Antimicrobial Efficacy of Synthetic Pyranochromenones and (Coumarinyloxy)acetamides

Four (1, 2, 4 and 6) synthetic quaternary ammonium derivatives of pyranochromenones and (coumarinyloxy)acetamides were synthesized and investigated for their antimicrobial efficacy on MRSA (Methicillin-resistant Staphylococcus aureus), and multi-drug resistant Pseudomonas aeruginosa, Salmonella enteritidis and Mycobacterium tuberculosis H37Rv strain. One of the four compounds screened i.e. N,N,N-triethyl-10-((4,8,8-trimethyl-2-oxo-2,6,7,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)decan-1-aminium bromide (1), demonstrated significant activity against S. aureus, P. aeruginosa and M. tuberculosis with MIC value of 16, 35, and 15.62 µg/ml respectively. The cytotoxicity evaluation of compound 1 on A549 cell lines showed it to be a safe antimicrobial molecule, TEM study suggested that the compound led to the rupture of the bacterial cell walls.     

2-(chromon-3-yl)imidazole derivatives as potential antimicrobial agents: synthesis,biological evaluation and molecular docking studies

A series of novel 2-(chromon-3-yl)-4,5-diphenyl-1H-imidazoles (4a-h) were synthesized by one pot condensation of substituted 3-formylchromones (1a-h), benzil (2) and ammonium acetate (3) in refluxing acetic acid at 110 °C under N2 atmosphere. Allylation of compounds 4a-h with allyl bromide in the presence of fused K₂CO₃ furnished N-allyl-2-(chromon-3-yl)-4,5-diphenyl-1H-imidazoles (6a-h). The synthesized compounds were characterized spectroscopically and evaluated for in vitro antimicrobial activity against various pathogenic bacterial and fungal strains by disc diffusion method. Compounds bearing electron withdrawing substituents such as bromo (4f) showed significant inhibitory activity against S. cerevisiae (MIC 1.4 μg/ml) and 4g containing chloro substituent, displayed more inhibitory potential against C. albicans (MIC 1.5), as compared to the standard drugs. Compounds 6a and 4c exhibit remarkable inhibitory potential against B. subtilis with MIC 0.98 and 1.23, respectively. The time kill assay for active compound 6a was performed by viable cell count (VCC) method to elucidate the microbicidal nature of 2-(chromon-3-yl)imidazoles. A molecular docking study of most active compounds with target ‘lanosterol 14α-demethylase’ (CYP51) was performed to unravel the mode of antifungal action.     

Design,synthesis, and characterization of 2,2-bis(2,4-dinitrophenyl)-2-(phosphonatomethylamino)acetate as a herbicidal and biological active agent

The present study was designed to synthesize the bioactive molecule 2,2-bis(2,4-dinitrophenyl)-2-(phosphonatomethylamino)acetate (1), having excellent applications in the field of plant protection as a herbicide. Structure of newly synthesized molecule 1 was confirmed by using the elemental analysis, mass spectrometric, NMR, UV-visible, and FTIR spectroscopic techniques. To obtain better structural insights of molecule 1, 3D molecular modeling was performed using the GAMESS programme. Microbial activities of 1 were checked against the pathogenic strains Aspergillus fumigatus (NCIM 902) and Salmonella typhimurium (NCIM 2501). Molecule 1 has shown excellent activities against fungal strain A. fumigates (35 μg/l) and bacterial strain S. typhimurium (25 μg/l). To check the medicinal significance of molecule 1, interactions with bovine serum albumin (BSA) protein were checked. The calculated value of binding constant of molecule 1–BSA complex was 1.4 × 10⁶ M^?1, which were similar to most effective drugs like salicylic acid. More significantly, as compared to herbicide glyphosate, molecule 1 has exhibited excellent herbicidal activities, in pre- and post-experiments on three weeds; barnyard grass (Echinochloa Crus), red spranglitop (Leptochloa filiformis), and yellow nuts (Cyperus Esculenfus). Further, effects of molecule 1 on plant growth-promoting rhizobacterial (PGPR) strains were checked. More interestingly, as compared to glyphosate, molecule 1 has shown least adverse effects on soil PGPR strains including the Rhizobium leguminosarum (NCIM 2749), Pseudomonas fluorescens (NCIM 5096), and Pseudomonas putida (NCIM 2847).     

