Biomolecules

The phylum Armatimonadota represents one of the least characterized bacterial lineages, with only three formally described species despite its widespread distribution in various environments. Deep subsurface thermal environments harbor significant microbial diversity and represent promising sources for novel enzyme discovery through metagenomic approaches. This study reports the identification, cloning, and biochemical characterization of Cel7465, a novel endoglucanase from an uncultured GBS-DC family within the order Fimbriimonadales. The enzyme was identified through metagenomic analysis of microbial mats from the Biragzang deep thermal well (North Ossetia, Russia, 48 °C) and successfully expressed in cells of Escherichia coli strain ArcticExpress (DE3). Phylogenetic analysis assigned Cel7465 to glycoside hydrolase family 5 subfamily 36. The purified recombinant enzyme exhibited optimal activity at 55 °C and pH 8.0, with high specific activity of 4347 U/mg. The enzyme demonstrated broad pH tolerance (50% activity retained from pH 4.0 to 10.0) and notable thermal stability, retaining 60% activity after one hour at 80 °C and 20% after four hours. Remarkably, the presence of Mn²⁺ ions enhanced enzyme activity more than 7-fold, while Mg²⁺ and Ca²⁺ ions provided moderate activation. Cel7465 represents the first biochemically characterized glycoside hydrolase from the order Fimbriimonadales, expanding our understanding of enzymatic capabilities within the understudied phylum Armatimonadota and demonstrating the continued potential of extreme environments as sources of novel industrial biocatalysts.

Muscle gradually loses its regenerative capacity with aging. Recent evidence highlights age-related immune dysregulation as a key driver of satellite cell dysfunction and reduced muscle regeneration. Timely elimination of apoptotic cells by phagocytes through efferocytosis is essential for tissue repair. Therefore, exploring age-related alterations in the molecular machinery of efferocytosis and their impact on muscle regeneration is of great relevance. This study examined the efferocytic machinery in the gastrocnemius muscle tissue of young and aged rats after doxorubicin-induced acute myotoxicity and assessed the potential of Vitamin B12-loaded chitosan nanoparticles (B12 CS NPS) to enhance efferocytosis and promote skeletal muscle injury repair in aged rats. Aged rats exhibited impaired efferocytosis with a significant reduction in MerTK, PPARγ, and miR-124 expression, and increased ADAM17 expression. B12 CS NPS administration significantly improved efferocytosis and reduced necrotic tissue areas, accompanied by increased MerTK, PPARγ, and miR-124, and reduced ADAM17 expression. Supplementation with B12 CS NPS significantly enhanced satellite cell proliferation and differentiation, which was indicated by upregulated expression of Pax7, Myog, and MyoD. These findings reveal that age-related alterations in regulatory molecules impair efferocytosis in aged muscle and demonstrate the potential of B12 CS NPs to enhance efferocytosis and improve skeletal muscle repair.

The naphthoquinone juglone (5-hydroxynaphthalene-1,4-dione) (1) occurs abundantly in nature, especially in species belonging to the Juglandaceae family. Due to its multifaceted biological activities, this compound is considered a privileged structure in Medicinal Chemistry for the development of new prototypes with several biological and pharmacological actions. However, the regioselective synthesis of 2-substituted juglones is challenging due to the non-symmetric naphthoquinone nucleus. Starting from non-symmetric 2,3-unsubstituted naphthalenes, in this paper we describe two general synthetic routes to juglone derivatives bearing an unsaturated or an oxygenated aliphatic side chain at C(2) or C(3). In an MTT test, a few products were more active than the parent unsubstituted juglone as inhibitors of the viability of human lung cancer H460 and breast cancer MCF-7 cells. The most potent compound featured a 1′-acetoxyhomoprenyl sidechain at the carbon C(2) of juglone.