The influence of the structural features of carrageenan on the functional properties of the films was studied. The carrageenans and chitosan films, as well as three-layer films containing a polyelectrolyte complex (PEC) of the two, were prepared. The X-ray diffractograms of carrageenan films reflected its amorphous structure, whereas chitosan and three-layer films were characterized by strong reflection in the regions of 20° and 15° angles, respectively. The SEM of the cross-sectional morphology showed dense packing of the chitosan film, as well as the layer-by-layer structure of different densities for the PEC. Among the tested samples, κ/β-carrageenan and chitosan films showed the highest tensile strength and maximum elongation. Films containing the drug substance echinochrome were obtained. Mucoadhesive properties were assessed as the ability of the films to swell on the mucous tissue and their erosion after contact with the mucosa. All studied films exhibited mucoadhesive properties. All studied films exhibited mucoadhesive properties which depended on the carrageenans structure. Multilayer films are stronger than single-layer carrageenan films due to PEC formation. The resulting puncture strength of the obtained films was comparable to that of commercial samples described in the literature.

Inclusion of drugs in liposomes offers the potential for localized and sustained delivery to mucosal surfaces. The inclusion of the carrageenan matrix with echinochrome A ((Ech)—the active substance of the drug Histochrome) in liposomes was studied. According to the spectral characteristics, Ech was not oxidized and retained stability after encapsulation in the liposomes and the lyophilization process. Loading the liposomes with negatively charged polysaccharide results in the increase in the zeta potential to more negative values (from −14.6 to −24.4 mV), that together with an increasing in the sizes of liposomes (from 125.6 ± 2.5 nm to 159.3 ± 5.8 nm) propose of the formation of the polymer coating on liposomes. The interactions of liposomes with porcine stomach mucin was determined by the DLS and SEM methods. The changes in the zeta-potential and size of the mucin particles were observed as the result of the interaction of liposomes with mucin. To evaluate the mucoadhesive properties of liposomes and the penetration of Ech in the mucosa, a fresh-frozen inner surface of the small intestine of a pig as a model of mucous tissue was used. Polysaccharide-coated liposomes exhibit very good mucoadhesive properties −50% of Ech remains on the mucosa.

Nanoparticles formation is one of the ways to modulate the physicochemical properties and enhance the activity of original polysaccharides. For this purpose, based on the polysaccharide of red algae, κ-carrageenan (κ-CRG), it polyelectrolyte complex (PEC), with chitosan, were obtained. The complex formation was confirmed by ultracentrifugation in a Percoll gradient, with dynamic light scattering. According to electron microscopy and DLS, PEC is dense spherical particles with sizes in the range of 150–250 nm. A decrease in the polydispersity of the initial CRG was detected after the PEC formation. Simultaneous exposure of Vero cells with the studied compounds and herpes simplex virus type 1 (HSV-1) showed that the PEC exhibited significant antiviral activity, effectively inhibiting the early stages of virus–cell interaction. A two-fold increase in the antiherpetic activity (selective index) of PEC compared to κ-CRG was shown, which may be due to a change in the physicochemical characteristics of κ-CRG in PEC.

