Simultaneously Determined Antioxidant and Pro-Oxidant Activity of Randomly Selected Plant Secondary Metabolites and Plant Extracts.

Oxidative stress is a well-known phenomenon arising from physiological and nonphysiological factors, defined by the balance between antioxidants and pro-oxidants. While the presence and uptake of antioxidants are crucial, the pro-oxidant effects have not received sufficient research attention. Several methods for assessing pro-oxidant activity, utilizing various mechanisms, have been published. In this paper, we introduce a methodology for the simultaneous determination of antioxidant and pro-oxidant activity on a single microplate in situ, assuming that the FRAP method can measure both antioxidant and pro-oxidant activity due to the generation of pro-oxidant Fe2+ ions in the Fenton reaction. Systematic research using this rapid screening method may help to distinguish between compounds with dominant antioxidant efficacy and those with dominant pro-oxidant effects. Our preliminary study has revealed a dominant pro-oxidant effect for compounds with a higher number of oxygen heteroatoms, especially sp2 hybridized compounds (such as those containing keto groups), such as flavonoids and plant extracts rich in these structural types. Conversely, catechins, carotenoids, and surprisingly, extracts from birch leaves and chestnut leaves have demonstrated dominant antioxidant activity over pro-oxidant. These initial findings have sparked significant interest in the systematic evaluation of a more extensive collection of compounds and plant extracts using the developed method.

High Emergence of Multidrug-Resistant Sequence Type 131 Subclade C2 among Extended-Spectrum ß-Lactamase (ESBL)-Producing Escherichia coli Isolated from the University Hospital Bratislava, Slovakia.

The expansion of sequence type 131 (ST131) extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli (E. coli) represents major worldwide challenges. E. coli strains originating from healthcare facilities (labeled No. 1 and No. 2) of the University Hospital Bratislava (UHB) were analyzed for ST131 emergence, including its (sub)lineages and clonal relatedness. Antimicrobial resistance was determined in most strains. Of a total of 354 E. coli strains, 263 (74.3%) belonged to ST131; of these, 177 (67.3%) were from No. 1. Generally, among 260 ST131 E. coli, clades A/B were confirmed in 20 (7.7%), while clade C was noted in 240 (92.3%) strains; within them, subclades were detected as follows: C0 (17; 7.1%), C1 (3; 1.2%), and C2 (220; 91.7%). Among fifteen randomly selected E. coli strains that were investigated for ST and clonal relatedness, seven STs were identified: eight (53.3%) ST131, two (13.3%) ST73, and one each (6.7%) of ST10, ST12, ST14, ST1193, and ST1196. From No. 1, two ST131 in the first internal clinic and one ST131 from No. 2 in the aftercare department were highly clonally related, suggesting possible epidemiological association. Antimicrobial resistance was as follows: ciprofloxacin 93.8%, ceftazidime 78.4%, meropenem 0%, fosfomycin 2.9% and nitrofurantoin 1.4%. Prevention of ESBL-producing E. coli dissemination, especially for ST131 clade C2, is inevitably necessary for reducing drug resistance and decreasing healthcare-associated infections.

The Adapted POM Analysis of Avenanthramides In Silico.

POM analysis and related approaches are significant tools based on calculating various physico-chemical properties and predicting biological activity, ADME parameters, and toxicity of a molecule. These methods are used to evaluate a molecule's potential to become a drug candidate. Avenanthramides (AVNs) are promising secondary metabolites specific to Avena spp. (oat). They comprise the amides of anthranilic acid linked to various polyphenolic acids with or without post-condensation molecule transformation. These natural compounds have been reported to exert numerous biological effects, including antioxidant, anti-inflammatory, hepatoprotective, antiatherogenic, and antiproliferative properties. To date, almost 50 various AVNs have been identified. We performed a modified POM analysis of 42 AVNs using MOLINSPIRATION, SWISSADME, and OSIRIS software. The evaluation of primary in silico parameters revealed significant differences among individual AVNs, highlighting the most promising candidates. These preliminary results may help coordinate and initiate other research projects focused on particular AVNs, especially those with predicted bioactivity, low toxicity, optimal ADME parameters, and promising perspectives.

