Bioassay Results Research Articles

Efficacy of rhizobacteria to enhance the growth of Vigna mungo (L.)

Vigna mungo (L.), commonly known as black gram, is a highly nutritious crop most commonly found in Asia. The present study aimed to evaluate the effect of the Bacillus strains on the growth parameters of the plant. Biochemical characterization of the bacterial strains was carried out. After that, a seed germination assay was carried out in vitro. For this purpose, seeds were treated with the monocultures and mixed cultures (Z-06+Z-43, Z-06+Z-07, Z-02+Z-43, Z-02+Z-07) of bacterial strains for 1 week. Monocultures showed a germination percentage in the range of 14%-50% while the mixed cultures showed a germination percentage in the range of 33%-100%. Auxin bioassay was carried out in which strains were inoculated in the medium containing tryptophan and also without tryptophan. Z-07 and Z-43 gave 83.3% and 62.5% more promising results than Z-02 and Z06. Analysis of auxin-producing strains was done by FTIR (Fourier Transformed Infrared spectroscopy). A pot trial was carried out of the auxin-producing strains in monocultures and mixed cultures. Two harvestings were done after 1 month and 2 months, respectively. In both harvestings, plant parameters were measured including shoot length, fresh weight, dry weight, and number of pods. It was shown that plant growth parameters were improved after treating the seeds with the bacterial cultures. Z-07 and Z-43 gave more promising results in auxin bioassay and increase in plant growth parameters. So, these strains can be used in agricultural applications.

Identification and characterization of ATP-binding cassette transporters involved in chlorantraniliprole tolerance of model insect Drosophila melanogaster and agricultural pest Spodoptera frugiperda

ATP-binding cassette (ABC) transporter family is one of the largest transporter families, which plays an important role in insecticide tolerance. In this study, we found that the ABC transporter inhibitor verapamil could significantly enhance the toxicity of chlorantraniliprole (CHL) to the model insect Drosophila melanogaster. Forty-six ABC transporter genes of D. melanogaster were knocked down through the daughterless-GAL4 (Da-GAL4) strain. The subsequent bioassay result showed that D. melanogaster with DmCG5772, DmCG1494, and DmCG5853 genes silencing significantly increased mortality after CHL treatment. Based on the genome of the fall armyworm (FAW), three genes with the best hits were identified, and SfABCA1 (XM_035576510.2) and SfABCG10 (XM_035577893.2) were successfully cloned. Spatiotemporal expression pattern analysis showed that SfABCA1 and SfABCG10 were both highly expressed in adult and pupal stages. Hemolymph was also a tissue with high expression of these two genes. LC10 dose of CHL could induce the expression levels of SfABCA1 and SfABCG10, with SfABCG10 upregulated 8-fold after 48 h of CHL treatment. Furthermore, overexpression of SfABCA1 and SfABCG10 increased the viability of Sf9 cell under CHL treatment. Our findings indicate that SfABCA1 and SfABCG10 might associate with the tolerance of CHL in S. frugiperda. These results are not only helpful in understanding the role of ABC transporters in CHL tolerance of other agricultural pests, but also lay a theoretical foundation for delaying the development of CHL resistance in pest management.

Synthesis of 2-(morpholin-4-yl)-5-(piperazin-1-yl)pyrido[4,3-d]pyrimidine derivatives, crsystal structure, molecular docking studies, and anti-oxidant activities

A series of new 10 novel compounds of 2-(morpholin-4-yl)-5-(piperazin-1-yl)pyrido[4,3-d]pyrimidine 8a-8j derivatives have been designed and synthesized. Target compounds were synthesized via Aza-Michael addition, intermolecular condensation followed by cyclization reactions of corresponding starting materials and intermediates. All the synthesized intermediates and target compound were well characterized using various spectral techniques (1H and 13C NMR, LCMS, IR) including crystal strcture. This process will be useful for the large-scale synthesis of substituted pyrido[4,3-d]pyrimidine derivatives without the use of column chromatography. The detailed molecular docking studies were performed which showed very promising binding scores obtained against cytochrome c peroxidase enzyme (PDB code: 2×08) for all the synthesized compounds. The results of preliminary bioassay indicated that all the synthesized compounds possess enhanced antioxidant activity compared to ascorbic acid standard.

