The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: mechanistic and functionalisation studies

The synthesis of a range of brominated-B n -containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-B n -PAHs were isolated as either the borinic acids or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E 1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-Bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters directly from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the B n -PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.

Characterization of a novel AICARFT inhibitor which potently elevates ZMP and has anti-tumor activity in murine models

AICARFT is a folate dependent catalytic site within the ATIC gene, part of the purine biosynthetic pathway, a pathway frequently upregulated in cancers. LSN3213128 is a potent (16 nM) anti-folate inhibitor of AICARFT and selective relative to TS, SHMT1, MTHFD1, MTHFD2 and MTHFD2L. Increases in ZMP, accompanied by activation of AMPK and cell growth inhibition, were observed with treatment of LY3213128. These effects on ZMP and proliferation were dependent on folate levels. In human breast MDA-MB-231met2 and lung NCI-H460 cell lines, growth inhibition was rescued by hypoxanthine, but not in the A9 murine cell line which is deficient in purine salvage. In athymic nude mice, LSN3213128 robustly elevates ZMP in MDA-MB-231met2, NCI-H460 and A9 tumors in a time and dose dependent manner. Significant tumor growth inhibition in human breast MDA-MB231met2 and lung NCI-H460 xenografts and in the syngeneic A9 tumor model were observed with oral administration of LSN3213128. Strikingly, AMPK appeared activated within the tumors and did not change even at high levels of intratumoral ZMP after weeks of dosing. These results support the evaluation of LSN3213128 as an antineoplastic agent.

Discovery of N-(6-Fluoro-1-oxo-1,2-dihydroisoquinolin-7-yl)-5-[(3R)-3-hydroxypyrrolidin-1-yl]thiophene-2-sulfonamide (LSN 3213128), a Potent and Selective Nonclassical Antifolate Aminoimidazole-4-carboxamide Ribonucleotide Formyltransferase (AICARFT) Inhibitor Effective at Tumor Suppression in a Cancer Xenograft Model

A hallmark of cancer is unbridled proliferation that can result in increased demand for de novo synthesis of purine and pyrimidine bases required for DNA and RNA biosynthesis. These synthetic pathways are frequently upregulated in cancer and involve various folate-dependent enzymes. Antifolates have a proven record as clinically used oncolytic agents. Our recent research efforts have produced LSN 3213128 (compound 28a), a novel, selective, nonclassical, orally bioavailable antifolate with potent and specific inhibitory activity for aminoimidazole-4-carboxamide ribonucleotide formyltransferase (AICARFT), an enzyme in the purine biosynthetic pathway. Inhibition of AICARFT with compound 28a results in dramatic elevation of 5-aminoimidazole 4-carboxamide ribonucleotide (ZMP) and growth inhibition in NCI-H460 and MDA-MB-231met2 cancer cell lines. Treatment with this inhibitor in a murine based xenograft model of triple negative breast cancer (TNBC) resulted in tumor growth inhibition.

Investigation of resistance levels and mechanisms to nicosulfuron conferred by non-target-site mechanisms in large crabgrass (Digitaria sanguinalis L.) from China

Large crabgrass is a major grass weed widely distributed across China. This weed infests maize fields and has evolved resistance to the acetolactate synthase (ALS)-inhibiting herbicide nicosulfuron due to continuous and intensive use. In this study, a total of 25 out of 26 large crabgrass populations collected from maize field demonstrated resistance to nicosulfuron. Amino acid modifications in ALS known to confer resistance to ALS-inhibiting herbicides in other weeds, were not found in the 9 tested resistant populations. The P450 inhibitor malathion significantly reversed resistance to nicosulfuron in 3 tested populations, indicating one or more P450s may be involved. Nicosulfuron was metabolized more rapidly in one resistant large crabgrass population than in a susceptible biotype. This demonstrates that the metabolic resistance mechanisms involving one or more P450s may be responsible for large crabgrass resistance to nicosulfuron in this biotype.

Mediator kinase inhibition further activates super-enhancer-associated genes in AML

Super-enhancers (SEs), which are composed of large clusters of enhancers densely loaded with the Mediator complex, transcription factors (TFs), and chromatin regulators, drive high expression of genes implicated in cell identity and disease, such as lineage-controlling TFs and oncogenes ^{1, 2}. BRD4 and CDK7 are positive regulators of SE-mediated transcription^3,4,5. In contrast, negative regulators of SE-associated genes have not been well described. Here we report that Mediator-associated kinases cyclin-dependent kinase 8 (CDK8) and CDK19 restrain increased activation of key SE-associated genes in acute myeloid leukaemia (AML) cells. We determined that the natural product cortistatin A (CA) selectively inhibited Mediator kinases, had antileukaemic activity in vitro and in vivo, and disproportionately induced upregulation of SE-associated genes in CA-sensitive AML cell lines but not in CA-insensitive cell lines. In AML cells, CA upregulated SE-associated genes with tumour suppressor and lineage-controlling functions, including the TFs CEBPA, IRF8, IRF1 and ETV6^{6, 7, 8}. The BRD4 inhibitor I-BET151 downregulated these SE-associated genes, yet also has antileukaemic activity. Individually increasing or decreasing expression of these TFs suppressed AML cell growth, providing evidence that leukaemia cells are sensitive to dosage of SE-associated genes. Our results demonstrate that Mediator kinases can negatively regulate SE-associated gene expression in specific cell types and can be pharmacologically targeted as a therapeutic approach to AML.

