Phenotypic investigation of 4-nitrophenylacetyl- and 4-nitro-1H-imidazoyl-based compounds as antileishmanial agents.

Cutaneous leishmaniasis (CL) is a spectrum of clinical manifestations characterized by severe skin ulcerations that leads to social stigma. There are limited treatment options for CL, and the available drugs are becoming less efficacious due to drug resistance. More efficacious and safer antileishmanial drugs are needed. In this study, the biological effect of seven synthetically accessible nitroaromatic compounds was evaluated in vitro against amastigotes of Leishmania amazonensis, followed by in vivo evaluation using mouse models of CL. Two compounds (6 and 7) were active against amastigotes in vitro [half-maximal effective concentration (EC50): 4.57 ± 0.08 and 9.19 ± 0.68 µm, respectively], with selectivity indexes >50, and the other compounds were not selective. In vivo, compounds 6 and 7 (10 mg kg−1, twice a day for 14 days) failed to reduce skin lesion sizes and parasite loads determined by light microscopy of lesion imprints and quantitative polymerase chain reaction. Nevertheless, the in vitro leishmanicidal efficacy sustained their use as templates for nitroimidazole-based antileishmanial drug discovery programmes focusing on analogues with more suitable properties.

Nopol-Based Quinoline Derivatives as Antiplasmodial Agents.

Malaria remains a significant cause of morbidity and mortality in Sub-Saharan Africa and South Asia. While clinical antimalarials are efficacious when administered according to local guidelines, resistance to every class of antimalarials is a persistent problem. There is a constant need for new antimalarial therapeutics that complement parasite control strategies to combat malaria, especially in the tropics. In this work, nopol-based quinoline derivatives were investigated for their inhibitory activity against Plasmodium falciparum, one of the parasites that cause malaria. The nopyl-quinolin-8-yl amides (2-4) were moderately active against the asexual blood stage of chloroquine-sensitive strain Pf3D7 but inactive against chloroquine-resistant strains PfK1 and PfNF54. The nopyl-quinolin-4-yl amides and nopyl-quinolin-4-yl-acetates analogs were generally less active on all three strains. Interesting, the presence of a chloro substituent at C7 of the quinoline ring of amide 8 resulted in sub-micromolar EC50 in the PfK1 strain. However, 8 was more than two orders of magnitude less active against Pf3D7 and PfNF54. Overall, the nopyl-quinolin-8-yl amides appear to share similar antimalarial profile (asexual blood-stage) with previously reported 8-aminoquinolines like primaquine. Future work will focus on investigating the moderately active and selective nopyl-quinolin-8-yl amides on the gametocyte or liver stages of Plasmodium falciparum and Plasmodium vivax.

In Vitro and In Vivo Evaluation of an Adamantyl-Based Phenyl Sulfonyl Acetamide against Cutaneous Leishmaniasis Models of Leishmania amazonensis.

Phenotypic assay against Leishmania amazonensisin vitro and in vivo led to identification of an adamantyl-based phenyl sulfonyl acetamide (compound 1) as a promising antileishmanial agent. Compound 1 inhibited the growth of intracellular forms of L. amazonensis (50% inhibitory concentration [IC50] = 4 µM) and exhibited low toxicity to host cells, with a selectivity index (SI) of >125. However, in a cutaneous leishmaniasis (CL) mouse model, compound 1 did not reduce lesions and parasite load when administered as monotherapy or when given simultaneously with a suboptimal dose of miltefosine.

A New One-Pot Fluorescence Derivatization Strategy for Highly Sensitive MicroRNA Analysis.

