Background. The search for new effective antibiotics is one of the main tasks in the field of medicine, which is due to the spread of antibiotic-resistant pathogens that are not amenable to traditional chemotherapy. The aim of the study was the search for a microorganism that could potentially produce an antibiotic exhibiting antimicrobial activity against pathogenic bacteria with multiple drug resistance. The object of the study was a bacterium isolated from a freshwater indoor aquarium, identified as Aquipseudomonas alcaligenes and deposited in the collection of NIINA under the number INA 01568. Materials and methods . For the surface cultivation of A. alcaligenes, bacterial and fungal strains, universal medium No. 2 Gause was used. Submerged cultivation was carried out in 18 nutrient media of different compositions. An agar diffusion method was used to determine the antimicrobial activity. Thirteen collection test strains of bacteria and fungi were used as test strains. Species identification was carried out by morphological features and the 16S rRNA gene. Results. When cultured under submerged conditions on 2 media out of 18, the A. alcaligenes INA 01568 strain demonstrated antimicrobial activity against 6 test strains, including bacteria from the ESKAPE group, namely MRSA, Pseudomonas aeruginosa, as well as the vancomycin-resistant strain Leuconostoc mesenteroides; activity against these strains has been described for the first time. Activity against fungi was not detected. Conclusion . The A. alcaligenes strain INA 01568 is promising for chemical research.

The problem of antibiotic resistance is one of the challenges that science and medicine face in the 21st century. Nucleoside analogs have already proven as antiviral and antitumor agents, and, currently, there are more and more reports on their antibacterial and antifungal activity. The substitution of an oxygen atom by a sulfur one leads to the emergence of unique properties. Here, we report the synthesis of eight new 4-thioanalogs of 5-substituted (5-alkyloxymethyl and 5-alkyltriazolylmethyl) derivatives of 2'-deoxyuridine and uridine, which were active against Mycobacterium tuberculosis and Gram-positive bacteria. The novel sulfur-containing nucleosides were synthesized via activation of the pyrimidine C4 position, followed by condensation with thioacetic acid and deblocking. To increase the solubility, oligoglycol carbonate depot forms were obtained via activation of the 3'-hydroxyl group using N,N'-carbonyldiimidazole and condensation with triethylene glycol. The highest inhibitory activity was demonstrated by 3'-triethylene glycol depot forms of 4-thio-5-undecyl- and 5-dodecyloxymethyl-2'-deoxyuridine (4a,b) against two strains of M. smegmatis. The most promising compounds were 5-[4-decyl-(1,2,3-triazol-1-yl)methyl]-4-thio-2'-deoxy- and ribouridine (3c,g) and 5-undecyloxymethyl 4-thiouridine (3e) active toward clinical M. intracellulare isolates. Overall, novel sulfur-containing nucleoside analogs were low toxic, demonstrated better inhibitory activity compared to their C4-oxo ones, and, thus, are promising compounds for the development of new antibacterial agents.

In current work, we for the first time studied the antimicrobial activity of representatives of mold fungi, which occupy a rather specific ecological niche, since they are destructors of tempera painting materials. We screened 24 molds that had previously been isolated from exhibits and in the halls of the State Tretyakov Gallery and for which the ability to destroy materials used in tempera painting and scientific restoration was shown. Screening for antimicrobial activity was carried out against a panel of 16 test cultures, characteristic for identifying activities of various types. The strains exhibited activity, including against Staphylococcus aureus INA 00761 (MRSA), S. aureus FDA 209P (MSSA), Pseudomonas aeruginosa ATCC 27853, Mycobacterium smegmatis VKPM Ac-1339, M. smegmatis mc2 155 and Leuconostoc mesenteroides VKPM B-4177. Among the studied paint-degrading fungi, strains Simplicillium lamellicola STG-96, Cerarobasidium sp. STG-324, Penicillium sp. STG-327 and Penicillium sp. STG-344 turned out to be the most promising for further research related to the determination what specific highly active compounds they produce.

