Lunaemycins, New Cyclic Hexapeptide Antibiotics from the Cave Moonmilk-Dweller Streptomyces lunaelactis MM109T.

Streptomyces lunaelactis strains have been isolated from moonmilk deposits, which are calcium carbonate speleothems used for centuries in traditional medicine for their antimicrobial properties. Genome mining revealed that these strains are a remarkable example of a Streptomyces species with huge heterogeneity regarding their content in biosynthetic gene clusters (BGCs) for specialized metabolite production. BGC 28a is one of the cryptic BGCs that is only carried by a subgroup of S. lunaelactis strains for which in silico analysis predicted the production of nonribosomal peptide antibiotics containing the non-proteogenic amino acid piperazic acid (Piz). Comparative metabolomics of culture extracts of S. lunaelactis strains either holding or not holding BGC 28a combined with MS/MS-guided peptidogenomics and 1H/13C NMR allowed us to identify the cyclic hexapeptide with the amino acid sequence (D-Phe)-(L-HO-Ile)-(D-Piz)-(L-Piz)-(D-Piz)-(L-Piz), called lunaemycin A, as the main compound synthesized by BGC 28a. Molecular networking further identified 18 additional lunaemycins, with 14 of them having their structure elucidated by HRMS/MS. Antimicrobial assays demonstrated a significant bactericidal activity of lunaemycins against Gram-positive bacteria, including multi-drug resistant clinical isolates. Our work demonstrates how an accurate in silico analysis of a cryptic BGC can highly facilitate the identification, the structural elucidation, and the bioactivity of its associated specialized metabolites.

Cytotoxicity, cellular uptake, and subcellular localization of a nitrogen oxide and aminopropyl-ß-lactose derivative ruthenium complex used as nitric oxide delivery agent.

This work investigates how the luminescent ruthenium-nitrite complexes cis-[Ru(py-bodipy)(dcbpy)2(NO2)](PF6) (I) and cis-[Ru(py-bodipy)(dcbpy-aminopropyl-ß-lactose)2(NO2)](PF6) (II) behave toward the melanoma cancer cell line B16F10. The chemical structure and purity of the synthesized complexes were analyzed by UV-Visible and FTIR spectroscopy, MALDI, HPLC, and 1H NMR. Spectrofluorescence helped to determine the fluorescence quantum yields and lifetimes of each of these complexes. In vitro MTT cell viability assay on B16F10 cancer cells revealed that the complexes possibly have a tumoricidal role. The metal-nitrite complexes evidenced the dichotomous NO nature: at high concentration, NO exerted a tumoricidal effect, whereas cancer cells grew at low NO concentration. Flow cytometry or fluorescence microscopy aided cellular uptake calculation. Cell staining followed by fluorescence microscopy associated with organelle markers such as DAPI and Rhodamine 123 detected preferential intracellular localization of the ruthenium-nitrite py-bodipy and aminopropyl lactose derivative ruthenium complex in mitochondria. Thus, the cytotoxicity of compounds (I) and (II) against B16F10 cancer cell line show concentration-dependent results. The present studies suggest that nitric oxide ruthenium derivative compounds could be new potential chemotherapeutic agents against cytotoxic cells.

Novel fluorescent lapachone-based BODIPY: synthesis, computational and electrochemical aspects, and subcellular localisation of a potent antitumour hybrid quinone.

For the first time, a fluorescent lapachone-based BODIPY was synthesised and characterised by NMR and mass spectrometry. Computational and electrochemical aspects, as well as cytotoxic activity and subcellular localisation, were studied. Confocal microscopy experiments indicated that the probe was a specific mitochondria-staining agent. These in-detail analyses were useful in understanding the cytotoxic effects and mechanism of action of this novel hybrid compound. This molecule constitutes a promising prototype owing to its potential biological activities and the new strategies aimed at mechanistic investigations in cells and in vivo, and opens up an interesting avenue of research.

Topical Skin Cancer Therapy Using Doxorubicin-Loaded Cationic Lipid Nanoparticles and lontophoresis.

