Palladium Supported on Porous Organic Polymer as Heterogeneous and Recyclable Catalyst for Cross Coupling Reaction.

Palladium immobilized on an amide and ether functionalized porous organic polymer (Pd@AEPOP) is reported to be an effective heterogeneous catalyst for the Heck cross-coupling reaction of aryl iodides with styrene for the synthesis of diphenylethene derivatives. Excellent yields can be obtained using a 0.8 mol% Pd catalyst loading under the optimized reaction condition. The heterogeneous Pd@AEPOP catalyst can also be applied on the Suzuki reaction and the reduction of nitroarene.

Effects of drying methods on the nutritional aspects, flavor, and processing properties of Chinese chestnuts.

To select a suitable drying process for using chestnut products in the food industry, this study investigated the effect of five drying methods, including natural drying, microwave drying (MD), hot air drying (HAD), freeze-vacuum drying (FVD) and microwave-vacuum drying (MVD) on the nutritional composition, flavor, and functional properties of dried chestnuts. The results indicated that the nutritional aspects and functional properties of chestnuts were enhanced by the freeze-drying process compared with the other four drying methods. The quality of the chestnuts dried using the MVD was second to the FVD. The hot-air dried products were quite similar to the naturally dried samples in terms of their functional component content and processability. In terms of the produce texture, the HAD was found to be the best. In total, 45 flavor components were identified in the samples, which comprised the following: 5 aldehydes, 4 alcohols, 4 esters, 8 terpenes, 16 hydrocarbons and, 8 others substances. The highest relative content of the ingredients in microwave-vacuum dried samples was pyrazine and 3-ethyl-2, 5-dimethyl. In the samples treated using the other four drying methods, benzyl alcohol was the ingredient with the highest concentration. Considering the fast drying rate, low energy consumption, and improved quality of chestnut products, MVD is the most suitable dehydration method for commercial production of Chinese chestnuts.

Sensory properties of rehydrated Toona sinensis shoots after dehydrated by different drying methods and association with gamma-glutamyl transferase reaction.

Sulfur-containing compounds are responsible for the aroma of Toona sinensis shoot (TS). In this study, vacuum-freeze-drying (VFD), microwave-drying (MD), and hot-air-drying at 100 and 40 °C (HAD100 and HAD40, respectively), were applied to dehydrate perishable TS for preservation. VFD-TS retained most aroma of fresh/raw TS after rehydration. The content of sulfur-containing compounds reached to 118.00 µg/g with leading by methyl thiirane, (E,E)/(E,Z)/(Z,Z)-bis-(1-propenyl) disulfides, and (Z)/(E)-2-mercapto-3,4-dimethyl-2,3-dihydrothiophenes accounting for 86.33 %. They were undetected in the rehydrated MD-TS and HAD100-TS, as the indigenous enzymes in TS were deactivated under their dehydration conditions. Interestingly, the sulfur-containing compounds was restored by 77.47 % after the TS was treated by gamma-glutamyl transferase (GGT). Thus, the release of sulfur-containing compounds from TS could depend on GGT reaction. It was different from alliaceous vegetables relying on alliinase reaction. The results revealed the aroma formation in TS and provided an approach to enhance the aroma of TS dried by different methods.

Isolation, identification and characterization of a glyphosate-degrading bacterium, Bacillus cereus CB4, from soil.

A bacterial strain named CB4, with highly effective glyphosate degradation capability, was isolated from soil after enrichment. On the basis of the Biolog omniLog identification system (Biolog) and 16S ribosomal RNA (rRNA) gene sequencing methods, strain CB4 was identified as Bacillus cereus. Further experiments were carried out to optimize the growth of strain CB4 and the glyphosate degradation activity by high performance liquid chromatography (HPLC). The optimal conditions were found as follows: initial pH 6.0, incubation temperature 35°C, glyphosate concentration 6 g L(-1), inoculation amount 5% and incubation time 5 days. Under the optimal conditions, stain CB4 utilized 94.47% of glyphosate. This is the first report on B. cereus with a capacity to utilize herbicide glyphosate, and it can degrade glyphosate concentrations up to 12 g L(-1). Metabolization of glyphosate by strain B. cereus CB4 was studied. Results indicated that two concurrent pathways were capable of degrading glyphosate to AMPA, glyoxylate, sarcosine, glycine and formaldehyde as products. Glyphosate breakdown in B. cereus CB4 was achieved by the C-P lyase activity and the glyphosate oxidoreductase activity.

Synthesis and in vitro antifungal evaluation of 1,3,5-trisubstituted-2-pyrazoline derivatives.