STAT5B, Akt and p38 Signaling Activate FTZ-F1 to Regulate the Xenobiotic Tolerance-Related Gene SlCyp9a75b in Spodoptera litura.

Cytochrome P450 monooxygenases in insects have been verified to implicated in insecticide and phytochemical detoxification metabolism. However, the regulation of P450s, which are modulated by signal-regulated transcription factors (TFs), is less well studied in insects. Here, we found that the Malpighian tubule specific P450 gene SlCYP9A75b in Spodoptera litura is induced by xenobiotics. The transgenic Drosophila bioassay and RNAi results indicated that this P450 gene contributes to α-cypermethrin, cyantraniliprole, and nicotine tolerance. In addition, functional analysis revealed that the MAPKs p38, PI3K/Akt, and JAK-STAT activate the transcription factor fushi tarazu factor 1 (FTZ-F1) to regulate CYP9A75b expression. These findings provide mechanistic insights into the contributions of CYP9A genes to xenobiotic detoxification and support the possible involvement of different signaling pathways and TFs in tolerance to xenobiotics in insects.

The effects of long-term application of fomesafen on weed seedbank and resistance levels of Amaranthus retroflexus L.

Amaranthus retroflexus L. is one of the invasive malignant weeds in soybean fields. Diphenyl ether herbicides are commonly used to control weeds in soybean fields currently, among which fomesafen is the most widely used. With the long-term use of fomesafen, the weed species in soybean fields in multiple areas declined, and the control effect of fomesafen against Amaranthus retroflexus decreased significantly. This study aims to confirm the effects of long-term use of fomesafen on weed community richness and the current resistance level of Amaranthus retroflexus. In this paper, the result of seed germination indicated that the weed community richness decreased significantly due to the long-term application of fomesafen, and the primary dominant weed was Amaranthus retroflexus. The result of the whole-plant bioassay showed that Amaranthus retroflexus has developed resistance to fomesafen, and the resistance index was 50~59 g a.i. ha-1. The resistance level and mechanism of Amaranthus retroflexus were clarified by target gene detection, enzyme activity determination, and gene expression analysis. The results showed that there were both target resistance with Arg128Gly mutation in the PPX2 gene and non-target resistance (NTSR), with increased activity of metabolic enzymes (cytochromes P450 (P450s) and glutathione S-transferase (GSTs)) and protective enzymes (peroxidase (POD) and catalase (CAT)) in Amaranthus retroflexus.

Ziziphus mauritiana Lam. Bark and Leaves: Extraction, Phytochemical Composition, In Vitro Bioassays and In Silico Studies.

In this work, homogenizer-assisted extraction (HAE) and maceration (MAE) were applied on leaves and bark of Ziziphus mauritiana using water and methanol (MeOH) as solvents. HAE and MAE extracts were compared through liquid chromatography coupled with mass spectrometry (LC-MS) and evaluating the antioxidant activity, and enzyme inhibition against acetylcholinesterase (AChE), butrylcholinesterase (BChE), tyrosinase, α-amylase, and α-glucosidase. Considering the phytochemical contents and the bioassays results, the HAE extracts resulted favorably with larger content of phenolics and higher antioxidant activity. The MeOH extracts displayed the highest α-amylase inhibitory activity, with HAE MeOH leaf extract leading at 0.78 mmol acarbose equivalent (ACAE)/g. In conclusion, the study highlights that HAE can increase the extraction of phenolic and flavonoid from Z. mauritiana plant materials compared to maceration. Further research could explore the potential therapeutic applications of Z. mauritiana extracts, especially HAE MeOH leaf extracts, for their notable antioxidant and enzyme inhibitory activities, facilitating the way for the development of novel pharmaceutical interventions.

Discovery, Optimization, and Biological Evaluation of Novel Pyrazol-5-yl-phenoxybenzamide Derivatives as Potent Succinate Dehydrogenase Inhibitors.