MicroRNAs (miRNAs) modulate the expression of over 30 % of mammalian genes during development and apoptosis, and abnormal expression of miRNAs may lead to a range of human pathologies. Therefore, analysis of miRNAs is valuable for disease diagnostics. In this work, a novel one-pot fluorescence derivatization strategy was developed for miRNA analysis. The mechanism of the derivatization reaction was explored by using instrumental methods, including liquid chromatography, fluorescence spectroscopy, and mass spectrometry. Highly fluorescent N6 -ethenoadenine (ϵ-adenine) was formed and detached from the miRNA sequence through the reaction of adenine in nucleic acids with 2-chloroacetaldehyde (CAA) at 100 °C. This is the first experimental evidence that the cooperation of formed ϵ-adenine and water-mediated hydrogen-bond interaction between the proton at the 2'- and the oxyanion at 3'-positions stabilized the oxocarbenium significantly, which makes the depurination and derivatization of miRNA highly effective. Based on this derivatization strategy, a facile and sensitive high-performance liquid chromatography method was developed for quantitative assay of miRNAs. In combination with magnetic solid-phase extraction (MSPE), the HPLC method was shown to be useful for the determination of microRNAs at sub-picomolar level in serum samples.

Vinyl sulfone-based inhibitors of trypanosomal cysteine protease rhodesain with improved antitrypanosomal activities.

The number of reported cases of Human African Trypanosmiasis (HAT), caused by kinetoplastid protozoan parasite Trypanosoma brucei, is declining in sub-Saharan Africa. Historically, such declines are generally followed by periods of higher incidence, and one of the lingering public health challenges of HAT is that its drug development pipeline is historically sparse. As a continuation of our work on new antitrypanosomal agents, we found that partially saturated quinoline-based vinyl sulfone compounds selectively inhibit the growth of T. brucei but displayed relatively weak inhibitory activity towards T. brucei's cysteine protease rhodesain. While two nitroaromatic analogues of the quinoline-based vinyl sulfone compounds displayed potent inhibition of T. brucei and rhodesain. The quinoline derivatives and the nitroaromatic-based compounds discovered in this work can serve as leads for ADME-based optimization and pre-clinical investigations.

Genetic-based dissection of arsenic accumulation in maize using a genome-wide association analysis method.

Understanding the mechanism of arsenic (As) accumulation in plants is important in reducing As's toxicity to plants and its potential risks to human health. Here, we performed a genome-wide association study to dissect the genetic basis of the As contents of different maize tissues in Xixian, which was irrigated with As-rich surface water, and Changge using an association population consisting of 230 representative maize inbred lines. Phenotypic data revealed a wide normal distribution and high repeatability for the As contents in maize tissues. The As concentrations in maize tissues followed the same trend in the two locations: kernels < axes < stems < bracts < leaves. In total, 15, 16 and 15 non-redundant quantitative trait loci (QTLs) associated with As concentrations were identified (P ≤ 2.04 × 10-6 ) in five tissues from Xixian, Changge, and the combination of the locations, respectively, explaining 9.70%-24.65% of the phenotypic variation for each QTL, on average. Additionally, four QTLs [involving 15 single nucleotide polymorphisms (SNPs)] were detected in the single and the combined locations, indicating that these loci/SNPs might be stable across different environments. The candidate genes associated with these four loci were predicted. In addition, four non-redundant QTLs (6 SNPs), including a QTL that was detected in multiple locations according to the genome-wide association study, were found to co-localize with four previously reported QTL intervals. These results are valuable to understand the genetic architecture of As mechanism in maize and facilitate the genetic improvement of varieties without As toxicity.

Discovery of a quinoline-based phenyl sulfone derivative as an antitrypanosomal agent.

A series of natural products-based phenyl sulfone derivative and their property-based analogues were investigated as potential growth inhibitors of Trypanosoma brucei. Trypanosoma brucei is a kinetoplastid protozoan parasite that causes trypanosomiasis. In this work, we found that nopol- and quinoline-based phenyl sulfone derivative were the most active and selective for T. brucei, and they were not reactive towards the active thiol of T. brucei's cysteine protease rhodesain. A thiol reactive variant of the quinoline-based phenyl sulfone was subsequently investigated and found to be a moderate inhibitor of rhodesain. The quinoline-based compound that is not reactive towards rhodesain can serve a template for phenotypic-based lead discovery while its thiol-active congener can serve as template for structure-based investigation of new antitrypanosomal agents.

