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Stjepan Pepeljnjak

Publications and source records attributed to Stjepan Pepeljnjak.

At least 19 recordsLinked to original sources
PubMed2006

A year-round aeromycological study in Zagreb area, Croatia.

A 1-year aeromycological study was conducted in the area of Zagreb, the capital of Croatia, in order to establish seasonal variations in the composition and concentration of aeromycota. Sampling was carried out at 3 locations: the city centre, the Pharmaceutical botanical garden and the mountain of Medvednica, at regular intervals using the Mas 100 Eco Air-sampler with Sabouraud-dextrose agar. Airborne fungi peaked during spring and summer (110-284 cfu/m3), while lower levels were detected in autumn and winter at each of the 3 sampling sites (6-128 cfu/m3). Significantly lower concentrations were found in Medvednica region (p < 0.01) during most sampling periods. Yeasts were present in higher concentrations in autumn and winter (11-46 cfu/m3) than during spring and summer (9-11 cfu/m3) in the city centre and botanical garden. In the Medvednica region, yeasts were found at significantly lower concentrations than at other locations only during the autumn and winter (1-16 cfu/m3). The dominant fungi contributing to these differences were species of Cladosporium, Penicillium and Alternaria. These genera comprised between 30.4-79.5% of the samples. Other stable components of aeromycota were Fusarium, Aspergillus and sterile mycelia (11.1-44.0%). Total counts of airborne fungi as well as individual counts of Cladosporium and Alternaria showed significant positive correlations with temperature and solar radiation (p < 0.05). Alternaria also showed a significant correlation with wind speeds while Cladosporium was negatively correlated with atmospheric pressure (p < 0.05). Yeasts showed a significant positive correlation with relative humidity, yet were negatively correlated with temperature and solar radiation in the city centre and the botanical garden. In contrast, a significant positive correlation in the case of yeasts was observed in the Medvednica region with respect to temperature and solar radiation (p < 0.05).

Air Microbiology↗
PubMed2005

Influence of media and temperature on gliotoxin production in Aspergillus fumigatus strains.

Gliotoxin is a secondary metabolite of the epipolythiodioxopiperazine family with biologically active internal disulfide bridge. It is produced by many fungal species, including Aspergillus fumigatus and A. terreus. A. fumigatus, which produces gliotoxin and more than twenty other secondary metabolites, is the leading cause of invasive aspergillosis. Gliotoxin production in situ influence the development of aspergillosis. This study investigated the in vitro production of gliotoxin in nine A. fumigatus isolates from the upper respiratory tract of immunocompromised patients. The effects of media composition and incubation temperature were studied. Gliotoxin was extracted from biomass and its concentration was semi-quantitatively analysed using thin-layer chromatography. Gliotoxin production was higher in the yeast-extract liquid medium (YES) than in the synthetic Czapek-Dox liquid medium (CZA). Incubation at 37 degrees C resulted in higher gliotoxin production than at 25 degrees C, probably because higher temperatures favour expansive growth of the mycelium. Gliotoxin could be detected after three days of incubation at concentrations 4.06 mg mL(-1) (in YES at 37 degrees C) and 1.07 mg mL(-1) (in CZA at 25 degrees C). YES broth as a medium containing 4% sucrose and 2% of yeast extract is a very rich substrate for the production of gliotoxin in vitro.

Aspergillus fumigatus↗
PubMed2005

Toxigenic potential of Fusarium species isolated from non-harvested maize.

The objective of this study was to determine the frequencies of distribution and the toxigenic potential of Fusarium species isolated from non-harvested maize left in field over winter in 1999 (N = 56) and 2003 (N = 56) in northern Croatia. Zearalenone and trichothecenes (DON, DAS, T-2) were isolated and detected using multitoxin extraction and TLC method. Modified TLC method was applied to detect fumonisin B1. Fusarium species were the most frequent fungi found in maize with 78.6% in 1999 and 85.0% in 2003. Among fusaria F. verticillioides was dominant species found in 12.5% (1999) and 35.7% (2003) of maize samples. Other determined fusaria were F. graminearum (8.9% in 2003), F. poae and F. sporotrichoides (2.0% to 3.6%), F. tricinctum and F. tabacinum (2.0% in 1999). Production of FB1 was established for all F. verticillioides (7/7) isolated in 1999 in concentration range from 280 mg L(-1) to 918 mg L(-1), and for 11 of 20 strains found in 2003 (48 mg L(-1) to 400 mg L(-1)). Three strains also produced zearalenone: one strain in 1999 produced 3.80 mg L(-1) and 2 strains in 2003 produced 20.0 mg L(-1) and 70.0 mg L(-1). In addition, four strains of F. graminearum isolated in 2003 produced higher amounts of zearalenone (60.0 mg L(-1) to 180.0 mg L(-1)). T-2 production was found in F. tricinctum (1.55 mg L(-1)) isolated in 1999.

