Sujing Liu

The Pd-catalyzed hydrodechlorination of chlorophenols in aqueous solutions under mild conditions: A promising approach to practical use in wastewater

Catalytic hydrotreating of chlorophenols was carried out in water with Pd/C at 25 degrees C under atmospheric pressure. 1.0% (w/w) monocholophenols was completely dechlorinated within 60 min. Phenol, cyclohexanone and cyclohexanol were formed. In contrast to the dechlorination of monochlorophenols, the hydrogenation reaction of polychlorinated phenols became difficult and reaction rates were strongly dependent upon the number of the chlorine atoms. The solvent property had a considerably important influence on the dechlorination reaction. Water as a solvent showed more advantages than organic solvents. It was much easier to be hydrodechlorinated for chlorophenols in aqueous solutions. However, the presence of THF, dioxane, DMSO or DMF in water was disadvantageous to the reaction and easily to cause Pd/C deactivation. Additionally, when different halogenated organic compounds were present in aqueous solution, the dehalogenation reaction was the competitive hydrogenation process.

Purification of quercetin-3-O-sophoroside and isoquercitrin from Poacynum hendersonii leaves using macroporous resins followed by Sephadex LH-20 column chromatography

In China, Poacynum hendersonii is frequently used as a substitute for Apoacynum venetum L (Luobuma), which is a famous traditional Chinese medicine. Quercetin-3-O-sophoroside and isoquercitrin are two major flavonoids in Poacynum hendersonii leaves. In this work, a suitable method was established for the large-scale preparation of quercetin-3-O-sophoroside (QOS) and isoquercitrin (ISO) from Poacynum hendersonii leaves using macroporous resin combined with Sephadex LH-20 column chromatography. The adsorption/desorption capacities and desorption ratios of six macroporous resins were evaluated using static experiments. The HPD-300 resin had the best adsorption performance because it had the largest surface area, and was selected for further study. Compared with pseudo-first-order and intraparticle diffusion kinetics models, the pseudo-second-order model could better fit the adsorption kinetics of both QOS and ISO on the HPD-300 resin. In addition, the adsorption isotherms of the two compounds on the HPD-300 resin were fitted well to the Langmuir model. Under optimal conditions, the purities of QOS and ISO in the product were increased from 2.16% and 1.26% to 21.34% and 10.70% with recovery yields of 82.1% and 77.3%, respectively. Subsequently, Sephadex LH-20 column chromatography was employed for improving the purities of the two compounds. After separation by Sephadex LH-20 column chromatography, the purities of QOS and ISO achieved 93.5% and 95.6%, respectively.

Ecotoxicity and Preliminary Risk Assessment of Nonivamide as a Promising Marine Antifoulant

The unclear environmental performance of nonivamide limits its application as a marine antifoulant. In this study, the natural degradation of nonivamide was studied in seawater and tap water. The half-life was 5.8 d, 8.8 d, 12.2 d, and 14.7 d in seawater and tap water in photolysis and biolysis, respectively. Furthermore, the ecotoxicity of nonivamide was assessed using marine microalgae, Chlorella vulgaris and Platymonas sp.; values on the growth of Chlorella vulgaris and Platymonas sp. were 16.9 mg L−1 and 19.21 mg L−1, respectively. The toxicity and environmental risk of nonivamide on microalgae were significantly decreased due to the natural degradation in seawater.

A new minor diketopiperazine from the sponge-derived fungus Simplicillium sp. YZ-11

Chemical investigation of the cultures of a sponge-derived fungus Simplicillium sp. YZ-11 led to the isolation of a new minor diketopiperazine alkaloid cyclo-(2-hydroxy-Pro-Gly) (1) and a natural lactone (S)-dihydro-5-[(S)- hydroxyphenylmethyl]-2(3H)-furanone (2), together with five known ergostane-type sterols (3–7). Their structures were established based on extensive spectroscopic methods (1H and 13C NMR, 1H-1H COSY, HSQC and HMBC) and optical rotation analysis.

Metal fluoride promoted catalytic hydrogenation of aromatic nitro compounds over RANEY® Ni

The catalytic hydrogenation reactivity of aromatic nitro compounds over RANEY (R) Ni was substantially improved when a moderate amount of metal fluoride (NaF, KF, MgF2, and CaF2) was added into the reaction system.

