Assessing physical properties of amphoteric fluoroquinolones using phosphorescence spectroscopy

Magneto-Fluorescent Mesoporous Nanocarriers for the Dual-Delivery of Ofloxacin and Doxorubicin to Tackle Opportunistic Bacterial Infections in Colorectal Cancer

Cancer-related opportunistic bacterial infections are one major barrier for successful clinical therapies, often correlated to the production of genotoxic factors and higher cancer incidence. Although dual anticancer and antimicrobial therapies are a growing therapeutic fashion, they still fall short when it comes to specific delivery and local action in in vivo systems. Nanoparticles are seen as potential therapeutic vectors, be it by means of their intrinsic antibacterial properties and effective delivery capacity, or by means of their repeatedly reported modulation and maneuverability. Herein we report on the production of a biocompatible, antimicrobial magneto-fluorescent nanosystem (NANO3) for the delivery of a dual doxorubicin-ofloxacin formulation against cancer-related bacterial infections. The drug delivery capacity, rendered by its mesoporous silica matrix, is confirmed by the high loading capacity and stimuli-driven release of both drugs, with preference for tumor-like acidic media. The pH-dependent emission of its surface fluorescent SiQDs, provides an insight into NANO3 surface behavior and pore availability, with the SiQDs working as pore gates. Hyperthermia induces heat generation to febrile temperatures, doubling drug release. NANO3-loaded systems demonstrate significant antimicrobial activity, specifically after the application of hyperthermia conditions. NANO3 structure and antimicrobial properties confirm their potential use in a future dual anticancer and antimicrobial therapeutical vector, due to their drug loading capacity and their surface availability for further modification with bioactive, targeting species.

Ofloxacin@Doxorubicin-Epirubicin functionalized MCM-41 mesoporous silica-based nanocarriers as synergistic drug delivery tools for cancer related bacterial infections

Mesoporous silica nanoparticles (MNs) emerged as new promising drug-delivery platforms capable to overcome resistance in bacteria. Dual loading of drugs on these nanocarriers, exploiting synergistic interactions between the nanoparticles and the drugs, could be considered as a way to increase the efficacy against resistant bacteria with a positive effect even at very low concentrations. Considering that patients with cancer are highly susceptible to almost any type of bacterial infections, in this work, nanocarriers mesoporous silica-based, MNs and MNs@EPI were synthetized and submitted to single and/or dual loading of antibiotics (ofloxacin - OFLO) and anticancer drugs (Doxorubicin - DOX; Epirubicin - EPI), and investigated regarding their antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Enterococcus faecalis and Pseudomonas aeruginosa. Formulations containing ofloxacin such as MNs-OFLO, MNs-EPI + OFLO, MNs-DOX + OFLO and MNs@EPI + OFLO, present antibacterial activity in all bacterial strains tested. All these are more effective in E.coli with MIC and MBC values for MNs-OFLO, MNs-EPI + OFLO and MNs-DOX + OFLO of around 1 and 2 µg_nanomaterial/mL, corresponding to ofloxacin concentrations of 0.03, 0.02 and 0.04 µg/mL, respectively. In the cocktail formulations the conjugation of epirubicin with ofloxacin presents a more effective antibacterial activity with more than 3-fold reduction of ofloxacin concentration when comparing to the single ofloxacin system. By far, the most effective synergistic effect was obtained for the system where epirubicin was functionalized at nanoparticles surface (MNs@EPI), where a 40-fold and 33-fold reductions of ofloxacin concentration were obtained, in P. aeruginosa in comparison to the MNs-OFLO and MNs-EPI + OFLO systems, respectively. These effects are shown in all bacterial strains tested, even in strains that have acquired resistance mechanisms, such as MRSA.

