The global spread of antibiotic resistance is forcing the scientific community to find new molecular strategies to counteract it. Deep functional profiling of microbiomes provides an alternative source for the discovery of novel antibiotic producers and probiotics. Recently, we implemented this ultrahigh-throughput screening approach for the isolation of Bacillus pumilus strains efficiently producing the ribosome-targeting antibiotic amicoumacin A (Ami). Proteomics and metabolomics revealed essential insight into the activation of Ami biosynthesis. Here, we applied omics to boost Ami biosynthesis, providing the optimized cultivation conditions for high-scale production of Ami. Ami displayed a pronounced activity against Lactobacillales and Staphylococcaceae, including methicillin-resistant Staphylococcus aureus (MRSA) strains, which was determined using both classical and massive single-cell microfluidic assays. However, the practical application of Ami is limited by its high cytotoxicity and particularly low stability. The former is associated with its self-lactonization, serving as an improvised intermediate state of Ami hydrolysis. This intramolecular reaction decreases Ami half-life at physiological conditions to less than 2 h, which is unprecedented for a terminal amide. While we speculate that the instability of Ami is essential for Bacillus ecology, we believe that its stable analogs represent attractive lead compounds both for antibiotic discovery and for anticancer drug development.

The substrate-driven closure determines an outstanding efficacy of antibiotic inactivation in a new kinase subfamily.

The ability of a series of novel modified external guide sequences (EGS oligonucleotides) to induce the hydrolysis of target RNA with bacterial ribonuclease P has been studied; the most efficient modification variants have been selected. We have found patterns of the oligonucleotide sugar-phosphate backbone modi-fications that enhance oligonucleotide stability in the biological environment and do not violate the ability to interact with the enzyme and induce the RNA hydrolysis. It has been shown that analogues of EGS oligonucleotides selectively modified at 2'-position (2'-O-methyl and 2'-fluoro) or at internucleotide phosphates (phosphoryl guanidines) can be used for the addressed cleavage of a model RNA target by bacterial RNase P. The ability of new phosphoryl guanidine analogues of oligodeoxyribonucleotides that are stable in biological media to induce the hydrolysis of target RNA with bacterial ribonuclease P has been shown for the first time. The modified EGS oligonucleotides with an optimal balance between functional activity and stability in biological media can be considered as potential antibacterial agents.

The ability of a series of novel modified external guide sequences (EGS oligonucleotides) to induce the hydrolysis of target RNA with bacterial ribonuclease P has been studied; the most efficient modification variants have been selected. We have found patterns of the oligonucleotide sugar-phosphate backbone modi-fications that enhance oligonucleotide stability in the biological environment and do not violate the ability to interact with the enzyme and induce the RNA hydrolysis. It has been shown that analogues of EGS oligonucleotides selectively modified at 2'-position (2'-O-methyl and 2'-fluoro) or at internucleotide phosphates (phosphoryl guanidines) can be used for the addressed cleavage of a model RNA target by bacterial RNase P. The ability of new phosphoryl guanidine analogues of oligodeoxyribonucleotides that are stable in biological media to induce the hydrolysis of target RNA with bacterial ribonuclease P has been shown for the first time. The modified EGS oligonucleotides with an optimal balance between functional activity and stability in biological media can be considered as potential antibacterial agents.

INTRODUCTION. Developing novel medicines based on non-pathogenic enterovirus strains exhibiting oncotropic and oncolytic properties represents an up-to-date and safe approach to complex cancer treatment and postoperative metastasis prevention. Safety pharmacology studies are a necessary step in the preclinical development of medicinal products. AIM. The study aimed to investigate the single and repeated-dose general toxicity, local tolerance, safety pharmacology, and pyrogenicity of medicinal products based on non-pathogenic LEV4, LEV7, LEV8, LEV14, and Russo enterovirus strains as part of preclinical safety studies. MATERIALS AND METHODS. The study used medicinal products of highly purified group A, B, and C enteroviruses at a titre of 2×107–5×108 CPD ₅₀ /mL (CPD ₅₀ is a cytopathogenic dose of the virus causing 50% cell lysis) and normal saline as a diluent. The viruses were propagated in Vero cells. The safety study used 220 male and female BALB/c mice, 440 male and female Wistar rats, and 18 male Soviet chinchilla rabbits. The study animals received an intravenous dose of 1×105 or 1×106 CPD ₅₀ /animal once (single-dose toxicity) or weekly for 90 days (repeated-dose toxicity). Clinical examination, laboratory testing, and necropsy were performed on Days 45 and 91 of the experiment. Statistical data processing was performed using Prism 8.0 software (GraphPad Software, Inc., USA). RESULTS. Upon single administration of each of the five enterovirus medicinal products to mice and rats, the authors observed complete survival, upward trends in body weight gain, and no gross or histopathological changes in the brain, spleen, liver, kidneys, lungs, or at the injection site. Upon repeated administration at the study doses, the medicinal products caused no functional changes in the organs and systems. All the studied parameters were within the normal physiological ranges for male and female rats. Histopathological examination revealed no pathological changes or specific cytolytic and/or cytopathic effects. No local irritation was observed. None of the investigational medicinal products showed pyrogenicity. CONCLUSIONS. The obtained preclinical results demonstrate the safety of antineoplastic agents based on live non-pathogenic LEV4, LEV7, LEV8, LEV14, and Russo enteroviruses.