Borut Strukelj’s research while affiliated with University of Ljubljana and other places

The present study screened various fungal species for inhibitors of alpha-glucosidase, alpha-amylase, and DPP-4, enzymes that are crucial in carbohydrate metabolism. Ethanolic extracts exhibited superior inhibitory activity compared to water extracts, suggesting their potential as sources of anti-diabetic agents. Further fractionation revealed fomentariol from Fomes fomentarius as a potent inhibitor of alpha-glucosidase and DPP-4, with higher activity against alpha-glucosidase than acarbose. Fomentariol presents a novel avenue for diabetes management, demonstrating the simultaneous inhibition of key enzymes in glucose metabolism. However, comprehensive clinical studies are needed to evaluate its safety and efficacy in humans.

Clostridioides difficile causes a range of debilitating intestinal symptoms that may be fatal. It is particularly problematic as a hospital-acquired infection, causing significant costs to the health care system. Antibiotics, such as vancomycin and fidaxomicin, are still the drugs of choice for C. difficile infections, but their effectiveness is limited, and microbial interventions are emerging as a new treatment option. This paper focuses on alternative treatment approaches, which are currently in various stages of development and can be divided into four therapeutic strategies. Direct killing of C. difficile (i) includes beside established antibiotics, less studied bacteriophages, and their derivatives, such as endolysins and tailocins. Restoration of microbiota composition and function (ii) is achieved with fecal microbiota transplantation, which has recently been approved, with standardized defined microbial mixtures, and with probiotics, which have been administered with moderate success. Prevention of deleterious effects of antibiotics on microbiota is achieved with agents for the neutralization of antibiotics that act in the gut and are nearing regulatory approval. Neutralization of C. difficile toxins (iii) which are crucial virulence factors is achieved with antibodies/antibody fragments or alternative binding proteins. Of these, the monoclonal antibody bezlotoxumab is already in clinical use. Immunomodulation (iv) can help eliminate or prevent C. difficile infection by interfering with cytokine signaling. Small-molecule agents without bacteriolytic activity are usually selected by drug repurposing and can act via a variety of mechanisms. The multiple treatment options described in this article provide optimism for the future treatment of C. difficile infection.

Objectives The potential protective effect of fullerenol C60(OH)24, a strong antioxidant, was investigated at a single dose of 25 mg/kg, administered orally (per os; p.o.) and intraperitoneally (i.p.), in the liver, lung, kidney, heart, and spleen of healthy pigs, prior to doxorubicin-induced toxicity at a single i.p. dose of 10 mg/kg. Methods We used the F1 generation of an in vivo pig model (whose parents were Swedish Landrace and Large Yorkshire), to explore whether fullerenol, administered 6 h for p.o. and 30 min for i.p. prior to doxorubicin treatment, could protect organs against damage caused by oxidative stress. Key findings According to the macroscopic, hematological, biochemical, and physiological results, fullerenol exerted a potential protective effect on all investigated organs (heart, liver, lung, spleen, and kidney) in pigs after i.p. administration. However, the results from fullerenol p.o. administration were inconclusive, therefore warranting further investigation. Conclusions Fullerenol at a low dose of 25 mg/kg demonstrated satisfactory organ protection against doxorubicin-induced toxicity in healthy pigs after i.p. injection, However, additional follow-up studies in pig models of cancer and with longer doxorubicin and fullerenol treatment periods would be required to further delineate the optimal and clinically-relevant conditions for fullerenol administration.

Background: Clinical and experimental analyses indicate a pathognomonic role for allergen IgE crosslinking through epitope-paratope interactions as a major initial step in the cascade leading to effector cell activation and clinical manifestations of lgE-mediated food allergies. We aimed to undertake the initial development and assessment of Ara h 2-specific IgE epitope-like peptides that can bind to allergen-specific IgE paratopes and suppress effector cell activation. Methods: We performed biopanning, screening, IgE binding, selection and mapping of peptides. We generated synthetic peptides for use in all functional experiments. ImmunoCAP inhibition, basophil and mast cell activation tests, with LAD2 cells, a human mast cell line were performed. Twenty-six children or young adults who had peanut allergy were studied. Results: We identified and selected three linear peptides (DHPRFNRDNDVA, DHPRYGP and DHPRFST), and immunoblot analyses revealed binding to lgE from peanut-allergic individuals. The peptide sequences were aligned to the disordered region corresponding to the loop between helices 2 and 3 of Ara h 2, and conformational mapping showed that the peptides match the surface of Ara h 2 and h 6 but not other peanut allergens. In ImmunoCAP inhibition experiments, the peptides significantly inhibit the binding of IgE to Ara h 2 (p < .001). In basophil and mast cell activation tests, the peptides significantly suppressed Ara h 2-induced effector cell activation (p < .05) and increased the half-maximal Ara h 2 effective concentration (p < .05). Binding of the peptides to specific IgEs did not induce activation of basophils or mast cells. Conclusions: These studies show that the indicated peptides reduce the allergenic activity of Ara h 2 and suppress lgE-dependent basophil and mast cell activation. These observations may suggest a novel therapeutic strategy for food allergy based on epitope-paratop blocking.

