Gram-negative Bacterial Strains Research Articles

Antimicrobial and antibiofilm activity of specialized metabolites isolated from Centaurea hyalolepis.

The discovery of plant-derived compounds that are able to combat antibiotic-resistant pathogens is an urgent demand. Over years, Centaurea hyalolepis attracted considerable attention because of its beneficial medical properties. Phytochemical analyses revealed that Centaurea plant species contain several metabolites, such as sesquiterpene lactones (STLs), essential oils, flavonoids, alkaloids, and lignans.The organic extract of C.hyalolepis plant, collected in Palestine, showed significant antimicrobial properties towards a panel of Gram-negative and Gram-positive bacterial strains when the Minimal Inhibitory Concentration (MIC) values were evaluated by broth microdilution assays. A bio-guided fractionation of the active extract via multiple steps of column and thin layer chromatography allowed us to obtain three main compounds. The isolated metabolites were identified as the STLs cnicin, 11β,13-dihydrosalonitenolide and salonitenolide by spectroscopic and spectrometric analyses. Cnicin conferred the strongest antimicrobial activity among the identified compounds. Moreover, the evaluation of its antibiofilm activity by biomass assays through crystal violet staining revealed almost 30% inhibition of biofilm formation in the case of A. baumannii ATCC 17878 strain. Furthermore, the quantification of carbohydrates and proteins present in the extracellular polymeric substance (EPS) revealed the ability of cnicin to significantly perturb biofilm structure. Based on these promising results, further investigations might open interesting perspectives to its applicability in biomedical field to counteract multidrug resistant infections.

Synthesis and Evaluation of Imidazole Derivatives Bearing Imidazo[2,1-b] [1,3,4]thiadiazole Moiety as Antibacterial Agents.

Drug-resistant infections kill hundreds of thousands of people globally every year. In previous work, we found that tri-methoxy- and pyridine-substituted imidazoles show strong antibacterial activities. The aim of this work was to investigate the antibacterial activities and bacterial resistances of imidazoles bearing an aromatic heterocyclic, alkoxy, or polycyclic moiety on the central ring. Three series of 2-cyclopropyl-5-(5-(6-methylpyridin-2-yl)-2-substituted-1H-imidazol-4- yl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazoles (13a-e, 14a-d, and 15a-f) were synthesized and their antibacterial activity was evaluated. The structures were confirmed by their 1H NMR, 13C NMR, and HRMS spectra. All the synthesized compounds were screened against Gram-positive, Gramnegative, and multidrug-resistant bacterial strains. More than half of the compounds showed moderate or strong antibacterial activity. Among them, compound 13e (MICs = 1-4 μg/mL) showed the strongest activity against Gram-positive and drug-resistant bacteria as well as high selectivity against Gram-negative bacteria. Furthermore, it showed no cytotoxicity against HepG2 cells, even at 100 μM, and no hemolysis at 20 μM. These results indicate that compound 13e is excellent candicate for further study as a potential antibacterial agent.

Microwave-enhanced antibacterial activity of polydopamine-silver hybrid nanoparticles.

The ever-increasing risks posed by antibiotic-resistant bacteria have stimulated considerable interest in the development of novel antimicrobial strategies, including the use of nanomaterials that can be activated on demand and result in irreversible damage to pathogens. Microwave electric field-assisted bactericidal effects on representative Gram-negative and Gram-positive bacterial strains were achieved in the presence of hybrid polydopamine-silver nanoparticles (PDA-Ag NPs) under low-power microwave irradiation using a resonant cavity (1.3 W, 2.45 GHz). A 3-log reduction in the viability of bacterial populations was observed within 30 minutes which was attributed to the attachment of PDA-Ag NPs and associated membrane disruption in conjunction with the production of intra-bacterial reactive oxygen species (ROS). A synergistic effect between PDA and Ag has been demonstrated whereby PDA acts both as an Ag NP carrier and a microwave enhancer. These properties together with the remarkable adhesivity of PDA are opening a route to design of antibacterial adhesives and surface coatings for prevention of biofilm formation.