Bauerenol Acetate, the Pentacyclic Triterpenoid from Tabernaemontana longipes, is an Antitrypanosomal Agent.

The Latin American plant Tabernaemontana longipes was studied in this work as a potential source of antiparasitic agents. The chloroform extract of T. longipes leaves was separated into several fractions, and tested for antitrypanosomal activity. One of the fractions displayed significant growth inhibitory activity against Trypanosoma brucei. The active principle in the fraction was isolated, purified, and characterized by NMR and mass spectrometry. The antitrypanosomal agent in the CHCl3 extract of T. longipes leaves is the pentacyclic triterpenoid bauerenol acetate. A metabolite profiling assay suggest that the triterpenoid influences cholesterol metabolism. The molecular target(s) of bauerenol and its acetate, like many other antiparasitic pentacyclic triterpenoids is/are unknown, but they present privileged structural scaffolds that can be explored for structure-based activity optimization studies using phenotypic assays.

[Mechanism of Salinization of Shallow Groundwater in Taocheng District, Hengshui City].

In order to understand the characteristics and origin of groundwater salinization in Taocheng district of Hengshui City, the recharge and salinization procession of shallow groundwater were analyzed with isotopic and geochemical data of the shallow groundwater (buried depth ≤ 100 m) and the soluble salt in boreholes. The results showed that the shallow groundwater was weak alkaline salt water, with the total dissolved solid (TDS) in the groundwater ranging from 176.06 to 17569.65 mg·L-1and the soil total salinity in unconsolidated sediments ranging from 1.830 to 6.509 g·kg-1. The hydrochemical types were mainly SO4·Cl-Na·Mg and Cl·SO4-Na·Ca in the shallow groundwater and the soluble salt. The main recharge resource of shallow groundwater was precipitation with different geological periods. The hydrochemical compositions of shallow groundwater mainly came from the dissolution of halite and sulfate weathering and experienced intense evaporation and the reduction environment. Meanwhile, the groundwater salinization was barely affected by human activities and seawater intrusion.

Physiological and omics analysis of maize inbred lines during late grain development.

BACKGROUND: There were significant differences in the change of moisture content and grain composition at the late stage of grain development among different maize varieties, but the regulation mechanism is not clear. OBJECTIVE: To explore the key genes causing the variation in physiological traits of two typical maize inbred lines in late grain development. METHODS: The grains at different development stages were selected as materials to determine the content of water, sucrose, starch and ABA. Transcriptomic and proteomic analysis of the materials were performed to screen relevant genes. RESULTS: The grain dehydration rate and the content of sucrose, starch and ABA were showed significant differences between two varieties in the late stage of grain development. The enrichment analysis of common differentially expressed genes (proteins) showed that most of the genes (proteins) were enriched in the extracellular region. The downregulated genes were mainly concentrated in carbohydrate metabolism and lipid metabolism, while the upregulated genes were mainly in response to stress. Furthermore, this study also identified many key candidate genes (dehydrin genes, pathogenesis-related genes, sucrose synthase and secondary metabolites related genes) related to late grain development of maize. CONCLUSIONS: The suggested genes related to late grain development of maize can be candidates for further functional study.

Bacterial community structure in geothermal springs on the northern edge of Qinghai-Tibet plateau.