Antibacterial Potential of Microwave-Assisted Extraction Prepared Hydrolates from Different Salvia Species.

Salvia is a widely used herb that also contains essential oils and other valuable compounds. In this work, the hydrolates of five Salvia sp. were evaluated for their potential antimicrobial and antioxidant activity against four bacterial strains. The hydrolates were obtained from fresh leaves by microwave-assisted extraction. Chemical composition analysis by gas chromatography and mass spectrometry revealed that their major constituents were isopulegol (38.2-57.1%), 1,8-cineole (4.7-19.6%), and thujone (5.6-14.1%). The minimum inhibitory concentration (MIC) of the plant hydrolates was tested by the microdilution method at concentrations ranging from 1.0 to 512 µg/mL. The hydrolates prepared from Salvia officinalis and S. sclarea showed inhibitory activity on the tested Gram-positive and Gram-negative bacteria, taxon Salvia nemorosa showed inhibitory activity only partially. The hydrolate of S. divinorum had practically no antibacterial effect. Enterobacter asburiae was the only bacterium for which we found sensitivity to the hydrolate of S. aethiopis, with a MIC50 value of 216.59 µL/mL. The antioxidant activity of the hydrolates was low, ranging from 6.4 to 23.3%. Therefore, salvia hydrolates could be used as antimicrobial agents in medicine, cosmetics, and food preservation.

Next-Generation Sequencing of Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated from Patients Hospitalized in the University Hospital Facilities.

Carbapenem-resistant (CR) Klebsiella pneumoniae represents an urgent worldwide threat. We focused on CR K. pneumoniae in selected facilities of the University Hospital Bratislava (UHB) to investigate sequence types (STs), clonal relatedness, and antimicrobial resistance. Suspected carbapenem-nonsusceptible K. pneumoniae strains were obtained from hospitalized patients. Further examination included carbapenemase confirmation, cgMLST, and quantitative susceptibility testing. Of the total 41 CR K. pneumoniae strains, 26 (63.4%) were determined as ST11 in hospital No. 1; of these ST11, 22 (84.6%) were found in the first internal clinic. Six (14.6%) ST258 and three (7.3%) ST584 occurred in hospital No. 2; the most, i.e., four (66.7%), ST258 were detected in the geriatric clinic. In hospital No. 3, we found two (4.8%) ST584 and one (2.4%) ST258. Of the ST11 set, 24 (92.3%) produced NDM-1. Furthermore, seven (87.5) ST258 and five (100%) ST584 strains generated KPC-2. Antimicrobial resistance was as follows: ertapenem 97.6%, meropenem 63.4%, tigecycline 7.3%, eravacycline 7.3%, and colistin 2.5%. We revealed a presumably epidemiological association of ST11 with transmission, particularly in the first internal clinic of hospital No. 1, while ST258 and ST584 were related to interhospital dissemination between medical facilities No. 2 and No. 3. It is essential to prevent the circulation of these pathogens within and between healthcare facilities.

Antioxidant and Proteinase Inhibitory Activities of Selected Poppy (Papaver somniferum L.) Genotypes.

Poppy seeds (Papaver somniferum L.) belong to tasty food ingredients however, they should be considered also as valuable source of biologically active compounds. Content of selected metabolites, antioxidant and proteinase inhibitory activities were analyzed in vitro in extracts from seeds of fifteen poppy genotypes. Considerable variation in all parameters was detected within the set of analyzed poppy genotypes. The genotype Major expressed the highest antioxidant activity determined by all four methodological approaches (DPPH, ABTS, FRAP, RP). The genotype MS 423 exhibited the highest inhibitory activities against trypsin, thrombin and collagenase. Very specific position among all had the genotype Redy. Its grain extract reached significantly high levels in 9 out of 14 measured parameters (TPC, TFC, TTC, TAC, FRAP, RP, inhibitory activities against trypsin, thrombin, collagenase). Edible grains of poppy are valuable source of natural compounds which may be beneficial in pathological states associated with oxidative stress or increased proteinase activities.