Phytochemical analysis, antioxidant and antibacterial activity of Pereskia bleo flowers

Pereskia bleo, belongs to the Cactaceae family has been traditionally used for treating various diseases. This study aimed to determine the phytochemical analysis, antibacterial activity, antioxidant activity, total phenolic content, and total flavonoid content of Pereskia bleo flowers. Phytochemical screening revealed the presence of glycoside, alkaloid, flavonoid, saponin, tannin, steroid, and terpenoid. The antioxidant activity test indicated that the crude extract of Pereskia bleo flowers had an average IC50 value of 6 ± 0.4359, confirming positive results in the phenolic content test. The total phenolic content of the Pereskia bleo flower crude extract was calculated as 75.295 mg/g at a concentration of 15.059 μg/ml and absorbance of 0.165. In contrast, the calculated total flavonoid content was 7.385 mg/g at a concentration of 9.477 μg/ml, suggesting the present of flavonoid compounds in the flowers of Pereskia bleo. The antibacterial activity of this sample was also tested using the disc-diffusion method against Gram-negative (Salmonella sp., Pseudomonas sp., E. coli) and Gram-positive (Staphylococcus aureus, Bacillus sp., Staphylococcus epidermidis) bacterial strains. The collected data showed that both 100 μg/ml and 500 μg/ml sample concentrations exhibited potent activity against Salmonella sp. and Pseudomonas sp.

PCR combined with lateral flow dipstick assay (PCR-LFD) for a rapid diagnosis of melioidosis.

Melioidosis is an infectious disease caused by Burkholderia pseudomallei. Septicemic melioidosis patients have a high mortality rate within 48 hours. To develop a polymerase chain reaction (PCR) combined with a lateral flow dipstick (LFD) assay for detection of B. pseudomallei in blood samples. The PCR with wcbG gene primers and a PCR-LFD test were developed. The specificity and sensitivity were determined using the B. pseudomallei and other bacterial DNAs. They were evaluated using 43 B. pseudomallei positive blood samples and another 43 blood samples positive for other microbial infections. The detection limit of the PCR-LFD test was 50 fg of bacterial gDNA or 1.0 CFU per 200 μl of blood. All B. pseudomallei were positive while B. thailandensis and selected gram-negative bacterial strains were negative. The PCR-LFD gave all positives with all 43 B. pseudomallei culture positive patient blood samples and all negative with 43 blood samples that were culture positive for K. pneumoniae, E. gallinarum, E. faecium, E. coli, S. aureus, A. baumannii, A. hydrophila, S. haemolyticus, S. pneumoniae, P. aeruginosa, E. cloacae, S. hominis, E. aerogenes, P. mirabilis, C. neoformans, C. albicans, A. caviae, E. faecalis and K. variicola. The developed PCR-LFD assay provided 100% sensitivity and 100% specificity compared to the conventional blood culture. The technique took only 1.5 hours that is easy and quick to perform compared to the 3-7 days of culture method. The new method of PCR with LFD could facilitate the detection to be a semi-point-of-care testing (POCT).

Chemical Composition and Antibacterial activity of Essential Oils from Fruits of Vismia baccifera and Vismia macrophylla Collected at different Locations in Venezuelan Andes

Background: Genus Vismia (Hipericaceae/Clusiaceae) is distributed mainly in tropical and subtropical areas of Central America and South America although some species have been reported in Africa as well. Species of this genus have been used in traditional medicine to alleviate different ailments such as skin infections, to treat urinary tract disorders, as antirrheumatic, antipyretic, among others. Previous investigations have revealed that species from Vismia genus are composed mainly of terpenes, anthrones, lignans, flavonoids, anthraquinones, steroids and xanthones. The purpose of the investigation was to determine the chemical composition and antimicrobial activity of essential oils from the fruits of V. baccifera and V. macrophylla collected in Venezuelan Andes. Methods: Vimia species were collected at different locations in Mérida and Táchira state, Venezuela. Essential oils were obtained through Hidrodistilation and chemical compositon was performed by GC and GC/MS techniques. Antimicrobial analysis was carried out by disc diffusion assays. Results: GC and GC/MS analysis showed that these species are mainly composed of sesquiterpenes being α-curcumene, β-curcumene, germacrene D, γ-bisabolene and β-caryophyllene among the major components. Antimicrobial activity was also performed with species under investigation. Results showed a broad spectrum of activity since both species were able to inhibit not only Gram- positive (Stpahylococcus aureus, Enterococcus faecalis) and Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa) but yeast (Candida albicans and Candida krusei) as well. Conclusions: According to the results observed in the investigation, Vismia species might be considered as an alternative to aid infectious diseases.

