Approaches to Configuration Determinations of Flexible Marine Natural Products: Advances and Prospects.

Flexible marine natural products (MNPs), such as eribulin and bryostatin, play an important role in the development of modern marine drugs. However, due to the multiple chiral centers and geometrical uncertainty of flexible systems, configuration determinations of flexible MNPs face great challenges, which, in turn, have led to obstacles in druggability research. To resolve this issue, the comprehensive use of multiple methods is necessary. Additionally, configuration assignment methods, such as X-ray single-crystal diffraction (crystalline derivatives, crystallization chaperones, and crystalline sponges), NMR-based methods (JBCA and Mosher's method), circular dichroism-based methods (ECCD and ICD), quantum computational chemistry-based methods (NMR calculations, ECD calculations, and VCD calculations), and chemical transformation-based methods should be summarized. This paper reviews the basic principles, characteristics, and applicability of the methods mentioned above as well as application examples to broaden the research and applications of these methods and to provide a reference for the configuration determinations of flexible MNPs.

Discovery of Bioactive Indole-Diketopiperazines from the Marine-Derived Fungus Penicillium brasilianum Aided by Genomic Information.

Identification and analysis of the whole genome of the marine-derived fungus Penicillium brasilianum HBU-136 revealed the presence of an interesting biosynthetic gene cluster (BGC) for non-ribosomal peptide synthetases (NRPS), highly homologous to the BGCs of indole-diketopiperazine derivatives. With the aid of genomic analysis, eight indole-diketopiperazines (1-8), including three new compounds, spirotryprostatin G (1), and cyclotryprostatins F and G (2 and 3), were obtained by large-scale cultivation of the fungal strain HBU-136 using rice medium with 1.0% MgCl2. The absolute configurations of 1-3 were determined by comparison of their experimental electronic circular dichroism (ECD) with calculated ECD spectra. Selective cytotoxicities were observed for compounds 1 and 4 against HL-60 cell line with the IC50 values of 6.0 and 7.9 µM, respectively, whereas 2, 3, and 5 against MCF-7 cell line with the IC50 values of 7.6, 10.8, and 5.1 µM, respectively.

Aspergixanthones I⁻K, New Anti-Vibrio Prenylxanthones from the Marine-Derived Fungus Aspergillus sp. ZA-01.

Marine-derived fungi are a rich source of structurally diverse metabolites. Fungi produce an array of compounds when grown under different cultivation conditions. In the present work, different media were used to cultivate the fungus Aspergillus sp. ZA-01, which was previously studied for the production of bioactive compounds, and three new prenylxanthone derivatives, aspergixanthones I⁻K (1⁻3), and four known analogues (4⁻7) were obtained. The absolute configuration of 1 was assigned by ECD experiment and the Mo2(AcO)4 ICD spectrum of its methanolysis derivative (1a). All the compounds (1⁻7) were evaluated for their anti-Vibrio activities. Aspergixanthone I (1) showed the strongest anti-Vibrio activity against Vibrio parahemolyticus (MIC = 1.56 µM), Vibrio anguillarum (MIC = 1.56 µM), and Vibrio alginolyticus (MIC = 3.12 µM).

Cytotoxic and Antiviral Triterpenoids from the Mangrove Plant Sonneratia paracaseolaris.

A chemical investigation was conducted on the aerial parts of the mangrove plant Sonneratia paracaseolaris, yielding five new triterpenoid paracaseolins A-E (1-4, and 11) together with twelve known analogues (5-10, 12-17). Their structures were established by extensive spectroscopic methods and comparisons their spectroscopic data with those of the known related compounds. The cytotoxicities against P388, HeLa, A549, and K562 tumor cell lines and anti-H1N1 (Influenza A virus) activities for the isolates were evaluated. Compound 4 showed potent cytotoxicity against the A549 cell line with an IC50 value of 1.89 µM, and compound 1 exhibited significant anti-H1N1 virus activity with an IC50 value of 28.4 µg/mL. A preliminary structure activity relationship was discussed.

Characteristic Steroids from the South China Sea Gorgonian Muricella sibogae and Their Cytotoxicities.