Pharmacophore modeling, docking and the integrated use of a ligand- and structure-based virtual screening approach for novel DNA gyrase inhibitors: synthetic and biological evaluation studies

Fluoroquinolones, a class of compound, act via inhibiting DNA gyrase and topoisomerase IV enzymes. This is an important class of drugs with high success rates for the treatment of tuberculosis and other bacterial infections. An indirect drug design approach was used to develop a meaningful pharmacophore model using the HypoGen module of Discovery Studio 2.0 on a set of 27 structurally diverse compounds with a wide range of biological activity (5 log units). The best hypothesis had three hydrogen bond acceptors (HBA) and one hydrophobic (Hy) moiety, showing r = 0.95, and it predicts the test set of 44 compounds well, with r 2 = 0.823. The same features (acceptor and hydrophobic functionality) were validated at the binding site of the DNA gyrase active site using GOLD version 3.0.1 and Molegro Virtual Docker, which showed corresponding hydrogen bond interactions and also π-π stacking interactions that correlated well with the PIC50 values (r 2 = 0.6142). The thoroughly validated model was used to screen an extensive database of 0.25 million compounds to identify potential leads. The validated model was implemented for the identification, design, synthesis, and biological evaluation of leads. Ten new chemical entities were synthesized based on our scaffold hopping techniques from the identified virtual screening and tested against the tuberculosis bacterium to obtain preliminary MIC values. The results showed that 3 out of 10 synthesized compounds exhibited good MICs, from 1.25 to 50 μM. This proves the robustness and applicability of the developed model, which is a promising tool for identifying new topoisomerase II inhibitors for the treatment of tuberculosis.

Ability of the Putative Decomposition Products of 2,3-dioxetanes of Indoles to Photosensitize Cyclobutane Pyrimidine Dimer (CPD) Formation and its Implications for the "Dark" (Chemisensitized) Pathway to CPDs in Melanocytes†

The formation of cyclobutane pyrimidine dimers (CPDs) by a "dark" pathway in melanocytes has been attributed to chemisensitization by dioxetanes produced from peroxynitrite oxidation of melanin or melanin precursors. These dioxetanes are proposed to decompose to triplet state compounds which sensitize CPD formation by triplet-triplet energy transfer. To determine whether such compounds are capable of sensitizing CPD formation, the putative decomposition products of 2,3-dioxetanes of variously substituted indoles were synthesized and their triplet state energies determined at 77 K. Their ability to photosensitize CPD formation was determined by an enzyme-coupled gel electrophoresis assay in comparison with norfloxacin (NFX) which has the lowest triplet energy known to sensitize CPD formation. The decomposition products of 2,3-dioxetanes of 5-hydroxy and 5,6-dimethoxy indoles used as models for melanin precursors had lower triplet energies and were incapable of photosensitizing CPD formation. Theoretical calculations suggest that the decomposition products of the 2,3-dioxetanes of melanin precursors DHI and DHICA will have similarly low triplet energies. Decomposition products of the 2,3-dioxetanes of indoles lacking oxygen substituents had higher triplet energies than NFX and were capable of photosensitizing CPD formation, suggesting that peroxynitrite oxidation of tryptophan could play a hitherto unrecognized role in the dark pathway to CPDs.

Sustained dual release of ciprofloxacin and lidocaine from ionic exchange responding film based on alginate and hyaluronate for wound healing

This study presents a new antibiotic-anesthetic film (AA-film) based on natural polyelectrolytes ionically complexed with lidocaine and ciprofloxacin to manage pain associated with infected wounds. The rational selection of the components resulted in the AA-films being transparent, compatible with wound skin pH and highly water vapor permeable. The drug release properties evaluated in saline solution and water revealed an ionic exchange mechanism for the release of both drugs and showed that ciprofloxacin acts as a cross-linker, as was confirmed by rheological evaluation. The in vitro antimicrobial efficacy against S. aureus and P. aeruginosa was demonstrated. Furthermore, AA-films exhibit a high fluid absorption capacity and act as a physical barrier for microorganisms. This work highlights the great potential of this smart system as an attractive dressing for skin wounds, surpassing currently available treatments.