Design, synthesis, and biological activity evaluation of BACE1 inhibitors with antioxidant activity.

The proteolytic enzyme ß-secretase (BACE1) plays a central role in the synthesis of the pathogenic ß-amyloid peptides (Aß) in Alzheimer's disease (AD), antioxidants could attenuate the AD syndrome and prevent the disease progression. In this study, BACE1 inhibitors (D1-D18) with free radical-scavenging activities were synthesized by molecular hybridization of 2-aminopyridine with natural antioxidants. The biological activity evaluation showed that D1 had obvious inhibitory activity against BACE1, and strong antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS+• ) assay, which could be used as a lead compound for further study.

Design, synthesis and evaluation of 2-amino-imidazol-4-one derivatives as potent ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1) inhibitors.

Inhibition of ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) to prevent brain ß-amyloid (Aß) peptide's formation is a potential effective approach to treat Alzheimer's disease. In this report we described a structure-based optimization of a series of BACE1 inhibitors derived from an iminopyrimidinone scaffold W-41 (IC50 = 7.1 µM) by Wyeth, which had good selectivity and brain permeability but low activity. The results showed that occupying the S3 cavity of BACE1 enzyme could be an effective strategy to increase the biological activity, and five compounds exhibited stronger inhibitory activity and higher liposolubility than W-41, with L-5 was the most potent inhibitor against BACE1 (IC50 = 0.12 µM, logP = 2.49).

Protective effect of 6-O-methyl-scutellarein on repeated cerebral ischemia/reperfusion in rats.

Scutellarin (1) possesses protective effects against neuronal injury, while 6-O-methyl-scutellarein (3), as the main metabolite of scutellarin in vivo, has not been reported about its protective effects previously. The present study mainly investigated whether the neural injury caused by ischemia/reperfusion would be influenced by different doses of 6-O-methyl-scutellarein (3). The results of behavioral, neurological, and histological examinations indicated that 6-O-methyl-scutellarein (3) could improve neuronal injury, and exhibit significant difference among the various doses. More importantly, 6-O-methyl-scutellarein (3) had better protective effects than scutellarin in rat cerebral ischemia.

Synthesis and Bioactivity Characterization of Scutellarein Sulfonated Derivative.

Scutellarin (1) has been widely used to treat acute cerebral infarction in clinic, but poor aqueous solubility decreases its bioavailability. Interestingly, scutellarin (1) could be metabolized into scutellarein (2) in vivo. In this study, a sulfonic group was introduced at position C-8 of scutellarein (2) to enhance the aqueous solubility of the obtained derivative (3). DPPH (1,1-diphenyl-2-picrylhydrazyl)-radical scavenging ability and antithrombic activity were also conducted to determine its bioactivity. The result showed that scutellarein derivate (3) could be a better agent for ischemic cerebrovascular disease treatment.

Synthesis of scutellarein derivatives to increase biological activity and water solubility.

In order to improve the biological activity and water solubility of scutellarin (1), some derivatives of its main metabolite (scutellarein) were designed and synthesized. All the compounds were tested for their thrombin inhibition activity through the analyzation of thrombin time (TT), activated partial thromboplastin time (APTT), prothrombin time (PT) and fibrinogen (FIB). Their antioxidant activities were assessed by measuring their scavenging capacities toward 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and the ability to protect PC12 cells against H2O2-induced cytotoxicity, their water solubility were also assessed by ultraviolet (UV) spectrophotometer. The results showed that compound 8b demonstrated stronger anticoagulant and antioxidant activity, better water solubility compared with scutellarein (2), which warrants it as a promising agent for the treatment of ischemic cerebrovascular disease.

A new and practical synthetic method for the synthesis of 6-O-methyl-scutellarein: one metabolite of scutellarin in vivo.

Scutellarin (1) has been used for the treatment of angina pectoris, cerebral infarction and coronary heart disease with a large market share in China. Pharmacokinetic studies on scutellarin showed that scutellarin (1) is readily converted into its metabolites in vivo. In this paper, a new and practical synthetic method for the synthesis of 6-O-methyl-scutellarein (3) (one metabolite of scutellarin in vivo) is reported. The benzyl bromide was firstly used to selectively replace the acetyl group at C-7 in 7, and was then used to protect the hydroxy groups at C-4' in 10, 6-O-methyl-scutellarein (3) is obtained in high yield through these methods.

