Interaction of human dendritic cell receptor DEC205/CD205 with keratins.

DEC205 (CD205) is one of the major endocytic receptors on dendritic cells and has been widely used as a receptor target in immune therapies. It has been shown that DEC205 can recognize dead cells through keratins in a pH-dependent manner. However, the mechanism underlying the interaction between DEC205 and keratins remains unclear. Here we determine the crystal structures of an N-terminal fragment of human DEC205 (CysR∼CTLD3). The structural data show that DEC205 shares similar overall features with the other mannose receptor family members such as the mannose receptor and Endo180, but the individual domains of DEC205 in the crystal structure exhibit distinct structural features that may lead to specific ligand binding properties of the molecule. Among them, CTLD3 of DEC205 adopts a unique fold of CTLD, which may correlate with the binding of keratins. Furthermore, we examine the interaction of DEC205 with keratins by mutagenesis and biochemical assays based on the structural information and identify an XGGGX motif on keratins that can be recognized by DEC205, thereby providing insights into the interaction between DEC205 and keratins. Overall, these findings not only improve the understanding of the diverse ligand specificities of the mannose receptor family members at the molecular level but may also give clues for the interactions of keratins with their binding partners in the corresponding pathways.

Assembly and recognition of keratins: A structural perspective.

Keratins are one of the major components of cytoskeletal network and assemble into fibrous structures named intermediate filaments (IFs), which are important for maintaining the mechanical properties of cells and tissues. Over the past decades, evidence has shown that the functions of keratins go beyond providing mechanical support for cells, they interact with multiple cellular components and are widely involved in the pathways of cell proliferation, differentiation, motility and death. However, the structural details of keratins and IFs are largely missing and many questions remain regarding the mechanisms of keratin assembly and recognition. Here we briefly review the current structural models and assembly of keratins as well as the interactions of keratins with the binding partners, which may provide a structural view for understanding the mechanisms of keratins in the biological activities and the related diseases.

A highly parallel DTT/MB-DNA/Au electrochemical biosensor for trace Hg monitoring by using configuration occupation approach and SECM.

Environmental pollution and medicine safety have aroused increasing public concerns due to human health. Amongst various contaminants, mercury is of special attention owing to their environmental persistence and biogeochemical recycling and ecological risks. Herein, a simple and highly parallel electrochemical biosensor for Hg determination was designed and investigated. The proposed biosensor was prepared and compared between (1) DTT/MB-DNA/Au with configuration occupation approach and (2) MCH/MB-DNA/Au with passivation approach. According to the combined results of scanning electrochemical microscope (SECM) and Randles-Sevcik equation, the DTT modified electrode exhibited high uniformity on DNA distribution and superb stability on electron transfer in Hg2+ detection. Evidentially, the response value of proposed DTT/MB-DNA/Au was increased from 57.518% to 97.607%, while RSD% between duplicate runs had dropped from 22.658% to 0.223% (n = 3). Moreover, the increased proportion of effective working area was 467.380% compared with general sensors. Besides, DTT concentration, DNA concentration as well as assembly time were optimized, utilizing electrochemical impedance spectroscopy (EIS), Cyclic Voltammetry (CV) and Square Wave Anode Stripping Voltammetry (SWASV). This optimized biosensor exhibited an excellent selectivity toward Hg2+ over Cu2+, As2+, Cd2+, Pb2+, Cr3+, Ni2+ and Zn2+ etc., and the stability of DTT/MB-DNA/Au were at least two times better even after 3 days under room temperature. Also, a linear relation was observed between the peak current and Hg2+concentrations in a range from 0.25 nM to 2.00 µM with a detection limit of 53.00 pM under optimal conditions. Finally, DTT/MB-DNA/Au was applied for plants and medical products analysis. In all, this optimized DTT/MB-DNA/Au with advantages of high repeatability and sensitivity would provide a new insight into the design and application of biosensor for reliable sensing in safeguarding plant protection and medicinal safety.

Interactions of ferritin with scavenger receptor class A members.