Isolation and Antibiotic Screening of Fungi from a Hydrothermal Vent Site and Characterization of Secondary Metabolites from a <Emphasis Type="Italic">Penicillium</Emphasis> Isolate

Five new compounds were isolated from Penicillium sp. Y-5-2 including an austin derivative 4, four isocoumarins 9, 11, 12, and 13, together with two known isocoumarins 8 and 10, and six known austin derivatives 1, 2, 3, 5, 6, and 7 and one phenol 14. Their structures and relative configurations were established by spectroscopic means. The absolute configurations of 4, 11, and 13 were defined mainly by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. The cyclization of the pentan-2-ol pendant at C-3 in compound 13 allowed the assignment of a new 2,3,4,4a,6,10b-hexahydro-1H-benzo[c]chromene isocoumarin skeleton. New compounds 9, 11, and 13 revealed inhibitory activities against E. coli at MIC values around 32 μg/mL. The known compound 14 showed potent antibiotic activity against Staphylococcus aureus and Bacillus subtilis with MIC values 8 and 2 μg/mL, respectively, with no cytotoxicity when tested in vitro. A rapid and efficient technique for selecting antibiotic fungal strain among eight marine-derived fungi was also described.     

Production of macrolide antibiotics from a cytotoxic soil <Emphasis Type="Italic">Streptomyces</Emphasis> sp. strain ZDB

Crude extract from a culture of a soil Streptomyces sp. strain ZDB showed toxicity towards Artemia salina and antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Chlorella vulgaris, and Chlorella sorokiniana. Large scale fermentation of the strain led to the isolation of the macrolide antibiotics, bafilomycins A1 (1), B1 (2), and D (3) together with nonactic acid (4) and bostrycoidin-9-methyl ether (5). Structures of the antibiotics were determined based on spectral data analysis. We describe the isolation of the compounds and characterization of the producing strain.     

Localization of magnetized electrons in current filaments as a fundamental cause of Coulomb explosion

Mechanisms for generating current filaments in a dense plasma under the action of focused laser pulses and in a Z-pinch configuration are discussed. The main properties of current filaments with a zero and nonzero electron vorticity Ω _e =B?(c/e)?×p _e that originate at magnetic fields in the range 4πn _e m _e c²?B²?4πn _i m _i c² are investigated under the conditions of Coulomb explosion at currents below the ion Alfvén current. A study is made of the equilibrium configurations of nonquasineutral current filaments in a purely longitudinal (B_z) and a purely azimuthal (B_θ) magnetic field and also in a more general case of a helical magnetic field, having two components, under conditions such that the charge separation occurs on a spatial scale on the order of the magnetic Debye radius r_B ? |B|/(4πen_e. It is shown that strong electric fields generated in the current filaments are comparable in magnitude to the atomic field and are capable of accelerating ions to energies of several tens of megaelectronvolts. The ion dynamics in strong electric fields of the filaments is calculated numerically and is shown to lead to the formation of collisionless shock waves on time scales on the order of several inverse ion plasma frequencies ω _pi ^?1 . The possible formation of current filaments on different spatiotemporal scales is considered.     

Bioactive compounds of <Emphasis Type="Italic">Aspergillus terreus</Emphasis>—F7, an endophytic fungus from <Emphasis Type="Italic">Hyptis suaveolens</Emphasis> (L.) Poit

The compounds terrein (1), butyrolactone I (2), and butyrolactone V (3) were isolated from the ethyl acetate extract (EtOAc) of the endophytic fungus Aspergillus terreus—F7 obtained from Hyptis suaveolens (L.) Poit. The extract and the compounds presented schistosomicidal activity against Schistosoma mansoni; at 100 µg/mL for EtOAc extract, 1297.3 µM for compound 1, 235.6 µM for compound 2, and 454.1 µM for compound 3, they killed 100% of the parasites after 72 h of treatment. Compounds 1, 2, and 3 exerted moderate leishmanicidal activity against Leishmania amazonensis (IC₅₀ ranged from 23.7 to 78.6 µM). At 235.6 and 227.0 µM, compounds 2 and 3, respectively, scavenged 95.92 and 95.12% of the DPPH radical (2,2-diphenyl-1-picryl-hydrazyl), respectively. Regarding the cytotoxicity against the breast tumor cell lines MDA-MB-231 and MCF-7, compound 2 gave IC₅₀ of 34.4 and 17.4 µM, respectively, while compound 3 afforded IC₅₀ of 22.2 and 31.9 µM, respectively. At 117.6 µM, compound 2 inhibited the growth of and killed the pathogen Escherichia coli (ATCC 25922). Compounds 1, 2, and 3 displayed low toxicity against the normal line of human lung fibroblasts (GM07492A cells), with IC₅₀ of 15.3?×?10³, 3.4?×?10³, and 5.8?×?10³ µM, respectively. This is the first report on (i) the in vitro schistosomicidal and leishmanicidal activities of the EtOAc extract of A. terreus—F7 and compounds 1, 2, and 3; and (ii) the antitumor activity of compounds 2 and 3 against MDA-MB-231 and MCF-7 cells.     