Twenty-four steroid-based natural products, 9,10-secosteroids (1-10), 1,4-dien-3-one steroids (11-19), and 4-en-3-one steroids (20-24), containing varying side-chains, were isolated from the South China Sea gorgonian Muricella sibogae. The structures of one new 9,10-secosteroid, sibogol D (1), and two new 1,4-dien-3-one steroids, sibogols E and F (11 and 12), were elucidated by extensive spectroscopic analyses and by comparison with the literature data. Cytotoxicities for all the isolates were evaluated against four selected tumor cell lines, HL-60, HCT116, K562, and P388. Compounds 3, 9, and 13 exhibited potent cytotoxic activities against the HL-60 cell line, with IC50 values ranging from 1.27 to 10.05 µM, and compound 3 was also cytotoxic against HCT116 with an IC50 value of 5.8 µM. The bioassay results also indicated a potential relationship between structural patterns and activity. The newly presented series of 1,4-dien-3-one and 4-en-3-one types of steroids relating to the unique 9,10-secosteroids in biogenesis were found in this species for the first time, which is of considerable chemotaxonomic significance.

Polyhydroxylated steroids from the South China Sea soft coral Sarcophyton sp. and their cytotoxic and antiviral activities.

Chemical investigation on the soft coral Sarcophyton sp. collected from the South China Sea yielded three new polyhydroxylated steroids, compounds (1-3), together with seven known ones (4-10). Their structures were established by extensive spectroscopic methods and comparison of their data with those of the related known compounds. All the isolates possessed the 3ß,5α,6ß-trihydroxylated steroidal nucleus. The cytotoxicities against selected HL-60, HeLa and K562 tumor cell lines and anti-H1N1 (Influenza A virus (IAV)) activities for the isolates were evaluated. Compounds 2, 3 and 5-8 exhibited potent activities against K562 cell lines with IC50 values ranging from 6.4 to 10.3 µM. Compounds 1, 6-8 potently inhibited the growth of HL-60 tumor cell lines, and 6 also showed cytotoxicity towards HeLa cell lines. In addition, preliminary structure-activity relationships for the isolates are discussed. The OAc group at C-11 is proposed to be an important pharmacophore for their cytotoxicities in the 3ß,5α,6ß-triol steroids. Compounds 4 and 9 exhibited significant anti-H1N1 IAV activity with IC50 values of 19.6 and 36.7 µg/mL, respectively.

Computational and Experimental Approaches to Decipher the Binding Mechanism of General Odorant-Binding Protein 2 from Athetis lepigone to Chlorpyrifos and Phoxim.

Insect resistance to insecticides is an increasingly serious problem, and the resistant mechanisms are complicated. The resistance research based on the chemosensory pathway is one of the hot problems at present, but the specific binding mechanism of chemosensory genes and insecticides remains elusive. The binding mechanism of AlepGOBP2 (belong to insect chemosensory gene) with two insecticides was investigated by computational and experimental approaches. Our calculation results indicated that four key residues (Phe12, Ile52, Ile94, and Phe118) could steadily interact with these two insecticides and be assigned as hotspot sites responsible for their binding affinities. The significant alkyl-π and hydrophobic interactions involved by these four hotspot residues were found to be the driving forces for their binding affinities, especially for two residues (Phe12 and Ile94) that significantly contribute to the binding of chlorpyrifos, which were also validated by our binding assay results. Furthermore, we also found that the AlepGOBP2-chlorpyrifos/phoxim complexes can be more efficiently converged in the residue-specific force field-(RSFF2C) and its higher accuracy and repeatability in protein dynamics simulation, per-residue free energy decomposition, and computational alanine scanning calculations have also been achieved in this paper. These findings provided useful insights for efficient and reliable calculation of the binding mechanism of relevant AlepGOBPs with other insecticides, facilitating to develop new and efficient insecticides targeting the key sites of AlepGOBP2.

[Determining the content of trace element in Potentilla parvifolia Fisch at different altitudes].

Determining the content of Ca, Fe, Mn, Zn, Cu and Mg in Potentilla parvifolia Fisch by atomic absorption spectrometry was studied. Recovery and RSD of the method is 98.3%-103.2% and 1.21%-3.01% respectively, and the method is rapid and precise. The order of the content in Potentilla parvifolia Fisch is Mg>Ca>Fe>Mn>Zn>Cu. There is not a relation between altitude and content. The mean of the content of Mg, Ca and Fe is 5079.641, 2760.188 and 1070.297 mg * kg(-1) respectively. The result of Potentilla parvifolia Fisch can provide theoretical basis for medicine research.