Food Contamination↗
PubMed2005

[Beauvericin: chemical and biological aspects and occurrence].

Beauvericin (BEA) is a cyclic hexadepsipeptide produced by Beauveria bassiana, Paecilomyces fumosoroseus, Paecilomyces tenuipes, Polyporus sulphurous, and a variety of Fusarium species. This mycotoxin shows antimicrobial, insecticidal, cytotoxic, and apoptotic activity. It is the most potent specific inhibitor of cholesterol acyltransferase and possesses ionophoric properties. BEA increases ion permeability in biological membranes by forming a complex with essential cations (Ca2+, Na+, K+), which may affect the ionic homeostasis. BEA has been frequently found in maize samples in Europe, USA and Africa and co-contamination with other Fusarium toxins such as fumonisins, and moniliformin was also found. There is only one report of BEA occurrence and co-occurrence with fumonisin B1, fumonisin B2 and ochratoxin A in Croatia. Biological activity of BEA may increase the toxicity of other mycotoxins that co-occur with BEA in food. The role of BEA in the development of human and animal mycotoxicosis is still unknown.

Depsipeptides↗
PubMed2005

Toxic effects of Ustilago maydis and fumonisin B1 in rats.

The toxicity of Ustilago maydis and the possible synergism with fumonisin B1 (FB1) were studied in Fischer rats by evaluating pathological changes and biochemical parameters in blood serum (LDH, ALT, GGT, ChE) and tissue homogenate of brain and liver (AChE, ChE, GGT, ALP). One experimental group (US) consumed diet with 70% of U. maydis galls and the other group (US+FB1) was fed pellets containing 70% of U. maydis galls and 1 mg of FB1 per kg of diet for 17 days. Control group (C) consumed standard pellets. During the trial, experimental animals were more excited, showing hyperactivity. Body mass gains slightly increased in both groups compared to the control. Gross pathological changes in liver, lungs, uterus and ovaries were more pronounced in the US+FB1 than in the US group. Specific catalytic activities of AChE decreased by 61% and by 63% in the liver and brain homogenate of the US group (p<0.05) compared to the control, indicating neurotoxic activity of U. maydis. Also, specific catalytic concentration of AChE and ALP was significantly decreased in the liver of the US+FB(1) group (p<0.05). Activity of LDH in the blood serum was increased up to 166% and 165% in the US+FB1 group (p<0.05) compared to the control and US group values, respectively, which indicates that FB1 was responsible for the disruption of cell membrane integrity. These findings suggest that Ustilago maydis and FB1 showed neurotoxicity in Fischer rats, which could be related to the alkaloids of U. maydis and disruption of sphingolipid metabolism by FB1 activity.

Acetylcholinesterase↗
PubMed2005

Verruculogen production in airborne and clinical isolates of Aspergillus fumigatus Fres.

Among airborne aspergilli sampled in outdoor air of the Zagreb area (2002/2003), Aspergillus niger (v. Teigh.) and A. fumigatus (Fres.) were the most abundant species (20-30%), with low mean annual concentrations (0.21-1.04 CFU m-3). Higher concentrations of A. fumigatus were observed in autumn and winter (0.5-1.05 CFU m-3) than in spring and summer (0-0.4 CFU m-3). On the other hand, A. fumigatus was found to be the most frequent isolate from upper and/or lower respiratory tracts of imunocompromised patients in many studies. This species produces several mycotoxins, including the tremorgenic mycotoxin verruculogen that can be found in spores and during myceliar growth. Verruculogen production ability was tested on 30 airborne and 33 clinical isolates of A. fumigatus. In both groups, high percentage of verruculogen-producing strains was noticed (84% of airborne and 91% of clinical isolates). Verruculogen production was not significantly different in the groups of airborne isolates (0.34+/-0.16 mg mL-1), and clinical isolates (0.26+/-0.19 mg mL-1).