Antioxidant and antimicrobial potential of compounds isolated from Carissa opaca

Carissa opaca Stapf ex Haines is an edible fruit plant (Apocynaceae) traditionally used for the treatment of asthma, fever, diarrhea, hepatitis and cardiac problems. Five compounds named Naringin, Prunin, Ursolic acid, Uvaol and Procrim a, were isolated from C. opaca and tested for their antioxidant, and antimicrobial properties. Antioxidant activity was performed against various radicals i.e. DPPH, ABTS, –O2, –OH and non-radical e.g. H2O2. Naringin, Prunin and Ursolic acid were highly active against these radicals with significant IC50 values. All compounds were tested for their antibacterial activity against various Gram-positive and Gram-negative bacterial strains. All compounds were displaying MIC values in promising ranges. Antifungal activity was also determined using various fungal strains e.g. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and Fusarium solani. Naringin and Ursolic acid expressed significant inhibition of growth all fungal strains. It is concluded that these biologically active compounds isolated from edible plant C. opaca can be used against various free radical and infectious diseases.

Simple co-precipitation synthesis of activated carbon-cobalt ferrite (AC-CoFe2O4) nanocomposites: enhanced photocatalytic dye degradation and antimicrobial activity

Abstract In this present work, spinel cobalt ferrite nanoparticles (CoFe2O4 NPs) and activated carbon-CoFe2O4 nanocomposites (AC-CoFeO4 NCs) were synthesized by simple co-precipitation method and used for photocatalytic dye degradation (PCD) of rhodamine-B (Rh-B) dye. The antimicrobial study of the as-synthesized CoFe2O4 NPs was also performed. The as-synthesized CoFe2O4 NPs and AC-CoFe2O4 NCs were analyzed by ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) studies, scanning electron spectroscopy (FE-SEM) techniques. Powder XRD analysis showed that the as-synthesized CoFeO4 NPs and AC-CoFeO4 NCs had average particle size of 18 nm and 46 nm, respectively. The FE-SEM showed that the CoFe2O4 samples have sphere like morphology and were well decorated on activated carbon in order to provide high surface area. AC-CoFe2O4 NCs have effectively used for the PCD of Rh-B dye with high efficiency. Furthermore, spinel CoFe2O4 NPs acted as a more effective antimicrobial agent against Gram-negative and Gram-positive bacterial strains. Moreover, AC-CoFe2O4 NCs can be used as the precursor materials for supercapacitor, sensors etc.

Moraxella haemolytica sp. nov., isolated from a goat with respiratory disease.

An aerobic, haemolytic, Gram-negative and rod-shaped bacterial strain ZY171148T was isolated from the lung of a dead goat with respiratory disease in Southwest China. The strain grew at 24-39°C, at pH 6.0-9.0 and in the presence of 0.5-2.0% (w/v) NaCl. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belongs to the genus Moraxella. The nucleotide sequence similarity analysis of the 16S rRNA gene showed that the strain has the highest similarity of 98.1% to Moraxella (M.) caprae ATCC 700019T. Phylogenomic analysis of 800 single-copy protein sequences indicated that the strain is a member of the genus Moraxella and forms a separated branch on the Moraxella phylogenetic tree. The strain exhibited the highest orthologous average nucleotide identity (OrthoANI) and average amino acid identity (AAI) values of 77.0 and 77.9% to M. nasibovis CCUG 75921T and M. ovis CCUG 354T, respectively. The strain shared the highest digital DNA-DNA hybridization (dDDH) value of 26.2% to M. osloensis CCUG 350T. The genome G + C content of strain ZY171148T was 42.6mol%. The strain had C18:1 ω9c (41.7%), C18:0 (11.2%), C16:0 (14.1%) and C12:0 3OH (9.7%) as the predominant fatty acids and CoQ-8 as the major respiratory quinone. The strain contained phosphatidylglycerol, phosphatidylethanolamine, cardiolipin, dilysocardiolipin, monolysocardiolipin and phosphatidic acid as the major polar lipids. β-haemolysis was observed on Columbia blood agar. All results confirmed that strain ZY171148T represents a novel species of the genus Moraxella, for which the name Moraxella haemolytica sp. nov. is proposed, with strain ZY171148T = CCTCC AB 2021471T = CCUG 75920T as the type strain.

