A novel synthetic use of 2-bromo- 1-methylpyridinium iodide for macrolactamization

Using 2-bromo-1-methylpyridimium iodide as carboxyl activating agent, 10 ansa-macrolactams were prepared conveniently from the corresponding seco-precursor w-aminoacids in the yields of 78-2%.     

Quantum chemical studies on antimalarial of artemisinin (qinghaosu) derivatives

In this paper theoretical studies were performed on artemisinin (qinghaosu) derivatives with semiempirical quantum chemical methods AMI and PM3. The antimalarial activity -logC has an obvious correlation with the net charge of C(16) and bond orders of bonds O(1)-C(10), O(2)-C(6), O(1)-O(2) and O(5)-C(16). According to the calculation results, we derived structure-activity relationship, presented the probable pharmacophore of qinghaosu derivatives and the interaction fashion between the drugs and the plasmodium receptor.     

Organic solvent enhanced α-helical formation of a nonadecapeptide derived from Trichosanthin (TCS 182-200)

A model peptide,TDK,was studied by circular dichroism to elucidate the effect of organic solvent on α-helical formation.The α-helicities enhanced by various alcohol solvents,especially fluorine-substituted alcohols were systematically compared.The relations between α-helical formation of a peptide and external environment were also discussed in detail.These environmental elements mainly include hydrophobicity dielectric constant and acidity of the solvents.     

Comparative studies on the mechanism of uridine phosphorolysis

We have used quantum mechanical method to study the transition states(TSs) of uridine phosphorolysis reaction. Comparing the four different reaction pathways and the five transition states obtained, we conclude that enzymatic uridine phosphorolysis takes place mainly according to acid-catalyzed SN2 mechanism. The proposed reaction pathway is consistent with many experimental results.     

A stereoselective synthesis of the C(3)-C(13) and C(14)-C(24) fragments of macrolactin A

Synthetic studies towards(he C(3)-C(13)and C(14)-C(24)segments(3,4)of the potent antiviral and antitumor compound macrolactin A(1)are presented.Compound 3 was constructed via a convergent and facile approach,exploiting Wittig olefination to generate the sensitive E,Z-diene moiety.Compound 4 was synthesized from the chiral-pod derived sul-fone 39a via an o-alkylation-desulfonation reaction sequence.Cu(Ⅱ)-catalyzed coupling of a Grignard reagent with an al-lylic bromide and Julia olefination were also investigated for the preparation of compound 4.     

Magnetic Screening of the Potential Targeted Protein of Salvianolic Acid B Using T7 Phage Display Library

Salvianolic acid B is one of the effective components from the Chinese traditional drug Salvia miltiorrhiza (Danshen), which is widely used as a usual clinic drug for atherosclerosis-related disorder patients in China. But the targeting protein of salvianolic acid B is still not known. The possible targeting proteins of salvianolic acid B were explored by high throughput screening in this paper. Attached to the magnetic nanoparticles, salvianolic acid B was used for screening the high-affinity protein from the displaying cDNA peptide library phage. After biopanning, the selected protein or peptide sequences were used to explore the whole proteins containing the selected sequences in the National Center for Biotechnology Information website using blast. One of the selected phages was carried out by affinity analysis with salvianolic acid B using capillary electrophoresis (CE). The CE results indicated that the protein or peptide on the surface of the selected phages could bind the drug salvianolic acid B. The results are helpful to preliminarily explain the pharmacology of salvianolic acid B.     

A novel synthetic strategy for the stereospecific total synthesis of (±)-biotin

A concise and efficient TEA-mediated desymmetrization of meso-thioanhydride 6 with 5-ethoxy-5-oxopentylzinc bromine has been developed, which affords a convenient strategy for the stereospecific total synthesis of (±)-biotin 1.     

Size-controlled flow synthesis of metal-organic frameworks crystals monitored by in-situ ultraviolet-visible absorption spectroscopy

Size-controlled flow synthesis of nanoporous particles are of considerable interest for future industrial applications,however,is facing challenges due to lack of in-situ method for size-characterization in fluidic environment.We present that ultraviolet-visible(UV-vis) absorption spectroscopy can be integrated into a flow-synthesis system which was produced by femtosecond laser micro machining.The shift of the absorption peak position of the ex-situ and in-situ UV-vis spectra correlates to variation of size of porous metal-organic frameworks crystals.ZIF-67 crystals with a size in the range from 200 nm to1025 nm are fabricated with the assistance of tri-ethylamine under monitoring of in-situ UV-vis spectra.The ZIF-67 crystals are converted into nanoporous carbons particles with controlled sizes.These materials show size-dependent performance in Na-ion battery and size-independent performance in metal/H_2 O seawater battery.