Pollinator visitation closely tracks diurnal patterns in pollen release.

PREMISE: Animal-pollinated plants face a high risk of pollen loss during its transfer. To limit the negative effect of pollen losses by pollen consumption and heterospecific transfer, plant species may adjust and stratify their pollen availability during the day (i.e., "schedule" their pollen presentation) and attract pollinators in specific time frames. METHODS: We investigated diurnal patterns of pollen availability and pollinator visitation in three coflowering plant species: Succisa pratensis with open flowers and accessible pollen, pollinated mainly by pollen-feeding hoverflies; Centaurea jacea with open flowers and less accessible pollen, pollinated mainly by pollen-collecting bees; and Trifolium hybridum with closed flowers and pollen accessible only after the active opening of the flower, pollinated exclusively by bees. RESULTS: The three plant species differed in the peak pollen availability, tracked by the visitation activity of their pollinators. Succisa pratensis released all pollen in the morning, while pollinator activity was still low and peaked with a slight delay. In contrast, C. jacea and T. hybridum had distinct pollen presentation schedules, peaking in the early afternoon. The pollinator visitation to both of these species closely matched their pollen availability. CONCLUSIONS: Stratifying pollen availability to pollinators during the day may be one of several mechanisms that allow coflowering plants to share their pollinators and decrease the probability of heterospecific pollen transfer.

A threefold approach including quantum chemical, molecular docking and molecular dynamic studies to explore the natural compounds from Centaurea jacea as the potential inhibitors for COVID-19 / Uma abordagem tríplice incluindo química quântica, docking molecular e estudos dinâmicos moleculares para explorar os compostos naturais de Centaurea jacea como inibidores potenciais para Covid-19

In the current report, we studied the possible inhibitors of COVID-19 from bioactive constituents of Centaurea jacea using a threefold approach consisting of quantum chemical, molecular docking and molecular dynamic techniques. Centaurea jacea is a perennial herb often used in folk medicines of dermatological complaints and fever. Moreover, anticancer, antioxidant, antibacterial and antiviral properties of its bioactive compounds are also reported. The Mpro (Main proteases) was docked with different compounds of Centaurea jacea through molecular docking. All the studied compounds including apigenin, axillarin, Centaureidin, Cirsiliol, Eupatorin and Isokaempferide, show suitable binding affinities to the binding site of SARS-CoV-2 main protease with their binding energies -6.7 kcal/mol, -7.4 kcal/mol, -7.0 kcal/mol, -5.8 kcal/mol, -6.2 kcal/mol and -6.8 kcal/mol, respectively. Among all studied compounds, axillarin was found to have maximum inhibitor efficiency followed by Centaureidin, Isokaempferide, Apigenin, Eupatorin and Cirsiliol. Our results suggested that axillarin binds with the most crucial catalytic residues CYS145 and HIS41 of the Mpro, moreover axillarin shows 5 hydrogen bond interactions and 5 hydrophobic interactions with various residues of Mpro. Furthermore, the molecular dynamic calculations over 60 ns (6×106 femtosecond) time scale also shown significant insights into the binding effects of axillarin with Mpro of SARS-CoV-2 by imitating protein like aqueous environment. From molecular dynamic calculations, the RMSD and RMSF computations indicate the stability and dynamics of the best docked complex in aqueous environment. The ADME properties and toxicity prediction analysis of axillarin also recommended it as safe drug candidate. Further, in vivo and in [...].

No presente relatório, estudamos os possíveis inibidores de Covid-19 de constituintes bioativos de Centaurea jacea usando uma abordagem tripla que consiste em técnicas de química quântica, docking molecular e dinâmica molecular. Centaurea jacea é uma erva perene frequentemente usada em remédios populares de doenças dermatológicas e febre. Além disso, as propriedades anticâncer, antioxidante, antibacteriana e antiviral de seus compostos bioativos também são relatadas. A Mpro (proteases principais) foi acoplada a diferentes compostos de Centaurea jacea por meio de docking molecular. Todos os compostos estudados, incluindo apigenina, axilarina, Centaureidina, Cirsiliol, Eupatorina e Isokaempferide, mostram afinidades de ligação adequadas ao sítio de ligação da protease principal SARS-CoV-2 com suas energias de ligação -6,7 kcal / mol, -7,4 kcal / mol, - 7,0 kcal / mol, -5,8 kcal / mol, -6,2 kcal / mol e -6,8 kcal / mol, respectivamente. Dentre todos os compostos estudados, a axilarina apresentou eficiência máxima de inibidor, seguida pela Centaureidina, Isokaempferida, Apigenina, Eupatorina e Cirsiliol. Nossos resultados sugeriram que a axilarina se liga aos resíduos catalíticos mais cruciais CYS145 e HIS41 do Mpro, além disso a axilarina mostra 5 interações de ligações de hidrogênio e 5 interações hidrofóbicas com vários resíduos de Mpro. Além disso, os cálculos de dinâmica molecular em uma escala de tempo de 60 ns (6 × 106 femtossegundos) também mostraram percepções significativas sobre os efeitos de ligação da axilarina com Mpro de SARS-CoV-2 por imitação de proteínas como o ambiente aquoso. A partir de cálculos de dinâmica molecular, os cálculos RMSD e RMSF indicam a estabilidade e dinâmica do melhor complexo ancorado em ambiente [...].