Air Microbiology↗
PubMed2005

Mycotoxigenicity of clinical and environmental Aspergillus fumigatus and A. flavus isolates.

Clinical isolates of fifty strains of A. fumigatus and 30 strains of A. flavus from immmunocompromised patients from the hematological unit were analyzed for mycotoxin production and compared with the same number of environmental isolates (from soil, compost, and air). Only 9 (18%) strains of A. fumigatus produced gliotoxin in a mean concentration 2.22 mg mL-1 (range 0.5-5 mg mL-1). Aflatoxin B1 was detected in 7 (23%) isolates (range from 0.02 to 1.2 mg L-1) and aflatoxin G1 in one (3%) of clinical A. flavus isolates (0.12 mg L-1). In the group of environmental isolates, 11 (37%) were positive for aflatoxin B1 production (range from 0.02 to 1.2 mg L-1) and one for aflatoxin G1 (0.02 mg L-1). Bioautoantibiogram ("bioassay in situ") on TLC plates against Bacillus subtilis NCTC 8236 showed that only gliotoxin-producing strains have bactericidal activity of Rf values corresponding to gliotoxin. The secondary-metabolite profiles of clinical and environmental A. fumigatus and A. flavus isolates were homogeneous, except for gliotoxin production, which was detected only in the group of clinical isolates of A. fumigatus (18%).

Aflatoxin B1↗
PubMed2005

Antifungal activity of fluid extract and essential oil from anise fruits (Pimpinella anisum L., Apiaceae).

Antifungal activities of fluid extract and essential oil obtained from anise fruits Pimpinella anisum L. (Apiaceae) were tested in vitro on clinical isolates of seven species of yeasts and four species of dermatophytes. Diffusion method with cylinders and the broth dilution method were used for antifungal activity testing. Anise fluid extract showed antimycotic activity against Candida albicans, C. parapsilosis, C. tropicalis, C. pseudotropicalis and C. krusei with MIC values between 17 and 20% (v/v). No activity was noticed against C. glabrata, and anis fruits extracts showed growth promotion activity on Geotrichum spp. Anise fruits extract inhibited the growth of dermatophyte species (Trichophyton rubrum, T. mentagrophytes, Microsporum canis and M. gypseum) with MIC values between 1.5 and 9.0% (V/V). Anise essential oil showed strong antifungal activity against yeasts with MIC lower than 1.56% (V/V) and dermatophytes with MIC lower than 0.78% (V/V). Significant differences in antifungal activities were found between anise fluid extract and anise essential oil (p<0.01). Anise essential oil exhibited stronger antifungal activities against yeasts and dermatophytes with MIC values between 0.10 and 1.56% (V/V), respectively.

Antifungal Agents↗
PubMed2005

Antimicrobial activity of some hydroxamic acids.

Several hydroxamic acids, viz., N-benzyl-N'-hydroxysuccinamide (BHS), poly[alpha,beta-(N-hydroxy)-DL-aspartamide] (PHA), poly[alpha,beta-(N-hydroxy-N-methyl-DL-aspartamide)] (PMHA) and poly[alpha,beta-(N-hydroxy)-DL- aspartamide]/poly[alpha,beta-(N-2-hydroxyethyl)-DL-aspartamide] (PHA-PHEA 1:1) were prepared and screened for their antimicrobial activity. Ten Gram-positive and 7 Gram-negative species of bacteria, 5 Candida species, 4 dermatophyte species and 3 mould species were used in tests. Compound showed no antimicrobial activity on any of the tested microorganisms. Other compounds showed a narrow spectrum of antibacterial activity, but no antifungal activity.

Anti-Infective Agents↗
PubMed2005

Investigation of antimicrobial activity of Pelargonium radula (Cav.) L'Hérit.

Antimicrobial activities of two ethanolic extracts, made from fresh and dried leaves of Pelargonium radula (Cav.) L'Hérit, were tested against fourteen species of bacteria and fifteen species of fungi. The well-diffusion method indicated the strongest activity against Pseudomonas aeruginosa. The broth dilution method revealed that the most sensitive microorganisms were Bacillus pumilus, Bacillus subtilis, Escherichia coli and Serratia marcescens. Extract prepared from fresh leaves showed significantly higher antimicrobial activity than the extract prepared from dried leaves.

