization and G2/M phase arrest preceding apoptosis. Phosphor-cdc2 (thr14/tyr15) reduction, cyclin B1 accumulation and aberrant spindles denoted the cyclin B1-cdc2 complex active and M phase arrest in HT-1080 cells treated with DAT-230. Apoptosis induced by DAT-230 was related with the activation of caspase-9, caspase-3 and PARP cleavage, which were at the downstream of mitochondria. The decrease ratio of Bcl-2/Bax, elevation of NO and disruption of ΔΨm confirmed the causal relationship between DAT-230 and mitochondrial pathway. In vivo, DAT-230 delayed tumor growth, induced tumor perfusion decrease and extensive hemorrhagic-necrosis.ConclusionsDAT-230 is a promising microtubule inhibitor that has great potential for the treatment of fibrosarcoma in vitro and in vivo. Its potential to be a candidate of anti-cancer agent is worth being further investigated.

Amphipathic silica nanoparticles induce cytotoxicity through oxidative stress mediated and p53 dependent apoptosis pathway in human liver cell line HL-7702 and rat liver cell line BRL-3A

The aim of this study was to evaluate the potential cytotoxicity and the underlying mechanism of amphipathic silica nanoparticles (SiO2 NPs) exposure to human normal liver HL-7702 cells and rat normal liver BRL-3A cells. Prior to the cellular studies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X ray diffraction (XRD) were used to characterize SiO2 NPs, which proved the amorphous nature of SiO2 NPs with TEM diameter of 19.8±2.7nm. Further studies proved that exposure to SiO2 NPs dose-dependently induced cytotoxicity as revealed by cell counting kit (CCK-8) and lactate dehydrogenase (LDH) assays, with more severe cytotoxicity in HL-7702 cells than BRL-3A cells. Reactive oxygen species (ROS) and glutathione (GSH) assays showed elevated oxidative stress in both cells. Morphological studies by microscopic observation, Hochest 33258 and AO/EB staining indicated significant apoptotic changes after the cells being exposed to SiO2 NPs. Further studies by western blot indicated that SiO2 NPs exposure to both cells up-regulated p53, Bax and cleaved caspase-3 expression and down-regulated Bcl-2 and caspase-3 levels. Activated caspase-3 activity detected by colorimetric assay kit and caspase-3/7 activity detected by fluorescent real-time detection kit were significantly increased by SiO2 NPs exposure. In addition, antioxidant vitamin C significantly attenuated SiO2 NPs-induced caspase-3 activation, which indicated that SiO2 NPs-induced oxidative stress was involved in the process of HL-7702 and BRL-3A cell apoptosis. Taken together, these results suggested that SiO2 NPs-induced cytotoxicity in HL-7702 and BRL-3A cells was through oxidative stress mediated and p53, caspase-3 and Bax/Bcl-2 dependent pathway and HL-7702 cells were more sensitive to SiO2 NPs-induced cytotoxicity than BRL-3A cells.

Microwave-assisted synthesis and biological evaluation of 3,4-diaryl maleic anhydride/N-substituted maleimide derivatives as combretastatin A-4 analogues.

A series of new CA-4 analogues bearing maleic anhydride/N-substituted maleimide moiety were synthesized via a microwave-assisted process. They were evaluated for the anti-proliferative activities against three tumor cell lines (SGC-7901, HT-1080 and KB). Most compounds showed moderate potencies in micromolar range, with the most promising analogue 6f showing active at submicromolar concentration against HT-1080 cancer cells which was selected to investigate the antitumor mechanisms. In addition, molecular docking studies within the colchicine binding site of tubulin were also in good agreement with the tubulin polymerization inhibitory data and provided a basis for further structure-guided design of novel CA-4 analogues.

Berberine acutely inhibits the digestion of maltose in the intestine.