A threefold approach including quantum chemical, molecular docking and molecular dynamic studies to explore the natural compounds from Centaurea jacea as the potential inhibitors for COVID-19

Abstract In the current report, we studied the possible inhibitors of COVID-19 from bioactive constituents of Centaurea jacea using a threefold approach consisting of quantum chemical, molecular docking and molecular dynamic techniques. Centaurea jacea is a perennial herb often used in folk medicines of dermatological complaints and fever. Moreover, anticancer, antioxidant, antibacterial and antiviral properties of its bioactive compounds are also reported. The Mpro (Main proteases) was docked with different compounds of Centaurea jacea through molecular docking. All the studied compounds including apigenin, axillarin, Centaureidin, Cirsiliol, Eupatorin and Isokaempferide, show suitable binding affinities to the binding site of SARS-CoV-2 main protease with their binding energies -6.7 kcal/mol, -7.4 kcal/mol, -7.0 kcal/mol, -5.8 kcal/mol, -6.2 kcal/mol and -6.8 kcal/mol, respectively. Among all studied compounds, axillarin was found to have maximum inhibitor efficiency followed by Centaureidin, Isokaempferide, Apigenin, Eupatorin and Cirsiliol. Our results suggested that axillarin binds with the most crucial catalytic residues CYS145 and HIS41 of the Mpro, moreover axillarin shows 5 hydrogen bond interactions and 5 hydrophobic interactions with various residues of Mpro. Furthermore, the molecular dynamic calculations over 60 ns (6×106 femtosecond) time scale also shown significant insights into the binding effects of axillarin with Mpro of SARS-CoV-2 by imitating protein like aqueous environment. From molecular dynamic calculations, the RMSD and RMSF computations indicate the stability and dynamics of the best docked complex in aqueous environment. The ADME properties and toxicity prediction analysis of axillarin also recommended it as safe drug candidate. Further, in vivo and in vitro investigations are essential to ensure the anti SARS-CoV-2 activity of all bioactive compounds particularly axillarin to encourage preventive use of Centaurea jacea against COVID-19 infections.

Resumo No presente relatório, estudamos os possíveis inibidores de Covid-19 de constituintes bioativos de Centaurea jacea usando uma abordagem tripla que consiste em técnicas de química quântica, docking molecular e dinâmica molecular. Centaurea jacea é uma erva perene frequentemente usada em remédios populares de doenças dermatológicas e febre. Além disso, as propriedades anticâncer, antioxidante, antibacteriana e antiviral de seus compostos bioativos também são relatadas. A Mpro (proteases principais) foi acoplada a diferentes compostos de Centaurea jacea por meio de docking molecular. Todos os compostos estudados, incluindo apigenina, axilarina, Centaureidina, Cirsiliol, Eupatorina e Isokaempferide, mostram afinidades de ligação adequadas ao sítio de ligação da protease principal SARS-CoV-2 com suas energias de ligação -6,7 kcal / mol, -7,4 kcal / mol, - 7,0 kcal / mol, -5,8 kcal / mol, -6,2 kcal / mol e -6,8 kcal / mol, respectivamente. Dentre todos os compostos estudados, a axilarina apresentou eficiência máxima de inibidor, seguida pela Centaureidina, Isokaempferida, Apigenina, Eupatorina e Cirsiliol. Nossos resultados sugeriram que a axilarina se liga aos resíduos catalíticos mais cruciais CYS145 e HIS41 do Mpro, além disso a axilarina mostra 5 interações de ligações de hidrogênio e 5 interações hidrofóbicas com vários resíduos de Mpro. Além disso, os cálculos de dinâmica molecular em uma escala de tempo de 60 ns (6 × 106 femtossegundos) também mostraram percepções significativas sobre os efeitos de ligação da axilarina com Mpro de SARS-CoV-2 por imitação de proteínas como o ambiente aquoso. A partir de cálculos de dinâmica molecular, os cálculos RMSD e RMSF indicam a estabilidade e dinâmica do melhor complexo ancorado em ambiente aquoso. As propriedades ADME e a análise de previsão de toxicidade da axilarina também a recomendaram como um candidato a medicamento seguro. Além disso, as investigações in vivo e in vitro são essenciais para garantir a atividade anti-SARS-CoV-2 de todos os compostos bioativos, particularmente a axilarina, para encorajar o uso preventivo de Centaurea jacea contra infecções por Covid-19.

