Asymmetric Construction of 4 H-Pyrano[3,2- b]indoles via Cinchonine-Catalyzed 1,4-Addition of 2-Ylideneoxindole with Malononitrile.

A highly enantioselective [4 + 2] annulation of 2-ylideneoxindole with malononitrile has been accomplished by cinchonine catalysis under mild conditions. The corresponding enantiomerically enriched 4 H-pyrano[3,2- b]indoles were generated in moderate to high yields (up to 94%) with excellent enantioselectivities (up to 98% ee). To explain the stereoselectivity of the organocatalytic Michael-ammonization cascade, we also carried out the control experiments and proposed plausible transition-state models for the catalytic cycle based on the observed stereochemistry of the products. In addition, some of the products showed moderate antibacterial activity against S. aureus and S. epidermidis in vitro, which might be considered as a potential clue for the discovery of new antimicrobial agents.

[Analysis on DNA methylation of mosaic and moxa type leaves of Aconitum carmichaeli by MSAP].

An MSAP analysis method was established for detecting DNA methylation of Aconitum carmichaeli leaves, and the DNA methylation of different leaf shapes and different leaf position was analyzed by MSAP. The study made experiments on the leaves of different position of mosaic and moxa leaf type A. carmichaeli, researched the effects of restriction digestion of genomic DNA by using two restriction enzymes, screened the suitable selective amplification primers, and analyzed the methylation differences of leaves by calculating the 6% acrylamide gel electrophoresis bands and lane. The best reaction system of MSAP was obtained, under the conditions of 37 ℃, the 16 h incubated time was more suitable for 150 ng DNA, and 25 pairs of selective amplification primers were selected from 256 pairs. Totally, 273 electrophoresis bands were obtained by 25 pairs of selective primers, including 228 non methylation or single chain methylation bands,27 double chain methylation bands,and 18 single stranded methylation bands, the total methylation rate was 16.48%. The methylation rate was slightly different in mosaic and moxa leaf type A. carmichaeli leaf, which were 15.36%, 14.34%, respectively, and article 8, article 6 nucleotide fragments of genome methylation modification differences were obtained, accounted for 3%, 2.26% of the total number of bands. Based on this study it can provide new ideas for molecular identification, breeding and cultivation, and genetic evolution of A. carmichaeli.

Panax ginseng and its ginsenosides: potential candidates for the prevention and treatment of chemotherapy-induced side effects.

Chemotherapy-induced side effects affect the quality of life and efficacy of treatment of cancer patients. Current approaches for treating the side effects of chemotherapy are poorly effective and may cause numerous harmful side effects. Therefore, developing new and effective drugs derived from natural non-toxic compounds for the treatment of chemotherapy-induced side effects is necessary. Experiments in vivo and in vitro indicate that Panax ginseng (PG) and its ginsenosides are undoubtedly non-toxic and effective options for the treatment of chemotherapy-induced side effects, such as nephrotoxicity, hepatotoxicity, cardiotoxicity, immunotoxicity, and hematopoietic inhibition. The mechanism focus on anti-oxidation, anti-inflammation, and anti-apoptosis, as well as the modulation of signaling pathways, such as nuclear factor erythroid-2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1), P62/keap1/Nrf2, c-jun N-terminal kinase (JNK)/P53/caspase 3, mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinases (ERK), AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR), mitogen-activated protein kinase kinase 4 (MKK4)/JNK, and phosphatidylinositol 3-kinase (PI3K)/AKT. Since a systemic review of the effect and mechanism of PG and its ginsenosides on chemotherapy-induced side effects has not yet been published, we provide a comprehensive summarization with this aim and shed light on the future research of PG.

[Detecting the DNA damage of N-ras gene induced by potassium dichromate].

OBJECTIVE: Applying RDPCR to detect the DNA damage of N-ras gene induced by Potassium dichromate METHODS: Preparing single-stranded probes of exon 1 of N-ras gene in human. The genomic DNA was treated with Potassium dichromate, then amplified by RDPCR and detected by Southern hybridization with the probe. RESULTS: The clear hybridized bands can be seen in the position which is induced by Potassium dichromate on the dose of 100 micromol/L, but can't be detected on the dose over 1000 mol/L. CONCLUSION: It indicates that Potassium dichromate can cause the DNA damage of N-ras gene, which should be the key point of its carcinogenesis mechanisms.

[Application with single-stranded probes in randomized terminal linker-dependent PCR].

OBJECTIVE: Preparing single-stranded (ss) probes in place of double-stranded (ds) probes to improve the hybridization efficiency and specificity of randomized terminal linker-dependent PCR (RDPCR). METHODS: Using asymmetric PCR and single-primer PCR to prepare ss probes of extron 7 of p53 gene in rat, then comparing the results hybridized with ss probes and ds probes. RESULTS: Preparation of ss probes by asymmetric PCR and single-primer PCR gets success. Hybridization results showed that the ss probes could get better signals and less noise than ds probes. CONCLUSION: In comparison with ds probes, the application of ss probes can increase the hybridization sensitivity and specificity of RDPCR.

[Establishing a method to detect the DNA damage of N-ras gene].

OBJECTIVE: Applying RDPCR to detect the DNA damage of N-ras gene in human. METHODS: Single-primer PCR was used to prepare single strand (ss) probes of extron 1 of N-ras gene in human. The genomic DNA was digested completely by restriction endonuclease, then amplified by RDPCR and detected by Southern hybridization with the probe. RESULTS: The ss probes were successfully prepared by single-primer PCR. The hybridized bands were clearly seen in the expected migration positions. CONCLUSION: The result shows that the method to detect the damaged position of N-ras gene has been established, which would be helpful to further studies on chemical carcinogenesis and on the prevention of tumor.