The rapid increase in the antibiotic resistance of microorganisms, capable of causing diseases in humans as destroying cultural heritage sites, is a great challenge for modern science. In this regard, it is necessary to develop fundamentally novel and highly active compounds. In this study, a series of N4-alkylcytidines, including 5- and 6-methylcytidine derivatives, with extended alkyl substituents, were obtained in order to develop a new generation of antibacterial and antifungal biocides based on nucleoside derivatives. It has been shown that N4-alkyl 5- or 6-methylcytidines effectively inhibit the growth of molds, isolated from the paintings in the halls of the Ancient Russian Paintings of the State Tretyakov Gallery, Russia, Moscow. The novel compounds showed activity similar to antiseptics commonly used to protect works of art, such as benzalkonium chloride, to which a number of microorganisms have acquired resistance. It was also shown that the activity of N4-alkylcytidines is comparable to that of some antibiotics used in medicine to fight Gram-positive bacteria, including resistant strains of Staphylococcus aureus and Mycobacterium smegmatis. N4-dodecyl-5- and 6-methylcytidines turned out to be the best. This compound seems promising for expanding the palette of antiseptics used in painting, since quite often the destruction of painting materials is caused by joint fungi and bacteria infection.

Background. The spread of pathogenic antibiotic-resistant microorganisms often leads to the inefficiency of antimicrobial therapy. One of the solutions to this problem is the search for new active natural antibiotics.The aim of the study. The search for producers that show antibiotic activity in relation to resistant test microorganisms, including those from the ESKAPE group, in the natural environment. The object of the study was bacteria isolated from a poorly studied environment — the soil of the tropical desert, namely the soil of the Sinai Peninsula.Methods. Soil suspensions were sown on universal sterling agar environment No. 2 Gause, suitable for the growth of many bacteria and fungi. The isolated microorganisms were identified by morphological characteristics and by the analysis of ribosomal RNA genes. Deep cultivation was carried out in nutrient media of various compositions under aeration conditions. Test strains of gram-positive and gram-negative bacteria, as well as fungi, were used to evaluate antimicrobial activity.Results. 38 cultures of microorganisms were isolated: 9 strains of fungi, 5 strains of streptomycetes, 2 strains of Bacillus subtilis, and 22 strains of representatives of other taxonomic groups of bacteria. 5 strains of streptomycetes and 2 strains of B. subtilis exhibit antibiotic activity, in particular against resistant pathogens of the ESKAPE group, namely methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Escherichia coli, as well as Mycobacterium smegmatis — a preliminary test in the search for anti-tuberculosis drugs.Conclusion. The search for antibiotic producers from the isolated desert soil was productive, due to the fact that a quarter of the isolated bacterial strains exhibited antimicrobial activity, even against multidrug-resistant test strains. Bio-synthesis conditions have been developed for subsequent isolation and chemical study. The most promising strains are Streptomyces rochei INA 01452 and INA 01509, as well as Streptomyces sp. INA 01523.

Antimicrobial peptides (AMPs) have recently attracted attention as promising antibacterial agents capable of acting against resistant bacterial strains. In this work, an approach was applied, consisting of the conjugation of a peptide related to the sequences of bactenecin 7 (Bac7) and oncocin (Onc112) with the alkyl(triphenyl)phosphonium (alkyl-TPP) fragment in order to improve the properties of the AMP and introduce new ones, expand the spectrum of antimicrobial activity, and reduce the inhibitory effect on the eukaryotic translation process. Triphenylphosphonium (TPP) derivatives of a decapeptide RRIRPRPPYL were synthesized. It was comprehensively studied how the modification of the AMP affected the properties of the new compounds. It was shown that while the reduction in the Bac7 length to 10 a.a. residues dramatically decreased the affinity to bacterial ribosomes, the modification of the peptide with alkyl-TPP moieties led to an increase in the affinity. New analogs with structures that combined a decapeptide related to Bac7 and Onc112—Bac(1–10, R/Y)—and TPP attached to the C-terminal amino acid residue via alkylamide linkers, inhibited translation in vitro and were found to be more selective inhibitors of bacterial translation compared with eukaryotic translation than Onc112 and Bac7. The TPP analogs of the decapeptide related to Bac7 and Onc112 suppressed the growth of both Gram-negative bacteria, similar to Onc112 and Bac7, and Gram-positive ones, similar to alkyl-TPP derivatives, and also acted against some resistant laboratory strains. Bac(1–10, R/Y)-C2-TPP, containing a short alkylamide linker between the decapeptide and TPP, was transferred into the E. coli cells via the SbmA transporter protein. TPP derivatives of the decapeptide Bac(1–10, R/Y) containing either a decylamide or ethylamide linker caused B. subtilis membrane depolarization, similar to alkyl-TPP. The Bac(1–10, R/Y)-C2-TPP analog was proven to be non-toxic for mammalian cells using the MTT test.

