Oral formulations for highly lipophilic drugs: Impact of surface decoration on the efficacy of self-emulsifying drug delivery systems.

AIM: To evaluate the impact of the surface decoration of cannabidiol (CBD) loaded self-emulsifying drug delivery systems (SEDDS) on the efficacy of the formulations to cross the various barriers faced by orally administered drugs. METHODS: Polyethylene glycol (PEG)-free polyglycerol (PG)-based SEDDS, mixed zwitterionic phosphatidyl choline (PC)/PEG-containing SEDDS and PEG-based SEDDS were compared regarding stability against lipid degrading enzymes, surface properties, permeation across porcine mucus, cellular uptake and cytocompatibility. RESULTS: SEDDS with a size of about 200 nm with narrow size distributions were developed and loaded with 20-21 % of CBD. For PG containing PEG-free SEDDS increased degradation by lipid degrading enzymes was observed compared to PEG-containing formulations. The surface hydrophobicity of placebo SEDDS increased in the order of PG-based to mixed PC/PEG-based to PEG-based SEDDS. The influence of this surface hydrophobicity was also observed on the ability of the SEDDS to cross the mucus gel layer where highest mucus permeation was achieved for most hydrophobic PEG-based SEDDS. Highest cellular internalization was observed for PEG-based Lumogen Yellow (LY) loaded SEDDS with 92 % in Caco-2 cells compared to only 30 % for mixed PC/PEG-based SEDDS and 1 % for PG-based SEDDS, leading to a 100-fold improvement in cellular uptake for SEDDS having highest surface hydrophobicity. For cytocompatibility all developed placebo SEDDS showed similar results with a cell survival of above 75 % for concentrations below 0.05 % on Caco-2 cells. CONCLUSION: Higher surface hydrophobicity of SEDDS to orally deliver lipophilic drugs as CBD seems to be a promising approach to increase the intracellular drug concentration by an enhanced permeation through the mucus layer and cellular internalization.

Secretory Cells in Halla parthenopeia (Oenonidae): Potential Implications for the Feeding and Defence Strategies of a Carnivorous Burrowing Polychaete.

Carnivorous polychaetes are known to bear diversified and often unique anatomical and behavioural adaptations for predation and defence. Halla parthenopeia, a species known to be a specialized predator of clams, thrives in the soft bottoms of the Mediterranean Sea, holding potential for polyculture and biotechnology due to the secretion of bioactive compounds. Our objective was to provide a comprehensive description of H. parthenopeia's anatomy and microanatomy, shedding light on the relation between morphology and habitat, chemical defences, and feeding behaviour. The pharynx, housing maxillae and mandibles connected to an extensive mucus gland, occupies a considerable portion of the worm's length, reaching beyond the oesophagus. This unique gland is responsible for secreting the feeding mucus, which immobilizes and aids in the digestion of clams probably acting as a vehicle of bioactive compounds synthesized by specialized serous cells in the mouth. Moreover, H. parthenopeia combines behavioural tactics, such as burrowing, and anatomical defences to evade predators. Examination of its epidermis revealed a thick cuticle layer and abundant mucocytes secreting locomotion mucus, both of which save the worm from mechanical harm during movement. When it is preyed upon, the worm can release a substantial amount of Hallachrome, a toxic anthraquinone produced by specific cells in its distal region. This pigment, with its known antimicrobial properties, likely acts as a chemical shield in case of injury. The results suggest that the ability of H. parthenopeia to prey on bivalves and to provide mechanical protection plus defence against pathogens rely on its ability to secrete distinct types of mucus. The interplay between highly specialized microanatomical features and complex behaviours underscores its adaptation as a predator in marine benthic environments.

Antimicrobial, Antioxidant and Anti-Inflammatory Activities of the Mucus of the Tropical Sea Slug Elysia crispata.