Introduction: In order to reveal the composition of the subsurface hydrothermal bacterial community in the zones of magmatic tectonics and their response to heat storage environments. Methods: In this study, we performed hydrochemical analysis and regional sequencing of the 16S rRNA microbial V4-V5 region in 7 Pleistocene and Lower Neogene hot water samples from the Gonghe basin. Results: Two geothermal hot spring reservoirs in the study area were found to be alkaline reducing environments with a mean temperature of 24.83°C and 69.28°C, respectively, and the major type of hydrochemistry was SO4-Cl·Na. The composition and structure of microorganisms in both types of geologic thermal storage were primarily controlled by temperature, reducing environment intensity, and hydrogeochemical processes. Only 195 ASVs were shared across different temperature environments, and the dominant bacterial genera in recent samples from temperate hot springs were Thermus and Hydrogenobacter, with both genera being typical of thermophiles. The correlation analysis showed that the overall level of relative abundance of the subsurface hot spring relied on a high temperature and a slightly alkaline reducing environment. Nearly all of the top 4 species in the abundance level (53.99% of total abundance) were positively correlated with temperature and pH, whereas they were negatively correlated with ORP (oxidation-reduction potential), nitrate, and bromine ions. Discussion: In general, the composition of bacteria in the groundwater in the study area was sensitive to the response of the thermal storage environment and also showed a relationship with geochemical processes, such as gypsum dissolution, mineral oxidation, etc.

A unimolecular DNA fluorescent probe for determination of copper ions based on click chemistry.

A homogenous fluorescence method was constructed for Cu2+ detection by employing DNA-templated click chemistry and exonuclease reaction. In this strategy, a dumbbell shaped DNA probe, which contained an alkyne group and an azide group at its ends, was designed as the template for the click chemistry reaction, and also the signal probe. In the absence of Cu2+, the DNA probe was digested into small oligonucleotide fragments by exonuclease, resulting in a low fluorescence background. However, this DNA probe can be sealed at its two ends by Cu2+-induced click chemistry ligation in the presence of Cu2+. This closed structure of DNA would remain stable after addition of exonuclease, and could then be stained by SYBR Green I. A strong fluorescence signal was observed, which was related to the concentration of Cu2+. This assay showed high selectivity and reached the detection limit of 39 nM. Moreover, the proposed strategy exhibited satisfactory detection results in real complex sample analysis, and has promising application in environmental monitoring and food safety.

Comparative proteomic analysis of mitochondrial proteins from maize CMS-C sterile, maintainer and restorer anthers.

The maize C system of cytoplasmic male sterility (CMS) and its fertility restoration gene Rf4 have been widely used for maize hybrid production; however, the underlying mechanism is still uncertain. The sterility factor functions in mitochondria, where it interacts directly or indirectly with the restorer. Mitoproteomics can capture all participants involved in CMS and restoration at the organelle level. In the present study, we identified and quantified anther mitochondrial proteins from CMS, maintainer and restorer lines. We obtained 14,528 unique peptides belonging to 3,369 proteins. Comparative analysis of 1840 high-confidence proteins revealed 68 were differentially accumulated proteins likely involved in CMS or its restoration within mitochondria. These proteins were mainly associated with fatty acid metabolism, amino acid metabolism and protein-processing pathways. These results suggest that an energy deficiency caused by the sterility factor hinders other proteins or protein complexes required for pollen development through nuclear-mitochondrial interaction. The restorer factor may boost the energy generation by activating alternative metabolic pathways and by improving the post-translation processing efficiency of proteins in energy-producing complexes to restore pollen fertility. Our findings may aid detailed molecular analysis and contribute to a better understanding of maize CMS-C restoration and sterility.

Vinyl Sulfone-Based Inhibitors of Nonstructural Protein 2 Block the Replication of Venezuelan Equine Encephalitis Virus.

Emerging infectious diseases like those caused by arboviruses such as Venezuelan equine encephalitis virus (VEEV) pose a serious threat to public health systems. Development of medical countermeasures against emerging infectious diseases are of utmost importance. In this work, an acrylate and vinyl sulfone-based chemical series was investigated as promising starting scaffolds against VEEV and as inhibitors of the cysteine protease domain of VEEV's nonstructural protein 2 (nsP2). Primary screen and dose response studies were performed to evaluate the potency and cytotoxicity of the compounds. The results provide structural insights into a new class of potent nonpeptidic covalent inhibitors of nsP2 cysteine protease represented by compound 11 (VEEV TrD, EC50 = 2.4 µM (HeLa), 1.6 µM (Vero E6)). These results may facilitate the evolution of the compounds into selective and broad-spectrum anti-alphaviral drug leads.

