Microorganisms inhabiting saline environments have been known for decades as producers of many valuable bioproducts. These substances include antimicrobial peptides (AMPs), the most recognizable of which are halocins produced by halophilic Archaea. As agents with a different modes of action from that of most conventionally used antibiotics, usually associated with an increase in the permeability of the cell membrane as a result of a formation of channels and pores, AMPs are a currently promising object of research focused on the investigation of antibiotics with non-standard modes of action. The aim of this study was to investigate antimicrobial activity against multidrug-resistant human pathogens of three peptides, which were synthetised based on sequences identified in metagenomes from saline environments. The investigations were performed against Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Subsequently, the cytotoxicity and haemolytic properties of the tested peptides were verified. An in silico analysis of the interaction of the tested peptides with molecular targets for reference antibiotics was also carried out in order to verify whether or not they can act in a similar way. The P1 peptide manifested the growth inhibition of E. faecalis at a MIC₅₀ of 32 µg/mL and the P3 peptide at a MIC₅₀ of 32 µg/mL was shown to inhibit the growth of both E. faecalis and S. aureus. Furthermore, the P1 and P3 peptides were shown to have no cytotoxic or haemolytic activity against human cells.

(1) Background: The aim of this study was to identify the degradation product of ramipril (RAM) formed under dry air and to verify its potential modes of carcinogenicity. We intended to check whether its formation and presence in final dosage forms could pose a cancer risk to humans who are treated with RAM due to cardiological indications. The carcinogenicity of this compound was evaluated with respect to two mechanisms: a potential direct DNA-damage and indirect toxicity, secondary to forming mutagenic N-nitroso metabolites. (2) Methods: Firstly, a forced ageing test under dry air was conducted for pure RAM in order to induce its degradation. The validated HPLC system was used to describe the kinetic order of this reaction. The emerging degradation impurity was identified by HPLC-MS. In the second stage, the cancer risk of the identified RAM degradant was predicted using a structure-based assessment by in silico QSAR model, employing three endpoints: carcinogenicity, genotoxicity and mutagenicity. In the third stage, the obtained QSAR results were experimentally verified. To verify genotoxicity prediction, in vitro micronucleus assay was employed. It enabled us to assess the potential direct DNA-damaging properties of RAM degradant at high concentrations (as screening series) and at concentrations usually observed in human blood (to mimic the clinical scenario). To verify the QSAR mutagenicity prediction, an in vitro Ames test was carried out. It was designed so as to detect two mechanisms of mutagenicity: a direct one (for pure degradant) and an indirect one (via N-nitroso-metabolites formation). N-nitroso-metabolites for mutagenicity assessment were obtained using NAP test. (3) Results: The kinetic mechanism of RAM degradation was first-order, the degradation rate constant was k = 1.396 ± 0.133 × 10⁻⁵ s⁻¹ (T = 373 K), thus the formation of impurity was rapid. Energy of activation was 174.12 ± 46.2 kJ/mol, entropy was positive, thus reaction was bimolecular and favored; enthalpy was 171.65 ± 48.7 kJ/mol, thus reaction was endothermic. Only one degradation impurity was formed, and it was identified as RAM diketopiperazine derivative (DKP). QSAR simulation predicted that DKP could be carcinogenic and genotoxic, but this result had only moderate reliability. DKP was also predicted to be non-mutagenic and this prediction was strong (endpoint score 0.2). The confirmatory micronucleus experiment for genotoxicity prediction suggested that DKP was cytotoxic and it could be also aneugenic at a high concentration (0.22 mg/mL), evidenced by a three-fold increase in micronuclei relative to the control (11.86:33.33%, p = 0.0184). At physiologic concentrations, its cytotoxicity and genotoxicity did not occur. This means that the genotoxicity of DKP was limited by a threshold mechanism. In the mutagenicity in vitro assessment, pure DKP was not mutagenic, but its nitrosation product induced base substitutions mutations in test bacteria TA100 following metabolic activation at a concentration of 4.5 mg/mL, confirming its mutagenicity. (4) Conclusions: RAM rapidly cyclizes to diketopiperazine derivative under dry air. This impurity resides in drugs administered to patients. DKP is potentially aneugenic and cytotoxic at high concentrations, yet at concentrations typically occurring in human blood, this effect is unlikely. The exposure of patients to high concentrations of DKP, exceeding the typical blood level and standard RAM dosing, could lead to cancer development, thus the safe threshold for human exposure to DKP must be verified in follow-up in vivo experiments. Based on our results, it is impossible to establish the maximum safe dose of pure DKP to humans. Furthermore, DKP itself is not mutagenic, but it is liable to the formation of mutagenic nitroso-metabolites in vivo. Nitroso-derivatives of DKP are in vitro mutagens and their real-life impact on humans must be further evaluated in in vivo studies. Until this is carried out, RAM should not be formulated by manufacturers using dry procedures to minimize DKP formation and reduce risk of human carcinogenesis, since DKP could cause cancer via two independent mechanisms: direct genotoxicity when the exposure over standard RAM dosing occurs, and indirect mutagenicity via in vivo N-nitrosamine formation.