Scavenger receptors are a superfamily of membrane-bound receptors that recognize both self and nonself targets. Scavenger receptor class A (SR-A) has five known members (SCARA1 to -5 or SR-A1 to -A5), which are type II transmembrane proteins that form homotrimers on the cell surface. SR-A members recognize various ligands and are involved in multiple biological pathways. Among them, SCARA5 can function as a ferritin receptor; however, the interaction between SCARA5 and ferritin has not been fully characterized. Here, we determine the crystal structures of the C-terminal scavenger receptor cysteine-rich (SRCR) domain of both human and mouse SCARA5 at 1.7 and 2.5 Å resolution, respectively, revealing three Ca2+-binding sites on the surface. Using biochemical assays, we show that the SRCR domain of SCARA5 recognizes ferritin in a Ca2+-dependent manner, and both L- and H-ferritin can be recognized by SCARA5 through the SRCR domain. Furthermore, the potential binding region of SCARA5 on the surface of ferritin is explored by mutagenesis studies. We also examine the interactions of ferritin with other SR-A members and find that SCARA1 (SR-A1, CD204) and MARCO (SR-A2, SCARA2), which are highly expressed on macrophages, also interact with ferritin. By contrast, SCARA3 and SCARA4, the two SR-A members without the SRCR domain, have no detectable binding with ferritin. Overall, these results provide a mechanistic view regarding the interactions between the SR-A members and ferritin that may help to understand the regulation of ferritin homeostasis by scavenger receptors.

Functional expression and characterization of the envelope glycoprotein E1E2 heterodimer of hepatitis C virus.

Hepatitis C virus (HCV) is a member of Hepacivirus and belongs to the family of Flaviviridae. HCV infects millions of people worldwide and may lead to cirrhosis and hepatocellular carcinoma. HCV envelope proteins, E1 and E2, play critical roles in viral cell entry and act as major epitopes for neutralizing antibodies. However, unlike other known flaviviruses, it has been challenging to study HCV envelope proteins E1E2 in the past decades as the in vitro expressed E1E2 heterodimers are usually of poor quality, making the structural and functional characterization difficult. Here we express the ectodomains of HCV E1E2 heterodimer with either an Fc-tag or a de novo designed heterodimeric tag and are able to isolate soluble E1E2 heterodimer suitable for functional and structural studies. Then we characterize the E1E2 heterodimer by electron microscopy and model the structure by the coevolution based modeling strategy with Rosetta, revealing the potential interactions between E1 and E2. Moreover, the E1E2 heterodimer is applied to examine the interactions with the known HCV receptors, neutralizing antibodies as well as the inhibition of HCV infection, confirming the functionality of the E1E2 heterodimer and the binding profiles of E1E2 with the cellular receptors. Therefore, the expressed E1E2 heterodimer would be a valuable target for both viral studies and vaccination against HCV.

[Health risk assessment of exogenous harmful pollutants in Chinese medicine: a review].

In recent years, the quality and safety problems have been limiting the internationalization of Chinese medicine. The pollutants in Chinese medicine, particularly the exogenous harmful pollutants mainly including mycotoxins, pesticide residues, heavy metals, harmful elements, and sulfur dioxide, are of high risks for people. Therefore, the World Health Organization(WHO) and relevant national organizations have clearly defined the maximum residue limits(MRLs) of such pollutants. Chinese Pharmacopoeia(2020 edition, volume Ⅳ) also demonstrates the detection methods, MRLs and preliminary risk assessment methods for four typical exogenous harmful pollutants in Chinese medicine. Therefore, continuous optimization of the health risk assessment system can further help further raise the quality and safety of Chinese medicine. This paper reviews the research on the health risk assessment of four typical exogenous harmful pollutants in Chinese medicine and discusses the problems of and challenges for the assessment system, which is expected to lay a scientific basis for the establishment of the risk warning mode and response measures suitable for specific types of Chinese medicine.

[Domestic and international research progress of edible and medicinal Arecae Semen].

Arecae Semen, as the first place among "Four South Medicines" in China, has great dual-use value of medicine and food. The research of Arecae Semen was mainly focused on the active ingredients and efficacy value, and its potential safety hazards were also concerned. Until now, there is still a lack of clear boundaries between medicine and food, resulting in its safety cannot be guaranteed. Therefore, it is of great significance to establish clear boundaries of medicine and food use and health risk assessment. In this paper, the differences of pretreatment and application methods of Arecae Semen were analyzed, and the research progress of Arecae Semen in chemical composition identification and toxicology research and safety evaluation were reviewed emphatically. Finally, the differences of quality control and safety evaluation of Arecae Semen in pharmacopoeias or standards were analyzed at home and abroad. It was expected to provide reference value for quality control, safety evaluation and international standardization research of Arecae Semen.