Madurastatin B3, a rare aziridine derivative from actinomycete <Emphasis Type="Italic">Nocardiopsis</Emphasis> sp. LS150010 with potent anti-tuberculosis activity

Since the discovery of the first antibiotic, natural products have played an important role in chemistry, biology and medicine. To explore the potential of bioactive compounds from microbes isolated from the southeast of Tibet, China, a crude extract library was constructed and screened against Staphylococcus aureus. The strain Nocardiopsis sp. LS150010 was scaled up and subjected to further chemical studies, resulting in the identification of N-salicyloyl-2-aminopropan-1,3-diol (2) and its rare aziridine derivative, madurastatin B3 (1). Their structures were determined by detailed analysis of 1D, 2D NMR and HRMS data. Compounds 1 and 2 displayed significant inhibitory activity against S. aureus and methicillin resistant S. aureus, with MIC values of 6.25 µg/mL. Compound 1 also showed potent inhibitory activity against Bacillus subtilis and Escherichia coli, as well as activity in a Mycobacterium tuberculosis Bacillus Calmette-Guérin infected THP-1 cell model.     

New and little-known crickets of the subfamily Phalangopsinae (Orthoptera,Gryllidae). 11. The genus <Emphasis Type="Italic">Parendacustes</Emphasis> (Part 2)

Discussions concerning the composition of the genus Parendacustes Chop., in particular, its subgenus Minizacla Gor., are continued. Eleven new taxa of this subgenus are described: P. trusmadi sp. n., P. mulu sp. n., P. brevispina sp. n., P. modispina sp. n., P. longispina sp. n., P. forficula sabah subsp. n., P. doloduo sp. n., P. buton sp. n., P. pallescens sp. n., P. kendari sp. n., and P. lindu sp. n. New data on P. makassari Gor. are also provided.     

Nematicidal metabolites from <Emphasis Type="Italic">Gliocladium roseum</Emphasis> YMF1.00133

A strain of the fungus Gliocladium roseum YMF1.00133 was found to secrete nematicidal metabolites against nematodes Panagrellus redivivus, Caenothabditis elegans and Bursaphelenchus xylophilus in experiments searching for nematicidal fungi. Through bioassay-guided fractionations, a unique trioxopiperazine alkaloid, gliocladin C (compound 1), and an alkylane resorcinol, 5-n-heneicosylresorcinol (compound 2) were obtained from the methanol extract of the fungus and determined by single-crystal X-ray analysis and spectroscopic data. In vitro immersion experiments showed that the ED₅₀ values of compounds 1 and 2 after 24 h incubation were 15 and 30 μg/mL against C. elegans, 50 and 80 μg/mL against P. redivivus, and 200 and 180 μg/mL against B. xylophilus, respectively. The X-ray diffraction data of compound 1 and the nematicidal activity of compounds 1 and 2 were reported for the first time.     

Bioactive phytochemicals from shoots and roots of <Emphasis Type="Italic">Salvia</Emphasis> species