The diphenyl ether molecular pharmacophore has played a significant role in the development of fungicidal compounds. In this study, a variety of pyrazol-5-yl-phenoxybenzamide derivatives were synthesized and evaluated for their potential to act as succinate dehydrogenase inhibitors (SDHIs). The bioassay results indicate certain compounds to display a remarkable and broad-spectrum in their antifungal activities. Notably, compound 12x exhibited significant in vitro activities against Valsa mali, Gaeumannomyces graminis, and Botrytis cinerea, with EC50 values of 0.52, 1.46, and 3.42 mg/L, respectively. These values were lower or comparable to those of Fluxapyroxad (EC50 = 12.5, 1.93, and 8.33 mg/L, respectively). Additionally, compound 12x showed promising antifungal activities against Sclerotinia sclerotiorum (EC50 = 0.82 mg/L) and Rhizoctonia solani (EC50 = 1.86 mg/L), albeit lower than Fluxapyroxad (EC50 = 0.23 and 0.62 mg/L). Further in vivo experiments demonstrated compound 12x to possess effective protective antifungal activities against V. mali and S. sclerotiorum at a concentration of 100 mg/L, with inhibition rates of 66.7 and 89.3%, respectively. In comparison, Fluxapyroxad showed inhibition rates of 29.2 and 96.4% against V. mali and S. sclerotiorum, respectively. Molecular docking analysis revealed that compound 12x interacts with SDH through hydrogen bonding, π-cation, and π-π interactions, providing insights into the probable mechanism of action. Furthermore, compound 12x exhibited greater binding energy and SDH enzyme inhibitory activity than Fluxapyroxad (ΔGcal = -46.8 kcal/mol, IC50 = 1.22 mg/L, compared to ΔGcal = -41.1 kcal/mol, IC50 = 8.32 mg/L). Collectively, our results suggest that compound 12x could serve as a promising fungicidal lead compound for the development of more potent SDHIs for crop protection.

Bacillus velezensis HN-2: a potent antiviral agent against pepper veinal mottle virus.

Pepper veinal mottle virus (PVMV) belongs to the genus Potyvirus within the family Potyviridae and is a major threat to pepper production, causing reduction in yield and fruit quality; however, efficient pesticides and chemical treatments for plant protection against viral infections are lacking. Hence, there is a critical need to discover highly active and environment-friendly antiviral agents derived from natural sources. Bacillus spp. are widely utilized as biocontrol agents to manage fungal, bacterial, and viral plant diseases. Particularly, Bacillus velezensis HN-2 exhibits a strong antibiotic activity against plant pathogens and can also induce plant resistance. The experimental subjects employed in this study were Bacillus velezensis HN-2, benzothiadiazole, and dufulin, aiming to evaluate their impact on antioxidant activity, levels of reactive oxygen species, activity of defense enzymes, and expression of defense-related genes in Nicotiana benthamiana. Furthermore, the colonization ability of Bacillus velezensis HN-2 in Capsicum chinense was investigated. The results of bioassays revealed the robust colonization capability of Bacillus velezensis HN-2, particularly in intercellular spaces, leading to delayed infection and enhanced protection against PVMV through multiple plant defense mechanisms, thereby promoting plant growth. Furthermore, Bacillus velezensis HN-2 increased the activities of antioxidant enzymes, thereby mitigating the PVMV-induced ROS production in Nicotiana benthamiana. Moreover, the application of Bacillus velezensis HN-2 at 5 dpi significantly increased the expression of JA-responsive genes, whereas the expression of salicylic acid-responsive genes remained unchanged, implying the activation of the JA signaling pathway as a crucial mechanism underlying Bacillus velezensis HN-2-induced anti-PVMV activity. Immunoblot analysis revealed that HN-2 treatment delayed PVMV infection at 15 dpi, further highlighting its role in inducing plant resistance and promoting growth and development. These findings underscore the potential of Bacillus velezensis HN-2 for field application in managing viral plant diseases effectively.