Identification of poliumoside metabolites in rat plasma, urine, bile, and intestinal bacteria with UPLC/Q-TOF-MS.

Poliumoside is representative of phenylethanoid glycosides, which are widely found in many plants. Poliumoside is also regarded as the main active component of Callicarpa kwangtungensis Chun (CK), though its oral bioavailability in rat is extremely low (0.69%) and its in vivo and in vitro metabolism has not yet been systematically investigated. In the present study, an ultra performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) method was employed to identify the metabolites and investigate the metabolic pathways of poliumoside in rat after oral administration 1.5 g·kg-1 of poliumoside. As a result, a total of 34 metabolites (30 from urine, 17 from plasma, and 4 from bile) and 9 possible metabolic pathways (rearrangment, reduction, hydration, hydrolyzation, dehydration, methylation, hydroxylation, acetylation, and sulfation) were proposed in vivo. The main metabolite, acteoside, was quantified after incubated with rat intestinal bacteria in vitro. In conclusion, the present study systematically explored the metabolites of poliumoside in vivo and in vitro, proposing metabolic pathways that may be significant for further metabolic studies of poliumoside.

Effects of miR-338 on morphine tolerance by targeting CXCR4 in a rat model of bone cancer pain.

The present study aimed to investigate the effects of miR-338 on morphine tolerance through the targeting of CXC chemokine receptor-4 (CXCR4) in a rat model of bone cancer pain (BCP). Sprague-Dawley (SD) rats were obtained and divided into model saline (n=10), model morphine (n=50), normal saline (n=10) and normal morphine (healthy rats, n=10) groups. After BCP rat model establishment, the remaining SD rats (n=40) in the model saline group were assigned into pLV-THM-miR-338, pLV-THM-anti-miR-338, CXCR4 shRNA, blank and PBS groups. Luciferase reporter gene assay was used for luciferase activity. Quantitative real-time PCR (qRT-PCR) and Western blotting were performed to detect the miR-338 and CXCR4 mRNA and protein expression. The model saline group showed increased mRNA and protein expressions of CXCR4 but decreased miR-338 compared with the model saline group, and the model morphine group had increased mRNA and protein expressions of CXCR4 but decreased miR-338 compared with the model saline group. The mRNA and protein expressions of miR-338 in the pLV-THM-miR-338 group increased remarkably while those of the pLV-THM-anti-miR-338 group decreased significantly compared with the CXCR4 shRNA, blank and PBS groups. The pLV-THM-miR-338, pLV-THM-anti-miR-338, CXCR4 shRNA and CXCR4 mRNA groups all had lower mRNA and protein expressions of CXCR4 than those in the blank and PBS groups. miR-338 exerts significant influence in the inhibition of morphine tolerance by suppressing CXCR4 in BCP.

[Construction and identification of recombinant adenovirus containing the polyproteins coding regions of O type foot-and-mouth disease virus by homologous recombination in Escherichia coli].

The gene coding for the polyprotein (PP) of foot-and-mouth disease virus (FMDV)was obtained by PCR from recombinant plasmid rpMD18-T/PP. The PCR product was digested with Xba I and Not I and inserted into the cloning site of the adenovirus shuttle vector pAdTrack-CMV, previously digested with the same enzymes. This recombinant shuttle plasmid was designated rpAd-CMV/PP. The recombinant adenovirus vector rpAd/PP was obtained by homologous recombination of plasmid rpAd-CMV/PP and adenovirus skeletal vector pAdeasy-1 in E. coli. Plasmid rpAd/PP was linearized by Pme I and transformed into 293 competent cells to pack the adenovirus using liposome mediated gene transfer method and, as a result, the recombinant adenovirus rAd/PP that contained the polyprotein coding gene was obtained. Obvious CPE could be observed under an inverted microscope, the green fluorescence protein expression can be detected under fluorescence microscope and the empty capsid of FMDV was observed under electron microscope. These results indicated that the recombinant adenovirus rAd/PP expressed the PP protein and that this protein could be assembled into the empty capsid of FMDV. The recombinant adenovirus obtained in this study can be used for further research for making FMDV recombinant adenovirus vaccine.

MicroRNA-93-5p may participate in the formation of morphine tolerance in bone cancer pain mouse model by targeting Smad5.