Aim: Magnesium has many important functions in the body and one of its less known roles is its contribution to weight management. It triggers the release of cholecystokinin from the small intestines, which leads to suppression of hunger, lowers food intake, and reduces body weight. In this article we reviewed research that investigates this process as well as the individual steps of this pathway. Methods: Comprehensive literature search was done in September 2019 with several databases using the key words “magnesium AND (cholecystokinin OR hunger OR obesity)” and research was critically evaluated. Results: The ability of magnesium to stimulate the release of cholecystokinin was demonstrated in many animal and human studies. The influence of cholecystokinin on hunger/satiety sensation and or food intake was shown in several experimental models. Some studies demonstrated the overall link between magnesium intake and obesity. Conclusions: Even if there is still some controversy, most of the studies show that magnesium suppresses hunger, lowers food intake, and reduces body weight. The most probable mechanism is through magnesium stimulating cholecystokinin, which plays an important inhibitory role in the control of feeding behavior.

Development of targeted treatment for colorectal cancer is crucial to avoid side effects. To harness the possibilities offered by microbiome engineering, we prepared safe multifunctional cancer cell‐targeting bacteria Lactococcus lactis. They displayed, on their surface, binding proteins for cancer‐associated transmembrane receptors epithelial cell adhesion molecule (EpCAM) and human epidermal growth factor receptor 2 (HER2) and co‐expressed an infrared fluorescent protein for imaging. Binding of engineered L. lactis to tumour antigens EpCAM and HER2 was confirmed and characterised in vitro using soluble receptors. The proof‐of‐principle of targeting was demonstrated on human cell lines HEK293, HT‐29 and Caco‐2 with fluorescent microscopy and flow cytometry. The highest L. lactis adhesion was seen for the HEK293 cells with the overexpressed tumour antigens, where colocalisation with their tumour antigens was seen for 39% and 67% of EpCAM‐targeting and HER2‐targeting bacteria, respectively. On the other hand, no binding was observed to HEK293 cells without tumour antigens, confirming the selectivity of the engineered L. lactis. Apart from cell targeting in static conditions, targeting ability of engineered L. lactis was also shown in conditions of constant flow of bacterial suspension over the HEK293 cells. Successful targeting by engineered L. lactis support the future use of these bacteria in biopharmaceutical delivery for the treatment of colorectal cancer.

Recently, growing interest is devoted to investigation of compounds with antimicrobial activity due to rising cases of resistance of microbes to known therapy. Reliable and versatile source of novel drug discovery was recently found among endophytic fungi. Up to now, the research usually enclosed with in vitro evaluation of antimicrobial activity and chemical structure elucidation of biomolecules extracted from fungal material. Therefore, this research was designed as an extension to previous investigations of endophytic fungi growing on conifer needles by means of conducting a molecular docking study. The in silico methods were used with the main goal to make a contribution to the understanding of the mechanisms underlying the interaction of biomolecules isolated from fungus Phomopsis species and eight different types of receptors that belong to usually multidrug resistant bacterial pathogens. The results revealed valuable interactions with receptors 3G7B (Staphylococcus aureus?s gyrase B), 1F0K (1.9 ? structure of Escherichia Coli?s transferase) and 1SHV (Klebsiella pneumoniae?s SHV-1 ? -lactamase) thus pointing out to the receptors which trigger antibiotic response upon activation by the most potent compounds 325-3, 325-5, phomoenamide and phomol. These findings also recommended further discovery of novel potent and broad-spectrum antibiotics based on the structure of selected molecules.

The two most important bacterial phyla in the gastrointestinal tract, Firmicutes and Bacteroidetes, have gained much attention in recent years. The Firmicutes/Bacteroidetes (F/B) ratio is widely accepted to have an important influence in maintaining normal intestinal homeostasis. Increased or decreased F/B ratio is regarded as dysbiosis, whereby the former is usually observed with obesity, and the latter with inflammatory bowel disease (IBD). Probiotics as live microorganisms can confer health benefits to the host when administered in adequate amounts. There is considerable evidence of their nutritional and immunosuppressive properties including reports that elucidate the association of probiotics with the F/B ratio, obesity, and IBD. Orally administered probiotics can contribute to the restoration of dysbiotic microbiota and to the prevention of obesity or IBD. However, as the effects of different probiotics on the F/B ratio differ, selecting the appropriate species or mixture is crucial. The most commonly tested probiotics for modifying the F/B ratio and treating obesity and IBD are from the genus Lactobacillus. In this paper, we review the effects of probiotics on the F/B ratio that lead to weight loss or immunosuppression.

Recently, growing interest is devoted to investigation of bioactive secondary metabolites of endophytic fungi. Thus, as an extension to our previous achievements related to antimicrobial potential of endophytic fungi, Phomopsis species isolated from conifer needles was selected as appropriately promising natural source for drug discovery. Its dichloromethane and ethanol extracts considerably inhibited growth of Escherichia coli and Staphylococcus aureus. Moreover, the individual compounds of dichloromethane extract have been separated, collected and purified using semi preparative liquid chromatographic analysis and comprehensively characterized using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). Based on their antimicrobial activity and unique structural characteristics in comparison with well-established drugs from the same therapeutic category, two dominant compounds (Z)-(Z)-2-acetoxyprop-1-en-1-yl-3-(3-((E)-3,4-dihydroxypent-1-en-1-yl)oxiran-2-yl)acrylate (denoted as 325-3) and (Z)-(Z)-2-acetoxyprop-1-en-1-yl 3-(3-((E)-4-hydroxy-3-oxopent-1-en-1-yl)oxiran-2-yl)acrylate (denoted as 325-5) were recognized as valuable leading structures for future discovery of novel antibiotics.