A threefold approach including quantum chemical, molecular docking and molecular dynamic studies to explore the natural compounds from Centaurea jacea as the potential inhibitors for COVID-19 / Uma abordagem tríplice incluindo química quântica, docking molecular e estudos dinâmicos moleculares para explorar os compostos naturais de Centaurea jacea como inibidores potenciais para Covid-19

Abstract In the current report, we studied the possible inhibitors of COVID-19 from bioactive constituents of Centaurea jacea using a threefold approach consisting of quantum chemical, molecular docking and molecular dynamic techniques. Centaurea jacea is a perennial herb often used in folk medicines of dermatological complaints and fever. Moreover, anticancer, antioxidant, antibacterial and antiviral properties of its bioactive compounds are also reported. The Mpro (Main proteases) was docked with different compounds of Centaurea jacea through molecular docking. All the studied compounds including apigenin, axillarin, Centaureidin, Cirsiliol, Eupatorin and Isokaempferide, show suitable binding affinities to the binding site of SARS-CoV-2 main protease with their binding energies -6.7 kcal/mol, -7.4 kcal/mol, -7.0 kcal/mol, -5.8 kcal/mol, -6.2 kcal/mol and -6.8 kcal/mol, respectively. Among all studied compounds, axillarin was found to have maximum inhibitor efficiency followed by Centaureidin, Isokaempferide, Apigenin, Eupatorin and Cirsiliol. Our results suggested that axillarin binds with the most crucial catalytic residues CYS145 and HIS41 of the Mpro, moreover axillarin shows 5 hydrogen bond interactions and 5 hydrophobic interactions with various residues of Mpro. Furthermore, the molecular dynamic calculations over 60 ns (6×106 femtosecond) time scale also shown significant insights into the binding effects of axillarin with Mpro of SARS-CoV-2 by imitating protein like aqueous environment. From molecular dynamic calculations, the RMSD and RMSF computations indicate the stability and dynamics of the best docked complex in aqueous environment. The ADME properties and toxicity prediction analysis of axillarin also recommended it as safe drug candidate. Further, in vivo and in vitro investigations are essential to ensure the anti SARS-CoV-2 activity of all bioactive compounds particularly axillarin to encourage preventive use of Centaurea jacea against COVID-19 infections.

Resumo No presente relatório, estudamos os possíveis inibidores de Covid-19 de constituintes bioativos de Centaurea jacea usando uma abordagem tripla que consiste em técnicas de química quântica, docking molecular e dinâmica molecular. Centaurea jacea é uma erva perene frequentemente usada em remédios populares de doenças dermatológicas e febre. Além disso, as propriedades anticâncer, antioxidante, antibacteriana e antiviral de seus compostos bioativos também são relatadas. A Mpro (proteases principais) foi acoplada a diferentes compostos de Centaurea jacea por meio de docking molecular. Todos os compostos estudados, incluindo apigenina, axilarina, Centaureidina, Cirsiliol, Eupatorina e Isokaempferide, mostram afinidades de ligação adequadas ao sítio de ligação da protease principal SARS-CoV-2 com suas energias de ligação -6,7 kcal / mol, -7,4 kcal / mol, - 7,0 kcal / mol, -5,8 kcal / mol, -6,2 kcal / mol e -6,8 kcal / mol, respectivamente. Dentre todos os compostos estudados, a axilarina apresentou eficiência máxima de inibidor, seguida pela Centaureidina, Isokaempferida, Apigenina, Eupatorina e Cirsiliol. Nossos resultados sugeriram que a axilarina se liga aos resíduos catalíticos mais cruciais CYS145 e HIS41 do Mpro, além disso a axilarina mostra 5 interações de ligações de hidrogênio e 5 interações hidrofóbicas com vários resíduos de Mpro. Além disso, os cálculos de dinâmica molecular em uma escala de tempo de 60 ns (6 × 106 femtossegundos) também mostraram percepções significativas sobre os efeitos de ligação da axilarina com Mpro de SARS-CoV-2 por imitação de proteínas como o ambiente aquoso. A partir de cálculos de dinâmica molecular, os cálculos RMSD e RMSF indicam a estabilidade e dinâmica do melhor complexo ancorado em ambiente aquoso. As propriedades ADME e a análise de previsão de toxicidade da axilarina também a recomendaram como um candidato a medicamento seguro. Além disso, as investigações in vivo e in vitro são essenciais para garantir a atividade anti-SARS-CoV-2 de todos os compostos bioativos, particularmente a axilarina, para encorajar o uso preventivo de Centaurea jacea contra infecções por Covid-19.