Physicochemical contrivance for exploring host-guest inclusion complex of a significant green solvent with a cyclic oligosaccharide and its innovative application optimized by computational approach

Abstract Our modern study is going to inspect new inclusion phenomena between the 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [Bdmim]BF4 ionic liquid (IL) and the host α-Cyclodextrin (α-CD) by a 1:1 ratio and newly formed inclusion complex was further explored by the 1H-NMR, FT-IR, UV–vis spectroscopy, PXRD, DSC, and SEM analysis. Molecular docking was also performed to investigate the encapsulation of the inclusion complex in which orientation and it have been seen that the IL [Bdmim]BF4 enters into the α-CD cavity with a 1:1 ratio was further established with the help of Job’s plot. Furthermore, the antibacterial activity of [Bdmim]BF4 IL and its inclusion complex was verified against some Gram-positive and Gram-negative bacterial strains.

Phenolic compounds and antimicrobial activity of leaves of the genus Sorbus species and natural hybrids

The identification of new sources of biologically active substances is an actual direction of research in recent years, in particular, the demand for antimicrobial compounds and natural preservatives of plant origin is growing. Plants of the genus Sorbus L. are known in folk medicine, but for the rational use of plant material, there is a lack of systematic study of the features of the secondary metabolites’ accumulation and the spectrum of biological activity of plants during vegetation in different environmental conditions. In the present work, the seasonal dynamics of the total content of polyphenols, flavonoids and free phenolic acids in the leaves of rowan plants natural to the flora of Ukraine and introduced in the steppe region were investigated. The highest accumulation of phenolic compounds was found in the leaves of S. domestica, S. latifolia, S. hybrida, S. torminalis and S. aucuparia in the first half of June, and in S. aria and S. intermedia in May, which will serve as a criterion for selecting the best plant material to obtain biologically active compounds. The seasonal dynamics of the content of flavonoids and phenolic acids in the leaves of plants had significant species differences, which require more in-depth studies of the phytocompounds component composition. Antimicrobial activity of leaf ethanol extracts of rowan plant was found to be high against gram-negative bacterial strain Klebsiella pneumoniae B920 (especially the activity of S. aria, S. intermedia and S. aucuparia extracts) and Pseudomonas aeruginosa B907 (especially the activity S. torminalis and S. domestica), clinical gram-positive strains of Staphylococcus epidermidis (the highest activity of S. aria, S. domestica and S. intermedia extracts), as well as against clinical strains of fluconazole-resistant fungus Candida albicans (especially the activity of extracts of S. latifolia S. torminalis and S. intermedia). A conclusion was made about the prospects of using leaf extracts of the genus Sorbus plants as an economical and affordable natural source of biologically active polyphenols with a wide spectrum of antimicrobial activity. Further research may be aimed at elucidating the component composition of rowan leaf extracts and establishing the relationship between individual phytocompounds and the antimicrobial effects of plant extracts.

Modulatory Effect of Croton heliotropiifolius Kunth Ethanolic Extract on Norfloxacin Resistance in Staphylococcus aureus

The high frequency of infectious diseases has spurred research into effective tactics to combat microorganisms that are resistant to several drugs. The overproduction of the transmembrane efflux pump protein NorA, which may export hydrophilic fluoroquinolones, is a common mechanism of resistance in S. aureus strains. This work evaluated the antimicrobial activity of the ethanolic extract from the leaves of Croton heliotropiifolius (EECH) against different bacterial and fungal strains, as well as investigating its modulating effect on the resistance to norfloxacin in a Staphylococcus aureus SA1199B overproducing the NorA efflux pump. Microdilution assays were used to assess the EECH’s antibacterial efficacy. The MIC of norfloxacin or ethidium bromide (EtBr) against the SA1199B strain was determined in the presence or absence of the EECH in order to assess the modifying influence on drug resistance. The EECH showed no activity against the Gram-positive and Gram-negative bacterial strains tested. The EECH also showed no antifungal activity against Candida albicans ATCC 10231. On the other hand, the extract reduced the MIC values for norfloxacin against SA1199B at subinhibitory concentrations. In addition, the EECH also reduced the MIC values of EtBr at subinhibitory concentrations, suggesting the occurrence of phytochemicals that inhibit efflux pumps. Molecular docking showed that retusin, a flavonoid found in the extract, could compete with norfloxacin at the orthosteric site of the NorA, indicating that it could be a potential efflux pump inhibitor. However, isolated retusin did not enhance the activity of norfloxacin or EtBr and it did not inhibit the EtBr efflux, showing that it is not a NorA inhibitor. Even though C. heliotropiifolius is a source of phytochemicals that function as adjuvants for norfloxacin, isolated retusin cannot be used in conjunction with norfloxacin to treat infections brought on by S. aureus that overproduces NorA.