The plants of the genus Salvia L. are important medicinal herbs of the Lamiaceae family and some of them such as S. officinalis (sage), S. miltiorrhiza (red sage, Danshen) and S. sclarea (clary sage) have been used as medicinal plants in the folk medicine of several countries. In this review, we discuss the reports that have examined Salvia species with the aim of isolation of pure compounds with different biological activities. The phytochemical analyses of various sage plants have reported 10 monoterpenoids (1–10), 1 sesquiterpenoid (11), 8 labdane (13–20), 15 ent-kaurane (21–35), 82 abietane, rearranged abietane and tanshinone (36–117), 3 icetexane (118–120), 43 clerodane (121–163), and 3 pimarane (164–166) diterpenoids with cytotoxic and antimicrobial, antiprotozoal, antioxidant, phytotoxic and insecticide effects. The other heavier terpenoids, including 3 sesterterpenes (167–169), 10 triterpenoids and β-sitosterol (170–180) have been introduced as minor bioactive compounds in the sage plants. Sahandinone (107), 6,7-dehydroroyleanone, 7-α-acetoxyroyleanone (40), and tanshinone like diterpenoids have been isolated from the roots’ extracts of different Salvia species. On the other hand, several radical scavenger phenolic compounds like simple phenolics and caffeic acid derivatives (181–201) including rosmarinic acid, flavonoids (202–217) as well as phenolic diterpenoids, such as carnosol and carnosic acid have been isolated from the aerial parts of these plants. One pyrrole (218) and 3 antimicrobial oxylipins (219–221) are among the other less detected constituents in the members of Salvias. Furthermore, sages also synthesize antifungal, antileishmanial and antimalarial phytochemicals in their roots and shoots, which are reviewed in this paper. We also examine the allelopathic phenomena and the ecologically important phytochemicals identified in different parts of the sage plants. Finally, antifeedant and insecticide phenomena, which are due to the presence of volatile monoterpenes and clerodane diterpenes in these plants, are discussed. Considering the presence of diverse biologically active phytochemicals in the sage plants, they can be suggested as suitable candidates for the formulation of valuable natural medicines.     

Tyrosinase and catechol oxidase activity of copper(I) complexes supported by imidazole-based ligands: structure–reactivity correlations

Four new imidazole-based ligands, 4-((1H-imidazol-4-yl)methyl)-2-phenyl-4,5-dihydrooxyzole (L _OL 1), 4-((1H-imidazol-4-yl)methyl)-2-(tert-butyl)-4,5-dihydrooxyzole (L _OL 2), 4-((1H-imidazol-4-yl)methyl)-2-methyl-4,5-dihydrooxyzole (L _OL 3), and N-(2,2-dimethylpropylidene)-2-(1-trityl-1H-imidazol-4-yl-)ethyl amine (L _imz 1), have been synthesized. The corresponding copper(I) complexes [Cu(I)(L _OL 1)(CH₃CN)]PF₆ (CuL _OL 1), [Cu(I)(L _OL 2)(CH₃CN)]PF₆ (CuL _OL 2), [Cu(I)(L _OL 3)(CH₃CN)]PF₆ (CuL _OL 3), [Cu(I)(L _imz 1)(CH₃CN)₂]PF₆ (CuL _imz 1) as well as the Cu(I) complex derived from the known ligand bis(1-methylimidazol-2-yl)methane (BIMZ), [Cu(I)(BIMZ)(CH₃CN)]PF₆ (CuBIMZ), are screened as catalysts for the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC-H₂) to 3,5-di-tert-butylquinone (3,5-DTBQ). The primary reaction product of these oxidations is 3,5-di-tert-butylsemiquinone (3,5-DTBSQ) which slowly converts to 3,5-DTBQ. Saturation kinetic studies reveal a trend of catalytic activity in the order CuL _OL 3 ≈ CuL _OL 1 > CuBIMZ > CuL _OL 2 > CuL _imz 1. Additionally, the catalytic activity of the copper(I) complexes towards the oxygenation of monophenols is investigated. As substrates 2,4-di-tert-butylphenol (2,4-DTBP-H), 3-tert-butylphenol (3-TBP-H), 4-methoxyphenol (4-MeOP-H), N-acetyl-l-tyrosine ethyl ester monohydrate (NATEE) and 8-hydroxyquinoline are employed. The oxygenation products are identified and characterized with the help of UV/Vis and NMR spectroscopy, mass spectrometry, and fluorescence measurements. Whereas the copper complexes with ligands containing combinations of imidazole and imine functions or two imidazole units (CuL _imz 1 and CuBIMZ) are found to exhibit catalytic tyrosinase activity, the systems with ligands containing oxazoline just mediate a stoichiometric conversion. Correlations between the structures of the complexes and their reactivities are discussed.     