The ultrastructural organization of the nuclei of the tegmental region in juvenile chum salmon (Oncorhynchus keta) was examined using transmission electron microscopy (TEM). The dorsal tegmental nuclei (DTN), the nucleus of fasciculus longitudinalis medialis (NFLM), and the nucleus of the oculomotor nerve (NIII) were studied. The ultrastructural examination provided detailed ultrastructural characteristics of neurons forming the tegmental nuclei and showed neuro–glial relationships in them. Neurons of three size types with a high metabolic rate, characterized by the presence of numerous mitochondria, polyribosomes, Golgi apparatus, and cytoplasmic inclusions (vacuoles, lipid droplets, and dense bodies), were distinguished. It was found that large interneurons of the NFLM formed contacts with protoplasmic astrocytes. Excitatory synaptic structures were identified in the tegmentum and their detailed characteristic are provided for the first time. Microglia-like cells were found in the NIII. The ultrastructural characteristics of neurogenic zones of the tegmentum of juvenile chum salmon were also determined for the first time. In the neurogenic zones of the tegmentum, adult-type neural stem progenitor cells (aNSPCs) corresponding to cells of types III and IVa Danio rerio. In the neurogenic zones of the tegmentum, neuroepithelial-like cells (NECs) corresponding to cells previously described from the zebrafish cerebellum were found and characterized. In the tegmentum of juvenile chum salmon, patterns of paracrine neurosecretion were observed and their ultrastructural characteristics were recorded. Patterns of apoptosis in large neurons of the tegmentum were examined by TEM. Using immunohistochemical (IHC) labeling of the brain lipid-binding protein (BLBP) and aromatase B (AroB), patterns of their expression in the tegmentum of intact animals and in the post-traumatic period after acute injury to the medulla oblongata were characterized. The response to brainstem injury in chum salmon was found to activate multiple signaling pathways, which significantly increases the BLBP and AroB expression in various regions of the tegmentum and valvula cerebelli. However, post-traumatic patterns of BLBP and AroB localizations are not the same. In addition to a general increase in BLBP expression in the tegmental parenchyma, BLBP overexpression was observed in the rostro-lateral tegmental neurogenic zone (RLTNZ), while AroB expression in the RLTNZ was completely absent. Another difference was the peripheral overexpression of AroB and the formation of dense reactive clusters in the ventro-medial zone of the tegmentum. Thus, in the post-traumatic period, various pathways were activated whose components were putative candidates for inducers of the “astrocyte-like” response in the juvenile chum salmon brain that are similar to those present in the mammalian brain. In this case, BLBP acted as a factor enhancing the differentiation of both radial glia and neurons. Estradiol from AroB+ astrocytes exerted paracrine neuroprotective effects through the potential inhibition of inflammatory processes. These results indicate a new role for neuronal aromatization as a mechanism preventing the development of neuroinflammation. Moreover, our findings support the hypothesis that BLBP is a factor enhancing neuronal and glial differentiation in the post-traumatic period in the chum salmon brain.

Using a nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry, localization and morphology of putative nitric oxide synthase-containing elements were studied in the intestine of the following bivalves: Ruditapes philippinarum, Callithaca adamsi, Mercenaria stimpsoni (Veneridae), Corbicula japonica (Corbiculidae), Nodularia vladivostokensis and Cristaria tuberculata (Unionidae). NADPH-d-positive nerve cells and plexuses were found in the intestine of all species studied. Labelled diformazan bipolar nerve cells were present in the epithelium of the intestinal groove and typhlosole of the anterior midgut, the midgut proper, and the hindgut. Their apical process extended towards the gut lumen, whereas the basal one was connected with the basiepithelial NADPH-d-positive nerve plexus. In the typhlosole of N. vladivostokensis, these cells constituted up to 2.68% of the total number of epithelial cells. The bivalve species studied exhibit a similar distribution pattern of NADPH-d-positive cells, which lie separately or form small groups of two to three in the basal part of the epithelium. Basiepithelial NADPH-d-positive plexus was connected by separate fibres with subepithelial NADPH-d-positive nerve plexus. Both the plexuses were moderately developed in all intestinal regions in the majority of the species examined.

Liposomal drug delivery systems are successfully used in various fields of medicine for external and systemic applications. Marine organisms contain biologically active substances that have a unique structure and exhibit a wide range of biological activities. Polysaccharide of red seaweed (carrageenan (CRG)), and water-insoluble sea urchin pigment (echinochrome (Ech)) interact with each other and form a stable complex. We included the CRG/Ech complex in liposomes for better permeability into cells. In our research, tetramethylrhodamine isothiocyanate TRITC-labeled CRG was synthesized to study the interaction of the complex encapsulated in liposomes with human epidermal keratinocytes (HaCaTs) widely used to expose the skin to a variety of substances. Using confocal microscopy, we found that liposomes were able to penetrate HaCaT cells with maximum efficiency within 24 h, and pre-incubation of keratinocytes with liposomes resulted in the delivery of the CRG/Ech complex into the cytoplasm. We investigated the anti-inflammatory effects of liposomes, including the lysosomal regulation, increased intracellular ROS levels, and increased NO synthesis in lipopolysaccharide (LPS)- or Escherichia coli (E. coli)-induced inflamed skin cells. Liposomes containing the CRG/Ech complex significantly reduced lysosomal activity by 26% in LPS-treated keratinocytes and decreased ROS levels in cells by 23% after LPS exposure. It was found that liposomes with the complex improved the migration of HaCaT keratinocytes incubated with high-dose LPS by 47%. The results of the work, taking into account the good permeability of liposomes into keratinocytes, as well as the anti-inflammatory effect on cells treated with LPS or E. coli, show the prospects of using liposomes containing the CRG/Ech complex as an anti-inflammatory agent in the fight against skin infections.