Elysia crispata (Sacoglossa, Gastropoda) is a tropical sea slug known for its ability to incorporate functional chloroplasts from a variety of green macroalgae, a phenomenon termed kleptoplasty. This sea slug, amenable to laboratory cultivation, produces mucus, a viscous secretion that serves diverse purposes including protection, locomotion, and reproduction. In this study, we profiled the antimicrobial, antioxidant, and anti-inflammatory activities of the mucus of this sea slug. Results revealed inhibitory activity against several bacterial strains, more pronounced for Gram-negative bacteria. Particularly interesting was the strong inhibitory effect against Pseudomonas aeruginosa, a bacterial species classified by the WHO as a high-priority pathogen and associated with high-risk infections due to its frequent multidrug-resistant profile. Similar inhibitory effects were observed for the mucus native protein extracts, indicating that proteins present in the mucus contributed significantly to the antimicrobial activity. The mucus also showed both antioxidant and anti-inflammatory activities. The latter activities were associated with the low molecular weight (<10 kDa) fraction of the mucus rather than the native protein extracts. This study opens the way to further research on the biotechnological applications of the mucus secreted by this unique marine organism, particularly as an antimicrobial agent.

Modelling Mucus Clearance in Sinuses: Thin-Film Flow Inside a Fluid-Producing Cavity Lined with an Active Surface.

The paranasal sinuses are a group of hollow spaces within the human skull, surrounding the nose. They are lined with an epithelium that contains mucus-producing cells and tiny hairlike active appendages called cilia. The cilia beat constantly to sweep mucus out of the sinus into the nasal cavity, thus maintaining a clean mucus layer within the sinuses. This process, called mucociliary clearance, is essential for a healthy nasal environment and disruption in mucus clearance leads to diseases such as chronic rhinosinusitis, specifically in the maxillary sinuses, which are the largest of the paranasal sinuses. We present here a continuum mathematical model of mucociliary clearance inside the human maxillary sinus. Using a combination of analysis and computations, we study the flow of a thin fluid film inside a fluid-producing cavity lined with an active surface: fluid is continuously produced by a wall-normal flux in the cavity and then is swept out, against gravity, due to an effective tangential flow induced by the cilia. We show that a steady layer of mucus develops over the cavity surface only when the rate of ciliary clearance exceeds a threshold, which itself depends on the rate of mucus production. We then use a scaling analysis, which highlights the competition between gravitational retention and cilia-driven drainage of mucus, to rationalise our computational results. We discuss the biological relevance of our findings, noting that measurements of mucus production and clearance rates in healthy sinuses fall within our predicted regime of steady-state mucus layer development.

KDELR2 is necessary for chronic obstructive pulmonary disease airway Mucin5AC hypersecretion via an IRE1α/XBP-1s-dependent mechanism.

Airway mucus hypersecretion, a crucial pathological feature of chronic obstructive pulmonary disease (COPD), contributes to the initiation, progression, and exacerbation of this disease. As a macromolecular mucin, the secretory behaviour of Mucin5AC (MUC5AC) is highly dependent on a series of modifying and folding processes that occur in the endoplasmic reticulum (ER). In this study, we focused on the ER quality control protein KDEL receptor (KDELR) and demonstrated that KDELR2 and MUC5AC were colocalized in the airway epithelium of COPD patients and COPD model rats. In addition, knockdown of KDELR2 markedly reduced the expression of MUC5AC both in vivo and in vitro and knockdown of ATF6 further decreased the levels of KDELR2. Furthermore, pretreatment with 4µ8C, an IRE1α inhibitor, led to a partial reduction in the expression of KDELR2 and MUC5AC both in vivo and in vitro, which indicated the involvement of IRE1α/XBP-1s in the upstream signalling cascade. Our study revealed that KDELR2 plays a crucial role in airway MUC5AC hypersecretion in COPD, which might be dependent on ATF6 and IRE1α/XBP-1s upstream signalling.

Tracing the path of Quorum sensing molecules in cystic fibrosis mucus in a biomimetic in vitro permeability platform.