Natural products as potential lead compounds to develop new antiviral drugs over the past decade.

Virus infection has been one of the main causes of human death since the ancient times. Even though more and more antiviral drugs have been approved in clinic, long-term use can easily lead to the emergence of drug resistance and side effects. Fortunately, there are many kinds of metabolites which were produced by plants, marine organisms and microorganisms in nature with rich structural skeletons, and they are natural treasure house for people to find antiviral active substances. Aiming at many types of viruses that had caused serious harm to human health in recent years, this review summarizes the natural products with antiviral activity that had been reported for the first time in the past ten years, we also sort out the source, chemical structure and safety indicators in order to provide potential lead compounds for the research and development of new antiviral drugs.

Preclinical characterization of danatinib as a novel FLT3 inhibitor with excellent efficacy against resistant acute myeloid leukemia.

The therapeutic benefits of available FLT3 inhibitors for AML are limited by drug resistance, which is related to mutations, as well toxicity caused by off-target effects. In this study, we introduce a new small molecule FLT3 inhibitor called danatinib, which was designed to overcome the limitations of currently approved agents. Danatinib demonstrated greater potency and selectivity, resulting in cytotoxic activity specific to FLT3-ITD and/or FLT3-TKD mutated models. It also showed a superior kinome inhibition profile compared to several currently approved FLT3 inhibitors. In diverse FLT3-TKD models, danatinib exhibited substantially improved activity at clinically relevant doses, outperforming approved FLT3 inhibitors. In vivo safety evaluations performed on the granulopoiesis of transgenic myeloperoxidase (MPO) zebrafish and mice models proved danatinib to have an acceptable safety profile. Danatinib holds promise as a new and improved FLT3 inhibitor for the treatment of AML, offering long-lasting remissions and improved overall survival rates.

[Comparison of activated carbon and ultrafiltration technique in the production process of huoxue tongluo injection].

OBJECTIVE: To research the applicability of activated carbon and ultrafiltration technique in the production process of Huoxue Tongluo Injection. METHODS: The kinetic-turbidimetric method was used to determine the content of bacterial endotoxins in Huoxue Tongluo solution. Particle size change in Huoxue Tongluo solution was determined by nanometer particle size instrument before and after the use of different concentration activated carbon and different molecular weight ultrafiltration membrane. RESULTS: The removal efficacy of bacterial endotoxins was 65.2%, 77.5%, 80.4% by using three concentrations of active carbon at 0.05%, 0.10%, 0.30% in Huoxue Tongluo Injection, respectively. It was above 95% by using cutoff molecular weight both 5 kDa and 10 kDa ultrafiltration membrane. Measure results by nanometer particle size instrument showed that particle size of filter liquor by 10 kDa cutoff molecular weight ultrafiltration membrane was much smaller than that of by use of different concentration activated carbon. CONCLUSION: Ultrafiltration method is more suitable to the removal of bacterial endotoxins. The solution is more clear after using ultrafiltration method, and large particles of solution is removed. The ultrafiltration method provides the basis for injection production.

[Effect on elimination of pyrogen and effectual components of Panax notoginseng saponins by ultrafiltration membranes of different cut-off molecular weight and different materials].

OBJECTIVE: To study the elimination effect of bacterial endotoxins and the transmittance of Panax notoginseng saponins by ultrafiltration membranes of different cut-off molecular weight and different materials. METHODS: The kinetic-turbidimetric method was used to determine the content of bacterial endotoxins in Panax notoginseng saponins solution before and after using the ultrafiltration. The change of the contents of active components was examined by HPLC,using notoginsennoside R1, ginsennoside Rg1, ginsennoside Rb1 and ginsennoside Rd as the mark components. RESULTS: The removal rate of bacterial endotoxin fell along with the increasing of membrane aperture. The removal rate was 20. 69% by ultrafiltration membranes of 100 KDa with polysulfone material,less than those of other ultrafiltration membranes with polysulfone material. But the removal rate of bacterial endotoxin by E membranes of blend materials was higher than those of other ultrafiltration membranes with polysulfone material. The contents of active components filtered by E membranes of blend materials was more than that of ultrafiltration membranes of 100 KDa with polysulfone material. CONCLUSION: The applicability of ultrafiltration membranes of large cut-off molecular weight and blend materials of effectual component in Panax notoginseng saponins and elimination of pyrogen is good.

