Rh(III)-Catalyzed C7-Alkylation of Isatogens with Malonic Acid Diazoesters

Rh(III)-catalyzed C7-alkylation of isatogens (indolin-3-one N-oxides) with malonic acid diazoesters has been developed. This strategy utilizes oxygen anion on the N-oxide group of isatogens as a directing group and successfully achieves the synthesis of a series of C7-alkylated isatogens with moderate to good yields (48-86% yields). Moreover, the N-oxides of isatogens can not only serve as the simple directing group for C7-H bond cleavage but also be deoxidized for easy removal.

Synthesis of diarylmethyl thioethers via a DABCO-catalyzed 1,6-conjugate addition reaction of p-quinone methides with organosulfur reagents

A rapid and simple method was developed for the synthesis of diarylmethyl thioethers via a DABCO-catalyzed 1,6-conjugate addition reaction of para-quinone methides (p-QMs) with organosulfur reagents. A series of diarylmethyl thioethers were synthesized at 13-85% yields by this method. After that, the antibacterial activities of synthesized diarylmethyl thioethers and their derivatives were evaluated. The MIC range (μg mL^-1) against Staphylococcus aureus ATCC 25923 and clinically isolated methicillin-resistant S. aureus was 8-128 and 64-128, respectively.

Synthesis and antibacterial activity studies in vitro of indirubin-3'-monoximes

Multi-drug-resistant microbial pathogens are a serious global health problem. New compounds with antibacterial activity serve as good candidates for developing novel antibacterial drugs which is very urgent and important. In this work, based on the unique scaffold of indirubin, an active ingredient of traditional Chinese medicine formulation Danggui Luhui Wan, we synthesized 29 indirubin-3'-monoximes and preliminarily evaluated their antibacterial activities. The antibacterial activity results demonstrated that the synthesized indirubin-3'-monoximes 5a-5z and 5aa-5ad displayed good potency against S. aureus ATCC25923 (MIC = 0.4-25.6 μg mL-1). Among them, we found that the 5-F, 5-Cl and 7-CF3 substituted indirubin-3'-monoximes 5r, 5s and 5aa also showed better antibacterial efficiency for S. aureus (MICs up to 0.4 μg mL-1) than the prototype natural product indirubin (MIC = 32 μg mL-1). More importantly, indirubin-3'-monoxime 5aa has certain synergistic effect with levofloxacin against clinic multidrug-resistant S. aureus (fractional inhibitory concentration index: 0.375). In addition, relevant experiments including electron microscopy observations, PI staining and the leakage of extracellular potassium ions and nucleic acid (260 nm) have been performed after treating S. aureus with indirubin-3'-monoxime 5aa, and the results revealed that indirubin-3'-monoximes could increase the cell membrane permeability of S. aureus. Although indirubin-3'-monoxime 5aa showed some cytotoxicity toward SH-SY5Y cells relative to compounds 5r and 5s, the skin irritation test of male mice after shaving showed that compound 5aa at a concentration of 12.8 μg mL-1 had no toxicity to mouse skin, and it could be used as a leading compound for skin antibacterial drugs.

Palladium-catalyzed direct C(sp3)–H arylation of indole-3-ones with aryl halides: a novel and efficient method for the synthesis of nucleophilic 2-monoarylated indole-3-ones

A novel and efficient method for the synthesis of nucleophilic 2-monoarylated indole-3-ones via palladium-catalyzed direct C(sp³)–H arylation of indole-3-ones with aryl halides has been developed.

The distribution of different virulence grass carp reovirus strains in some neglected tissues

Grass carp reovirus (GCRV) is the causative agent of hemorrhagic disease in infected grass carp. During an outbreak, a mortality rate of up to 85% can be experienced, thus leading to substantial economic losses. The current understanding of disease pathogenesis is limited, with the distribution and dynamics of replication amongst different GCRV strains in vivo largely unknown. We determined distribution of different GCRV strains in infected grass carp, especially in some neglected tissues, such as the gill, brain, blood and so on. The results showed elevated viral RNA copy numbers in the blood, with some tissues such as the kidney, heart, brain, and bladder exhibiting even higher viral loads following infection with the virulent GCRV-CL strain. Even more interesting is that the brain exhibited the highest viral load, with a copy number of 800,000 following GCRV-CL infection. Overall, this study provides further insight into GCRV viral load distributions following infection and potentially identified some new viral tropism sites to provide a foundation for further studies aimed at characterizing GCRV viral pathogenesis.

Synthesis, anti-HBV activity and renal cell toxicity evaluation of mixed phosphonate prodrugs of adefovir

A series of phosphonate ester prodrugs of adefovir incorporating l-amino (thio)acid and non-steroidal anti-inflammatory drug (NSAID) moieties were synthesized and their anti-HBV activity and renal cell toxicity were evaluated in HepG2 2.2.15 and HK-2 cells respectively. Bioactivity evaluation results revealed that this kind of adefovir prodrug have lower renal cell toxicity than adefovir dipivoxil. Compounds 8a and 8b, incorporating the NSAID ketoprofen and the l-amino acid (Val or Ile) structural fragments, exhibited more potent anti-HBV activity than adefovir dipivoxil with IC(50) = 0.51 and 0.73 μM, SI = 1697.64 and 881.92 respectively. In vitro stability studies showed that the synthesized prodrugs have higher chemical and plasma stability than the positive control adefovir dipivoxil.