The topical administration of chemotherapeutics is a promising approach for the treatment of skin cancer; however, different pharmaceutical strategies are required to allow large amounts of drug to penetrate tumors. This work examined the potential of the anodic iontophoresis of doxorubicin-loaded cationic solid lipid nanoparticles (DOX-SLN) to increase the distribution and tumor penetration of DOX. A double-labeled cationic DOX-SLN composed of the lipids stearic acid and monoolein and a new BODIPY dye was prepared and characterized. The skin distribution and penetration of DOX were evaluated in vitro using confocal microscopy and vertical diffusion cells, respectively. The antitumor potential was evaluated in vivo through the anodic iontophoresis of DOX-SLN in squamous cell carcinoma induced in nude BALB/c mice. The encapsulation of DOX drastically altered the DOX partition coefficient and increased the distribution of DOX in the lipid matrix of the stratum corneum (SC). The association with iontophoresis created high-concentration drug reservoir zones in the follicles of the skin. Although the iontophoresis of a DOX solution increased the penetration of DOX in the viable epidermis by approximately 4-fold, the iontophoresis of cationic DOX-SLN increased the DOX penetration by approximately 50-fold. In vivo, the DOX-SLN iontophoretic treatment was effective in inhibiting tumor cell survival and tumor growth and was accompanied by an increase in keratinization and consequent cell death. These results indicate a strong and synergic effect of iontophoresis with DOX-SLN and provide a potential strategy for the treatment of skin cancer.

Transcorneal iontophoresis of dendrimers: PAMAM corneal penetration and dexamethasone delivery.

Iontophoresis of nanocarriers in the eye has been proposed to sustain drug delivery and maintain therapeutic concentrations. Fourth generation polyamidoamine (PAMAM) dendrimers are semi-rigid nanoparticles with surface groups that are easily modified. These dendrimers are known to modulate tight junctions, increase paracellular transport of small molecules and be translocated across epithelial barriers, exhibiting high uptake by different cell lines. The first aim of this study was to investigate the effect of iontophoresis on PAMAM penetration and distribution into the cornea. The second aim was to evaluate, ex vivo and in vivo, the effect of these dendrimers in dexamethasone (Dex) transcorneal iontophoresis. Anionic (PAMAM G3.5) and cationic (PAMAM G4) dendrimers were labeled with fluorescein isothiocyanate (FITC), and their distribution in the cornea was investigated using confocal microscopy after ex vivo anodal and cathodal iontophoresis for various application times. The particle size distribution and zeta potential of the dendrimers in an isosmotic solution were determined using dynamic light scattering and Nanoparticle Tracking Analysis (NTA), where the movement of small particles and the formation of large aggregates, from 5 to 100 nm, could be observed. Transcorneal iontophoresis increased the intensity and depth of PAMAM-FITC fluorescence in the cornea, suggesting improved transport of the dendrimers across the epithelium toward the stroma. PAMAM complexes with Dex were characterized by (13)C-NMR, (1)H-NMR and DOSY. PAMAM G3.5 and PAMAM G4 increased the aqueous solubility of Dex by 10.3 and 3.9-fold, respectively; however, the particle size distribution and zeta potential remained unchanged. PAMAM G3.5 decreased the Dex diffusion coefficient 48-fold compared with PAMAM G4. The ex vivo studies showed that iontophoresis increased the amount of Dex that penetrated into the cornea by 2.9, 5.6 and 3.0-fold for Dex, Dex-PAMAM G4 and Dex-PAMAM G3.5, respectively. In vivo experiments, however, revealed that iontophoresis of Dex-PAMAM-G3.5 increased Dex concentration in the aqueous humor by 6.6-fold, while iontophoresis of Dex-PAMAM G4 and Dex increased it 2.5 and 2-fold, respectively. Therefore, iontophoresis targeted PAMAM to the cornea but it is the sustained delivery of the Dex from PAMAM that prevents its rapid elimination from the aqueous humor. In conclusion, iontophoresis of PAMAM complexes represents a promising strategy for targeted and sustained topical drug delivery to the eye.