Anti-Infective Agents↗
PubMed2005

Antimicrobial activity of juniper berry essential oil (Juniperus communis L., Cupressaceae).

Juniper essential oil (Juniperi aetheroleum) was obtained from the juniper berry, and the GC/MS analysis showed that the main compounds in the oil were alpha-pinene (29.17%) and beta-pinene (17.84%), sabinene (13.55%), limonene (5.52%), and mircene (0.33%). Juniper essential oil was evaluated for the antimicrobial activity against sixteen bacterial species, seven yeast-like fungi, three yeast and four dermatophyte strains. Juniper essential oil showed similar bactericidal activities against Gram-positive and Gram-negative bacterial species, with MIC values between 8 and 70% (V/V), as well as a strong fungicidal activity against yeasts, yeast-like fungi and dermatophytes, with MIC values below 10% (V/V). The strongest fungicidal activity was recorded against Candida spp. (MIC from 0.78 to 2%, V/V) and dermatophytes (from 0.39 to 2%, V/V).

Anti-Bacterial Agents↗
PubMed2005

Flavonoid analysis and antimicrobial activity of commercially available propolis products.

Propolis ethanolic solutions are the most used propolis products on the market for the treatment of minor ulcers in the mouth, angina, thrush or skin infections. Since it is still an unofficial drug in pharmacy, we analyzed the contents of flavonoids in ten commercially available ethanolic solutions of propolis from the Croatian market using two complementary colorimetric methods. Antimicrobial activities, determined with the diffusion method, against six bacterial species (Bacillus subtilis NCTC 8236, Staphylococcus aureus ATCC 25923, Streptococcus pyogenes ATCC 12204, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 27853, and one yeast-like fungus Candida albicans ATCC 10231 were compared. Results of flavonoids analysis suggested that the contents of flavones and flavonols in the products were uniform and ranged from 0.14 to 0.41%, but the content of flavanones varied greatly from 0.43 to 18.78%. Total flavonoid content, as the sum of two colorimetric methods, in propolis products was between 0.78 and 18.92%, and most products had the flavonoids content below 9%. All products with the total flavonoids content above 1% showed antimicrobial activity against the four Gram-positive bacterial species tested, and against P. aeruginosa and the yeast-like fungus C. albicans. Total flavonoids contents, expressed as the sum of two colorimetric methods, could be useful methods for estimating the flavonoid contents of propolis products. Our results indicate that the quality of commercially available propolis products requires verification.

Anti-Infective Agents↗
PubMed2005

Antimicrobial activity of flavonoids from Pelargonium radula (Cav.) L'Hérit.

Flavonoids from Pelargonium radula (Cav.) L'Hérit were purified by column chromatography. Two fractions were obtained: F1 (main flavonoid isoquercitrin) and F2 (main flavonoid rutin). In vitro antimicrobial activity of F1 and F2 were tested against eleven species of bacteria and eleven species of fungi. Both fractions demonstrated strong inhibitory activity against Staphylococcus aureus, Proteus rettgeri, Candida tropicalis and Microsporum gypseum. Staphylococcus sp. (coagulase-negative) and Candida lusitaniae were strongly inhibited only by fraction F1 and Fusarium graminearum only by fraction F2.

Anti-Infective Agents↗
PubMed2004

Galangin expresses bactericidal activity against multiple-resistant bacteria: MRSA, Enterococcus spp. and Pseudomonas aeruginosa.

The antimicrobial activity of three propolis ethanol extracts (EEP) was examined for various Gram-negative and Gram-positive bacterial species, including multiple-resistant Staphylococcus aureus, Enterococcus spp. and Pseudomonas aeruginosa strains. EEP had a good bactericidal activity against Gram-positive species, and all multiple-resistant bacterial strains tested were sensitive to EEP. Minimal inhibitory concentrations (MICs) were lower in samples of higher flavonoid content (from 0.65 to 7.81 mg mL(-1)), indicating the influence of the concentration of some potent bactericidal compound(s) in propolis or synergism among some bactericidal compounds. Antimicrobial-guided separation of flavonoid aglycones (bioassay in situ on thin-layer chromatogram) showed that galangin (3,5,7-trihydroxyflavone) is one compound in EEP with bactericidal activity. Galangin was isolated by preparative chromatography. After determining the quantity present, the MIC against multiple-resistant bacteria was determined. The MIC of galangin against multiple-resistant bacterial strains was significantly lower (from 0.16 to 0.44 mg mL(-1), p < 0.05) than that of EEP. The bactericidal activity of galangin against P. aeruginosa strains was present at 0.17+/-0.05 mg mL(-1).