Feeding specialization shapes the bottom‐up effect of arbuscular mycorrhizal fungi across a plant–aphid–parasitoid system

Societal Impact StatementArbuscular mycorrhizal fungi (AMF) impact the relationships between plants, aphids (insects that feed on plant phloem), and their natural enemies (insects that prey on or parasitize aphids). The presence of AMF influences the growth and population of different aphid species and affects the development of aphid‐killing wasps and their attraction to plants. This research has been conducted also considering the insects' feeding strategy and their feeding specialization. This study provides novel perspectives on how these fungi shape interactions in the natural world, offering potential insights for the development of sustainable pest management strategies in agriculture.Summary Arbuscular mycorrhizal fungi (AMF) are major root symbionts regulating plant physiology. Their presence affects the performance of aboveground insect herbivores in relation to their feeding strategy and their feeding specialization. For example, the effect of the arbuscular mycorrhizal (AM) symbiosis on chewing insects, positive for specialists and negative for generalists, has been previously demonstrated. Conversely, the impact of AMF on phloem‐suckers with relatively different levels of specialization remains unexplored. We tested the influence of the AM Funneliformis mosseae on the fitness of the specialist aphid Acyrthosiphon pisum and the generalist aphid Myzus persicae on Vicia faba plants. Further, we investigated the effects of AMF on the higher trophic level, the aphid parasitoids Aphidius ervi (specialist) and Aphidius colemani (generalist), by evaluating plant attractiveness and parasitoid fitness. To support the results of behavioral and biological bioassays we characterized the photosynthetic parameters, the volatilome and the transcriptome of tested plants. Mycorrhizal plants proved unsuitable for the generalist M. persicae but enhanced the fitness of the specialist A. pisum. The AM symbiosis had no effects on the behavioral response of A. colemani and enhanced the attraction and fitness of A. ervi. Volatilome and transcriptome profiling corroborated the results of bioassay highlighting a bottom‐up effect of the AMF across a plant–aphid–parasitoid system.

In vitro potential control of white root fungus in nutmeg (Myristica fragrans) based on botanical fungicide of coconut shell liquid smoke

Nutmeg (Myristica fragrans) is spice plant which has an important position as a source of essential oils. An important problem in nutmeg cultivation is white root disease which can reduce nutmeg production. Until now, white root disease is still a problem in nutmeg plantations in South Aceh district. One of the solution that can be explored as an environmentally friendly control measure is to use the botanical fungicide coconut shell liquid smoke. This research aims to determine the potential of coconut shell liquid smoke in controlling white root fungus in vitro. The research was carried out in the Plant Protection Laboratory, Faculty of Agriculture, Teuku Umar University. The research design used was a non-factorial Completely Randomized Design (CRD) consisting of nine levels of liquid smoke concentration treatment; control 0%, 0.5%, 1%, 2%, 3%, 4%, 6%, 8%, 10%. Each treatment involved three replications. Data analysis was carried out using analysis of variance and Tukey's least significant difference (HSD) test.The research stages carried out consisted of producing coconut shell liquid smoke, isolating white root fungus from the roots of infected nutmeg plants and potential assay of liquid smoke in inhibiting the growth of white root fungus. In vitro bioassay result showed that liquid smoke treatment 3% was the best treatment because it was the lowest concentration causing total inhibition of the growth of white root fungus.

Development and performance evaluation of a microbiological method for screening and LC-MS/MS for conformation of sulfonamides in animal-derived foods

This study developed a highly sensitive microbiological method utilizing a novel microtiter plate to screen 10 sulfonamides in chicken muscles, eggs, and prawns. This plate was fabricated from agar incorporating trimethoprim and spread with Bacillus megaterium. After residue detection by bioassay, the same test solutions were analyzed by LC-MS/MS for accurate identification and quantification. It also proved eco-friendly compared to using other quantitative methods. The residual drugs were extracted with McIlvaine buffer and purified using an Oasis® MCX cartridge. A triethylamine/methanol/water (0.5:75:24.5, v/v/v) mixture was used as the eluate. The obtained LOD values of the bioassay ranged from 5 to 25 µg kg−1 allowing the detection of the target drugs at the MRLs established in Japan. Adhering to ISO/IEC 17025 standards, the performance of the bioassay was evaluated. Based on the inhibition zone size in bioassay results, quality control yielded a Z score within ±2, indicating reasonable control over the screening process. Proficiency testing of a chicken muscle sample spiked with sulfadimidine demonstrated the inhibition zone detection of the bioassay and quantified value alignment of LC-MS/MS with reference values. In a surveillance study of 91 samples, sulfamethoxazole was detected in one prawn sample.