A variety of ribo-, 2′-deoxyribo-, and 5′-norcarbocyclic derivatives of the 8-aza-7-deazahypoxanthine fleximer scaffolds were designed, synthesized, and screened for antibacterial activity. Both chemical and chemoenzymatic methods of synthesis for the 8-aza-7-deazainosine fleximers were compared. In the case of the 8-aza-7-deazahypoxanthine fleximer, the transglycosylation reaction proceeded with the formation of side products. In the case of the protected fleximer base, 1-(4-benzyloxypyrimidin-5-yl)pyrazole, the reaction proceeded selectively with formation of only one product. However, both synthetic routes to realize the fleximer ribonucleoside (3) worked with equal efficiency. The new compounds, as well as some 8-aza-7-deazapurine nucleosides synthesized previously, were studied against Gram-positive and Gram-negative bacteria and M. tuberculosis. It was shown that 1-(β-D-ribofuranosyl)-4-(2-aminopyridin-3-yl)pyrazole (19) and 1-(2′,3′,4′-trihydroxycyclopent-1′-yl)-4-(pyrimidin-4(3H)-on-5-yl)pyrazole (9) were able to inhibit the growth of M. smegmatis mc2 155 by 99% at concentrations (MIC99) of 50 and 13 µg/mL, respectively. Antimycobacterial activities were revealed for 4-(4-aminopyridin-3-yl)-1H-pyrazol (10) and 1-(4′-hydroxy-2′-cyclopenten-1′-yl)-4-(4-benzyloxypyrimidin-5-yl)pyrazole (6). At concentrations (MIC99) of 40 and 20 µg/mL, respectively, the compounds resulted in 99% inhibition of M. tuberculosis growth.

In order to obtain antimicrobial compounds with improved properties, new conjugates comprising two different biologically active agents within a single chimeric molecule based on chloramphenicol (CHL) and a hydrophobic cation were synthesized and studied. Chloramphenicol amine (CAM), derived from the ribosome-targeting antibiotic CHL, and the plant isoquinoline alkaloid berberine (BER) are connected by alkyl linkers of different lengths in structures of these conjugates. Using competition binding, double reporter system, and toeprinting assays, we showed that synthesized CAM-Cn-BER compounds bound to the bacterial ribosome and inhibited protein synthesis like the parent CHL. The mechanism of action of CAM-C5-BER and CAM-C8-BER on the process of bacterial translations was similar to CHL. Experiments with bacteria demonstrated that CAM-Cn-BERs suppressed the growth of laboratory strains of CHL and macrolides-resistant bacteria. CAM-C8-BER acted against mycobacteria and more selectively inhibited the growth of Gram-positive bacteria than the parent CHL and the berberine derivative lacking the CAM moiety (CH3-C8-BER). Using a potential-sensitive fluorescent probe, we found that CAM-C8-BER significantly reduced the membrane potential in B. subtilis cells. Crystal violet assays were used to demonstrate the absence of induction of biofilm formation under the action of CAM-C8-BER on E. coli bacteria. Thus, we showed that CAM-C8-BER could act both on the ribosome and on the cell membrane of bacteria, with the alkylated berberine fragment of the compound making a significant contribution to the inhibitory effect on bacterial growth. Moreover, we showed that CAM-Cn-BERs did not inhibit eukaryotic translation in vitro and were non-toxic for eukaryotic cells.

New antibiotics are unquestionably needed to fight the emergence and spread of multidrug-resistant bacteria. To date, antibiotics targeting bacterial central metabolism have been poorly investigated. By determining the minimal inhibitory concentration (MIC) of desmethylphosphinothricin (Glu-γ-PH), an analogue of glutamate with a phosphinic moiety replacing the γ-carboxyl group, we previously showed its promising antibacterial activity on Escherichia coli. Herein, we synthetized and determined the growth inhibition exerted on E. coli by an L-Leu dipeptide derivative of Glu-γ-PH (L-Leu-D,L-Glu-γ-PH). Furthermore, we compared the growth inhibition obtained with this dipeptide with that exerted by the free amino acid, i.e., Glu-γ-PH, and by their phosphonic and non-desmethylated analogues. All the tested compounds were more effective when assayed in a chemically-defined minimal medium. The dipeptide L-Leu-D,L-Glu-γ-PH had a significantly improved antibacterial activity (2 μg/mL), at a concentration between the non-desmethytaled (0.1 μg/mL) and the phosphonic (80 μg/mL) analogues. Also, in Bacillus subtilis, the dipeptide L-Leu-D,L-Glu-γ-PH displayed an activity comparable to that of the antibiotic amoxicillin. This work highlights the antibacterial relevance of the phosphinic pharmacophore and proposes new avenues for the development of novel antimicrobial drugs containing the phosphinic moiety.