OBJECTIVE: In this study, we aim to find out the role of microRNA-93-5p (miR-93) and Smad5 in morphine tolerance in mouse models of bone cancer pain (BCP). RESULTS: At 7 days after injection of morphine, the PMWT showed no significant difference between the morphine model group and the saline model group (P < 0.05), suggesting that morphine tolerance had formed in the morphine model group. The morphine model group had higher miR-93 expression and lower Smad5 mRNA expression than the saline model group. Smad5 is a downstream target gene of miR-93. At 7, 9 and 14 days after injection of lentiviruses, the L/anti-miR-93 group had the lowest PMWTs, while the Smad5 shRNA group presented the highest PMWTs among these five groups (all P < 0.05). METHODS: We built mouse models of BCP and morphine tolerance and recorded 50% PMWT. After 6 days of modeling, we set saline control group, morphine control, saline model group and morphine model group (morphine tolerance emerged). We performed luciferase reporter gene assay to verify the relation between miR-93 and Smad5. After lentivirus transfection, the mice with morphine tolerance were assigned into L/anti-miR-93 group, Smad5 shRNA group, L/anti-miR-93 + Smad5 shRNA group, blank group and PBS control group. RT-qPCR, Western Blot assay and immumohistochemical staining were performed to observe the changes of miR-93 and Smad5. CONCLUSION: Up-regulation of miR-93 may contribute to the progression of morphine tolerance by targeting Smad5 in mouse model of BCP.

Synthesis of in-plane and stacked graphene/hexagonal boron nitride heterostructures by combining with ion beam sputtering deposition and chemical vapor deposition.

Graphene/hexagonal boron nitride (h-BN) heterostructures have attracted a great deal of attention in recent years due to their unique and complementary properties for use in a wide range of potential applications. However, it still remains a challenge to synthesize large-area high quality samples by a scalable growth method. In this work, we present the synthesis of both in-plane and stacked graphene/h-BN heterostructures on Cu foils by sequentially depositing h-BN via ion beam sputtering deposition (IBSD) and graphene with chemical vapor deposition (CVD). Due to a significant difference in the growth rate of graphene on h-BN and Cu, the in-plane graphene/h-BN heterostructures were rapidly formed on h-BN domain/Cu substrates. The large-area vertically stacked graphene/h-BN heterostructures were obtained by using the continuous h-BN film as a substrate. Furthermore, the well-designed sub-bilayered h-BN substrates provide direct evidence that the monolayered h-BN on Cu exhibits higher catalytic activity than the bilayered h-BN on Cu. The growth method applied here may have great potential in the scalable preparation of large-area high-quality graphene/h-BN heterostructures.

Two new eunicellin diterpenoids from the South China Sea gorgonian Muricella sibogae and their bioactivities.

A systematic re-study on gorgonian Muricella sibogae from South China Sea yielded 10 eunicellin-based diterpenoids including two new ones, sibogins C and D (1 and 2). Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR, IR and MS) and by comparison with data reported in literatures. All the isolates were tested for cytotoxic and antifouling activities. Compounds 3 and 5 showed significant antifouling activity against the green mussel Perna viridis, and especially 3 was suggested as a potent low-toxic antifouling agent with a large LC50/EC50 value of 18.6. This was the first report on the antifouling activity of the eunicellin-type diterpenoids against the green mussel.

Synthesis of TiO(2) supported on activated carbon by MOCVD: operation parameters study.

The metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalyst titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g x h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy E(a) of 51.09 kJ/mol. TiO(2) existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO(2) particles, which were mainly in the range of 10-20 nm.

[Predicting the impact of global warming on the geographical distribution pattern of Quercus variabilis in China].

The geographical distribution of Quercus variabilis in China with its climate characteristics was analyzed based on DIVA-GIS which was also used to estimate the response of future potential distribution to global warming by Bioclim and Domain models. Analysis results showed the geographical distribution of Q. variabilis could be divided into 7 subregions: Henduan Mountains, Yunnan-Guizhou Plateau, North China, East China, Liaodong-Shandong Peninsula, Taiwan Island, and Qinling-Daba Mountains. These subregions are across 7 temperature zones, 2 moisture regions and 17 climatic subregions, including 8 climate types. The modern abundance center of Q. variabilis is Qinling, Daba and Funiu mountains. The condition of mean annual temperature 7.5-19.8 degrees C annual precipitation 471-1511 mm, is suitable for Q. variabilis. Areas under the receiver operating characteristic curve (AUC values), of Domain and Boiclim models were 0.910, 0.779; the former predicted that the potential regions of high suitability for Q. variabilis are Qinling, Daba, Funiu, Tongbai, and Dabie mountains, eastern and western Yunnan-Guizhou Plateau, hills of southern Jiangsu and Anhui, part of the mountains in North China. Global warming might lead to the shrinking in suitable region and retreating from the south for Q. variabilis.