ANTIBACTERIAL PROPERTIES OF COMMERCIAL PEPPERMINT ESSENTIAL OIL AGAINST SOME GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

The authors of this article conducted research and studied the antibacterial properties of commercial peppermint essential oil (PEO) against several gram-positive and gram-negative bacteria provided by Polish manufacturers of essential oils (Naturalne Aromaty sp. z o.o., Klaj, Poland). Therefore, to conduct research with the aim of to study the antibacterial properties of commercial peppermint essential oil (PEO), an antimicrobial susceptibility test (Kirby-Bauer diffusion test) was used to measure diameters of bacterial growth inhibition zones). In the current study, Gram-negative strains such as Escherichia coli (Migula) Castellani and Chalmers (ATCC® 25922™ ), Escherichia coli (Migula) Castellani and Chalmers (ATCC® 35218™ ), Pseudomonas aeruginosa (Schroeter) Migula (ATCC® 27853™ ) and Gram-positive strains such as Staphylococcus aureus subsp. aureus Rosenbach (ATCC® 29213™ ), methicillin-resistant (MRSA), mecA positive Staphylococcus aureus (NCTC® 12493), Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™ ) (resistant to vancomycin; sensitive to teicoplanin) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™ ) were used. Results of the current study revealed that resistant to the PEO were Gram-negative bacterial strains, such as E. coli (Migula) Castellani and Chalmers (ATCC® 35218™ ) and P. aeruginosa (Schroeter) Migula (ATCC® 27853™ ) strains. The authors found that the diameters of the inhibition zones after application of PEO were similar to the control samples (96% ethanol). It was also found that after the application of REO, the increase in the diameters of the inhibition zones was 60.3% (p < 0.05) for the Escherichia coli strain (Migula) Castellani and Chalmers (ATCC® 25922™ ) compared to control samples (96% ethanol ). Accordingly, Gram-positive strains such as S. aureus subsp. aureus Rosenbach (ATCC® 29213™ ) and methicillin-resistant S. aureus (NCTC® 12493) were equally resistant to PEO, similarly. On the other hand, Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 29212™ ) and Enterococcus faecalis (Andrewes and Horder) Schleifer and Kilpper-Balz (ATCC® 51299™ ) were sensitive to PEO. After the application of PEO, the largest diameters of inhibition zones were observed for the E. faecalis strain. The results suggest that commercial peppermint essential oil provided by Polish essential oil manufacturers (Naturalne Aromaty sp. z o.o., Kłaj, Poland) possesses some noteworthy antimicrobial properties. In vivo studies are necessary to calculate the effective dose of EOs and determine their possible side effects and toxicity.

The effect of rose bengal activated with green diode laser light on selected Gram-positive and Gram-negative bacterial strains

In recent years the photodynamic activity of rose bengal activated with green light against selected bacterial strains has been reported. However, according to our knowledge, the differences between the sensitivity of Gram-positive and Gram-negative bacterial strains in the presence of this photosensitizer have not been described. The aim of the conducted research was to examine the antibacterial effect of 535 nm wavelength diode laser light in the presence of rose bengal as photosensitizer on selected reference bacterial strains: Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. Sterile 96-well microtiter plates were used to determine the antibacterial activity of the green light and rose bengal solutions at various concentrations. The labelled bacterial suspensions were placed to each well of the 96-well microtiter plate filled with liquid medium LB and solution of rose bengal. The plates were exposed to green diode laser light. After 24 hours of incubation at 37oC, the turbidance was read in a spectrophotometer. The irradiation in the presence of photosensitizer can act in an antibacterial manner, either bacteriostatically or bactericidally. The tested strains exhibit different sensitivity to irradiation because of the structure of the cell wall, the presence of different bacterial pigments and photoreceptor proteins in some species of bacteria. Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis were the most photosensitive strains due to the higher possibility of rose bengal penetration into the bacterial cell, leading to the bacteriostatic effect. Our results show that rose bengal may be applied in the treatment of Gram-positive infections.

