Silver nanoparticles green synthesis via cyanobacterium Phormidium sp.: characterization, wound healing, antioxidant, antibacterial, and anti-inflammatory activities.

OBJECTIVE: Green synthesis of silver nanoparticles (AgNPs) using cyanobacterial platforms is becoming more popular nowadays. In this study, the filamentous non-heterocystous cyanobacterium Phormidium sp. was used for AgNPs production. Then, it was investigated for its antibacterial and wound-healing properties. MATERIALS AND METHODS: The cyanobacterium cultures were challenged by AgNO3, and the obtained nanoparticles were characterized using UV and FTIR spectrometric methods. The antimicrobial activity of AgNPs was scrutinized against MRSA either alone or in combination 0.5% chloramphenicol. The green synthesized AgNPs were tested for their skin wound healing activity using several wound models at different concentrations. RESULTS: The cyanobacterial culture extract showed the characteristic surface plasmon resonance peak at 440 nm for AgNPs. Different functional groups that could contribute to the reduction of Ag+ to AgNPs or the stabilization of the nanoparticles were identified by the FTIR. AgNPs potentiated the antimicrobial activity of chloramphenicol against MRSA. Green synthesized silver nanoparticles have demonstrated topical effectiveness in different wound models, including excision, incision, and burn. Significant wound improvement and the increase in wound closure rate, hydroxyproline content, and the reduction in epithelialization period confirmed the wound healing potency of AgNPs. The enzymatic antioxidant level escalation and inflammatory cytokines attenuation supported the AgNPs substantial effect on wound repairing. CONCLUSIONS: Biogenic AgNPs produced by Phormidium sp. showed significant antimicrobial together with wound healing abilities.

Revisiting high-resolution crystal structure of Phormidium rubidum phycocyanin.

The crystal structure of phycocyanin (pr-PC) isolated from Phormidium rubidum A09DM (P. rubidum) is described at a resolution of 1.17 Å. Electron density maps derived from crystallographic data showed many clear differences in amino acid sequences when compared with the previously obtained gene-derived sequences. The differences were found in 57 positions (30 in α-subunit and 27 in ß-subunit of pr-PC), in which all residues except one (ß145Arg) are not interacting with the three phycocyanobilin chromophores. Highly purified pr-PC was then sequenced by mass spectrometry (MS) using LC-MS/MS. The MS data were analyzed using two independent proteomic search engines. As a result of this analysis, complete agreement between the polypeptide sequences and the electron density maps was obtained. We attribute the difference to multiple genes in the bacterium encoding the phycocyanin apoproteins and that the gene sequencing sequenced the wrong ones. We are not implying that protein sequencing by mass spectrometry is more accurate than that of gene sequencing. The final 1.17 Å structure of pr-PC allows the chromophore interactions with the protein to be described with high accuracy.

Anti-Inflammatory Activity of Exopolysaccharides from Phormidium sp. ETS05, the Most Abundant Cyanobacterium of the Therapeutic Euganean Thermal Muds, Using the Zebrafish Model.

The Euganean Thermal District (Italy) represents the oldest and largest thermal center in Europe, and its therapeutic mud is considered a unique product whose beneficial effects have been documented since Ancient Roman times. Mud properties depend on the heat and electrolytes of the thermal water, as well as on the bioactive molecules produced by its biotic component, mainly represented by cyanobacteria. The investigation of the healing effects of compounds produced by the Euganean cyanobacteria represents an important goal for scientific validation of Euganean mud therapies and for the discovering of new health beneficial biomolecules. In this work, we evaluated the therapeutic potential of exopolysaccharides (EPS) produced by Phormidium sp. ETS05, the most abundant cyanobacterium of the Euganean mud. Specifically, Phormidium EPS resulted in exerting anti-inflammatory and pro-resolution activities in chemical and injury-induced zebrafish inflammation models as demonstrated using specific transgenic zebrafish lines and morphometric and expression analyses. Moreover, in vivo and in vitro tests showed no toxicity at all for the EPS concentrations tested. The results suggest that these EPS, with their combined anti-inflammatory and pro-resolution activities, could be one of the most important therapeutic molecules present in the Euganean mud and confirm the potential of these treatments for chronic inflammatory disease recovery.