Rapid screening and identification of caffeic acid and its esters in Erigeron breviscapus by ultra-performance liquid chromatography/tandem mass spectrometry

Caffeic acid and its esters (CAEs) are widely distributed in the plant kingdom and have been reported to elicit a wide range of exceptional biological activities. Present methods for screening and characterization of CAEs normally need the use of liquid chromatography diode-array detection/multistage mass spectrometry (LC-DAD/MS(n)). In this report, a rapid and efficient method coupling ultra-performance liquid chromatography (UPLC) with fragment-targeted multi-reaction monitoring (MRM) has been developed for screening CAEs in a crude extract of Erigeron breviscapus, while a UPLC/quasi-MS(n) method has been applied in the structural identification of these compounds. Furthermore, a simple quasi-UPLC/MS/MS method based on in-source collision-induced dissociation (CID) has been proposed for rapid identification of the CAEs. As a result, a total of more than 34 CAEs were detected and their structures characterized. Nine of them were reported from E. breviscapus for the first time. Applications of these strategies in the chemical investigation of an injection of E. breviscapus resulted in the identifications of 16 CAEs. These strategies, if appropriate modifications are made, will be very useful in screening and characterization not only of CAEs, but of other structural types of compounds in various complex matrices.

N-doped SiO2/TiO2 mesoporous nanoparticles with enhanced photocatalytic activity under visible-light irradiation

Mesoporous nanocrystalline N-doped SiO2/TiO2 visible-light photocatalysts were prepared by treating SiO2/TiO2 xerogels in a flow of nitrogen gas bubbled through concentrated ammonia solution. Structural characterization and performance analysis results revealed that the addition of SiO2 remarkably altered the phase composition, specific surface area, microstructure, as well as the photocatalytic activity of N-doped TiO2. The presence of SiO2 in N-doped TiO2 particles suppressed the formation of rutile phase and the crystal growth of N-doped TiO2 particles during thermal calcinations. When weight ratio of SiO2/TiO2 was in 0.05-0.20, the N-doped SiO2/TiO2 exhibited higher photocatalytic activity than the N-doped TiO2, and optimum ratio was found to be 0.05. The enhanced photocatalytic activity could be attributed to the higher specific area, larger pore volume, and more surface hydroxyl groups in the catalyst.

[Design, synthesis and anti-HBV activity of L-amino acid ester prodrugs of acyclic nucleoside phosphonates]

To design and synthesis a series of novel L-amino acid esters prodrugs of acyclic nucleoside phosphonates with more potent anti-HBV activity, adefovir dipivoxil was used as lead compound, according to the results of enhanced oral bioavailability and antiviral activities of nucleoside L-amino acid ester prodrugs. Eleven novel L-amino acid ester prodrugs of acyclic nucleoside phosphonates were designed and synthesized, their anti-HBV activities were evaluated in HepG2 2.2.15 cells. Eight compounds exhibited antiviral activity, and compound 11 showed the most potent anti-HBV activity and highest selective index in vitro (EC50 0.0952 micromol x L(-1), SI 69523). Moreover, by analyzing the primary structure and activity relationship of these compounds, it could be suggested that L-amino acid ester strategy has significant potential in the acyclic nucleoside phosphonates prodrug design.

A rule-based approach for RNA pseudoknot prediction

RNA plays a critical role in mediating every step of cellular information transfer from genes to functional proteins. Pseudoknots are functionally important and widely occurring structural motifs found in all types of RNA. Therefore predicting their structures is an important problem. In this paper, we present a new RNA pseudoknot structure prediction method based on term rewriting. The method is implemented using the Mfold RNA/DNA folding package and the term rewriting language Maude. In our method, RNA structures are treated as terms and rules are discovered for predicting pseudoknots. Our method was tested on 211 pseudoknots in PseudoBase and achieves an average accuracy of 74.085% compared to the experimentally determined structure. In fact, most pseudoknots discovered by our method achieve an accuracy of above 90%. These results indicate that term rewriting has a broad potential in RNA applications ranging from prediction of pseudoknots to discovery of higher level RNA structures involving complex RNA tertiary interactions.

[Experimental safety study using rats and mice irradiated with the complex field cure instrument]

The complex field cure instrument is a new medical instrument. The complex field is composed of several sorts of physical quantum fields. Mice and rats are continuously irradiated by the complex field for 20 days to 90 days. The result shows that WBC, Hb and PLT value of the animals irradiated with the instrument are more than the control group, and their biochemical index is normal. The internal organs of the experimental animals show no toxicity. The visceval coefficient (liver, spleen) of the experimental animals is more than the control group. The marrow micronucleas test is negative. The chromosome test show no distortion. All of the results have proved that the instrument produces no toxicity side effect. Application of the instrument is safe and reliable and it may increase immune function of the body.

A study on the ecological habit of Armigeres subalbatus in Dawa area of the Mengshan Mountain in Shandong Province

Armigeres subalbatus (A.s.) was reported in Shandong Province for the first time in 1965 and found in five counties of south Shandong including Pingyi, Linyi etc. in 1986. In Dawa area of the Mengshan mountain A.s. alults could be found in the first ten days of May, which increased in number in July, and become the dominant species in mosquito colonies in Aug. and Sept., then decreased gradually in number in Oct. and disappeared in Nov. There were two peaks of activity and blood-sucking behavior during the 24 hours of a day, one at dusk and the other at dawn. When the temperature dropped to 16 degrees C and below in the last ten days of Oct., the wigglers began their diapause period. The survival ratio reached 90.5% after 12 h freezing at -5 degrees C and none survived after 60 hours freezing. When the temperature rose to 17 degrees C and above the over-winterting larvae developed into adults, which could suck blood only at the temperature above 17.5 degrees C.