A highly sensitive and selective signal-on strategy for microRNA quantification.

MicroRNAs (miRNAs) are associated with physiological and pathological processes. They are recognized as biomarkers for diseases diagnosis and treatment evaluation. Herein we propose a simple and cost-effective HPLC method for quantitative assay of target miRNAs with femtomolar sensitivity, single-base discrimination selectivity and low background. The assay is based on an innovative signal-on strategy. In this strategy, polyadenylation of poly(A) polymerase extends an all 'A' sequence at the end of target miRNA, and the substantially increased number of adenine bases are labeled with 2-Chloroacetaldehyde (CAA) to open a signal-on mode and realize a signal amplification. The linearly amplified fluorescence signal is separated from other inference signals and quantified by high performance liquid chromatography with fluorescence detection (HPLC-FD). Combining with affinity magnetic solid phase extraction (MSPE), the method is well suited for analysis of complex biological samples such as serum and cell lysate with nearly zero background fluorescence. Taking miRNA-21 as the model analyte, this absolute quantification method has a limit of detection of 200 fM and a linear calibration curve (R2 = 0.999) in the range from 2.00 pM to 1.00 nM. Using locked nucleic acid (LNA) modified probes rather than ssDNA probes, the assay selectivity is improved. Moreover, analysis of bovine serum and cell lysate samples by using the method is demonstrated. Intracellular content of miRNA-21 is found to be 0.0150 amol/cell in MCF-7 cells with an assay repeatability of 4.0% (RSD, n = 3). The present HPLC quantification of miRNA offers an accurate, reliable, and cost-effective means for quantitative assay of miRNAs occurring in biological samples. Also importantly, it eliminates the need for total RNA isolation for the analysis. It may be useful for more effective diagnosis of diseases and therapeutic evaluation.

Simultaneous Quantification of Adenosine and Deoxyadenosine Isomers in Foods with High Sensitivity.

Simultaneous quantification of adenosine and deoxyadenosine isomers, including 2'-deoxyadenosine (dA) and 3'-deoxyadenosine (cordycepin, COR) is a challenge because they are very similar in chemical structure. In some previous studies on food ingredients, adenine and dA might be mistakenly detected as COR that has been shown to have multiple health benefits. In this work, we developed a novel HPLC method with fluorescence detction (HPLC-FD) to simultaneously quantify COR, adenosine and dA. Pre-column derivatization with chloroacetaldehyde (CAA) was deployed. The proposed method has a limit of detection at the nM level for COR and adenosine, and is far more sensitive than the methods previously deveopled for COR determination. Using the present method, caterpillar fungi were analyzed as model food samples. The analysis revealed that COR was present in cordyceps militaris and cordyceps flowers in a concentration range from 0.314 to 0.735 mg/g, but not in cordyceps sinensis (C. sinensis), a natural and the priciest caterpillar fungus. These results suggest that the profile of active ingredients in C. sinensis has been wrongly claimed for many years. This finding was also supported by the results from further HPLC-MS/MS analyses.

Recoverable organorhodium-functionalized polyhedral oligomeric silsesquioxane: a bifunctional heterogeneous catalyst for asymmetric transfer hydrogenation of aromatic ketones in aqueous medium.

A bifuctional heterogeneous chiral rhodium catalyst exhibited excellent catalytic activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones and their analogues in aqueous medium, which could be recovered easily and used repetitively without affecting obviously its enantioselectivity.

Core-shell structured mesoporous silica: a new immobilized strategy for rhodium catalyzed asymmetric transfer hydrogenation.

A core-shell structured heterogeneous rhodium catalyst exhibited excellent catalytic activity and enantioselectivity in asymmetric transfer hydrogenation of aromatic ketones in aqueous medium, which could be recovered easily and used repetitively twelve times without affecting obviously its enantioselectivity.