Assessing human carcinogenicity risk of agrochemicals without the rodent cancer bioassay.

The rodent cancer bioassays are conducted for agrochemical safety assessment yet they often do not inform regulatory decision-making. As part of a collaborative effort, the Rethinking Carcinogenicity Assessment for Agrochemicals Project (ReCAAP) developed a reporting framework to guide a weight of evidence (WOE)-based carcinogenicity assessment that demonstrates how to fulfill the regulatory requirements for chronic risk estimation without the need to conduct lifetime rodent bioassays. The framework is the result of a multi-stakeholder collaboration that worked through an iterative process of writing case studies (in the form of waivers), technical peer reviews of waivers, and an incorporation of key learnings back into the framework to be tested in subsequent case study development. The example waivers used to develop the framework were written retrospectively for registered agrochemical active substances for which the necessary data and information could be obtained through risk assessment documents or data evaluation records from the US EPA. This exercise was critical to the development of a framework, but it lacked authenticity in that the stakeholders reviewing the waiver already knew the outcome of the rodent cancer bioassay(s). Syngenta expanded the evaluation of the ReCAAP reporting framework by writing waivers for three prospective case studies for new active substances where the data packages had not yet been submitted for registration. The prospective waivers followed the established framework considering ADME, potential exposure, subchronic toxicity, genotoxicity, immunosuppression, hormone perturbation, mode of action (MOA), and all relevant information available for read-across using a WOE assessment. The point of departure was estimated from the available data, excluding the cancer bioassay results, with a proposed use for the chronic dietary risk assessment. The read-across assessments compared data from reliable registered chemical analogues to strengthen the prediction of chronic toxicity and/or tumorigenic potential. The prospective case studies represent a range of scenarios, from a new molecule in a well-established chemical class with a known MOA to a molecule with a new pesticidal MOA (pMOA) and limited read-across to related molecules. This effort represents an important step in establishing criteria for a WOE-based carcinogenicity assessment without the rodent cancer bioassay(s) while ensuring a health protective chronic dietary risk assessment.

UDP-Glycosyltransferases UGT350C3 and UGT344L7 Confer Tolerance to Neonicotinoids in Field Populations of Aphis gossypii.

The cotton aphid, Aphis gossypii, is a polyphagous pest that stunts host plant growth via direct feeding or transmitting plant virus. Due to the long-term application of insecticides, A. gossypii has developed different levels of resistance to numerous insecticides. We found that five field populations had evolved multiple resistances to neonicotinoids. To explore the resistance mechanism mediated by uridine diphosphate glycosyltransferases (UGTs), two upregulated UGT genes in these five strains, UGT350C3 and UGT344L7, were selected for functional analysis of their roles in neonicotinoid detoxification. Transgenic Drosophila bioassay results indicated that compared with the control lines, the UGT350C3 and UGT344L7 overexpression lines were more tolerant to thiamethoxam, imidacloprid, and dinotefuran. Knockdown of UGT350C3 and UGT344L7 significantly increased A. gossypii sensitivity to thiamethoxam, imidacloprid, and dinotefuran. Molecular docking analysis demonstrated that these neonicotinoids could bind to the active pockets of UGT350C3 and UGT344L7. This study provides functional evidence of neonicotinoid detoxification mediated by UGTs and will facilitate further work to identify strategies for preventing the development of neonicotinoid resistance in insects.