P. aeruginosa employs specific quorum sensing (QS) mechanisms to orchestrate biofilm formation, enhancing resistance to host defences. In physiological conditions, QS molecules permeate the lung environment and cellular membrane to reach the cytoplasmic Aryl Hydrocarbon Receptor (AhR) that is pivotal for activating the immune response against infection. In pathological conditions like cystic fibrosis (CF) this interkingdom communication is altered, favouring P. aeruginosa persistence and chronic infection. Here, we aim to investigate the molecular journey of QS molecules from CF-like environments to the cytoplasm by quantifying via HPLC-MS the permeability of selected QS molecules (quinolones, lactones, and phenazines) through in vitro models of the two main biological lung barriers: CF-mucus and cellular membrane. While QS molecules not activating AhR exhibit intermediate permeability through the cellular membrane model (PAMPA) (1.0-4.0 × 10-6 cm/s), the AhR-activating molecule (pyocyanin) shows significantly higher permeability (8.6 ± 1.4 × 10-6 cm/s). Importantly, combining the CF mucus model with PAMPA induces a 50% decrease in pyocyanin permeability, indicating a strong mucus-shielding effect with pathological implications in infection eradication. This study underscores the importance of quantitatively describing the AhR-active bacterial molecules, even in vitro, to offer new perspectives for understanding P. aeruginosa virulence mechanisms and for proposing new antibacterial therapeutic approaches.

Cultivating complexity: Advancements in establishing in vitro models for the mucus-adhering gut microbiota.

A healthy mucus is essential for maintaining intestinal homeostasis and overall well-being. In recent years, extensive research focused on understanding the intricate interactions between mucus and the gut microbiota. Mucus-adhering bacteria play crucial roles in preserving barrier integrity, epithelial permeability and mucus architecture, as well as in the colonization resistance against pathogens. Unravelling the significance of these microorganisms in human health and disease is challenging, primarily because most of the studies on the human gut microbiota rely on faecal samples, which do not fully represent the microecological complexity found in the intestinal mucosa. This review discusses novel strategies to specifically target and evaluate the mucosal microbiota, such as culturomics applied to mucosal biopsies or brushings, intestinal organoids and artificial in vitro models incorporating mucus.

Planarian Mucus: A Novel Source of Pleiotropic Cytotoxic and Cytostatic Agents against Cancer Cells.

Biological evolution has generated a vast array of natural compounds produced by organisms across all domains. Among these, secondary metabolites, selected to enhance an organism's competitiveness in its natural environment, make them a reservoir for discovering new compounds with cytotoxic activity, potentially useful as novel anticancer agents. Slime secretions, the first barrier between epithelial surfaces and the surrounding environment, frequently contain cytotoxic molecules to limit the growth of parasitic organisms. Planarians, freshwater Triclads, continuously secrete a viscous mucus with multiple physiological functions. The chemical composition of planarian mucus has been only partially elucidated, and there are no studies reporting its cytotoxic or cytostatic effects. In this study, we developed a protocol for collecting mucus from Dugesia japonica specimens and we demonstrated that it inhibits the growth of cancer cells by activating cytostatic and ROS-dependent cytotoxic mechanisms inducing lipid droplet accumulation and mitochondrial membrane reorganization. Although further research is needed to identify the specific chemicals responsible for the anticancer activity of planarian mucus, this work opens up numerous research avenues aimed at better understanding the mechanisms of action of this product for potential therapeutic applications.

Evaluation of stress in farmed Atlantic salmon (Salmo salar) using different biological matrices.

Atlantic salmon were subjected to an acute crowding scenario, and their subsequent stress responses were observed under three distinct swimming speed/water flow (WF) conditions: 0.5, 1, and 1.5 body lengths per second (BL/s). Feces, dermal mucus, and plasma were collected for analysis at 1, 6, and 24 h (h) post-stress. Additionally, the head kidney and two regions of the brain (pituitary and POA) were collected for transcript expression analysis. Fish swimming at 0.5 BL/s exhibited higher pre-stress (baseline) cortisol levels. Across all groups and matrices, the highest cortisol/cortisol metabolites (CM) levels were observed at the 1 h post-stress sampling point. At 6 h (second sampling time point), a clear decline toward baseline levels were observe in all groups. Significant increases in mean plasma glucose levels were observed at 1 h post-stress for all groups. The mean plasma lactate levels varied based on WF treatments, with a significant increase observed at 1 h only for the 1.5 BL/s group. Additionally, significant decreases in mean plasma lactate were noted at 6 and 24 h post-stress for some groups. The mRNA abundances of the tested genes (star, cyp17a1, hsd11ß2, srd5a1) increased following the stress events. These changes were not uniform across all groups and were tissue dependent. In summary, the results indicate that mucus and feces can be used as potentially less invasive matrices than blood for evaluating stress and, consequently, the welfare of Atlantic salmon in captivity.