A reusable AuNPS with increased stability applied for fast screening of trace heavy metals in edible and medicinal marine products.

Heavy metal pollution in marine environment poses a severe threat to the safety of marine products and is thus causing increasingly concerns in terms of their toxicity and potential health risks pose to human. Due to the complex matrix of marine products, a fast screening method for heavy metals at trace level with low price, reusability, high accuracy and long lifetime is of urgency and necessity for consumers and processing factories. This work described a simplified screening system through the preparation, characterization and particular application of Au nano particle sensor (AuNPS) in the complex marine matrix, the main aim is to significantly increase the stability, sensitivity and lifetime of detection system dedicated to Cu and Hg trace analysis in marine products. It is worth mentioning that, the proposed screening system was characterized through electrochemical experiments and theoretical calculations, which could be a new evidence for selecting the detection system in commercially complex samples. Importantly, the discipline of deposition and oxidative stripping process on AuNPS was explained based on the mechanism of Metal Ion Deficient Layer (MIDL), and illustrated with SEM changes during stripping process, as well as the dissolving-out rate of metals on AuNPS material. Moreover, to further improve the reusability and stability of AuNPS sensor, the complex marine matrix was purified by pre-plating interferences on indium tin oxide glass electrode. The screening system exhibited a liner response in the range of 0.02-0.10 µg mL-1 for Hg, 0.01-0.10 µg mL-1 and 0.001-0.01 µg mL-1 for Cu with the detection limits of 0.138 mg kg-1 and 1.51 mg kg-1 in marine matrix, respectively. The sensitivity and lifetime was at least two times better as compared to similar works even after 20-times use. Finally, this proposed analysis system combined with purification procedure was successfully applied for the edible and medicinal marine products analysis, meanwhile, the accuracy and stability were confirmed with standard analytical methods.

Crystal structure of the CTLD7 domain of human M-type phospholipase A2 receptor.

M-type phospholipase A2 receptor (PLA2R) is a member of the mannose receptor family. Recent evidence shows that PLA2R is a major autoantigen causing idiopathic membranous nephropathy (IMN), which is an autoimmune disease and one of the most common causes for nephrotic syndrome in adults. The epitope mapping data suggest that the major epitopes of PLA2R locate at the CysR, CTLD1 and CTLD7 domains. However, due to the lack of the high-resolution structural information, it is unclear how the autoantibodies interact with PLA2R. Here we determine the crystal structure of the CTLD7 domain of PLA2R at 1.8 Å, showing that it adopts a typical CTLD fold, and the structural alignments also provide hints for the potential antibody binding regions. In addition, the high-resolution structural information of CTLD7 could be applied to identify the epitopes for autoantibodies, which would facilitate the therapeutic strategies against IMN.

[Establishment of health risk assessment model for assessing medicinal and edible plants contaminated by heavy metals--take Astragali Radix,Codonopsis Radix and Laminariae Thallus as examples].

With the improvement of living standard,the theory of " medicine and food homology" has developed rapidly in the field of diet,medicine and health preservation. In recent years,many literatures have been reported on the active ingredients and pharmacological effects of medicinal and edible plants,but relatively few reports have been reported on their safety investigation. Therefore,to further evaluate the quality and safety of medicinal and edible plants,Astragali Radix,Codonopsis Radix and Laminariae Thallus were selected as our research objects in this study. Moreover,the pollution level and the potential health risk of heavy metals were deeply assessed in different types of medicinal and edible plants. Especially,the contents of chromium,copper,arsenic,cadmium,mercury and lead in these three herbs were determined by inductively coupled plasma mass spectrometry( ICP-MS),and their health risk level was evaluated by target hazard coefficient method. The results showed that under the international heavy metal limit standard( ISO 18664-2015,GB 2762-2017),the over-standard rates were 25%,77% and 100% in 16 batches of Astragali Radix,26 batches of Codonopsis Radix and 9 batches of Laminariae Thallus,respectively. Besides,the values of target hazard quotients( THQ) for adults and children are 0. 028 244,0. 063 505 and 0. 014 485,0. 032 568 in Astragalus membranaceus and Codonopsis pilosula,respectively,which were higher than the standard values of 0. 02 and 0. 011 25. While,the total heavy metals THQ values for adults and children are 0. 023 734 and 0. 020 287 in Laminariae Thallus,which were much higher than the standard values of 0. 008 0 and 0. 007 5. However,the CR values of As,Cd and Pb in the three herbs were lower than 1×10~(-6). Above results indicated that those six harmful elements have certain health hazards to the exposed population,but there is no potential carcinogenic effect. It can be seen that,there were still presence of the pollution of harmful elements,and it is necessary to establish the reasonable limit standards and quality control methods of medicinal and edible plants in time.