Bufotenine and its derivatives: synthesis, analgesic effects identification and computational target prediction.

Natural product bufotenine (5) which could be isolated from Venenum Bufonis, has been widely used as a tool in central nervous system (CNS) studies. We present here its quaternary ammonium salt (6) which was synthesized with high yields using 5-benzyloxyindole as raw materials, and we firstly discover its analgesic effects in vivo. The analgesic evaluation showed that compounds 5 and 6 had stronger effects on the behavior of formalin induced pain in mice. Moreover, the combination of compound 6 and morphine has a synergistic effect. We intended to explain the molecular mechanism of this effect. Therefore, 36 analgesic-related targets (including 15 G protein-coupled receptors, 6 enzymes, 13 ion channels, and 2 others) were systemically evaluated using reverse docking. The results indicate that bufotenine and its derivatives are closely related to acetyl cholinesterase (AChE) or α4ß2 nicotinic acetylcholine receptor (nAChR). This study provides practitioners a new insight of analgesic effects.

Synthesis and Biological Evaluation of Scutellarein Alkyl Derivatives as Preventing Neurodegenerative Agents with Improved Lipid Soluble Properties.

BACKGROUND: Exogenous antioxidants are considered as a promising therapeutic approach to treat neurodegenerative diseases since they could prevent and/or minimize the neuronal damage by oxidation. OBJECTIVE: Three series of lipophilic compounds structurally based on scutellarein (2), which is one metabolite of scutellarin (1) in vivo, have been designed and synthesized. METHODS: Their antioxidant activity was evaluated by detecting the 2-thiobarbituric acid reactive substance (TBARS) produced in the ferrous salt/ascorbate-induced autoxidation of lipids, which were present in microsomal membranes of rat hepatocytes. The lipophilicity of these compounds indicated as partition coefficient between n-octanol and buffer was investigated by ultraviolet (UV) spectrophotometer. RESULTS: This study indicated that compound 5e which had a benzyl group substituted at the C4'- OH position showed a potent antioxidant activity and good lipophilicity. CONCLUSION: 5e could be an effective candidate for preventing or reducing the oxidative status associated with the neurodegenerative processes.

[Establishment and preliminary application of a gene chip for detection of hepatitis B virus "a" determinant hotpoint mutation].

OBJECTIVE: To develop a gene chip for rapid detection of the "a" determinant hotpoint mutation of hepatitis B virus (HBV). METHODS: Primers were designed in the HBV conservative region, and probes for detecting 126A, 126S, 144A, 145R, 145E, 144A+145R, and 144A+145E mutants were developed for that gene chip. PCR amplification and gene chip technology were optimized. The performance of the gene chip was evaluated by detecting the reference plasmids. Forty five samples of serum obtained from patients with chronic hepatitis B were used to compare the sensitivity of the gene chip and the direct sequencing of PCR products. RESULTS: The oligonucleotide microarray was specific for mutant and native plasmids. The sensitivity of the gene chip was 5 x 10(3)copies/micro l with a high reproducibility. The gene chip could detect minor variants when they were more than 10% among the HBV strains. The positive rates of 126A, 126S-1, 126S-2 detected in the 45 specimens by the gene chip (46.67%, 35.56% and 24.44%, respectively) were higher than those detected by direct sequencing of PCR products (9.00%, 4.44% and 2.22%; P=0.000, P=0.000 and P=0.002, respectively). The sequencing of cloned PCR products demonstrated that the gene chip was specific for the "a" determinant hotpoint mutation detection. CONCLUSION: HBV "a" determinant hotpoint mutations can be detected by oligonucleotide microarray with high sensitivity and specificity, providing a method for large scale screening of the mutants.

Design, Synthesis, and Biological Evaluation of Scutellarein Derivatives Based on Scutellarin Metabolic Mechanism In Vivo.