ETHNOPHARMACOLOGICAL RELEVANCE The Chinese Goldthread Rhizome has been used in the Traditional Chinese Medicine as an important ingredient of many formulas for the treatment of diabetes mellitus. Berberine, the main effective composition of Chinese Goldthread Rhizome, is also effective in treating diabetes in todays clinical practice of Traditional Chinese Medicine. AIM OF THE STUDY To evaluate the hypoglycemic activity of berberine which treats acutely on the postprandial blood glucose, and to explore the mechanism of this activity. MATERIALS AND METHODS 1. One-dose preprandial intragastric administrations of berberine were given to normal animals (dogs and rats), and the postprandial blood glucose concentration curves were measured. Serum insulin enzyme linked immunosorbent assay (ELISA) was only performed in rats. 2. The euglycemic clamp test was performed to evaluate the effect of one-dose berberine intragastric administration on the blood glucose transformation and utilization rate in rats. 3. In the Caco-2 cell monolayer test, the changes of glucose concentration on the apical and basolateral sides were measured when the maltose solution containing berberine was added to the apical side. 4. The inhibition ratio of berberine against α-glucosidase was measured in vitro. 5. The effect of berberine on the fluorescence emission spectrums of α-glucosidase was studied. RESULTS One-dose preprandial intragastric administration of berberine delayed the rise of post-maltose blood glucose, did not affect postprandial blood glucose after glucose meal, and did not affect the insulin level in normal rats; reduced post-maltose blood glucose in normal dogs. 2. The result of euglycemic clamp test showed that one-dose intragastric administration of berberine had no effect on the blood glucose transformation and utilization rate in rats. 3. Berberine added to the maltose solution on the apical side of Caco-2 cell monolayer reduced the glucose concentration on the apical side. Glucose in basolateral side of all groups cannot be detected. 4. Berberine inhibited the activity of α-glucosidase in vitro. 5. Berberine significantly and concentration dependently quenched the fluorescence emission spectrum of α-glucosidase. CONCLUSION Our findings suggest an additional mechanism of the hypoglycemic activity of berberine by demonstrating its ability to acutely inhibit the α-glucosidase, and support the traditional use of berberine and Chinese Goldthread Rhizome for the treatment of diabetes mellitus.

Effects of acute and chronic administration of MK-801 on c-Fos protein expression in mice brain regions implicated in schizophrenia with or without clozapine

This study investigated the effects of acute and chronic administration of the non-competitive NMDA receptor antagonists MK-801 on c-Fos protein expression in different brain regions of mice with or without clozapine. MK-801 (0.6 mg/kg) acute administration produced a significant increase in the expression of c-Fos protein in the layers III-IV of posterior cingulate and retrosplenial (PC/RS) cortex, which was consistent with the previous reports. Moreover, we presented a new finding that MK-801 (0.6 mg/kg) chronic administration for 8 days produced a significant increase of c-Fos protein expression in the PC/RS cortex, prefrontal cortex (PFC) and hypothalamus of mice. Among that, c-Fos protein expression in the PC/RS cortex of mice was most significant. Compared to acute administration, we found that MK-801 chronic administration significantly increased the expression of c-Fos protein in the PC/RS cortex, PFC and hypothalamus. Furthermore, pretreatment of mice with clozapine significantly decreased the expression of c-Fos protein induced by MK-801 acute and chronic administration. These results suggest that c-Fos protein, the marker of neuronal activation, might play an important role in the chronic pathophysiological process of schizophrenic model induced by NMDA receptor antagonist.

Ultrasound-promoted two-step synthesis of 3-arylselenylindoles and 3-arylthioindoles as novel combretastatin A-4 analogues

A series of 3-(3′-hydroxy-4′-methoxyphenyl)selenyl-5,6,7-trimethoxy-1H-indoles and 3-(3′-hydroxy-4′-methoxyphenyl)thio-5,6,7-trimethoxy-1H-indoles were obtained as a new class of combretastatin A-4 (CA-4) analogues via a convenient ultrasound (US)-assisted two-step process involving 3-selenenylation/sulfenylation followed by O-deallylation. With the assistance of US irradiation, both the reaction rates and yields of selenenylation, sulfenylation and O-deallylation could be significantly improved. A comparison of the reaction rates of O-deallylation and ester reduction demonstrated that O-deallylation was more sensitive to US irradiation. Finally, these products were evaluated for their antiproliferative activities, and most of them showed moderate to potent activities against three human cancer cell lines in vitro.