Recently, 5-[(4-ethoxyphenyl)imino]methyl-N-(4-fluorophenyl)-6-methyl-2-phenylpyrimidin-4-amine has been synthesized, characterized, and evaluated for its antibacterial activity against Enterococcus faecalis in combination with antineoplastic activity against gastric adenocarcinoma. In this study, new 5-iminomethylpyrimidine compounds were synthesized which differ in the substituent(s) of the aromatic ring attached to the imine group. The structures of newly obtained pyrimidine Schiff bases were established by spectroscopy techniques (ESI-MS, FTIR and ¹H NMR). To extend the current knowledge about the features responsible for the biological activity of the new 5-iminomethylpyrimidine derivatives, low-temperature single-crystal X-ray analyses were carried out. For all studied crystals, intramolecular N–H∙∙∙N hydrogen bonds and intermolecular C–H∙∙∙F interactions were observed and seemed to play an essential role in the formation of the structures. Simultaneously, their biological properties based on their cytotoxic features were compared with the activities of the Schiff base (III) published previously. Moreover, computational investigations, such as ADME prediction analysis and molecular docking, were also performed on the most active new Schiff base (compound 4b). These results were compared with the highest active compound III.

Pyrimidine displays a wide array of bioactivities, and thence, it is still considered a potent unit of new drug research. Its derivative, 5-hydroxymethylpyrimidine, can be found as a scaffold of nontypical nitrogen bases in DNA and as a core of some natural bioactive compounds. In this study, we obtained a series of 5-hydroxymethylpyrimidines that vary in the 4-position by the reduction of proper esters. All compounds were characterized by spectroscopic analysis, and single-crystal X-ray diffraction was performed for some of them. Biological investigations estimated cytotoxic properties against normal (RPTEC) and cancer (HeLa, HepaRG, Caco-2, AGS, A172) cell lines. It was found that the derivatives with an aliphatic amino group at the 4-position are generally less toxic to normal cells than those with a benzylsulfanyl group. Moreover, compounds with bulky constituents exhibit better anticancer properties, though at a moderate level. The specific compounds were chosen due to their most promising IC50 concentration for in silico study. Furthermore, antimicrobial activity tests were performed against six strains of bacteria and one fungus. They demonstrated that only derivatives with at least three carbon chain amino groups at the 4-position have weak antibacterial properties, and only the derivative with 4-benzylsulfanyl constituent exhibits any antifungal action.

Objectives: Alzheimer’s disease (AD) and other dementias represent a growing public health concern, highlighting the need for reliable biomarkers for early diagnosis and treatment monitoring. This study evaluated the potential utility of BIN1 and TOMM40 genotyping in diagnosing mild cognitive impairment (MCI) and early-stage dementia. Methods: The BIN1 rs744373 and TOMM40 rs2075650 polymorphisms were genotyped in a cohort of 105 individuals diagnosed with MCI or dementia and in 164 cognitively healthy controls. Genotype distributions were compared between the groups, and the potential role of these variants in diagnostic assessment was explored. Results: A significantly higher frequency of the TOMM40 rs2075650 GG genotype was observed in patients with AD compared with cognitively healthy controls. In contrast, no statistically significant differences in genotype distribution were found among individuals with mild MCI, vascular dementia, or mixed dementia. Furthermore, the distribution of BIN1 rs744373 alleles did not differ significantly across the analyzed groups. Conclusions: Data on the effects of BIN1 rs744373 and TOMM40 rs2075650 polymorphisms in MCI and dementia remain limited and inconsistent. In our study, significant differences were observed only for the TOMM40 rs2075650 GG genotype and G allele, which were more frequent in Alzheimer’s disease patients than in controls. No significant associations were found for MCI, vascular dementia, or mixed dementia, nor for the BIN1 rs744373 polymorphism. These results suggest that TOMM40 rs2075650 genotyping may serve as an additional marker for assessing AD risk.