Modeling Cystic Fibrosis Chronic Infection Using Engineered Mucus-like Hydrogels.

The airway mucus of patients with cystic fibrosis has altered properties, which create a microenvironment primed for chronic infections that are difficult to treat. These complex polymicrobial airway infections and corresponding mammalian-microbe interactions are challenging to model in vitro. Here, we report the development of mucus-like hydrogels with varied compositions and viscoelastic properties reflecting differences between healthy and cystic fibrosis airway mucus. Models of cystic fibrosis and healthy airway microenvironments were created by combining the hydrogels with relevant pathogens, human bronchial epithelial cells, and an antibiotic. Notably, pathogen antibiotic resistance was not solely dependent on the altered properties of the mucus-like hydrogels but was also influenced by culture conditions including microbe species, monomicrobial or polymicrobial culture, and the presence of epithelial cells. Additionally, the cystic fibrosis airway model showed the ability to mimic features characteristic of chronic cystic fibrosis airway infections including sustained polymicrobial growth and increased antibiotic tolerance.

Morphological and functional features of the colonic mucus barrier in patients with symptomatic uncomplicated diverticular disease and acute uncomplicated diverticulitis.

OBJECTIVE: Aim: The purpose was to identify the morphological and functional features of the colonic mucus barrier in patients with symptomatic uncomplicated diverticular disease and acute uncomplicated diverticulitis. PATIENTS AND METHODS: Materials and Methods: In the research, three groups were formed. Group 1 included fragments of the mucous membrane of the large intestine, which were collected from 12 people during autopsies. The results of autopsies and histological examination of the material did not reveal any gastrointestinal pathology. Group 2 included biopsies of the mucous membrane of the large intestine from the area of the diverticulum of 34 patients with symptomatic uncomplicated diverticular disease. Group 3 included biopsies of the mucous membrane of the large intestine of 26 patients with acute uncomplicated diverticulitis. Histological (hematoxylin and eosin staining), histochemical (PAS reaction) and immunohistochemical (mouse monoclonal antibodies to Mucin 2 (MUC2) and Mucin 4 (MUC4)) staining methods were used. A morphometric study was also carried out. RESULTS: Results: In patients with diverticular disease, the authors identified disturbances in the morphofunctional state of the mucus barrier of the colon, the structure and function of goblet cells contained in its mucous membrane, characterized by a decrease in the thickness of the mucus layer covering the surface of the mucous membrane; a decrease in the size and number of goblet cells with a decrease in their mucus-producing ability; a change in the mucin profile, characterized by a violation of the content of MUC2 and MUC4. These changes were greatest in patients with acute uncomplicated diverticulitis compared with patients with symptomatic uncomplicated diverticular disease. CONCLUSION: Conclusions: The identified disturbances in the morphofunctional state of the mucus barrier of the colon, structural and functional changes in goblet cells may be one of the mechanisms for the development of acute uncomplicated diverticulitis and symptomatic uncomplicated diverticular disease.

Reshaping and enzymatic activity may allow viruses to move through the mucus.

Filamentous viruses like influenza and torovirus often display systematic bends and arcs of mysterious physical origin. We propose that such viruses undergo an instability from a cylindrically symmetric to a toroidally curved state. This "toro-elastic" state emerges via spontaneous symmetry breaking under prestress due to short range spike protein interactions magnified by surface topography. Once surface stresses are sufficiently large, the filament buckles and the curved state constitutes a soft mode that can potentially propagate through the filament's material frame around a Mexican-hat-type potential. In the mucus of our airways, which constitutes a soft, porous 3D network, glycan chains are omnipresent and influenza's spike proteins are known to efficiently bind and cut them. We next show that such a non-equilibrium enzymatic reaction can induce spontaneous rotation of the curved state, leading to a whole body reshaping propulsion similar to - but different from - eukaryotic flagella and spirochetes.

Porcine ex-vivo intestinal mucus has age-dependent blocking activity against transmissible gastroenteritis virus.