Family Juncaceae: promising source of biologically active natural phenanthrenes

Phenanthrenes represent a relatively small group of aromatic secondary metabolites, which can be divided into three main subgroups (mono-, di-, and triphenanthrenes). Phenanthrenes are reported as an intensively researched field in phytochemistry according to their structural diversity and promising biological activities. Because of their limited occurrence phenanthrenes are considered to be as important taxonomic markers. Juncaceae is a relatively large plant family divided into seven genera of which Juncus and Luzula are the most important ones from phytochemical and pharmacological points of view. To date, almost one hundred natural phenanthrenes have been isolated but only from eight (Juncus acutus, J. effusus, J. inflexus, J. maritimus, J. roemerianus, J. setchuensis, J. subulatus, and Luzula luzuloides) Juncaceae species, including mono-, and diphenanthrenes, and phenanthrene glucosides. Great deal of the isolated compounds are substituted with a vinyl group. This substitution is characteristic exclusively to Juncaceae species. Juncusol (2) was isolated from every investigated species. The richest source of phenanthrenes, as well as the most extensively investigated species is J. effusus. Several isolated compounds possessed different biological activities, e.g. antiproliferative, antimicrobial, anti-inflammatory, antioxidant, spasmolytic, anxiolytic, and antialgal effects. Among them, dehydroeffusol (60) is the most promising one, as it showed antimicrobial, anxiolytic, sedative, spasmolytic, cellular protective and antiproliferative activities. The aim of this review is to summarize the occurrence of phenanthrenes in the family Juncaceae, and give a comprehensive overview of their isolation, structural characteristics and biological activities.     

New Taxa and Host Associations of the Weevil Subfamily Ceutorhynchinae (Coleoptera,Curculionidae) from Thailand

A new subgenus of Mecysmoderes Sch., Enzoellus Korotyaev, subgen. n. (type species Mecysmoderes carinatus Faust), two new genera of the tribe Hypohypurini Colonnelli, Siamohypurus Korotyaev, gen. n. (type species S. samuelsoni Korotyaev, sp. n.), Glikmanellus Korotyaev, gen. n. (type species G. rosti Korotyaev, sp. n.) and eleven new species of the weevil subfamily Ceutorhynchinae are described: Mecysmoderes (Memecyderes) sarukhanovi Korotyaev, sp. n. from Thailand, M. (Enzoellus) gressitti Korotyaev, sp. n. from Thailand and Laos, M. (Enzoellus) muratovi Korotyaev, sp. n., Megahypurus oroszi Korotyaev, sp. n., Cyphohypurus suppantschitschi Korotyaev, sp. n., Siamohypurus samuelsoni Korotyaev, sp. n., S. attilai Korotyaev, sp. n., Glikmanellus rosti Korotyaev, sp. n., all from Thailand; G. baloghi Korotyaev, sp. n. from Sri Lanka; G. obrieni Korotyaev, sp. n. and G. louisae Korotyaev, sp. n., both from India. A key to three species of Megahypurus from Thailand is given. Host plants are determined for Megahypurus alexandri Kor. and Glikmanellus rosti sp. n. from Koh Kood Island in southern Thailand, which were repeatedly collected from a tree of the family Rubiaceae.     

Metabolomics-guided analysis of isocoumarin production by <Emphasis Type="Italic">Streptomyces</Emphasis> species MBT76 and biotransformation of flavonoids and phenylpropanoids

Introduction

Actinomycetes produce the majority of the antibiotics currently in clinical use. The efficiency of antibiotic production is affected by multiple factors such as nutrients, pH, temperature and growth phase. Finding the optimal harvesting time is crucial for successful isolation of the desired bioactive metabolites from actinomycetes, but for this conventional chemical analysis has limitations due to the metabolic complexity.

Objectives

This study explores the utility of NMR-based metabolomics for (1) optimizing fermentation time for the production of known and/or unknown bioactive compounds produced by actinomycetes; (2) elucidating the biosynthetic pathway for microbial natural products; and (3) facilitating the biotransformation of nature-abundant chemicals.

Method

The aqueous culture broth of actinomycete Streptomyces sp. MBT76 was harvested every 24 h for 5 days and each broth was extracted by ethyl acetate. The extracts were analyzed by ¹H NMR spectroscopy and the data were compared with principal component analysis (PCA) and orthogonal projection to latent structures (OPLS) analysis. Antimicrobial test were performed by agar diffusion assay.