Pyrazolines, the well-known five-membered nitrogen-containing heterocyclic compounds, have received considerable interests in the fields of medicinal and agricultural chemistry because of their broad spectrum of biological activities. To discover more potent antifungal compounds, a series of structurally related 1,3,5-trisubstituted-2-pyrazoline derivatives have been synthesized by introducing furan rings regarded as bioactive substructure into the scaffold of pyrazolines and tested for their activities against six plant pathogenic fungi in vitro. The preliminary bioassays indicated that almost all synthesized compounds had displayed variable growth inhibitory effects on the tested pathogenic fungi. In particular, compounds 4, 7, 9, 12, 18, 19, and 38 displayed excellent antifungal activities against Rhizoctonia solani and their inhibition of growth reached 100% at the concentration of 20 mg/L. Additionally, compounds 9 and 19 bearing two furan rings, respectively, at site 3 and site 5 of the pyrazoline cycle showed the strongest activities against R. solani (the EC(50) were 3.46 mg/L and 3.20 mg/L). The bioactivity results provide good starting templates for further structural optimization of pyrazoline derivatives.

Mutational biosynthesis of neomycin analogs by a mutant of neomycin-producing Streptomyces fradiae.

Neomycin, produced by Streptomyces fradiae, has been widely used for the treatment of bacterial infections in clinical and agricultural applications. In this study, a neomycin nonproducing mutant of S. fradiae was obtained by gene disruption technique for mutational biosynthesis. A crucial gene neoC (neo7) which encodes 2-deoxystreptamine (2-DOS) synthases was disrupted. The mutant could resume producing neomycin in the presence of 2-DOS. Salen derivatives of 2-DOS were synthesized and individually added to cultures of the mutant. Antibacterial activity of the mutasynthesis products against Staphylococcus aureus and four plant pathogenic bacteria (Pseudomonas solanacarum, Erwinia carotovora, Xanthomonas oryzae, and Xanthomonas campestris) was detected quantitatively by Oxford cup method. It is suggested that all 2-DOS derivatives were incorporated by the mutant into new active neomycin analogs except for 2-DOS derivative 2d ((1R,2r,3S,4R,6S)-4,6-bis((E)-3,5-di-tert-butyl-2-hydroxybenzylideneamino)cyclohexane-1,2,3-triol). Neomycin analogs produced by feeding 2-DOS derivative 2a ((1R,2r,3S,4R,6S)-4,6-bis((E)-2 hydroxybenzylideneamino)cyclohexane-1,2,3-triol) to cultures of the mutant displayed a similar antibacterial activity with neomycin produced by wild strain.

Design, synthesis and in vitro antibacterial/antifungal evaluation of novel 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7(1-piperazinyl)quinoline-3-carboxylic acid derivatives.

A series of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7(1-piperazinyl)quinoline-3-carboxylic acid (norfloxacin) derivatives were prepared according to the principle of combinating bioactive substructures and tested for their activities against five plant pathogenic bacteria and three fungi in vitro. The preliminary bioassays indicated that almost all synthesized target compounds retained the antibacterial activities of norfloxacin and had some antifungal activities as carboxylic acid amide compounds. The activities of compounds 1 and 22 against Xanthomonas oryzae were better than norfloxacin and all tested compounds had better antibacterial activities as compared to the agricultural streptomycin sulfate (a commercial bactericide) against X. oryzae, Xanthomonas axonopodis and Erwinia aroideae. Additionally, compounds 2 and 20 displayed good antifungal activities against Rhizoctonia solani and their inhibition of growth reached 83% and 94% respectively at the concentration of 200mg/L.

Cloning, expression, and purification of insecticidal protein Pr596 from locust pathogen Serratia marcescens HR-3.

A novel insecticidal protein (Pr596) produced by Serratia marcescens HR-3 was found be a metalloprotease and responsible for insecticidal activity toward locusts. Two pairs of primers were designed to amplify Pr596, a putative open reading frame (ORF) by similarity search and the N-terminal amino-acid sequence of insecticidal protein. The results revealed that the ORF consisted of 1464 nucleotides encoding a protein of 487 amino-acid residues. Pr596 was cloned into expression vector pET32a(+) and was expressed in Escherichia coli BL21 (DE3)/pLysS strain with isopropyl-beta-D-thiogalactopyranoside induction. The Pr596 was found to be highly expressed as inclusion bodies by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Pr596 inclusion bodies were isolated and subjected to Ni-NTA His Bind Resins (Pharmacia, Germany). Pr596 purified and refolded was revealed by SDS-PAGE and had proteolytic activity and insecticidal activity. Results suggested that there is a potential to develop this protein to be used as an alternative locus control agent.