Synthesis and evaluation of polyacrylamides derived from polycyclic pendant naphthalene, indole, and phenothiazine based chalcone moiety as potent antimicrobial agents

Nonionic nontoxic antimicrobial polymers: indole-grafted poly(vinyl alcohol) with pendant alkyl or ether groups

A series of new nonionic antimicrobial polymers with a biodegradable polyvinyl alcohol (PVA) backbone grafted with indole units and different hydrophobic alkyl or ether groups were synthesized by facile esterification.

Synthesis, Enzymatic Degradation, and Polymer-Miscibility Evaluation of Nonionic Antimicrobial Hyperbranched Polyesters with Indole or Isatin Functionalities

Most macromolecular antimicrobials are ionic and thus lack miscibility/compatibility with nonionic substrate materials. In this context, nonionic hyperbranched polyesters (HBPs) with indole or isatin functionality were rationally designed, synthesized, and characterized. Antimicrobial disk diffusion assay indicated that these HBPs showed significant antibacterial activity against 8 human pathogenic bacteria compared to small molecules with indole or isatin groups. According to DSC measurements, up to 20% indole-based HBP is miscible with biodegradable polyesters (polyhydroxybutyrate or polycaprolactone), which can be attributed to the favorable hydrogen bonding between the N–H moiety of indole and the C=O of polyesters. HBPs with isatin or methylindole were completely immiscible with the same matrices. None of the HBPs leaked out from plastic matrix after being immersed in water for 5 days. The incorporation of indole into HBPs as well as small molecules facilitated their enzymatic degradation with PETase from Ideonella sakaiensis, while isatin had a complex impact. Molecular docking simulations of monomeric molecules with PETase revealed different orientations of the molecules at the active site due to the presence of indole or isatin groups, which could be related to the observed different enzymatic degradation behavior. Finally, biocompatibility analysis with a mammalian cell line showed the negligible cytotoxic effect of the fabricated HBPs.

Investigation of the Role of Aromatic Residues in the Antimicrobial Peptide BuCATHL4B

BACKGROUND

Antimicrobial Peptides (AMPs) are an attractive alternative to traditional small molecule antibiotics as AMPs typically target the bacterial cell membrane. A Trp-rich peptide sequence derived from water buffalo (Bubalus bubalis), BuCATHL4B was previously identified as a broad-spectrum antimicrobial peptide.

OBJECTIVE

In this work, native Trp residues were replaced with other naturally occurring aromatic amino acids to begin to elucidate the importance of these residues on peptide activity.

METHODS

Minimal Inhibitory Concentration (MIC) results demonstrated activity against seven strains of bacteria. Membrane and bilayer permeabilization assays were performed to address the role of bilayer disruption in the activity of the peptides. Lipid vesicle binding and quenching experiments were also performed to gain an understanding of how the peptides interacted with lipid bilayers.

RESULTS

MIC results indicate the original, tryptophan-rich sequence, and the phenylalanine substituted sequences exhibit strong inhibition of bacterial growth. In permeabilization assays, peptides with phenylalanine substitutions have higher levels of membrane permeabilization than those substituted with tyrosine. In addition, one of the two-tyrosine substituted sequence, YWY, behaves most differently in the lowest antimicrobial activity, showing no permeabilization of bacterial membranes. Notably the antimicrobial activity is inherently species dependent, with varying levels of activity against different bacteria.

CONCLUSION

There appears to be little correlation between membrane permeabilization and activity, indicating these peptides may have additional mechanisms of action beyond membrane disruption. The results also identify two sequences, denoted FFF and YYW, which retain antibacterial activity but have markedly reduced hemolytic activity.

Recent Developments in the Synthesis and Antimicrobial Activity of Indole and its Derivatives

BACKGROUND

Heterocyclic compounds containing nitrogen have been known to possess a very important role in the field of medicinal chemistry. Indole and its derivatives displayed a wide range of biological properties such as anti-inflammatory, analgesic, anti-microbial, anti-convulsant, antidepressant, anti-diabetic, antihelmintic and anti-allergic activities etc. The diverse biological activities exhibited by compounds containing indole moiety has provided the impetus to explore its anti-microbial activity in order to save the valuable life of patients.

OBJECTIVE

The review focuses on the advances in the synthesis of indole derivatives and antimicrobial properties exhibited by them.

CONCLUSION

A great deal of work has been done in order to synthesize indole derivatives and to evaluate antimicrobial potential, as indicated by the review. The information provided in this article may be helpful for the researchers for the development of efficient antimicrobial drugs.

Synthesis, Thermal Properties, and Rheological Characteristics of Indole-Based Aromatic Polyesters

Currently, there is an intensive development of bio-based aromatic building blocks to replace fossil-based terephthalates used for poly(ethylene terephthalate) production. Indole is a ubiquitous aromatic unit in nature, which has great potential as a bio-based feedstock for polymers or plastics. In this study, we describe the synthesis and characterization of new indole-based dicarboxylate monomers with only aromatic ester bonds, which can improve the thermal stability and glass-transition temperature (T _g) of the resulting polyesters. The new dicarboxylate monomers were polymerized with five aliphatic diols to yield 10 new polyesters with tunable chemical structures and physical properties. Particularly, the T _g values of the obtained polyesters can be as high as 113 °C, as indicated by differential scanning calorimetry and dynamic mechanical analysis. The polyesters showed decent thermal stability and distinct flow transitions as revealed by thermogravimetric analysis and rheology measurements.

The effect of anthracene-based chalcone derivatives in the resazurin dye reduction assay mechanisms for the investigation of Gram-positive and Gram-negative bacterial and fungal infection

A novel series of anthracene-based chalcone derivatives were synthesized and evaluated in terms of their antibacterial and antifungal activities.