Results

The secondary metabolites production by Streptomyces sp. MBT76 was growth phase-dependent. Isocoumarins (1–9), undecylprodiginine (10), streptorubin B (11), 1H-pyrrole-2-carboxamide (12), acetyltryptamine (13), and fervenulin (14) were identified, and their optimal production time was determined in crude extracts without tedious chromatographic fractionation. Of these compounds, 5,6,7,8-tetramethoxyl-3-methyl-isocoumarin (9) is as a novel compound, which was most likely synthesized by a type I iterative polyketide synthase (PKS) encoded by the icm gene cluster. Multivariate data analysis of the ¹H NMR spectra showed that acetyltryptamine (13) and tri-methoxylated isocoumarins (7 and 8) were the major determinants of antibiotic activity during later time points. The methoxylation was exploited to allow bioconversion of exogenously added genistein into a suite of methoxylated isoflavones (15–18). Methoxylation increased the antimicrobial efficacy of isocoumarins, but decreased that of the isoflavones.

Conclusion

Our results show the applicability of NMR-based metabolic profiling to streamline microbial biotransformation and to determine the optimal harvesting time of actinomycetes for antibiotic production.

     

A Review of the Fauna of the Planthopper Family Lophopidae (Homoptera,Fulgoroidea) from Vietnam with Descriptions of New Genera and Species and with Taxonomic Notes

Six new species are described from Vietnam, Apia simplexsp. n., Bisma angulatasp. n., Pitambara trypetoidessp. n., Sarmatoca cathemerinagen. et sp. n., Maracota soulieraegen. et sp. n., and Serida castaneasp. n., and Zeleja thoracalissp. n. from Malaysia. Two new genera, Maracotagen. n. (type species M. soulierae sp. n.) and Sarmatocagen. n. (type species S. cathemerina sp. n.), and a new subgenus Zelomachasubgen. n. (type species Zeleja thoracalis sp. n.) in the genus Zeleja are erected. The genus Binaluana Soulier-Perkins et Stroiński is downgraded to a subgenus of Zeleja Melichar. The genus Silvispina Wang et Soulier-Perkins with an uncertain systematic position is attributed to the subfamily Lophopinae and the tribe Lophopini. The placement of the genus Elasmoscelis Spinola (and, correspondingly, the tribe Elasmoscelini) in the subfamily Menoscinae, the genus Epiptyxis Gerstaecker in the tribe Menoscini, and the genus Jivatma Melichar in the tribe Lophopini is substantiated. New records of 11 species are given from Vietnam, some being first records for this country.     

Synthesis and characteristics of new fluorescent probes based on cardiolipin

New fluorescent lipid probes, cardiolipin derivatives AV12-CL and B7-CL, bearing the residues of 12-(9-anthryl)-11E-dodecenoic and 7-(4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacen-8-yl)heptanoic acid, respectively, have been synthesized by acylation of 1-lysocardiolipin, which had been obtained from bovine heart cardiolipin by enzymatic hydrolysis with bacterial lipase. The resulting probes are intended for the study of protein-anionic phospholipid interactions.     

Antimicrobial effect of OKCEL® H-D prepared from oxidized cellulose

The antimicrobial effect of OKCEL® H-D, a topical, absorbable hemostatic textile prepared from oxidized cellulose, was tested. Testing by dilution and diffusion methods was conducted on a spectrum of 27 select microorganisms, including also antibiotic-resistant strains. OKCEL® H-D showed inhibitory effects on nearly all tested bacteria. In testing using the dilution suspension method, the majority of bacteria showed decrease in cell density by 7–8 orders of magnitude after just 6 h of exposure. For clinical isolates of antibiotic-resistant strains, a reduction occurred after 24 h of exposure. In testing the antimicrobial effects of OKCEL® H-D by the dilution method was least effective on spore-forming Bacillus subtilis, for which no antimicrobial effect was detected after 48 h, and on Mycobacterium smegmatis, for which the number of cells decreased by four orders of magnitude only after 24 h. By the diffusion method, inhibition zones were recorded for nearly all test microorganisms except for Staphylococcus aureus, M. smegmatis, and Listeria monocytogenes. No growth beneath the tested OKCEL® H-D material was recorded, however, even for the latter-named bacteria strains, which attests to its good inhibitory effect.