Synthesis of cortistatins A, J, K and L

The cortistatins are a recently identified class of marine natural products characterized by an unusual steroidal skeleton, which have been found to inhibit differentially the proliferation of various mammalian cells in culture by an unknown mechanism. We describe a comprehensive route for the synthesis of cortistatins from a common precursor, which in turn is assembled from two fragments of similar structural complexity. Cortistatins A and J, and for the first time K and L, have been synthesized in parallel processes from like intermediates prepared from a single compound. With the identification of facile laboratory transformations linking intermediates in the cortistatin L synthetic series with corresponding intermediates to cortistatins A and J, we have been led to speculate that somewhat related paths might occur in nature, offering potential sequencing and chemical detail for cortistatin biosynthetic pathways.

[A clinical trial of oxymatrine in treating chronic viral hepatitis type B]

OBJECTIVE

To investigate the therapeutic effect of oxymatrine on chronic viral hepatitis type B.

METHODS

303 patients were randomly allocated either to a treatment group or a control group. The treatment group consisted of 253 patients treated with intravenous or intra-muscular injection of oxymatrine and oral oxymatrine capsule. Oral tiopronin was used in the control group.

RESULTS

At the end of treatment, the rate of normal ALT was similar among the different groups. The rate of normal ALT was 53.3% - 58.3% in the three oxymatrine groups six months after the end of treatment. It was higher than that of the tiopronin group (P < 0.05). After a follow up of six months, the rate of negative HBeAg was 30.0% - 40.9% in the three oxymatrine groups. It was higher than that of the tiopronin group (16.7%). The rate of negative HBV DNA was 39.2% - 49.5% in the three oxymatrine groups. It was also higher than that of the tiopronin group.

CONCLUSION

Oxymatrine can improve the liver function and increase the negative rate of HBeAg and HBV DNA in the patients with chronic hepatitis B. The therapeutic effect of oxymatrine will persist after the cessation of administration.

[Cloning and sequence analysis of truncated S gene from circulation of patients with chronic hepatitis B virus infection]

OBJECTIVE

To find different mutated status of HBV DNA in circulation from chronic HBV patients.

METHODS

Specially designed primers and polymerase chain reaction method were applied to amplify the whole S gene of HBV from the serum of 2 patients. After being sequenced, 4 clones were compared with HBV adr subtype (China strain) to identify the mutant sites.

RESULTS

Sequencing results implied that there was a truncated large/middle S gene in the serum of the patients. Besides that, HBsAg and HBV DNA polymerase defective clones were also detected.

CONCLUSIONS

Truncated middle S gene is found in the circulation of patients with chronical HBV infection, suggestive of a poor prognosis.

[A prospective study of histological changes after AraAMP treatment in patients with chronic hepatitis B infection]

OBJECTIVE

To investigate the histological changes in liver biopsy tissue induced by AraAMP therapy for 50 days in patients with chronic hepatitis B infection.

METHODS

Eleven patients were enrolled into this prospective study. All the patients had liver biopsy performed within 1 week before starting AraAMP therapy. A second liver biopsy was taken for comparison six months after the end of therapy. Blinded biopsies were scored according to Knodell's histology activity index (HAI), and examined for HBeAg and alpha-smooth muscle actin with immunohistochemistry as well as HBV DNA by using in situ hybridization.

RESULTS

Histological improvement of >or=2 points decrease in the necroinflammatory HAI scores was seen in 8 of the 11 (72.7%) of patients after treatment. In these patients histological assessment revealed a significant improvement in intralobular inflammation and fibrosis as compared with pretreatment values(P < 0.05). There was significant difference of HAI changes in 6 cases graded as G3 based on the degree of periportal interface hepatitis and spotty parenchymal injury, but not in 5 cases graded as G2. HBeAg disappeared from liver tissue in 4 of the 9 cases and a significant reduction of activated liver stellate cells was demonstrated in the second biopsy(P = 0.018). Of the nine cases with HBV DNA positive at the first biopsy with in situ hybridization examination, 4 were negative at the second biopsy.

CONCLUSION

Significant improvement in intralobular inflammation and fibrosis can be observed in liver tissue from patients with chronic hepatitis B infection treated with AraAMP.