[Pollution level and health risk assessment of heavy metals and hazardous elements in Bombyx Batryticatus].

In order to comprehensively analyze the pollution level and bioaccessibility of different types of heavy metals and hazardous elements in animal medicine,this paper selected Bombyx Batryticatus as the research object,and used inductively coupled plasma mass spectrometry( ICP-MS) to detect As,Cu,Hg,Pb,Ni,Cr,Zn and Cd. Based on the artificial gastrointestinal digestion model and the health risk assessment model of Chinese medicinal materials,the pollution level,in vivo and in vitro transfer rate and health risk grade of eight harmful elements in the above-mentioned medicinal materials of Bombyx Batryticatus were obtained respectively. The test result was found that under the ISO international standard of Chinese medicine-Chinese herbal medicine heavy metals,the unqualified rate was 50% for Bombyx Batryticatus,which including 2 batches of As and 4 batches of Cr exceeded the MRL. In artificial gastrointestinal digestion solution,the transfer rates of heavy metals As,Cu,Hg,Pb,Ni,Cr,Zn and Cd were 36. 849%,72. 372%,41. 152%,75. 354%,46. 603%,27. 981%,19. 707% and 76. 282%,respectively. The data of risk assessment model showed that the total THQ values of the most polluted batches for adults and children was 0. 021 548 and 0. 018 418,respectively. After digestion,the THQ values decreased to 0. 012 599 for adults and 0. 010 769 for children,which were still higher than the THQ standard values of animal medicine Bombyx Batryticatus. However,the CR value of carcinogenic risk is less than 1×10-6,so the potential non-carcinogenic risk caused by taking this batch of Bombyx Batryticatus medicines is higher and the carcinogenic risk can be ignored. To sum up,heavy metals and hazardous elements in Bombyx Batryticatus still exceed the standard,but the health risk level caused by heavy metals still needs to be investigated according to different medicinal materials,in order to provide data support for further improving the quality and safety of animal medicine.

[Safety evaluation of heavy metals contaminated Astragalus membranaceus using health risk assessment model].

To evaluate the safety of heavy metals contaminated Astragalus membranaceus,an appropriate protocol was established to study the heavy metals pollution level by health risk assessment. This study provided a detailed procedure to assess the medicinal herbs in quality control and safety evaluation,and expected to create awareness among the public on the safety of consuming of A. membranaceus or any other kinds of medicinal herbs. The heavy metals content of Cu,As,Cd,Pb and Hg in a total of 45 batches of A. membranaceus were carefully analyzed with a developed inductively coupled plasma mass spectrometry( ICP-MS). Besides,the heavy metal contamination level was further evaluated through 4 main assessment parameters,including maximum residue limit( MRL) set by International Standard Organization,estimated daily intake( EDI) set by IUPAC,target hazard quotients( THQ) and Total THQ set by USEPA and total THQs in raw herbs of A. membranaceus. In addition,the recommended MRLs of 5 main heavy metals aimed to A. membranaceus were calculated based on the regulated consumption quantity. The result showed that,under the ISO international standard of Chinese medicine-Chinese herbal medicine heavy metals,the unqualified rate was 8. 89% for A. membranaceus,which including 4 batches of A. membranaceus exceeded the MRL of As. Here,the standard THQ value of A. membranaceus was firstly proposed as 0. 02 and 0. 011 25 for adults and children,respectively,which were calculated with the recommended consumption quantity of 30 g and 9 g for adults and children. Furthermore,the values of THQ for As and total THQs in adults and children were exceeded the standard THQ in A. membranaceus,and the recommended MRLs of Pb,Cd,Hg and Cu in above medicinal materials that calculated based on health risk assessment model were higher than the regulated MRLs that set by ISO and Chinese Pharmacopeia. The research showed that the contents of heavy metals in A. membranaceus were not in the safe range and the certain non-carcinogenic risks to human body cannot be neglected. Based on above investigation result,it is easily known that the common evaluation method for raw herbs based on the comparison of MRL of heavy metals was not precise enough,and the international model of health risk assessment should be built for each medicinal herb. Above all,this study provided a more realistic research approach for safety evaluation of any other kinds of heavy metals contaminated medicinal herbs,including the establishment of heavy metals standard limit in a specified medicinal herb under recommended consumption quantity,and it is expected to create awareness among the public on the safety of consuming any other medicinal herbs.