Antioxidants, Enzyme Inhibitors, and Biogenic Compounds in Grain Extracts of Barleys.

The content of biogenic compounds and the biological activities of barley (Hordeum vulgare L.)-grain extracts was evaluated. The sufficiently large and heterogeneous set of barley genotypes (100 accessions) enabled the selection of special genotypes interesting for potential industrial, pharmaceutical, and medicinal applications. Barley genotypes with the highest contents of phenols, phenolic acids, flavonoids, biogenic thiols, and amines, radical-scavenging activity, as well as inhibitory activities of trypsin, thrombin, collagenase, urokinase, and cyclooxygenase were identified.

Inhibition activities of natural products on serine proteases.

Proteases play a key role in a variety of pathologies, including cancer, pancreatitis and thrombosis. Low molecular inhibitors can act as drugs to combat these pathologies. Twelve natural phenolic compounds and one alkaloid were evaluated. Quercetin was used as a standard in the in vitro tests on serine proteases (trypsin, thrombin and urokinase). Salicin showed a highly selective effect with a value of IC50 = 11.4 microm for thrombin, suggesting it may be a suitable lead structure for developing thrombin inhibitors and thus for perspective thrombolytics. Interesting results were also observed for hyperoside with IC50 = 8.3 microm for urokinase. The flavonoid skeleton seems to be a suitable structure for investigating urokinase inhibitors as prospective drugs for cancer therapy. A very high inhibitory activity on trypsin was observed for the flavonoid silybin (IC50 = 3.7 microm), indicating a prospective structure on which to base possible polyphenolic trypsin inhibitors.

Antiprotease and antimetastatic activity of ursolic acid isolated from Salvia officinalis.

Proteases play a regulatory role in a variety of pathologies including cancer, pancreatitis, thromboembolic disorders, viral infections and many others. One of the possible strategies how to combat with these pathologies seems to be the use of low molecular inhibitors. Natural products were evaluated in the in vitro antiprotease assay on serine proteases (trypsin, thrombin and urokinase) and on the cysteine protease cathepsin B. We found interesting results for beta-ursolic acid isolated from Salvia officinalis, which significantly inhibited all tested proteases in vitro in the micromolar range. beta-Ursolic acid showed the strongest inhibition activity to urokinase (IC50 = 12 microM) and cathepsin B (IC50 = 10 microM) as proteases included in tumour invasion and metastasis indicated possible anticancer effectivity. Therefore, we tested the ability of beta-ursolic acid at doses of 50, 75 and 100 mg/kg given i.p. to inhibit lung colonization of beta16 mouse melanoma cells in vivo. We found, that beta-ursolic acid significantly decreased the number of B16 colonies in the lungs of mice at the dose 50 mg/kg (p < 0.05).

Structural aspects of flavonoids as trypsin inhibitors.

In the search for new proteinase inhibitors we have focused on the screening and Computer Assisted Drug Design (CADD) studies of polyphenolic compounds. In this paper we report CADD of flavonoles and flavones as trypsin inhibitors concomitant by the screening results. 5,7-Dihydroxy flavonoid have been found to be a perspective trypsin/trypsin-like-enzyme inhibitor. Flavanones and isoflavones are less effective trypsin inhibitors due to a lost of the optimal geometry leading to hydrogen bond interactions. Four different interaction modes were observed, flavonoids are stabilised in S(1) region of beta-trypsin by formation of two (apigenin) or at least one hydrogen bond and other significant electrostatic interactions. Quercetin, myricetin and morin have shown to be the best trypsin inhibitors tested. In general, flavonoids with suitably located hydroxy groups and planar conformation are the building blocks able to replace guanidinobenzoyl part of successful inhibitors. Physiological nature of flavonoids reveals biotechnological source of new trypsin inhibitors as antipancreatitis, anticancer and anti-inflammation drugs.