The emergence of drug-resistant strains of pathogenic microorganisms necessitates the creation of new drugs. A series of uridine derivatives containing an extended substituent at the C-5 position as well as C-5 alkyloxymethyl, alkylthiomethyl, alkyltriazolylmethyl, alkylsulfinylmethyl and alkylsulfonylmethyl uridines were obtained in order to explore their antimicrobial properties and solubility. It has been shown that new ribonucleoside derivatives have an order of magnitude better solubility in water compared to their 2 & PRIME;-deoxy analogues and effectively inhibit the growth of a number of Gram-positive bacteria, including resistant strains of Mycobacterium smegmatis (MIC=15-200 & mu;g/mL) and Staphylococcus aureus (MIC=25-100 & mu;g/mL). Their activity is comparable to that of some antibiotics used in medicine. The emergence of drug-resistant strains of pathogenic microorganisms necessitates the creation of new drugs. A series of uridine derivatives containing an extended substituent at the C-5 position as well as C-5 alkyloxymethyl, alkylthiomethyl, alkyltriazolylmethyl, alkylsulfinylmethyl, and alkylsulfonylmethyl uridines were obtained in order to explore their antimicrobial properties and solubility. The new ribonucleoside derivatives have an order-of-magnitude better solubility in water than their 2 & PRIME;-deoxy analogues and effectively inhibit the growth of a number of Gram-positive bacteria.image

The fast spread of bacteria that are resistant to many classes of antibiotics (multidrug resistant) is a global threat to human and animal health with a worrisome scenario ahead. Novel therapeutical strategies are of crucial importance to combat this phenomenon. For this purpose, we investigated the antimicrobial properties of the naturally occurring tripeptide Bialaphos and a dipeptide L-leucyl-L-phosphinoithricin, the synthesis and diastereomers separation of which are herein described. We demonstrate that these compounds are effective on clinical isolates of the human pathogen Klebsiella pneumoniae, causing hospital-acquired and community-acquired infections. The tested isolates were remarkable for their resistance to more than 20 commercial antibiotics of different classes. Based on previous literature data and our experiments consisting of glutamine supplementation, we suggest that both compounds release phosphinothricin-a well-known nanomolar inhibitor of glutamine synthetase-after their penetration in the bacterial cells; and, in this way, exert their antibacterial effect by negatively affecting nitrogen assimilation in this pathogen.

Condensation of 3ʹ,5ʹ-di-O-acetyl-5-bromomethyl-2ʹ-deoxyuridine with 6-trifluoroacetylaminohexan1-ol yielded 5-(6-trifluoroacetylaminohexyl-1-oxymethyl)-3ʹ,5ʹ-di- O-acetyl-2ʹ-deoxyuridine. Its deblocking with an aqueous alcoholic solution of ammonia gave 5-(6-aminohexyl-1-oxymethyl)-2ʹ-deoxyuridine, and condensation with triazole and 2-chlorophenyl phosphorodichloridate followed by treatment with an aqueous solution of ammonia led to the formation of 5-(6-aminohexyl-1-oxymethyl)-2ʹ-deoxycytidine. The interaction of the obtained compounds with 2,4-dinitrofluorobenzene or N-hydroxysuccinimide esters of N-2,4-dinitrophenylaminohexanoic acid or 5-dimethylaminonaphthalene-1-sulfonyl glycine was used to synthesize DNP- and DNS-derivatives of 2ʹ-deoxyuridine as well as 5-(6-DNP-aminohexanoylaminohexyl-1-oxymethyl)-2ʹ-deoxycytidine. DNP derivatives of 2ʹ-deoxyuridine were shown to inhibit the growth of Micrococcus luteus.

In order to develop a new generation of antibacterial nucleosides, a representative set of novel 3'- and 5'-tri- or tetraethylene glycol prodrug forms of 5-alkyloxymethyl-2'- deoxyuridines was synthesized. These compounds were at least two orders of magnitude more soluble than the parent nucleosides, possessed significant inhibitory activity against a set of bacteria including resistant strains of Staphylococcus aureus and Mycobacterium smegmatis, and showed low cytotoxicity. The obtained data indicate that glycol carbonates are convenient and prospective for usage in prodrugs of nucleoside derivatives with antibacterial activity.