Genome sequences of four colistin-resistant ESKAPE bacterial strains isolated from patients within the same hospital.

The genomes of four clinical Gram-negative ESKAPE bacterial strains highly resistant to the last-resort antibiotic colistin were sequenced and analyzed. The strains were found to carry multidrug-resistant genes besides colistin-resistant genes.

Enhancement of antimicrobial properties by metals doping in nano-crystalline hydroxyapatite for efficient biomedical applications

In this study, we have introduced a method for the synthesis of various metal-doped nano-crystalline hydroxyapatites (HAp) using a standard wet chemical precipitation technique. Both divalent (Ni and Zn) and trivalent (Al and Fe) metals were selected for the doping process. Additional research work was also conducted to assess the antimicrobial efficacy of these doped-HAps against a range of gram-positive and gram-negative microorganisms. All the synthesized metal-doped hydroxyapatite (HAp) exhibited notable antibacterial characteristics against gram-negative bacterial strains, namely Escherichia coli (E. coli) and Salmonella typhi (S. typhi), outperforming the pure HAp. The inhibition zone observed for the metal-doped HAp ranged from 14 to 16 mm. The Fe ion displayed a notable inhibitory zone measuring 16 mm, proving to be the most expansive among all tested ions against both E. coli and S. typhi bacterial strains. The Zn-HAp exhibited a comparable inhibitory zone size of 14 mm against both S. typhi and E. coli. Additional characterization methods, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and Scanning electron microscopy (SEM), were used to validate the structural properties of the synthesized metal-doped hydroxyapatite (HAp) samples. The biocompatibility assessment of metal-doped hydroxyapatite (HAp) samples was carried out by haemolysis tests, which revealed that all synthesized hydroxyapatite (HAp) samples have the potential to serve as reliable biomaterials.

Pd-catalyzed synthesis, characterization, and biological evaluations of pyrazole derivatives: DFT, molecular modelling and antioxidant studies

Using Pd(PPh3)4 as a catalyst, a new series of coupling products (5a–5l) synthesized from pyrazole derivatives (4a-4c) and substituted boronic acids. Afterward, 1H, 13C-NMR, FT-IR, UV-visible, and LC-MS techniques were used to characterize the pyrazole derivatives. These pyrazole derivatives (4a-4c and 5a-5l) were assessed for their in-vitro antifungal activity, growth pattern evaluations, and hemolytic assays against the Candida strains. The antibacterial inhibitory potential of the lead compound 5c, with a panel of three Gram-positive bacterial strains and two Gram-negative bacterial strains, was employed to find out MIC, FICI, and toxicity. Results showed that the MIC values with all bacterial strains for compound 5c indicate substantial antimicrobial potential. Analog 5c was tested for its ability to interact with Ct-DNA using various techniques. Compound 5c showed binding constants (Kb) of 9.93 × 105 M−1 while the Gibbs free energy was -34.22 kJmol−1. The linear Stern-Volmer constant (KSV) for 5c was calculated to be 4.81 × 104. DFT calculation study has been investigated for the geometrical optimization and energy parameters calculation. Pyrazole derivative 5c was used for molecular modelling investigation with PDB: 1BNA, 2XCT, and 5FSA, which validated the manner of binding and supported in vitro DNA binding results. Utilizing the DPPH and H2O2 assay, derivative 5c was also tested for antioxidant activity.

Antibacterial and photocatalytic potential of bioactive compounds extracted from freshwater microalgae species (Spirogyra and Ocillatoria): A comparative analysis

Water pollution by pathogenic bacteria and organic dyes poses potential health hazards for human and aquatic life. This study aims to explore the potential of bioactive compounds extracted from two microalgae species (Spirogyra and Ocillatoria) for water pollution control. The optimization of the extraction process for bioactive compounds resulted in the highest yield at 25 min for Spirogyra and 30 min for Ocillatotia species. Further, the extracted bioactive compounds were analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC–MS). The bioactive compounds exhibited significant antibacterial activity against gram-positive and gram-negative bacteria. Notably, Spirogyra species exhibited a higher zone of inhibition (19.5–20.7 mm) than Ocillatoria species (17.0–18.0 mm) against both gram-positive and gram-negative bacterial strains. Furthermore, the photocatalytic potential of these bioactive compounds was examined by assessing the photodegradation of methylene blue (MB) and crystal violet (CV) dyes under different light sources. The findings revealed that Spirogyra species exhibited better photocatalytic activity than Ocillatoria species for MB and CV. For MB, 89.75 %, 77.82 % and 63.54 % were photodegraded when exposed to UV light, sunlight and visible light using Spirogyra extract, compared to 84.90 %, 74.70 % and 58.30 % by Ocillatoria extract. Regarding CV, Spirogyra extract achieved photodegradation efficiency of 88.94 %, 76.59 % and 64.50 % under UV light, sunlight and visible light, higher than 83.60 %, 73.60 % and 57.70 % by Ocillatoria extract. Both Spirogyra and Ocillatoria species demonstrated the best performance for dye photodegradation under UV irradiation, demonstrating great potential for nature-based water treatment.