Transmissible gastroenteritis virus (TGEV) causes high mortality in young piglets (< 3 days of age). With aging, the susceptibility/morbidity/mortality rates drop. We previously hypothesized that the age-related changes in the intestinal mucus could be responsible for this resistance. Hence, this study investigated the effect of porcine intestinal mucus from 3-day and 3-week-old pigs on the free mobility of the virulent TGEV Miller strain, and on the infection in swine testicle (ST) cells. Single particle tracking (SPT) revealed that TGEV had significantly higher diffusion coefficients in 3-day mucus compared to 3-week mucus. TGEV and charged and uncharged control nanoparticles diffused freely in 3-day mucus but were hindered by 3-week mucus in the diffusion model; TGEV mimicked the diffusion behavior of negatively charged carboxylated particles. Inoculation of ST cells with TGEV in the presence of 3-week mucus resulted in a significantly lower average number of infected cells (30.9 ± 11.9/5 fields) compared with 3-day mucus (84.6 ± 16.4/5 fields). These results show that 3-week mucus has a significant TGEV-blocking activity compared to 3-day mucus in free diffusion and infection of the underlying susceptible cells. Additionally, a label-free proteomics analysis revealed an increased expression of mucin 13, known for negatively regulating the tight junctions in intestinal epithelium, in 3-day-old pigs. In 3-week-old pigs, a higher expression of mucin 2, a type of secreted mucin which is known for inhibiting coronavirus infection, was observed. Concludingly, this study demonstrated a protective effect of 3-week mucus against viral infections.

Biotransformation and Epithelial Toxicity of Prenylated Phenolics from Licorice Roots (Glycyrrhiza spp.) in 3D Apical-Out Mucus-Producing Human Enteroids.

Apical-out enteroids mimic the in vivo environment well due to their accessible apical surface and mucus layer, making them an ideal model for studying the impact of (bioactive) food compounds. Generated human ileal apical-out enteroids showed a fucose-containing mucus layer surrounding the apical brush border on their exposure side, indicating their physiological relevance. Effects on the mucosal epithelium of antibacterial prenylated phenolics (glabridin, licochalcone A, and glycycoumarin) from licorice roots were investigated for cytotoxicity, cell viability, barrier integrity, and biotransformation. At concentrations up to 500 µg mL-1, licochalcone A and glycycoumarin did not significantly affect apical-out enteroids, with cytotoxicities of -6 ± 2 and -2 ± 2% and cell viabilities of 77 ± 22 and 77 ± 13%, respectively (p > 0.05). Conversely, 500 µg mL-1 glabridin induced significant cytotoxicity (31 ± 25%, p < 0.05) and reduced cell viability (21 ± 14%, p < 0.01). Apical-out enteroids revealed differential sensitivities to prenylated phenolics not observed in apical-in enteroids and Caco-2 cells. Both enteroid models showed phase II biotransformation but differed in the extent of glucuronide conversion. The apical mucus layer of apical-out enteroids likely contributed to these differential interactions, potentially due to differences in electrostatic repulsion. This study underscores the relevance of 3D apical-out enteroid models and highlights the promise of prenylated phenolics for antimicrobial applications.

Earthworm mucus contributes significantly to the accumulation of soil cadmium in tomato seedlings.

Whether earthworm mucus affects Cd transport behavior in soil-plant systems remains uncertain. Consequently, this study thoroughly assessed the impacts of earthworm mucus on plant growth and physiological responses, plant Cd accumulation, translocation, and distribution, as well as soil characteristics and Cd fractionation in a soil-plant (tomato seedling) system. Results demonstrated that the earthworm inoculation considerably enhanced plant Cd uptake and decreased plant Cd translocation, the effects of which were appreciably less significant than those of the earthworm mucus. This suggested that earthworm mucus may play a crucial role in the way earthworms influence plant Cd uptake and translocation. Moreover, the artificial mucus, which contained identical inorganic nitrogen contents to those in earthworm mucus, had no significant effect on plant Cd accumulation or translocation, implying that components other than inorganic nitrogen in the earthworm mucus may have contributed significantly to the overall effects of the mucus. Compared with the control, the earthworm mucus most substantially increased the root Cd content, the Cd accumulation amount of root and whole plant, and root Cd BCF by 93.7 %, 221.3 %, 72.2 %, and 93.7 %, respectively, while notably reducing the Cd TF by 48.2 %, which may be ascribed to the earthworm mucus's significant impacts on tomato seedling growth and physiological indicators, its considerable influences on the subcellular components and chemical species of root Cd, and its substantial effects on the soil characteristics and soil Cd fractionation, as revealed by correlation analysis. Redundancy analysis further suggested that the most prominent impacts of earthworm mucus may have been due to its considerable reduction of soil pH, improvement of soil DOC content, and enhancement of the exchangeable Cd fraction in soil. This work may help better understand how earthworm mucus influences the transport behavior of metals in soil-plant systems.

