Enhancement of iodinin solubility by encapsulation into cyclodextrin nanoparticles

Type Strains of Entomopathogenic Nematode-Symbiotic Bacterium Species, Xenorhabdus szentirmaii (EMC) and X. budapestensis (EMA), Are Exceptional Sources of Non-Ribosomal Templated, Large-Target-Spectral, Thermotolerant-Antimicrobial Peptides (by Both), and Iodinin (by EMC)

Antimicrobial multidrug resistance (MDR) is a global challenge, not only for public health, but also for sustainable agriculture. Antibiotics used in humans should be ruled out for use in veterinary or agricultural settings. Applying antimicrobial peptide (AMP) molecules, produced by soil-born organisms for protecting (soil-born) plants, seems a preferable alternative. The natural role of peptide-antimicrobials, produced by the prokaryotic partner of entomopathogenic-nematode/bacterium (EPN/EPB) symbiotic associations, is to sustain monoxenic conditions for the EPB in the gut of the semi-anabiotic infective dauer juvenile (IJ) EPN. They keep pathobiome conditions balanced for the EPN/EPB complex in polyxenic (soil, vanquished insect cadaver) niches. Xenorhabdus szentirmaii DSM16338(T) (EMC), and X. budapestensis DSM16342(T) (EMA), are the respective natural symbionts of EPN species Steinernema rarum and S. bicornutum. We identified and characterized both of these 15 years ago. The functional annotation of the draft genome of EMC revealed 71 genes encoding non-ribosomal peptide synthases, and polyketide synthases. The large spatial Xenorhabdus AMP (fabclavine), was discovered in EMA, and its biosynthetic pathway in EMC. The AMPs produced by EMA and EMC are promising candidates for controlling MDR prokaryotic and eukaryotic pathogens (bacteria, oomycetes, fungi, protozoa). EMC releases large quantity of iodinin (1,6-dihydroxyphenazine 5,10-dioxide) in a water-soluble form into the media, where it condenses to form spectacular water-insoluble, macroscopic crystals. This review evaluates the scientific impact of international research on EMA and EMC.

Solubility enhancement of mefenamic acid by inclusion complex with β-cyclodextrin: in silico modelling, formulation, characterisation, and in vitro studies

The aim of this study was to prepare and characterise inclusion complexes of a low water-soluble drug, mefenamic acid (MA), with β-cyclodextrin (β-CD). First, the phase solubility diagram of MA in β-CD was drawn from 0 to 21 × 10⁻³ M of β-CD concentration. A job’s plot experiment was used to determine the stoichiometry of the MA:β-CD complex (2:1). The stability of this complex was confirmed by molecular modelling simulation. Three methods, namely solvent co-evaporation (CE), kneading (KN), and physical mixture (PM), were used to prepare the (2:1) MA:β-CD complexes. All complexes were fully characterised. The drug dissolution tests were established in simulated liquid gastric and the MA water solubility at pH 1.2 from complexes was significantly improved. The mechanism of MA released from the β-CD complexes was illustrated through a mathematical treatment. Finally, two in vitro experiments confirmed the interest to use a (2:1) MA:β-CD complex.

Synthesis and Assessment of 3-Substituted Phenazines as Novel Antichlamydial Agents

BACKGROUND

In the past century, many phenazines were isolated from the marine microorganism, and some of these phenazines possessed potent antibacterial activities. We found that a few of the synthesized 4-substituted phenazines could block the infectivity of chlamydiae without host cell toxicity.

OBJECTIVE

The aim of this study was to design and synthesize two series of novel 3-substituted phenazines to find novel antichlamydial agents.

METHODS

The 3-substituted phenazines were synthesized via Buchwald-Hartwig cross coupling reaction and Suzuki reaction from 3-bromo-1-methoxyphenazine. The antichlamydial activity of these synthesized compounds was evaluated by determining their effect on the yield of infectious progeny EBs. Cytotoxicity of these compounds on host cells was assessed by the treatment of uninfected HeLa cells using WST-1 method.

RESULTS

Most of the 3-substituted phenazines possessed potent antichlamydial activity with IC50 values from 0.15 to 12.08 μM against Chlamydia trachomatis L2, C. muridarum MoPn and C. pneumoniae AR39. Among them, 7d and 9a exhibited better antichlamydial activity with IC50 values from 0.20 to 1.01 μM while they have no apparent cytotoxicity to host cells. Biological assay disclosed that both 7d and 9a inhibited chlamydial infection by reducing elementary body infectivity and disturbing chlamydial growth during the whole chlamydial developmental cycle.

CONCLUSION

Our findings suggested that 3-substituted phenazine derivatives might be a promising class of therapeutic agents for chlamydial infections. More effective phenazines with low toxicity could be acquired through further chemical modification on C-3 position rather than C-4 position of phenazine.