[Cloning and sequence analysis of a pseudogene of liver regeneration augmenter in rats]

OBJECTIVE

To investigate the status of the augmenter of liver regeneration (ALR) in rat's genome.

METHODS

Polymerase chain reaction (PCR) was used to amplify the genomic DNA of rat, with a set of specific primers designed according to the cDNA sequence of ALR. The products were ligated into pGEM Teasy vector. Two positive clones were sequenced separately.

RESULTS

Two products were amplified from the rat's genome by PCR. After sequencing, one pseudogene was identified. The homology of the amino acid sequence between the ALR and its pseudogene was 88.8%.

CONCLUSIONS

ALR pseudogene is found in rat's genome, implying that there is an ALR multigene family. This finding lays a foundation for further study of ALR molecular evolution mode.

[Transcription of antisense RNA of hepatitis B virus through retroviral mediated gene transfer]

To probe the ways by which the antisense gene of hepatitis B virus (HBV) can be transferred and transcripted in eukaryotic cells to inhibit HBV replication and expression. Two retroviral vectors that carried antisense gene of hepatitis B virus (HBV) PreC/C or PreS/S region were constructed. The HBV ayw PreC/C and PreS/S fragments were inserted into the vector pDO. R cloning site in the sense or antisense orientation and the recombinant retroviral vectors were then transfected into PA317 packaging cells by calcium phosphate coprecipitation, respectively. The stably transformed G418-resistant PA317 cells were selected and the recombinant retroviruses released from transfected G418-resistant PA317 cells were assayed by G418 selection method, using NIH 3T3 cells as target cells. Southern blot and RNA Dot blot analysis showed that the recombinant retroviral vector sequences were stably integrated into the chromosome of transfected PA317 cells and the antisense RNA of HBV PreS/S or PreC/C gene also transcripted in the transduced NIH 3T3 cells. These results suggested that antisense gene of HBV can be successfully transferred and transcripted in target cells through retroviral vector mediated gene transfer and the antisense retroviral vectors may be potentially useful for anti-HBV gene therapy.

[A study on the effects of three kinds of treatment in chronic hepatitis B]

To study the effects of three kinds of treatment: Zhuling polysaccharides combined with hepatitis B vaccine (group I), LAK cells, induced by interleukin-2 (IL-2) in vitro, transfusion therapy, (group II), bacille Calmette-Guerin (BCG) combined with persatin (group III) in chronic hepatitis B and the mechanism of their effects, we observed 286 patients with chronic hepatitis B, diagnosed according to the criteria made by The 6th National Meeting for Viral Hepatitis and Substantiated by the results of liver biopsy. The patients were divided into 3 treatment groups randomly, with interferon 3 MIU, thrice a week and 10% glucose 500 ml (i.v.) dripping everyday as two different control groups. The ALT recovery rates in group I, II, III were 64%, 35% and 57%, respectively. At the end of the treatment, the HBeAg and HBV DNA clearence rates in group I, II, III were 43% and 44%, 34% and 30%, 57% and 61%, respectively. After one year of follow up, the HBeAg and HBV DNA clearence rates in group I, II, III were 59%, 58%, 61% and 55%, 70%, 60%, respectively. The effects of these kinds of treatment were similar to these of interferon. We also injected Zhuling polysaccharides combined with hepatitis B vaccine, Zhuling polysaccharides alone and normal saline as control to DHBV vertical transmission duck. It was shown that serum DHBV DNA was cleared and the results were also proved by liver histologic change in the two treatment groups. According to these data, it is suggested that the three kinds of treatment for hepatitis B could restore the ALT level, suppress the replication of HBV and improve the liver histologic change. Their effects were similar to those of interferon.

[The evaluation of cefmetazole in clinical use. The study group of cefmetazole in clinical use]

To study the clinical effect of cefmetazole (CMZ), we treated with CMZ 1,926 patients with various infections involving the respiratory tract, gastrointestinal tract, liver and biliary tract, skin and soft tissue and others. The marked effect rate was 56.5%, and the effect rate 33.7%. The sensitivity test of CMZ was also performed in vitro. Staphylococcus aureus, streptococcus, staphylococcus epidermis, E. coli, S. typhi, B. salmonella, B. shigella, B. Klebsiella pneumoniae, B. proteus, etc. were sensitive to CMZ. Injecting CMZ can prevent the infection of operation. The study of the adverse reaction of CMZ showed, an adverse reaction rate of 4.2% (the gastrointestinal tract, allergy, kidney and nervous system). These results suggested that CMZ is an antibiotic of broad spectrum, high efficacy and low toxicity. It is effective in treating sensitive bacterial infection, unknown pathogenic infection and mixed bacterial infection, and preventing infection in surgery.

[The effect of cytokines on the liver necrosis]

OBJECTIVE

To investigate the effect of cytokines on liver necrosis.