Design of Auto-Adaptive Drug Delivery System for Effective Delivery of Peptide Drugs to Overcoming Mucus and Epithelial Barriers.

Oral administration of peptide represents a promising delivery route, however, it is hindered by the harsh gastrointestinal environment, leading to low in vivo absorption. In this study, auto-adaptive protein corona-AT 1002-cationic liposomes (Pc-AT-CLs) are constructed with the characteristic of hydrophilic and electrically neutral surface properties for the encapsulation of liraglutide. BSA protein corona is used to coat AT-CLs reducing the adherence of mucus, and may fall off after penetrating the mucus layer. Transmucus transport experiment demonstrated that the mucus penetration amount of Pc-AT-CLs are 1.45 times that of AT-CLs. After penetrating the mucus layer, AT-CLs complete transmembrane transport by the dual action of AT and cationic surface properties. Transmembrane transport experiment demonstrated that the apparent permeability coefficient (Papp) of AT-CLs is 2.03 times that of CLs. In vivo tests demonstrated that Pc-AT-CLs exhibited a significant hypoglycemic effect and enhanced the relative bioavailability comparing to free liraglutide. Pc-AT-CLs protect liraglutide from degradation, facilitate its absorption, and ultimately improve its oral bioavailability.

Mind the Particle Rigidity: Blooms the Bioavailability via Rapidly Crossing the Mucus Layer and Alters the Intracellular Fate of Curcumin.

Overcoming intestinal epithelial barriers to enhance bioavailability is a major challenge for oral delivery systems. Desirable nanocarriers should simultaneously exhibit rapid mucus penetration and efficient epithelial uptake; however, they two generally require contradictory structural properties. Herein, we proposed a strategy to construct multiperformance nanoparticles by modifying the rigidity of amphiphilic nanostructures originating from soy polypeptides (SPNPs), where its ability to overcome multibarriers was examined from both in vitro and in vivo, using curcumin (CUR) as a model cargo. Low-rigidity SPNPs showed higher affinity to mucin and were prone to getting stuck in the mucus layer. When they reached epithelial cells, they tended to be endocytosed through the clathrin and macropinocytosis pathways and further transferred to lysosomes, showing severe degradation and lower transport of CUR. Increased particle rigidity generally improved the absorption of CUR, with medium-rigidity SPNPs bloomed maximum plasma concentration of CUR by 80.62-fold and showed the highest oral bioavailability. Results from monocultured and cocultured cell models demonstrated that medium-rigidity SPNPs were least influenced by the mucus layer and changes in rigidity significantly influenced the endocytosis and intracellular fate of SPNPs. Those with higher rigidity preferred to be endocytosed via a caveolae-mediated pathway and trafficked to the ER and Golgi, facilitating their whole transcytosis, and avoiding intracellular metabolism. Moreover, rigidity modulation efficiently induces the reversible opening of intercellular tight junctions, which synergistically improves the transport of CUR into blood circulation. This study suggested that rigidity regulation on food originated amphiphilic peptides could overcome multiple physiological barriers, showing great potential as natural building block toward oral delivery.

Machine Learning-Driven Discovery and Evaluation of Antimicrobial Peptides from Crassostrea gigas Mucus Proteome.