Physical design for microfluidic biochips considering actual volume management and channel storage

In recent years, microfluidic biochips have been widely applied in various fields of human society. The optimization design of system-architecture based on continuous-flow microfluidic biochips has been widely studied. However, most previous work was based on the traditional chip architecture with dedicated storage, which not only limits the performance of biochips but also increases their manufacturing costs. In order to improve the execution efficiency and reduce the manufacturing cost, a distributed channel-storage architecture can be used to temporarily cache intermediate fluids in idle flow channels. Under this architecture, careful consideration of the volume management of the fluid to be cached is a prerequisite for ensuring the reliability of bioassay results. However, the existing work has not considered the volume management of the fluid to be cached in detail. This may cause the volume of the fluid to not match the capacity of the storage channel, which can contaminate other fluids and lead to incorrect bioassay results or increase the manufacturing cost of biochips due to long storage channels. In this paper, we propose a physical design method for microfluidic biochips that considers the actual volume of fluid while utilizing distributed channel storage. We address this problem by taking a placement and routing co-design strategy throughout the iterative process of the simulated annealing algorithm. Experimental results under multiple benchmarks show that the proposed method can effectively reduce the completion time of bioassays, minimize the flow path length, and decrease the number of intersections.

Unpacking WHO and CDC Bottle Bioassay Methods: A Comprehensive Literature Review and Protocol Analysis Revealing Key Outcome Predictors.

Resistance monitoring is a key element in controlling vector-borne diseases. The World Health Organization (WHO) and Centres for Disease Control and Prevention (CDC) have each developed bottle bioassay methods for determining insecticide susceptibility in mosquito vectors which are used globally. This study aimed to identify variations in bottle bioassay methodologies and assess the potential impact on the data that is generated. Our approach involved a systematic examination of existing literature and protocols from WHO and CDC, with a focus on the specifics of reported methodologies, variation between versions, and reported outcomes. Building on this, we experimentally evaluated the impact of several variables on bioassay results. Our literature review exposed a significant inconsistency in the how bioassay methods are reported, hindering reliable interpretation of data and the ability to compare results between studies. The experimental research provided further insight by specifically identifying two key factors that influence the outcomes of bioassays: mosquito dry weight and relative humidity (RH). This finding not only advances our comprehension of these assays but also underscores the importance of establishing precisely defined methodologies for resistance monitoring. The study also demonstrates the importance of controlling bioassay variables, noting the significant influence of wing length, as an indicator of mosquito size, on mortality rates in standardized bioassays. Generating data with improved protocol consistency and precision will not only deepen our understanding of resistance patterns but also better inform vector control measures. We call for continued research and collaboration to refine and build consensus on bioassay techniques, to help bolster the global effort against vector-borne diseases like malaria.

Synthesis, Nematicidal Activity, and Molecular Docking of Some New Pyrazole-5- carboxamide Derivatives with Flexible Chain

A series of new pyrazole-5-carboxamide derivatives was synthesized containing flexible chain moiety. The synthetic route involved four-step approach starting from ethyl 3-ethyl-1-methyl-1H-pyrazole-5-carboxylate (1). The primarily nematicidal bioassay results have shown that some of them exhibited moderate activity against Meloidogyne incognita at 10 mg/L. In addition, the molecular docking simulation results indicated that compound 5r interacts with succinate dehydrogenase (SDH) through p-cation, p-p, and hydrogen bond interaction, which may provide useful information to further design novel nematicides.. KEYWORDS :Molecular docking, Nematicidal activity, Pyrazole carboxamide, Synthesis.

Discovery of Novel Spike Inhibitors against SARS-CoV-2 Infection.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the current coronavirus disease pandemic. With the rapid evolution of variant strains, finding effective spike protein inhibitors is a logical and critical priority. Angiotensin-converting enzyme 2 (ACE2) has been identified as the functional receptor for SARS-CoV-2 viral entry, and thus related therapeutic approaches associated with the spike protein-ACE2 interaction show a high degree of feasibility for inhibiting viral infection. Our computer-aided drug design (CADD) method meticulously analyzed more than 260,000 compound records from the United States National Cancer Institute (NCI) database, to identify potential spike inhibitors. The spike protein receptor-binding domain (RBD) was chosen as the target protein for our virtual screening process. In cell-based validation, SARS-CoV-2 pseudovirus carrying a reporter gene was utilized to screen for effective compounds. Ultimately, compounds C2, C8, and C10 demonstrated significant antiviral activity against SARS-CoV-2, with estimated EC50 values of 8.8 μM, 6.7 μM, and 7.6 μM, respectively. Using the above compounds as templates, ten derivatives were generated and robust bioassay results revealed that C8.2 (EC50 = 5.9 μM) exhibited the strongest antiviral efficacy. Compounds C8.2 also displayed inhibitory activity against the Omicron variant, with an EC50 of 9.3 μM. Thus, the CADD method successfully discovered lead compounds binding to the spike protein RBD that are capable of inhibiting viral infection.

