Adenine Derivatives for Regenerable Antibacterial Surface Applications Based on A−T Base Pairing

The protective role of commensal gut microbes and their metabolites against bacterial pathogens

Multidrug-resistant microorganisms have become a major public health concern around the world. The gut microbiome is a gold mine for bioactive compounds that protect the human body from pathogens. We used a multi-omics approach that integrated whole-genome sequencing (WGS) of 74 commensal gut microbiome isolates with metabolome analysis to discover their metabolic interaction with Salmonella and other antibiotic-resistant pathogens. We evaluated differences in the functional potential of these selected isolates based on WGS annotation profiles. Furthermore, the top altered metabolites in co-culture supernatants of selected commensal gut microbiome isolates were identified including a series of dipeptides and examined for their ability to prevent the growth of various antibiotic-resistant bacteria. Our results provide compelling evidence that the gut microbiome produces metabolites, including the compound class of dipeptides that can potentially be applied for anti-infection medication, especially against antibiotic-resistant pathogens. Our established pipeline for the discovery and validation of bioactive metabolites from the gut microbiome as novel candidates for multidrug-resistant infections represents a new avenue for the discovery of antimicrobial lead structures.

The adenine-modified edible chitosan films containing choline chloride and citric acid mixture

A series of biopolymeric chitosan-based (Ch) films were prepared with choline chloride and citric acid plasticizer (deep eutectic solvent, DES). An effect of adenine (A, vitamin B4) addition on the functional properties of these films was evaluated. Several physicochemical and mechanical properties were tested: Fourier-transformed infrared spectra proved DES's plasticizing and crosslinking effect, while scanning electron microscopy and atomic force microscopy techniques confirmed the possible phase separation after adenine addition. These changes affected the mechanical characteristics and the water vapor and oxygen permeability. The prepared materials are not water soluble because the CA acts as a crosslinker. The adenine addition on antioxidative and antimicrobial properties was also checked. It was found that Ch-DES materials with A exhibit improved antioxidative properties (55.8-66.1% of H2O2 scavenging activity) in contrast to the pristine chitosan-DES material (51.1% of H2O2 scavenging activity), while the material is still non-mutagenic (lack of growth of Salmonella typhimurium) and possesses antimicrobial features (no E. coli observed for all the tested films and inhibition zones noted for S. aureus). The mentioned properties, reduced oxygen transmission (1.6-2.1 g m-2 h-1), and mechanical characteristics within the range of typical food packaging plastics proved the potential of Ch-DES-A films in the packaging sector. Moreover, the antioxidative properties, usage of substrates being allowed as food additives, and the presence of adenine create the advantage of the Ch-DES-A materials as edible coatings, being also a source of Vitamin B4.

Synthesis and Antimicrobial, Antiplatelet, and Anticoagulant Activities of New Isatin Deivatives Containing a Hetero-Fused Imidazole Fragment

A series of isatin derivatives containing an adenine or theophylline fragment have been synthesized. The corresponding N′-[2-(trimethylammonio)acetyl] and N′-(2-pyridinioacetyl) hydrazones have been found to exhibit neither cytotoxicity nor hemotoxicity. Quaternary salts based on adenine derivatives of 5-methyl- and 5-ethylisatins showed the highest antiplatelet activity which exceeded the activity of acetylsalicylic acid by a factor of 1.5.

Cross-Linked Polymer Brushes Containing N-Halamine Groups for Antibacterial Surface Applications

Microbial contamination is a significant issue in various areas, especially in the food industry. In this study, to overcome microbial contamination, cross-linked polymer brushes containing N-halamine were synthesized, characterized, and investigated for antibacterial properties. The cross-linked polymer brushes with different N-halamine ratios were synthesized by in-situ cross-linking methods with reversible addition-fragmentation chain transfer (RAFT) polymerization using a bifunctional cross-linker. The RAFT agent was immobilized on an amine-terminated silicon wafer surface and utilized in the surface-initiated RAFT polymerization of [N-(2-methyl-1-(4-methyl-2,5-dioxoimidazolidin-4-yl)propane-2-yl)acrylamide] (hydantoin acrylamide, HA), and N-(2-hydroxypropyl)methacrylamide) (HPMA) monomers. Measurement of film thickness, contact angle, and surface morphology of the resulting surfaces were used to confirm the structural characteristics of cross-linked polymer brushes. The chlorine content of the three different surfaces was determined to be approximately 8-31 × 1013 atoms/cm2. At the same time, it was also observed that the activation-deactivation efficiency decreased during the recharge-discharge cycles. However, it was determined that the prepared N-halamine-containing cross-linked polymer brushes inactivated approximately 96% of Escherichia coli and 91% of Staphylococcus aureus. In conclusion, in the framework of this study, high-performance brush gels were produced that can be used on antibacterial surfaces.