Controllable synthesis of ZnO nanostructures on the Si substrate by a hydrothermal route.

In this paper, controllable synthesis of various ZnO nanostructures was achieved via a simple and cost-effective hydrothermal process on the Si substrate. The morphology evolution of the ZnO nanostructures was well monitored by tuning hydrothermal growth parameters, such as the seed layer, solution concentration, reaction temperature, and surfactant. X-ray diffraction and photoluminescence measurements reveal that crystal quality and optical properties crucially depend on the morphology of the ZnO nanostructures. The ease of synthesis and convenience to tune morphology and optical properties bring this approach great potential for nanoscale applications.

[Emergent retention of organic liquid by modified bentonites: property and mechanism].

In this study, the property and mechanism of modified bentonites synthesized by long chain quaternary ammonium compounds which would be used in the emergent retention of typical organic liquid (benzene, chlorobenzene, nitrobenzene and diesel) were investigated and a pilot-scale simulation experiment was conducted. The unit retention capacity of modified bentonites for organic liquid (2.83-9.01 g x g(-1)) was much higher than that of conventional retention agents (0.28-1.17 g x g(-1)). The property and amount of the surfactants used and viscosity of organic liquid had a significant influence on the retention capacity of modified bentonites for the organic liquid, for example, the bentonites modified by cetyltrimethylammonium (CTMAB) with an adding quantity of 100% CEC showed the highest efficiency in the retention of organic liquid. In the simulation experiment, organic liquid could be retained effectively within 30 min by emergent retention device with modified bentonites and the retention efficiency might reach positively up to 90%. Results indicated that modifications using surfactants could enhance the hydrophobicity and interlayer space of the modified bentonites and make their retention capacities for organic liquid improved.

Plasmonic polymer tandem solar cell.

We demonstrated plasmonic effects in an inverted tandem polymer solar cell configuration by blending Au nanoparticles (NPs) into the interconnecting layer (ICL) that connects two subcells. Experimental results showed this plasmonic enhanced ICL improves both the top and bottom subcells' efficiency simultaneously by enhancing optical absorption. The presence of Au NPs did not cause electrical characteristics to degrade within the tandem cell. As a result, a 20% improvement of power conversion efficiency has been attained by the light concentration of Au NPs via plasmonic near-field enhancement. The simulated near-field distribution and experimental Raman scattering investigation support our results of plasmonic induced enhancement in solar cell performance. Our finding shows a great potential of incorporating the plasmonic effect with conventional device structure in achieving highly efficient polymer solar cells.

Relationship between serum erythropoietin levels and brain injury in preterm infants / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the relationship between the levels of erythropoietin (EPO) in serum and brain injury in preterm infants.</p><p><b>METHODS</b>Three hundred and four preterm infants (gestational age: 28-34 weeks) born between October 2014 and September 2015 were enrolled in this study. Brain injury was diagnosed using cerebral ultrasound and MRI. The levels of EPO, S100 protein, neuron-specific enolase (NSE) and myelin basic protein (MBP) in serum were detected using ELISA. To compare the incidence of brain injury in different serum EPO levels in preterm infants, and the relationship between brain injury and serum EPO levels was analyzed.</p><p><b>RESULTS</b>The incidence rate of brain injury in preterm infants was 41.1% (125/304). The incidence rate of brain injury in the low EPO level group was significantly higher than that in the middle-high EPO level groups (P<0.01). The serum levels of S100 protein, NSE, and MBP in the brain injury groups were significantly higher than in the control group (P<0.01). The serum EPO levels were negatively correlated with serum S100 protein concentration and NSE levels (P<0.05). According to the multiple logistic regression analysis, low gestational age, low birth weight, asphyxia, prolonged mechanical ventilation, anemia and low serum EPO levels were the risk factor for brain injury in preterm infants.</p><p><b>CONCLUSIONS</b>There is a higher incidence rate of brain injury in preterm infants with lower serum EPO levels. The serum EPO levels may be correlated with brain injury in preterm infants.</p>