Comparative Assessment of the Phytochemical Composition and Biological Activity of Extracts of Flowering Plants of Centaurea cyanus L., Centaurea jacea L. and Centaurea scabiosa L.

The data on the phytochemical composition and biological activity for flowering plant extracts of the genus Centaurea (Knapweed)-cornflower (Centaurea cyanus L.), brown knapweed (Centaurea jacea L.), and greater knapweed (Centaurea scabiosa L.), which are typical representatives of the flora in the middle belt of the Russian Federation, were obtained. For the first time, biologically active substances such as pyranone, coumaran (2,3-dihydrobenzofuran), and 5-hydroxymethylfurfural were identified in ethanol and methanol extracts of Centaurea scabiosa L. by gas chromatography-mass spectrometry. Catechol and α-amyrin were the major components of the ethanol extract from Centaurea cyanus L., and flavone was the major component of Centaurea jacea L. flower extract. The greatest antimicrobial activity against phytopathogens was detected in Centaurea scabiosa L. when extracting freshly harvested flower biomass with methyl tert-butyl ether at room temperature: the minimum inhibitory concentrations were 60-120 µg/mL, the minimum fungicidal concentration was 120 µg/mL, and the minimum bactericidal concentration was 250 µg/mL. The low antioxidant activity of the studied plant extracts was established using the maximum values of Centaurea jacea L. Ethanol extract of Centaurea cyanus L. flowers had low antimicrobial and antioxidant activity. The extracts showed no phytotoxicity to garden cress germination but inhibited the growth of juvenile plants, especially roots. The greatest phytotoxic effect was revealed with methyl tert-butyl ether, where the depression of growth indicators was 35% or more.

Investigating the root plasticity response of Centaurea jacea to soil water availability changes from isotopic analysis.

Root water uptake is a key ecohydrological process for which a physically based understanding has been developed in the past decades. However, due to methodological constraints, knowledge gaps remain about the plastic response of whole plant root systems to a rapidly changing environment. We designed a laboratory system for nondestructive monitoring of stable isotopic composition in plant transpiration of a herbaceous species (Centaurea jacea) and of soil water across depths, taking advantage of newly developed in situ methods. Daily root water uptake profiles were obtained using a statistical Bayesian multisource mixing model. Fast shifts in the isotopic composition of both soil and transpiration water could be observed with the setup and translated into dynamic and pronounced shifts of the root water uptake profile, even in well watered conditions. The incorporation of plant physiological and soil physical information into statistical modelling improved the model output. A simple exercise of water balance closure underlined the nonunique relationship between root water uptake profile on the one hand, and water content and root distribution profiles on the other, illustrating the continuous adaption of the plant water uptake as a function of its root hydraulic architecture and soil water availability during the experiment.

Associations between genomic ancestry, genome size and capitula morphology in the invasive meadow knapweed hybrid complex (Centaurea × moncktonii) in eastern North America.

