Matilde Tancredi

Melanins are pigments widely distributed in microbial, plant, and animal kingdoms. Their UV–visible light shielding capacity, metal chelation ability, antioxidant, and antimicrobial properties make these pigments suitable for different industrial applications like in cosmetic and bioremediation fields. The actual manufacturing process relies on the extraction from animal tissues like the ink of Sepia officinalis and/or on synthetic chemical procedures. Streptomycetes might be the ideal candidates for the development of biotechnological processes of melanin production due to their ability to produce pigments as secondary metabolites, extracellularly released. Here, a new strain of Streptomyces nigra, capable of efficiently producing eumelanin, was isolated from soil samples in Messina, Sicily, Italy, and characterized first by 16S rRNA analysis and then by whole genome sequencing, with a complete gene clusters analysis. The strain ability of growing and producing melanin was tested on four media, including newly formulated ones, and by also optimizing temperature and pH conditions of growth, a melanin production of 2.45 ± 0.01 g/L was reached. The pigment, once produced under the optimal conditions, was purified and characterized by UV–visible, FT-IR, NMR, and EPR spectroscopy, revealing an eumelanin-like structure. Key points: • A new Streptomyces nigra strain, MT6, was isolated and identified • A new formulated medium boosted melanin production up to 2.45 g/L • The extracellular pigment was characterized as eumelanin

Ruthenium or copper complexes have emerged as some of the most promising alternatives for the treatment of many types of cancer. They have enhanced activity, greater selectivity and reduced side effects compared to their predecessors, cisplatin and its analogues. On the other hand, polyamine metabolism is often deregulated in cancer, leading to increased intracellular concentrations of polyamines that promote cell proliferation, differentiation, and tumorigenesis. In the present work, we report the synthesis and characterization of a family of mono- and binuclear Ru(II) and Cu(II) complexes functionalized with polyamine ligands derived from norspermine. The computer-aided analysis of the electron paramagnetic resonance (EPR) spectra provided magnetic and dynamic parameters, which helped to identify prevalent Cu–N2 coordination in a partially distorted square planar geometry of the Cu(II) complexes and the flexibility of the complexes in solution, slowed down by both the complex size and the hydrophobic interactions between chains. In vitro studies focused on advanced prostate cancer have demonstrated that these new metal complexes present a high level of cytotoxicity against PC3 cells. Furthermore, these metallic compounds exhibit the ability to inhibit cell adhesion and migration while reducing intracellular reactive oxygen species levels, which are key factors of metastasis.

Biosurfactants, amphiphilic metabolites produced by bacteria and yeasts, fulfill a variety of functions in microbial life. They exhibit a well-recognized multifunctionality, spanning from the reduction in surface tension to specific biological activities, including antimicrobial, antiviral, anti-inflammatory, and anticancer effects. These compounds have the potential to serve as environmentally friendly alternatives to synthetic surfactants in industrial formulations, where they could act as emulsifiers and wetting agents. The exploitation of their full potentiality could be a significant added value. Biosurfactants are often cited as effective antioxidants. However, experimental evidence for their antioxidant activity/capacity is sparse. To shed light on the subject, in this review we collect and critically examine all the available literature data for each of the major classes of microbial biosurfactants: rhamnolipids, mannosylerythritol lipids, sophorolipids, and lipopeptides. Despite the variability arising from the diverse composition and polydispersity of the samples analyzed, along with the variety of testing methodologies, the findings consistently indicate a moderate-to-strong antioxidant capacity. Several hypotheses are advanced about the molecular mechanisms behind this action; however, further studies are needed to gain a molecular understanding. This knowledge would fully define the biological roles of biosurfactants and is a prerequisite for the development of innovative formulations based on the valorization of their antioxidant properties.