METHODS

We injected IL-1, IL-6, IFN gamma, TNF alpha with or without D-galactosamine (D-GAL) into the abdominal cavity of mice separately.

RESULTS

There was no effect on hepatocyte of normal mice after injection of IL-1, IL-6, IFN gamma alone or together. The serum total bilirubin (TBIL) and liver necrosis of mice increased more markedly by using of TNF alpha, IL-6 or IFN gamma separately with D-GAL (TBIL: 46.2 +/- 10.6 micromol/L, 44.6 +/- 12.9 micromol/L, 41.9 +/- 14.9 micromol/L), then by D-GAL alone (TBIL: 27 +/- 11 micromol/L) also the serum TBIL of mice and liver necrosis also increased after injection of IL-1, IL-6 with D-GAL and TNF alpha.

CONCLUSION

Cytokines like IL-1, IL-6, IFN gamma and TNF alpha joined the process of hepatocyte necrosis. They can enhance the degree of liver necrosis induced by D-GAL.

[The effect of tumor necrosis factor alpha on hepatic necrosis in viral hepatitis]

In order to investigate the effect of tumor necrosis factor alpha (TNF alpha) on hepatocyte necrosis in viral hepatitis, TNF alpha with or without D-galactosamine (D-Gal) was injected into the abdominal cavity of rats. No effect was observed after injection of TNF alpha alone. After injection of TNF alpha with D-Gal, the total bilirubin level in rat blood increased and hepatocyte necrosis appeared (P < 0.05). Moreover, anti-TNF alpha McAb blocked the effect of hepatocyte necrosis produced by D-Gal and lipopolysaccharide (LPS). 130 samples of hepatic tissue were stained with anti-TNF alpha McAb by using ABC immunohistochemistry method. It was found that more severe the hepatocyte necrosis, more the positive cells expressing TNF alpha. There were more TNF alpha positive cells in the tissue of severe hepatitis. These results suggested that TNF alpha is a mediator in hepatocyte necrosis.

[Human interleukin-2 gene transfer and expression inhibits hepatitis B virus surface antigen expression and enhances LAK activity of peripheral blood mononuclear cells of normal adults]

Using molecular cloning techniques, we constructed and transfected human interleukin-2 gene expressive retroviral vector into a packaging cell line PA317. Geneticin resistant cell clones were identified and pseudoviral particles titred as 3.75 x 10(6)CFU/ml in their culture supernatants. Human interleukin-2 expression level was 5.71IU/ml for NIH3T3, 6IU/ml for both 2. 2. 15 and peripheral blood mononuclear cells after infection with pseudoviral particles with 8 of multiplicity of infection (M. O. I). Low level interleukin-2 expression potentially inhibited hepatitis B virus surface antigens expression of 2. 2. 15 cell line and enhanced cytotoxicity of peripheral blood mononuclear cells against K562 and Raji as target cells, but neither pseudoviral particles without interleukin-2 cDNA nor reccombinant interleukin-2 at 6 IU/ml. These results indicated that retroviral vector-packaging cell line can efficiently transfer and express interleukin-2 cDNA in human somatic cells and low level expression of interleukin-2 potentially inhibits hepatitis B virus surface antigens expression and enhances LAK activity of peripheral blood mononuclear cells of normal persons.

[The effects of zhuling-duotang, hepatitis B vaccine and bacillus Calmette-Guerin on immunoactivities of peripheral blood mononuclear cells: an in vitro research]

"Zhuling-duotang (a polysaccharide preparation of the Chinese traditional herb medicine polyporusum bellatus) and hepatitis B vaccine (HB vaccine)" and "Persantin and bacillus calmeteguerin (BCG)" have been used to treat chronic hepatitis B. To elucidate their therapeutic mechanism, we studied the effects of zhuling-duotang, HB vaccine and BCG on immunoactivities of nomal human peripheral blood mononuclear cells (PBMCs). Cytotoxicity of PBMCs incubated with such drugs against target cells K562, HepG2 or 2.2.15 was detected by using 3H-TdR release assay. IL-2 and IFN-gamma activities of the supernatant were assayed. Immunofluorescent analysis of molecular CD4, CD8, CD16, IL-2R on the surface of PBMCs were done. The results showed that: (1) Zhuling-duotang and BCG could significantly increase the cytotoxicity of PBMCs. They could induce PBMCs to produce IL-2 but not IFN-gamma. They also could stimulate PBMCs to express IL-2R. Zhuling-duotang and BCG did not affect the percentage of CD4+, CD8+, CD16+ cells among PBMCs. (2) HB vaccine did not significantly increase the cytotoxicity of PBMCs. (3) The cytotoxicity of PBMCs induced by Zhuling-duotang combined with HB vaccine was not significantly higher than that of PBMCs induced by Zhuling-duotang alone.