Three series of scutellarein derivatives have been designed and synthesized based on metabolic mechanism of scutellarin (1) in vivo. Their thrombin inhibition activities were tested through the analyzation of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and fibrinogen (FIB). The antioxidant activities of these target products were assessed by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay and the ability to protect PC12 cells against H2 O2 -induced cytotoxicity, and their solubilities were evaluated by ultraviolet (UV) spectrophotometer. The results showed that the two isopropyl groups substituted derivative (18c) demonstrated stronger anticoagulant activity, better water solubility, and good antioxidant activity compared with scutellarein (2), which warrants further development of 18c as a promising agent for ischemic cerebrovascular disease treatment.

[Preparation and application of the national reference panel for hepatitis B virus DNA].

OBJECTIVES: To calibrate the national hepatitis B virus (HBV) DNA standard according to world health organization's standard material and prepare the national reference panel for HBV DNA reagents. METHODS: Sera from blood donors and HBV patients were collected and detected by home-made HBV DNA PCR kits, HBsAg kits, and anti-HBc kits, and then confirmed by HBV DNA PCR kits produced by Roche in German, which was recognized by the world health organization. The stability of the panel was detected by acceleration method. RESULTS: The convinced copies of the sensitivity samples were gotten by seven independent experiments, the coefficients of variation of logarithm of the copies of L0-L5 were all less than 15%. Regarding the national reference panel as the standard, the quality of most domestic HBV DNA PCR kits was improved, while part of the kits should be further qualified. CONCLUSION: The national reference panel for HBV DNA reagents is developed. It contains eight negative, nine positive sera and seven samples for sensitivity test

[Evaluation on the analytical sensitivity of 31 HBsAg enzyme immunoassay kits].

OBJECTIVE: To study the analytical sensitivity on 31 HBsAg enzyme immunoassy (EIA) test kits. METHODS: Thirty one HBsAg EIA kits produced by domestic or overseas manufactories and applied for approval during May 2007 to May 2008, were evaluated using the national reference panels. The hyperbolic curve of the log A value and log concentration for the national sensitivity standards was established. The cut-off value of each kit was substituted into the curvilinear equation to determine the analytical sensitivity which was compared between different HBsAg EIA kits. RESULTS: Twenty seven (351 lots) domestic and 4 (27 lots) overseas kits were compared. Among 378 lots of the 31 HBsAg EIA kits, only 2 lots of the domestic kits had a lower sensitivity when tested with the national HBsAg reference panels, with an average approvalr ate of 99.43% (349/351). The mean analytical sensitivity of the domestic kits for adr, adw, ay serotypes were 0.307, 0.419, 0.513 ng/ml, respectively. There was a significant difference between serotypes (F = 97.30, P < 0.01). The mean analytical sensitivity of the overseas kits for adr, adw, ay serotypes were 0.054, 0.066, 0.050 ng/ml respectively, with no significant difference between serotypes (F = 0.65, P > 0.05). The analytical sensitivity of the overseas kits for all the three serotypes was higher than that of the domestic kits (P < 0.01). There was no significant difference found between the analytical sensitivities of the kits produced by the same manufactory using 30- or 60-minute incubation of detection (P > 0.05). In contrast, there was significant difference noticed between the analytical sensitivities of the kits produced by the same manufactory when tested for 10 or 15-minute coloration of the results (P < 0.01). CONCLUSION: Analytical sensitivity of the HBsAg EIA domestic kits should be further improved, especially for detecting adw and ay serotypes.

[Sensitivity and specificity of 4 domestic ELISA kits for detection of hepatitis B virus markers].

OBJECTIVE: To compare and analyze the sensitivity, specificity of 4 domestic ELISA kits for detection of hepatitis B virus (HBV) markers (HBsAg, anti-HBs, HBeAg, anti-HBe, and anti-HBc). METHODS: Five hundred and ninety four serum samples collected from patients with chronic hepatitis B and abnormal blood donors were detected for HBV markers and by 4 domestic ELISA kits. Samples with conflicting results by different diagnostic kits were retested. Samples with the HBsAg values close to the cut-off point were detected by Abbott HBsAg confirmation kit (Architect HBsAg confirm). Sensitivity of the kits was determined, using the national sensitivity reference panels for HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc. RESULTS: The rates of sensitivity on 4 domestic kits for detection of HBsAg were 4 to 10 times lower, and on the 4 domestic kits for detection of anti-HBs, HBeAg, anti-HBe and anti-HBc were 4 to 16 times lower, as compared to Abbott Architect kits. In addition, the domestic HBV ELISA kits had some false positive results. The total coincidence rates of HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc were 96.46%-98.15%, 94.28%-98.15%, 98.15%-99.49%, 90.07%-96.30%, 92.09%-96.80%, respectively. CONCLUSION: Both sensitivity and specificity of the domestically produced HBV ELISA kits should be improved.