[Current situation of heavy metal pollution,detection and removal techniques in medicinal marine organisms in China].

As an important branch of traditional medicines,medicinal marine organisms have many advantages,including biological diversity,remarkable biological activity,especial for the treatment of anti-cancer,anti-virus,anti-coagulation,analgesia,anti-bacterial,cardiovascular and cerebrovascular diseases. In recent years,with the continuous exploration of marine organisms by human beings,many marine organisms with specific biological activities and medicinal prospects have been found,which have attracted great attention around the world and thus called " new hope" to solve human health problems. However,due to the rapid development of modern industry,heavy metal pollution not only poses a great threat to medicinal marine living resources,but also hinders the development of marine biomedical industry and threatens human health. In view of this,this paper introduced the development trend of medicinal marine organisms and the current situation of heavy metal pollution and focusing on the analysis technology and chemical removal technology of heavy metals in medicinal marine organisms,which is to provide reference for the heavy metals control in marine medicines and the development and utilization of marine medicines.

[Safety evaluation of heavy metals contaminated Xiaochaihu Tang using health risk assessment model].

In order to further improve the quality and safety evaluation standards of traditional Chinese medicine compound preparation,Xiaochaihu Tang compound preparations were selected to analyze the pollution level of heavy metals deeply,and the potential health risks were evaluated under taking such kind of compound preparations. In this study,the contents of copper( Cu),arsenic( As),cadmium( Cd),mercury( Hg),and lead( Pb) in different Xiaochaihu Tang compound preparations were determinated by the method of inductively coupled plasma mass spectrometry( ICP-MS). Moreover,combined with target hazard coefficient method and in vitro artificial system,the bioaccessibility and health risk level was investigated in three main consumption ways including powder,decoction and granule. The result was showed that,under the maximum residual limit set by International Standard Organization,only one batch of raw herb was eight times exceeded the Hg MRL,however,in water decoctions and granules,the heavy metal residue rate was reduced to 2. 02%( Hg in granules)-42. 85%( Cd in granules). So,the heavy metal pollutions and health risks can be reduced to safe region in spite of the serious pollution in raw herbs. Besides,the THQ and CR values of the three consumption methods were lower than the standard values of non-carcinogenic and carcinogenic risks of each heavy metal. It can be seen that even if the heavy metals in the raw herbs exceed the standard,the use of Xiaochaihu Tang decoction and granules can reduce the harm of heavy metals to the human body. Above all,the establishment of this health risk assessment model can be provided experimental basis and reference value for improving the safety evaluation standard of other heavy metals contained traditional Chinese medicine( TCM) compound preparations,and further improving the quality control methods of other different toxic compounds in clinical use.

[Analysis of arsenic speciation in Sepiae Endoconcha and research on its limit standard].