Homologous Design and Three-Dimensional Quantitative Structure-Activity Relationship Study of Acaricidal 2,4-Diphenyloxazolines Containing Different Heteroatoms and Alkyl Chains.

In order to speculate the three-dimensional structure of the potential binding pocket of the chitin synthase inhibitor, a series of 2,4-diphenyloxazoline derivatives with different lengths of alkyl chains and heteroatoms were designed and synthesized by a homologous strategy. The bioassay results indicate that both the length of the alkyl chains and the type of substituents can affect the acaricidal activity against mite eggs. Compounds containing chloropropyl, alkoxyalkyl, and para-substituted phenoxyalkyl or phenylthioalkyl groups exhibit good activity, while those containing steric hindrance substituents or carbonyl substituents on the benzene ring exhibit reduced activity. Three-dimensional quantitative structure-activity relationship (3D-QSAR) study showed that there may be a narrow hydrophobic region deep in the pocket, and the steric effect plays a more important role than the electrostatic effect. The current work will provide assistance for future molecular design and target binding research.

High enrichment factors in chemical analysis of progestins and in bioassays: insights beyond trace levels.

Concerns are growing about adverse effects of progestins on biota, even at ultra-trace concentrations. The enrichment factor (EF) from extraction of analytes in environmental samples that is needed for sample pre-concentration can affect not only performance of the analytical method but also the matrix effect. Therefore, the present study aimed to assess the influence of high sample EF on performance of the high-performance liquid chromatography with atmospheric pressure chemical ionization and photoionization coupled with high-resolution mass spectrometry (HPLC-APCI/APPI-HRMS) method for analysis of progestins in waste water treatment plant (WWTP) effluents and surface waters and analysis of (anti-)progestogenic activities measured by (anti-)PR-CALUX bioassays. The results showed that HPLC-APCI/APPI-HRMS coupled with solid-phase extraction and a high EF (33,333 Lwater/Lextract) enabled the detection of more compounds compared to samples with lower sample EF (10,000 Lwater/Lextract). The matrix effect did not increase proportionally compared to lower EFs (10,000 and 16,666 Lwater/Lextract), and lower limits of quantification were achieved in WWTP effluents and surface waters. The results of bioassays have shown that relative EF of 25 Lwater/Lbioassay appears high enough to detect progestogenic activity in treated waste water. Our study is one of the first to provide insights into sample pre-concentration in analysis of progestins and progestogenicity in aquatic environments.

Synthesis and Antifungal Activity of Norbornene Carboxamide/sulfonamide Derivatives as Potential Fungicides Targeting Laccase.

To explore more potential fungicides with new scaffolds, thirty-seven norbornene carboxamide/sulfonamide derivatives were designed, synthesized, and assayed for inhibitory activity against six plant pathogenic fungi and oomycetes. The preliminary antifungal assay suggested that the title derivatives showed moderate to good antifungal activity against six plant pathogens. Especially, compound 6 e presented excellent in vitro antifungal activity against Sclerotinia sclerotiorum (EC50=0.71 mg/L), which was substantially stronger than pydiflumetofen. In vivo antifungal assay indicated 6 e displayed prominent protective and curative effects on rape leaves infected by S. sclerotiorum. The preliminary mechanism research displayed that 6 e could damage the surface morphology and inhibit the sclerotia formation of S. sclerotiorum. In addition, the in vitro enzyme inhibition bioassay indicated that 6 e displayed pronounced laccase inhibition activity (IC50=0.63 μM), much stronger than positive control cysteine. Molecular docking elucidated the binding modes between 6 e and laccase. The bioassay results and mechanism investigation demonstrated that this class of norbornene carboxamide/sulfonamide derivatives could be promising laccase inhibitors for novel fungicide development.