Plant invasions are prime opportunities for studying hybridization and the nature of species boundaries, but hybrids also complicate the taxonomic treatment and management of introduced taxa. In this study, we use population genomics to estimate the extent of genomic admixture and test for its association with morphology and genome size in a hybrid complex of knapweeds invasive to North America: meadow knapweed (Centaurea × moncktonii) and its parental species (C. jacea and C. nigra). We sampled 20 populations from New York and Vermont, USA, and used genotyping by sequencing to identify single nucleotide polymorphisms in order to estimate genome-wide ancestry and classify individuals into hybrid genotype classes. We then tested for association between degree of genomic introgression and variation in a subset of traits diagnostic for the parental taxa, namely capitula morphology and monoploid genome size. Genomic clustering revealed two clearly defined lineages, as well as many admixed individuals forming a continuous gradation of introgression. Individual assignments to hybrid genotype classes revealed many advanced generation intercrosses and backcrosses, suggesting introgression has been extensive and unimpeded by strong reproductive barriers between taxa. Variation in capitula traits between the two unadmixed, presumed parental, lineages exhibited continuous, and in some cases transgressive, segregation among introgressed hybrids. Genome size was also divergent between lineages, although advanced generation hybrids had smaller genomes relative to additive expectations. Our study demonstrates deep introgression between the porous genomes of a hybrid invasive species complex. In addition to strong associations among genomic ancestry, genome size and morphology, hybrids expressed more extreme phenotypic values for capitula traits and genome size, indicating transgressive segregation, as well as a bias towards smaller genomes, possibly due to genomic downsizing. Future studies will apply these results to experimentally test how introgression, transgressive segregation and genome size reduction interact to confer invasiveness.

Cirsiliol Suppressed Epithelial to Mesenchymal Transition in B16F10 Malignant Melanoma Cells through Alteration of the PI3K/Akt/NF-κB Signaling Pathway.

Malignant melanoma is a highly aggressive form of skin cancer which has a propensity for metastasis. Epithelial mesenchymal transition (EMT) plays a primordial role in the progression of metastatic disease. Metastatic melanoma is resistant to conventional therapies. Hence, researchers have been exploring alternative approaches, including the utility of bioactive phytochemicals to manage metastatic disease. In the present study, we investigated the potential of cirsiliol, a flavonoid isolated from Centaurea jacea L., in modulating the aggressive behavior of B16F10 metastatic melanoma cells, including EMT, and associated molecular mechanisms of action. Cirsiliol was found to be effective in restraining the colony formation and migration of fibronectin-induced B16F10 metastatic melanoma cells. Cirsiliol inhibited the activity and expression of matrix metalloproteinase-9 (MMP-9). Cirsiliol also suppressed the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (also known as Akt)/nuclear factor-κB (NF-κB) signaling pathway which, in turn, caused upregulation of E-cadherin and downregulation of N-cadherin, Snail and Twist. Based on these results, cirsiliol may be considered a promising compound against EMT in the therapeutic management of malignant melanoma.

Secondary metabolites from the aerial parts of Centaurea pannonica (Heuff.) Simonk. from Serbia and their chemotaxonomic importance.

The non polar extract of Centaurea pannonica (Heuff.) Simonk., growing wild in Serbia, was studied and twenty-five compounds including 14 sesquiterpene lactones, 7 flavonoids, 3 lignans and 1 phenylpropanoid glycoside were isolated. All compounds were isolated for the first time from this species. Among them, one germacranolide 2α-hydroxy, 8-dehydroxy 15-O-methacrylate salonitenolide (1) and two guaianolides 2α,8α-dihydroxy-dehydrocostus lactone (2) and pannonin (3) are new natural compounds. The structures of the compounds were established on the basis of spectroscopic analyses (UV, IR, HREIMS and 1D & 2D NMR). The chemical profile of C. pannonica, which belongs to the "Centaurea jacea" group, was compared to previously studied taxa of the same group and used to assess the phylogenetic relationships in the group.

Ecological, morphological and allozymic differentiation between diploid and tetraploid knapweeds (Centaurea jacea) from a contact zone in the Belgian Ardennes.

In the northeastern part of Belgium, the Centaurea jacea complex shows extensive morphological variation and is represented by a diploid (2n = 22) and a tetraploid (2n = 44) cytotype. Polysomic inheritance of allozyme markers in the tetraploids, suggesting autopolyploidy, is here demonstrated for the first time. In order to test whether the two cytotypes occupy distinct habitats and possess different gene pools, patterns of allozymic and morphological variation were investigated in relation to ploidy level and site characteristics in 26 populations from the Belgian Ardennes. The two cytotypes showed a parapatric distribution, the diploids occurring at higher elevations (mostly above 500 m) than the tetraploids (mostly below 500 m). Three mixed populations were found near the contact zone of the two cytotypes. Within the mixed populations no triploid plant and no evidence for gene flow between cytotypes were found, despite widely overlapping flowering periods. The two cytotypes can be distinguished on the basis of morphological traits and enzymatic gene pools. The congruence of morphological and allozymic variation with chromosome numbers suggests a secondary contact between the two cytotypes with limited gene flow between them. The origin and persistence of the parapatric distribution are discussed.