Sepiae Endoconcha is a common marine animal medicine,which generally contains high concentration of arsenic( As).The Chinese Pharmacopoeia( 2010 edition,part I) stipulated that the total As content of Sepiae Endoconcha should not exceed 2 mg·kg~(-1),while this limit was revised to 10 mg·kg~(-1) in the 2015 edition. So far,there is no research on the speciation of As in Sepiae Endoconcha,which made it hard to accurately evaluate its security risk. In this study,32 batches of Sepiae Endoconcha from different sources were collected. The safety risk assessment was carried out by determining the total As content and As speciation,inorganic As[As( Ⅲ),As( Ⅴ) ]and organic As( MMA,DMA,As C,As B) by HPLC-ICP-MS,and then the limit standard was discussed. The results showed that As B was the main form of As in Sepiae Endoconcha,followed by DMA and As( Ⅴ) ． Of the 32 batches of Sepiae Endoconcha,9 batches( accounting for 28%) were detected possessing i As. The maximum concentration of As( Ⅲ) was 103. 3 µg·kg~(-1),and the maximum concentration of As( Ⅴ) was 222. 4 µg·kg~(-1). According to the limit of i As in food,18. 75% of the samples exceeded the standard. The results indicate that there is no simple positive correlation between total As and As morphology in Sepiae Endoconcha. Besides,there is a risk in the total As limit,especially after the relaxation of the total As limit. The problem of high i As content caused by pollution and other factors is difficult to regulate. Since the toxicity of inorganic As is much higher than that of organic As,it is of great practical significance to establish inorganic As form limits in Sepiae Endoconcha.

Synthesis and application of imidazolium-based ionic liquids as extraction solvent for pretreatment of triazole fungicides in water samples.

Five novel ionic liquids (ILs), 1,3-dibutylimidazolium bromide [BBMIm][Br], 1-pentyl-3-butylimidazolium bromide [BPMIm][Br], 1-hexyl-3-butylimidazolium bromide [BHMIm][Br], 1,1'-(butane-1,4-diyl)bis(3-butylimidazolium) bromide [C4(BMIm)2][Br2], and 1,1'-(butane-1,4-diyl)bis(3-methylimidazolium) bromide [C4(MIm)2][Br2], were prepared and used in situ to react with bis(trifluoromethane)sulfonamide lithium salt to extract the myclobutanil, tebuconazole, cyproconazole, and prothioconazole from water samples. The results showed that mono-cationic ILs had much better recovery than dicationic ILs, and mono-imidazolium IL bearing butyl groups at N-1 and N-3 sites had the best recovery. When the length of the alkyl substituent group was more than four carbons at N-3 site, the recovery decreased with increase of alkyl chain length of 1-butylimidazolium IL. The extraction efficiency order of triazoles from high to low was [BBMIm][Br], [BPMIm][Br], [BHMIm][Br], [BMIm][Br] (1-butyl-3-methylimidazolium bromide), [C4(BMIm)2]Br2, [C4(MIm)2]Br2. An in situ ionic liquid dispersive liquid-liquid microextraction combined with ultrasmall superparamagnetic Fe3O4 was established as a pretreatment method for enrichment of triazole fungicides in water samples by using the synthetic [BBMIm][Br] as the cationic IL and used to detect analytes followed by high-performance liquid chromatography. Under the optimized conditions, the proposed method showed a good linearity within a range of 5-250 µg L-1, with the determination coefficient (r2) varying from 0.998 to 0.999. High mean enrichment factors were achieved ranging from 187 to 323, and the recoveries of the target analytes from real water samples at spiking levels of 10.0, 20.0, and 50.0 µg L-1 were between 70.1% and 115.0%. The limits of detection for the analytes were 0.74-1.44 µg L-1, and the intra-day relative standard deviations varied from 5.23% to 8.65%. The proposed method can be further applied to analyze and monitor pesticides in other related samples. Graphical Abstract The scheme of the in-situ DLLME method for the determination of triazoles using the imidazolium-based ionic liquids.

Quantitative and fingerprinting analysis of Atractylodes rhizome based on gas chromatography with flame ionization detection combined with chemometrics.

This study assessed the feasibility of gas chromatography with flame ionization detection fingerprinting combined with chemometrics for quality analysis of Atractylodes rhizome. We extracted essential oils from 20 Atractylodes lancea and Atractylodes koreana samples by hydrodistillation. The variation in extraction yields (1.33-4.06%) suggested that contents of the essential oils differed between species. The volatile components (atractylon, atractydin, and atractylenolide I, II, and III) were quantified by gas chromatography with flame ionization detection and confirmed by gas chromatography with mass spectrometry, and the results demonstrated that the number and content of volatile components differed between A. lancea and A. koreana. We then calculated the relative peak areas of common components and similarities of samples by comparing the chromatograms of A. lancea and A. koreana extracts. Also, we employed several chemometric techniques, including similarity analysis, hierarchical clustering analysis, principal component analysis, and partial least-squares discriminate analysis, to analyze the samples. Results were consistent across analytical methods and showed that samples could be separated according to species. Five volatile components in the essential oils were quantified to further validate the results of the multivariate statistical analysis. The method is simple, stable, accurate, and reproducible. Our results provide a foundation for quality control analysis of A. lancea and A. koreana.