Bioactive, antioxidant and antimicrobial properties of chemically fingerprinted essential oils extracted from Eucalyptus globulus: in-vitro and in-silico investigations.

Innovative approaches are urgently required to treat divestating bacterial diseases in the face of rising bacterial resistance rates. The current investigative work focused on hydro-distilling Tasmanian blue gum (Eucalyptus globulus) to isolate the essential oil, which was then tested for bioactivity, antioxidant capacity, and antibacterial activity using in-vitro and in silico assays. The antioxidant activity was avualated against DPPH and FRAP. With results of 69.63 RSA (%) (µL/L AAE) at a concentration of 5mL/L and 51.56 (µL/L AAE) at concentration of 90ppm in the 2,20-diphenyl-1-picryl hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays, respectively, the extracted oil indicated considerable antioxidant activity. The extracted oil demonstrated powerful antibacterial activity in in-vitro tests against both Gram-positive and Gram-negative bacterial strains, including Bordetella bronchiseptica (21mm), Staphylococcus epidermidis (19mm), and Staphylococcus aureus (19mm), with significant minimal inhibitory (MIC) and minimum bactericidal (MIB) concentrations. Additionally, GC-MS analysis of the oil from E. globulus identified several low-molecular-weight compounds, including Eucalyptol, γ-Terpinene, Shisool acetate, 1,3-trans,5-cis-Octatriene, 2,6-Dimethyl-1,3,5,7-octatetraene, E,E, Cyclohexene, 1-methyl-4-(1-methylethylidene), Benzene, 1-methyl-4-(1-methylethenyl), Butanoic acid, 3-methyl-, 3-methylbutyl ester, and 1,3,8-p-Menthatriene. Several other compounds were also identified, including Fenchol, 2-Methyl-trans-3a,4,7,7a-tetrahydroindane, (E,E,E)-2,4,6-Octatriene, 1,2,3,6-Tetrahydrobenzylalcohol, acetate, Alloaromadendrene, Phenol, 2-ethyl-4,5-dimethyl, Phenol, 2-methyl-5-(1-methylethyl)-, p-Cymen-7-ol, 1,5,5-Trimethyl-6-methylene-cyclohexene, 1,3-Cyclohexadiene, 1-methyl-4-(1-methylethyl)-, 2,6-Octadien-1-ol, 3,7-dimethyl-, acetate, (Z), and more. The bioactive potential of Eucalyptus globulus essential oil against 1AJ6 and 1R4U was highlighted by molecular docking analyses, suggesting its utility as a natural source of antioxidant and antibacterial compounds with the potential to replace chemical disinfectants in a variety of applications.

CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF ESSENTIAL OIL OF $MENTHA~ARVENSIS$ L. HARVESTED AT HIGH ALTITUDE ARMENIAN FLORA

Currently it is relevant to reveal possible new sources of natural antibacterial components, the mechanisms of antibiotic resistance formation in bacteria, and the possible ways to overcome the problem of microbial resistance to antibiotics. So, our research aimed to study the chemical composition and antibacterial activity of the essential oil (EO) isolated from the herb Mentha arvensis harvested at high altitude Armenian landscape. Menthol constitutes a significant part of the EO components of the M. arvensis plant, reaching approximately 70%. The investigated EO showed high antimicrobial activity against several Gram-positive and Gram-negative bacterial strains. In particular, the EO equally suppressed the growth of both wild-type and kanamycin-resistant strains of Escherichia coli and manifested the minimal inhibitory concentration against all tested microorganisms of 0.18 mg/mL. So, M. arvensis EO is relevant for application in the food and cosmetic industry as a natural aromatizer and preservative.