From the intestines of millipedes of the species Nedyopus dawydoffiae and Orthomorpha sp. (class Diplopoda) and from their food substrates (plant residues), 72 bacterial strains belonging to 25 genera were isolated and identified. Among the studied strains, actinobacteria predominated, among which streptomycetes were the most numerous, although representatives of 14 other genera of actinobacteria were also present. High abundance of actinobacteria with antimicrobial activity was noted, including members of the "rare " genera Actinoplanes, Amycolatopsis, Kitasatospora, Lechevalieria, Micromonospora, Nocardiopsis, and Saccharopolyspora. This is the first report on antimicrobial activity in Kitasatospora saccharophila INA 01226 and Nocardiopsis umidischolae INA 01230. Heterogeneity in terms of antibiotic formation in the populations of Streptomyces pratensis and S. termitum was shown. The most promising bacterial strains chosen for the chemical study of antibiotics formed exhibited activity against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and vancomycin-resistant strain Leuconostoc mesenteroides VKPM B-4177 (VRLM).

From the intestinal microbiota of Colorado potato beetles and their larvae (Leptinotarsa decemlineata), as well as from their feed – potato leaves, 18 bacteria of different species exhibiting antimicrobial activity (56% of the total number of isolated strains) were isolated. The species of bacteria from all three sources of excretion are different. The following 12 species were described for the first time in the gut microbiota of L. decemlineata larvae and imago: Micromonospora phytophila, Neobacillus drentensis, Pseudomonas gessardii, P. poae, P. rhizosphaerae, Pantoea agglomerans, Streptomyces chartreusis, S. clavifer, S. microflavus, S. rishiriensis, S. badius, and S. coelicoflavus. Antimicrobial activity was not previously known for three species (Staphylococcus argenteus, S. camponoticapitis, S. clavifer). Antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Leuconostoc mesenteroides, multidrug-resistant P. aeruginosa, and Mycobacterium smegmatis was revealed. The gut microbiota of Colorado potato beetles can be considered an encouraging source of antibiotic–producing strains that overcome drug resistance of pathogenic bacteria, as well components of biopesticides.

Medicinal probiotic Sporobacterin is based on the Bacillus subtilis 534 strain, which has been shown to have antimicrobial activity against many bacteria, both the collection strains and the antibiotic-resistant forms of clinical isolates of pathogenic bacteria and fungi. Considering this strain as an antibiotic producer, a step-by-step mutagenic treatment was carried out in order to obtain a variant that consistently exhibits a certain high-level antibiotic activity. A mutant variant was obtained during the three stages of mutagenic treatment and selection; it effectively suppresses the growth of pathogenic staphylococci, including methicillin-resistant staphylococcus (MRSA).

A set of 3′-modified N4-alkyl-5-methyl-2′-deoxycytidines has been synthesized and evaluated for biological activity. The replacement of the 3′-hydroxyl group with amino, aminoethyl and dialkylamino groups significantly enhances antifungal activity.

Here, we report the complete genome sequence of Streptomyces albus strain INA 01303, which was isolated from the Salt Lake Tambukan (Russia). The genome consists of a linear 6,840,896-nucleotide chromosome. This strain is predicted to produce a range of novel secondary metabolites with antibiotic activity.

The emergence of antibiotic-resistant pathogenic bacteria in recent decades leads us to an urgent need for the development of new antibacterial agents. The species of the genus Amycolatopsis are known as producers of secondary metabolites that are used in medicine and agriculture. The complete genome sequences of the Amycolatopsis demonstrate a wide variety of biosynthetic gene clusters, which highlights the potential ability of actinomycetes of this genus to produce new antibiotics. In this review, we summarize information about antibiotics produced by Amycolatopsis species. This knowledge demonstrates the prospects for further study of this genus as an enormous source of antibiotics.

Currently, the problem of antibiotic resistance of opportunistic and pathogenic microorganisms is extremely urgent. In order to find new effective natural antibiotics, it is necessary to intensify the search process. In the gradual selection of the most promising producers, we introduced the stage of determining the antibiotic activity of the culture fluid of the studied natural strains against the clinical isolates of hospital microorganisms with multiple resistance to medical antibiotics. Determining the species affiliation of potential producers allows to select those producers of a particular species that differ in the antimicrobial spectrum of activity from those described in the literature. Four strains of actinomycetes that showed activity against resistant clinical isolates of yeast Candida albicans, C.famata, C.parapsilosis and Cryptococcus neoformans were selected, namely: Nocardia soli INA 01217, Streptomyces bottropensis INA 01214, S.chromofuscus INA 01211 and S.netropsis INA 01190. The N.soli INA 01217 strain also shows antibiotic activity against the Gram-negative bacterium Escherichia coli ATCC 25922. These strains of actinobacterial producers were selected for subsequent chemical studies of the antimicrobial compounds formed by them.