Marine antimicrobial peptides (AMPs) represent a promising source for combating infections, especially against antibiotic-resistant pathogens and traditionally challenging infections. However, traditional drug discovery methods face challenges such as time-consuming processes and high costs. Therefore, leveraging machine learning techniques to expedite the discovery of marine AMPs holds significant promise. Our study applies machine learning to develop marine AMPs, focusing on Crassostrea gigas mucus rich in antimicrobial components. We conducted proteome sequencing of C. gigas mucous proteins, used the iAMPCN model for peptide activity prediction, and evaluated the antimicrobial, hemolytic, and cytotoxic capabilities of six peptides. Proteomic analysis identified 4490 proteins, yielding about 43,000 peptides (8-50 amino acids). Peptide ranking based on length, hydrophobicity, and charge assessed antimicrobial potential, predicting 23 biological activities. Six peptides, distinguished by their high relative scores and promising biological activities, were chosen for bactericidal assay. Peptides P1 to P4 showed antimicrobial activity against E. coli, with P2 and P4 being particularly effective. All peptides inhibited S. aureus growth. P2 and P4 also exhibited significant anti-V. parahaemolyticus effects, while P1 and P3 were non-cytotoxic to HEK293T cells at detectable concentrations. Minimal hemolytic activity was observed for all peptides even at high concentrations. This study highlights the potent antimicrobial properties of naturally occurring oyster mucus peptides, emphasizing their low cytotoxicity and lack of hemolytic effects. Machine learning accurately predicted biological activity, showcasing its potential in peptide drug discovery.

Decoding Octopus Skin Mucus: Impact of Aquarium-Maintenance and Senescence on the Proteome Profile of the Common Octopus (Octopus vulgaris).

The common octopus (Octopus vulgaris) is an excellent candidate for aquaculture diversification, due to its biological traits and high market demand. To ensure a high-quality product while maintaining welfare in captive environments, it is crucial to develop non-invasive methods for testing health biomarkers. Proteins found in skin mucus offer a non-invasive approach to monitoring octopus welfare. This study compares the protein profiles in the skin mucus of wild, aquarium-maintained, and senescent specimens to identify welfare biomarkers. A tandem mass tag (TMT) coupled with an Orbitrap Eclipse Tribrid mass spectrometer was used to create a reference dataset from octopus skin mucus, identifying 1496 non-redundant protein groups. Although similar profiles were observed, differences in relative abundances led to the identification of potential biomarkers, including caspase-3-like, protocadherin 4, deleted in malignant brain tumors, thioredoxin, papilin, annexin, cofilin and mucin-4 proteins. Some of these proteins also revealed potential as bioactive peptides. This investigation provides the most extensive analysis of the skin mucus proteome in the common octopus and is the first to explore how aquarium maintenance and senescence alter the mucus proteome. This research highlights the potential of skin mucus protein/peptides as non-invasive monitoring biomarkers in cultured animals.

Biological Properties of the Mucus and Eggs of Helix aspersa Müller as a Potential Cosmetic and Pharmaceutical Raw Material: A Preliminary Study.

In recent years, snail mucus (SM) has become popular as an active ingredient in cosmetic and pharmaceutical products. In turn, snail eggs (SEs) also seem to be a promising active compound, but the biological activities of SEs are significantly less known. Therefore, our preliminary study aimed to compare the biological activities of the SEs and SM of Helix aspersa Müller. The metabolomic analysis (LC-MS technique), determination of the antimicrobial activity (agar diffusion test, broth microdilution methods), antioxidant activity (ABTS assay), cytotoxicity assay (MTT), and proapoptotic properties (flow cytometry) of the SEs and SM were evaluated. It was found that the SEs and SM contain 8005 and 7837 compounds, respectively. The SEs showed antibacterial activity against S. aureus (MIC 12.5 mg/mL) and P. aeruginosa (MIC 3.12 mg/mL). The EC50 estimation of the antioxidant activity is 89.64 mg/mL and above 100 mg/mL for the SEs and SM, respectively. The SEs also inhibited the cell proliferation of cancer cell lines (HCT-116, MCF-7, HT-29) more strongly compared to the SM. The highest proportion of apoptotic cells in HCT-116 was observed. The reach composition of the compounds in the SEs and SM may be crucial for the creation of new cosmetic and pharmaceutical raw materials with different biological activities. However, further extended studies on the biological activities of H. aspersa-delivered materials are still necessary.