Bisphosphocins: novel antimicrobials for enhanced killing of drug-resistant and biofilm-forming bacteria

Synthesis and Isolation of Phenol- and Thiol-Derived Epicatechin Adducts Prepared from Avocado Peel Procyanidins Using Centrifugal Partition Chromatography and the Evaluation of Their Antimicrobial and Antioxidant Activity

Polyphenols from agro-food waste represent a valuable source of bioactive molecules that can be recovered to be used for their functional properties. Another option is to use them as starting material to generate molecules with new and better properties through semi-synthesis. A proanthocyanidin-rich (PACs) extract from avocado peels was used to prepare several semi-synthetic derivatives of epicatechin by acid cleavage in the presence of phenol and thiol nucleophiles. The adducts formed by this reaction were successfully purified using one-step centrifugal partition chromatography (CPC) and identified by chromatographic and spectroscopic methods. The nine derivatives showed a concentration-dependent free radical scavenging activity in the DPPH assay. All compounds were also tested against a panel of pathogenic bacterial strains formed by Listeria monocytogenes (ATCC 7644 and 19115), Staphylococcus aureus (ATCC 9144), Escherichia coli (ATCC 11775 and 25922), and Salmonella enterica (ATCC 13076). In addition, adducts were tested against two no-pathogenic strains, Limosilactobacillus fermentum UCO-979C and Lacticaseibacillus rhamnosus UCO-25A. Overall, thiol-derived adducts displayed antimicrobial properties and, in some specific cases, inhibited biofilm formation, particularly in Listeria monocytogenes (ATCC 7644). Interestingly, phenolic adducts were inactive against all the strains and could not inhibit its biofilm formation. Moreover, depending on the structure, in specific cases, biofilm formation was strongly promoted. These findings contribute to demonstrating that CPC is a powerful tool to isolate new semi-synthetic molecules using avocado peels as starting material for PACc extraction. These compounds represent new lead molecules with antioxidant and antimicrobial activity.

The role of nanocomposites against biofilm infections in humans

The use of nanomaterials in several fields of science has undergone a revolution in the last few decades. It has been reported by the National Institutes of Health (NIH) that 65% and 80% of infections are accountable for at least 65% of human bacterial infections. One of their important applications in healthcare is the use of nanoparticles (NPs) to eradicate free-floating bacteria and those that form biofilms. A nanocomposite (NC) is a multiphase stable fabric with one or three dimensions that are much smaller than 100 nm, or systems with nanoscale repeat distances between the unique phases that make up the material. Using NC materials to get rid of germs is a more sophisticated and effective technique to destroy bacterial biofilms. These biofilms are refractory to standard antibiotics, mainly to chronic infections and non-healing wounds. Materials like graphene and chitosan can be utilized to make several forms of NCs, in addition to different metal oxides. The ability of NCs to address the issue of bacterial resistance is its main advantage over antibiotics. This review highlights the synthesis, characterization, and mechanism through which NCs disrupt Gram-positive and Gram-negative bacterial biofilms, and their relative benefits and drawbacks. There is an urgent need to develop materials like NCs with a larger spectrum of action due to the rising prevalence of human bacterial diseases that are multidrug-resistant and form biofilms.

Chitosan oligomer and zinc oxide nanoparticles for treating wastewaters: US20190134086 patent evaluation

With the utilisation of algae, wastewater reuse is becoming a viable option for the energy industry, especially green energy. The growth of these algae in these wastewaters provides an alternative source for bioenergetics, however, the growth of other microorganisms can directly affect the production of bioenergy, requiring the removal and reduction of contaminants in these waters, in addition to being a source of contamination for workers. Therefore, the use of nanoparticles in bioremediation has been an alternative to mitigate the contamination of these wastewaters that have microorganisms capable of reducing the algae growth capacity. The objective of this work was to verify in the United States Patent and Trademarker office database (USPTO) patents that used chitosan nanoparticles as a form of wastewater treatment and to carry out the analysis of patent US20190134086, which addresses the use of zinc oxide nanoparticles associated with chitosan that was developed and used to evaluate their antibacterial activity against resistant microorganisms and biofilm producers present in wastewater. Escherichia coli, Enterococcus faecium, and/or Pseudomonas aeruginosa are the microorganisms involved in the evaluated invention, bacteria present in the gastrointestinal tract, of clinical and environmental importance. The synthesized nanoparticles are arranged as a pharmaceutically acceptable and toxic vehicle against resistant bacteria, thus being described as nanoremediators. Given the analyzed patent, it was possible to verify the importance of alternatives to reduce the impact that pollution, in general, has on the environment, in addition to the proposed technology serving to maintain the survival and development capacity of the algae that will be able to produce green energy, the nanoparticles with antibacterial potential can help indirectly reduce these pathogenic strains with resistance to several antibiotics in the environment.