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

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.

Assessment of the resistance of highly ornamental plants of autochthonous flora to increased concentrations of pollutants

Aim. The purpose of the work is to assess the resistance of highly decorative plants of the native flora to a high level of salinity and the content of zinc, lead and cadmium for landscaping urban and roadside areas. Methods. We used seed germination under laboratory conditions with soaking in solutions of sodium chloride and salts of zinc, lead and cadmium, as well as the method of in vitro cell selection to increase resistance to salinity of Verbascum nigrum L. Results. The resistance of 7 species of highly decorative plants, representatives of the autochthonous flora of Belarus, to increasing concentrations of lead, zinc and cadmium salts was assessed. Germination capacity, length and morphology of roots, length of seedlings during germination of seeds of Betonica officinalis L., Centaurea jacea L., Verbascum nigrum, Knautia arvensis (L.) Coult., Galium verum L., Anthemis tinctoria L., Anthemis arvensis L., Viscaria vulgaris Bernh., Achillea millefolium L. in the presence of sodium chloride are shown. It has been shown that the in vitro cell selection method is promising for the selection of resistant lines of Verbascum nigrum. Conclusions. The presence of lead, zinc and cadmium salts had a significant effect on the average length of the root, hypocotyl, and cotyledonous leaves, as well as the germination capacity of highly decorative species of autochthonous flora. The most resistant to salinity were yarrow (Achillea millefolium), brown knapweed (Centaurea jacea) and black mullein (Verbascum nigrum). Lines of Verbascum nigrum, capable of growing in vitro at a sodium chloride concentration of 5 g/L, were selected. Keywords: salinity, heavy metals, seed germination, highly decorative species.

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.

Root Responses To Neighbors Depend On Neighbor Identity And Resource Distribution

Purpose: In a complex soil environment, competitive and environmental factors will interact with individual traits to influence a plant’s root growth patterns and ability to compete for resources. Here, we examine how root growth of a focal plant, Plantago lanceolata L., responds to resource heterogeneity and to presence of two neighbor species, Centaurea jacea L.and Poa pratensis L. Methods: A full factorial experiment tested the effects of nutrient heterogeneity, neighbors, and their interaction on root responses of Plantago. Roots in shared quadrants of a pot were harvested and quantified by qPCR for plants grown alone or with a neighbor, in patchy or even soil. The effects of experimental treatments on Plantago root mass distribution were tested with two-way ANOVA. Results: When soil resources were evenly distributed, Plantago individuals increased root allocation to soil shared with a Centaurea neighbor but not a Poa neighbor. When soil resources were patchy, Plantago responded more strongly to Poa than to Centuarea, and placed more roots in the high-resource patch. Conclusions: These results demonstrate that plants can respond differently to neighbors depending on species and that integrating multiple cues results in non-additive effects on root behavior.

Seed germination ecology of meadow knapweed (Centaurea × moncktonii) populations in New York State, USA

The introduced meadow knapweed (Centaurea × moncktonii C.E. Britton), a hybrid of black (Centaurea nigra L.) and brown (Centaurea jacea L.) knapweeds, is increasingly common in pastures, meadows, and waste areas across many U.S. states, including New York. We evaluated the effects of temperature, light, seed stratification, scarification, and population on percent germination in four experiments over 2 yr. Percent germination ranged from 3% to 100% across treatment combinations. Higher temperatures (30:20, 25:15, and sometimes 20:10 C day:night regimes compared with 15:5 C) promoted germination, especially when combined with the stimulatory effect of light (14:10 h L:D compared with continuous darkness). Under the three lowest temperature treatments, light increased percent germination by 15% to 86%. Cold-wet seed stratification also increased germination rates, especially at lower germination temperatures, but was not a prerequisite for germination. Scarification did not increase percent germination. Differences between C. × moncktonii populations were generally less significant than differences between temperature, light, and stratification treatments. Taken together, these results indicate that C. × moncktonii is capable of germinating under a broad range of environments, which may have facilitated this species’ range expansion in recent decades. However, C. × moncktonii also shows evidence of germination polymorphism: some seeds will germinate under suboptimal conditions, while others may remain dormant until the abiotic environment improves. Subtle differences in dormancy mechanisms and their relative frequencies may affect phenological traits like the timing of seedling emergence and ultimately shape the sizes and ranges of C. × moncktonii populations.

ANTIMICROBIAL ACTIVITY AND PHYTOTOXICITY OF EXTRACTS OF SOME SPECIES OF GENUS CENTAUREA PLANTS

The article presents data on the phytochemical composition and biological activity of extracts of plants of the genus Cornflower (Centaurea L.) - blue cornflower (Centaurea cyanus L.), meadow cornflower (Centaurea jacea L.), rough cornflower (Centaurea scabiosa L.), which are typical representatives flora of the middle zone of the Russian Federation, to assess the potential effectiveness of their use as plant protection drugs against phytopathogenic infections. The ethanol extracts were obtained by maceration of freshly harvested flowers, followed by filtration of the extract and concentration with the help of a rotary evaporator. The chemical composition of ethanol extracts was studied with the help of the gas chromatography/mass spectrometry (GC/MS) method. The qualitative and quantitative composition of the components differed depending on the plant types. The largest number of compounds was identified in the plant extract of cornflower rough, the seven components prevailing – coumaran, L-arctigenin, stigmasterol, γ-sitosterol, α-amyrin, β-amyrin and tocopherol acetate. The bacteriostatic, bactericidal and fungicidal properties of the extracts varied over a wide concentration range of 0.6...20 mg/ml. The highest indicators of antibacterial activity were found in the rough cornflower - the minimum inhibiting and bactericidal concentrations were 0.6…5 mg/ml, the lowest in the meadow cornflower - 5...20 mg/ml, respectively. Clavibacter michiganensis was characterized by the highest sensitivity to the components of plant extracts. In the case of the phytopathogenic fungus, the growth-inhibiting antimicrobial activity of cornflower extracts was the same for all studied species, and the fungicidal activity was most pronounced in the meadow cornflower - the effective concentration was 1 mg/ml. Presowing treatment with ethanol extracts had an inhibitory effect on the germination of test plant seeds: at a concentration of 1 mg/ml, the germination of watercress decreased by 8...42% compared to the control, 10 mg/ml - by 30...100%. Presowing seed treatment inhibited the linear growth of watercress roots by 35...52% and the accumulation of raw biomass of seedlings and roots by 23...89%.

ANTIRADICAL ACTIVITY OF EXTRACTS FROM SIBERIAN FLORA GENUS CENTAUREA PLANTS

The purpose of this research is to study the antiradical activity of various extracts from the Centaurea scabiosa L. aerial part (wild-growing and cultivated) and Centaurea jacea L. as potential sources of antioxidant herbal remedies. In the study of the antiradical activity of extracts from the aerial part of Centaurea jacea L., Centaurea scabiosa L. wild growing and cultivated, in the reaction with a stable diphenylpicrylhydrazyl radical, it was found that the degree of antiradical activity within each species correlates with the quantitative content of flavonoids. Lower values ​​of the antiradical activity of cultivated Centaurea scabiosa L. extracts compared to wild growing Centaurea scabiosa L. extracts are consistent with a lower content of flavonoids in the latter. The dependence of the Centaurea jacea L. and wild growing Centaurea scabiosa L. extracts antiradical activity on flavonoids quantitative and qualitative composition of these species has been established.