Seasonal variations in fouling diatom communities on the Yantai coast

Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

Toxic effects of environment‐friendly antifoulant nonivamide on Phaeodactylum tricornutum

Nonivamide, a synthetic derivate of natural capsaicin, has an effective antifouling activity. However, the poor understanding of the toxicity mechanism limits the application of nonivamide in antifouling paints. The present study investigated the inhibitory effects and toxicity mechanism of nonivamide on Phaeodactylum tricornutum. Under a 1.5 × 10(5) cells/ml of initial algal density (IAD), the effective concentration causing 50% inhibition at 4- d (4 d-EC50) value of nonivamide was 5.1 mg/L. Reactive oxygen species (ROS) level was significantly increased in nonivamide-treated algae. Algal antioxidants, including catalases (CAT), peroxidases (POD), superoxide dismutases (SOD), and glutathione (GSH), were all stimulated by the ROS burst. The excessive ROS substances led to the loss of algal photosynthetic pigments and also damage to the integrity of the lipid membrane. Furthermore, ROS-related genes, including psbA, psbD, psaB, rbcL, nad1, and cob, were found to be suppressed in the chloroplasts and mitochondria of nonivamide-treated algae, and the concentration of cytoplasmic Ca(2+) , an important regulator of chloroplast and mitochondrion, was elevated. The present study demonstrates that nonivamide could cause peroxidative damages to P. tricornutum by inducing ROS overproduction, which may be initiated by the suppression of ROS-related genes in algal chloroplasts and mitochondria.

Chemical constituents and their bioactivities from the fruits of Vitex negundo var. cannabifolia

Abstract Phytochemical investigation of the fruits of Vitex negundo var. cannabifolia led to the isolation of 22 compounds (1–22). Their structures were elucidated mainly by spectroscopic analysis and comparison with the literature data. Among them, compounds 1 and 2 were two new artificial lignans. Primary bioassay showed that the polymethoxyflavones 9–12 displayed moderate-to-weak cytotoxicity against human HepG2 and rat C6 cell lines, while the triterpenoids 13–17 exhibited significant brine shrimp lethality with LC50values of 7.5–29.4 μM.

Remediation of DDTr contaminated soil by the combination of solvent extraction and catalytic hydrodechlorination

A combination technique for remediation of DDT and its metabolites (DDTr) contaminated soil based on successive steps of solvent extraction, followed by catalytic hydrodechlorination (HDC) was studied. Firstly, solvent extraction was applied to extract DDTr contaminated soil at ambient temperature and pressure. According to GC-MS analysis, the extracts from DDTr contaminated soil are mainly composed of p,p′-DDT, o,p′DDT, p,p′-DDE, o,p′-DDE, p,p′-DDD, and DCBP. Subsequently, catalytic HDH over a Pd/C catalyst was introduced to treat the extract from DDTr contaminated soil, and the HDC process of DDTr was surveyed by monitoring the GC-MS analysis. These results demonstrate that the combined technique of solvent extraction and catalytic HDC can effectively remediate DDTr contaminated soil and reduce its toxicity.

The influence of bacterial quorum-sensing inhibitors against the formation of the diatom-biofilm

ABSTRACT Quorum-sensing inhibitor (QSI) is one of the most promising and environmentally friendly agents for marine antifouling. In this study, the activities of three kinds of QSIs 3,4-dibromo-2(5)H-furanone, 4-nitropyridine-N-oxide and indole were evaluated on the growth of two marine diatoms Cylinthrotheca sp. and Nitzschia closterium. At the same time, the effects of QSIs on the formation of the diatom-biofilm were also discussed. All the results showed that QSIs significantly inhibited the growth, and the effects depended on the dose and diatom species. The extracellular polymeric substance contents in the diatom-biofilm were significantly reduced by QSIs. However, the contents of polysaccharide in culture mediums were increased, which might result in the destruction of diatom cells. Combined with the results of crystal violet staining-biofilm and images of scanning electron microscopy, it was further demonstrated that QSIs inhibited the biofilm formation of Cylindrotheca sp., and the inhibitory effect of 4-nitropyridine-N-oxide was superior to that of 3,4-dibromo-2(5)H-furanone and indole.