Conformational Tuning of the Intramolecular Electronic Coupling in Molecular-Wire Biruthenium Complexes Bridged by Biphenyl Derivatives.

The synthesis and characterization of a series of biphenyl-derived binuclear ruthenium complexes with terminal {RuCl(CO)(PMe3)3} moieties and different structural arrangements of the phenyl rings are reported. Electrochemical studies revealed that the two metal centers of the binuclear ruthenium complexes interact with each other through the biphenyl bridge, and the redox splittings ΔE1/2 show a strong linear correlation with cos(2) ϕ, where ϕ is the torsion angle between the two phenyl rings. A combination of electrochemical, UV/Vis/NIR, and in situ IR differential spectroelectrochemical analysis clearly showed that: 1) the intramolecular electronic couplings in the binuclear ruthenium complexes could be modulated by changing ϕ; 2) the electronic ground state of the mixed-valent cations changes from delocalized to localized through the biphenyl bridge with increasing torsion angle ϕ, that is, the redox processes of these complexes change from significant involvement of the bridging ligand to an oxidation behavior with less participation of the bridge.

Determination of mycobiota and aflatoxin contamination in commercial bee pollen from eight provinces and one autonomous region of China.

The co-occurrence of fungi and mycotoxins in various foods has been frequently reported in many countries, posing a serious threat to the health and safety of consumers. In this study, the mycobiota in five types of commercial bee pollen samples from China were first revealed by DNA metabarcoding. Meanwhile, the content of total aflatoxins in each sample was investigated by high-performance liquid chromatography with fluorescence detection. The results demonstrated that Cladosporium (0.16 %-89.29 %) was the most prevalent genus in bee pollen, followed by Metschnikowia (0-81.12 %), unclassified genus in the phylum Ascomycota (0-81.13 %), Kodamaea (0-73.57 %), and Penicillium (0-36.13 %). Meanwhile, none of the assayed aflatoxins were determined in the 18 batches of bee pollen samples. In addition, the fungal diversity, community composition, and trophic mode varied significantly among five groups. This study provides comprehensive information for better understanding the fungal communities and aflatoxin residues in bee pollen from different floral origins in China.

Comprehensive analysis of neonicotinoids in Chinese commercial honey and pollen: A corresponding health risk assessment for non-targeted organisms.

Neonicotinoids are broad-spectrum and highly effective insecticides that work by affecting neural activity in insects. Neonicotinoids are systemic pesticides that are absorbed by plants, transported, and accumulated in plant tissues, including nectar and pollen. Currently, there is a lack of a comprehensive assessment of the level of neonicotinoid contamination and the associated health risks to non-targeted organisms in commercial honey and pollen produced in China. This study collected 160 batches of honey and 26 batches of pollen from different regions and plant sources in China, analyzed the residue patterns of neonicotinoid pesticides, and comprehensively evaluated the exposure risks to non-targeted organisms including bees (adults and larvae) and humans. Furthermore, this study addresses this imperative by establishing a high-throughput, rapid, and ultra-sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on broad-spectrum monoclonal antibodies to detect and quantify neonicotinoids, with validation conducted using the LC-MS/MS method. The findings indicated that 59.4 % of honey samples contained at least one of eight neonicotinoids, and the ic-ELISA rapid detection and calculation method could detect all the samples containing neonicotinoids. Additionally, the dietary risk assessment for humans and honeybees indicates that the consumption of a specific quantity of honey may not pose a health risk to human due to neonicotinoid intake. However, the Risk Quotient values for imidacloprid to adult bees and bee larvae, as well as clothianidin to bee larvae, were determined to be 2.22, 5.03, and 1.01, respectively-each exceeding 1. This highlights the elevated risk of acute toxicity posed by imidacloprid and clothianidin residues to honey bees. The study bears significant implications for the safety evaluation of non-targeted organisms in the natural food chain. Moreover, it provides scientific guidance for protecting the diversity and health of the ecosystem.