[Comparison of the kinesis of immune responses in mice vaccinated by different kinds of recombinant hepatitis B vaccines].

OBJECTIVE: To evaluate the kinesis of cellular and humoral immune responses to different kinds of recombinant hepatitis B(rHB) vaccines in the immunized mice. METHODS: At serial time points, the levels of IFN-gamma and IL-2 secreted by spleens mononuclear cells (MNC) of the vaccinated mice were detected by enzyme-linked immunospot methods (ELISPOT) after stimulation in vitro with HBsAg MHC class I peptide S28-39 or HBsAg. The lymphocytotoxicity of the immunized mice were also detected (CTL) by a specific lysis assay and the levels of anti-HBs were measured by the Abbott IMX kit. RESULTS: The peak values of IFN-gamma and IL-2 in vaccinated mice were detected by ELISPOT, 10 - 14 days after immunization. The CTL and the level of IFN-gamma induced by rHB vaccine derived from yeast cells (Hansenula polymorpha) (rHP vaccine) were significantly higher than the other two vaccines (P < 0.05). The maximum lysis of CTL appeared in the vaccinated mice on day 10 after immunization, with the percentage of 39.8%. The levels of IL-2 induced by rHP vaccine were significantly higher than the other two vaccines (P < 0.05). However, the IL-2 levels in the rSC (saccharomyces cerevisiae) vaccine group were higher as compared with the rCHO vaccine group at day 7 and day 14 (7 d t = 4.595, P = 0.001 < 0.05; 14 d t = 5.721, P = 0.000 < 0.05) after immunization. The cellular immune response to the rHP vaccine was the strongest while it was the lowest to the rCHO vaccine at day 7 after immunization. The sero-positive rates and the titers of anti-HBs in the vaccinated mice increased with time after vaccination. The titers of anti-HBs in the rCHO vaccine group at day 7 were similar to the rSC vaccine group, but significantly higher than that of the rHP vaccine group (P = 0.044 < 0.05). The anti-HBs titers of the rCHO vaccine group at day 14 were significantly higher as compared to the rSC (P = 0.012 < 0.05) and rHP (P = 0.009 < 0.05) vaccine groups. CONCLUSION: The immune responses induced by the three kinds of rHB vaccines were different in their patterns and levels. According to the intensity of early cellular immune response, the two yeast HB vaccines were superior to the rCHO vaccine, especially to the rHP vaccine. In contrast, the rCHO vaccine induced early seroconversion and high levels of anti-HBs.

[Preparation of the national reference panel for hepatitis B surface antigen].

OBJECTIVE: To establish the national quantity standard of hepatitis B surface antigen according to the world health organization' s standard material and prepare the national liner reference panel for hepatitis B surface antigen. METHODS: Sera from hepatitis B patients and health blood donors in different areas were collected and detected by domastic HBsAg kits, anti-HBs kits, HBeAg kits, anti-HBe kits, anti-HBc kits and anti-HCV, and then confirmed by the kits produced by Abbott, which was approved by WHO. One serum with high concentration of HBsAg was calibrated with the standard sample of WHO. And then it was diluted by 1.5 fold as the liner HBsAg reference panel. RESULTS: The HBsAg concentration of one serum was 1226 IU/ml calibrated by 21 independent standardization measurements with 7 kinds of kits. The coefficient of variation of each calibration were less then 15%. A panel contained 8 serial dilutions was established as the national liner HBsAg reference panel. The permitted range of every dilution was stipulated and the stability of the panel was detected by accelerated test. CONCLUSIONS: The national quantity standard of hepatitis B surface antigen was established and the national quantitative reference panel for HBsAg which contains eight liner serum was developed.