Anti-Bacterial Agents↗
PubMed2004

Quantitative analysis of the flavonoids in raw propolis from northern Croatia.

Spectrometric analyses of flavonoids in twenty propolis samples, collected from ten different geographic localities in northern Croatia using two complementary methods, are reported. Flavones and flavonols were determined using aluminum chloride and expressed as quercetine equivalent while flavanones were determined using 2,4-dinitrophenylhydrazine and expressed as naringenin. Contents of flavones and flavonols were similar for most samples and ranged from 2 to 2.3%, except for one sample with a concentration of 1.3% and one sample in which it was not possible to detect flavones and flavonols. The content of flavanones in propolis samples is very variable. 55% of samples contained flavanones between 15 and 24% and 45% of samples between 4 and 14%. Total levels of flavonoids in raw propolis samples ranged between 5 and 26%; for the majority of samples (75%), the total level of flavonoids ranged between 15 and 25.9%. The high variability of flavanone concentration will affect the biological activity of propolis preparations.

Colorimetry↗
PubMed2004

[Frequencies of airborne moulds in Zagreb].

Airborne fungi are sometimes associated with several respiratory diseases and allergies. This paper describes a study of qualitative and quantitative variations in the occurrence of airborne moulds in Zagreb area on three locations: centre of the city (C), Pharmaceutical Botanical Garden "Fran Kusan" (BG) and the mountain Medvednica (M) during autumn, winter, spring and summer 2002-03. Lower concentrations of airborne moulds were found in all three locations in autumn (up to 76.88 CFU/m3) and winter (31.46 CFU/m3), with significantly higher levels in C and BG than in M (P<0.001). In spring and summer, these concentrations were much higher in all sampling sites and were significantly higher in C (160.00 CFU/m3) and BG (134.00 CFU/m3) in spring than in M (90.07 CFU/m3) (P<0.001). In summer, significantly higher concentration was found in C (237.5 CFU/m3) than in BG (186.50 CFU/m3) (P<0.01), while concentrations in C and M (216.70 CFU/m3) were similar. Airspora belonging to 29 fungal genera were identified, and allergologicaly significant moulds, Cladosporium (up to 79.5%) and Alternaria (up to 59.4%) dominated in all sampling sites. Penicillium, Fusarium and Aspergillus were also constant fungal entities (43.0-70.5%), but in much lower concentrations than Cladosporium and Alternaria. Airsporas of Cladosporium and Alternaria were more frequent in spring and summer in all locations, with significantly higher concentrations in C and BG (P<0.05). The risk from allergies increases with higher airspora concentrations in spring and summer due to an increase in Cladosporium and Alternaria.

Air Microbiology↗
PubMed2004

[Chemistry and biological effects of gliotoxin].

Gliotoxin is a mycotoxin from the epipolythiodioxypipeazine family with biological active internal disulfide bridge. Gliotoxin has an antibacterial and antiviral activity, but it was discarded from clinical practice due to its toxicity. The most studied effect of gliotoxin is its influence on the cell of the immune system. Today, researches are focused on treating transplantation organs ex situ and making them immunologically silent. Its toxicity has been proven on several cells (macrophages, thymocites, splenocytes, and fibroblasts) causing apoptosis and necrosis and it has acted as inhibitor of several enzymes (farnesyl-transefases, NF-kappaB, and alcohol-dehydrogenases). Its mechanism of toxicity is connected with the production of mixed disulfide and covalent bonds, and oxidative effects. An important medical mould Aspergillus fumigatus and yeast Candida albicans can secrete gliotoxin in infected tissues and, because of the proven toxic effects of gliotoxin, it is suggested that gliotoxin can exacerbate mycoses (invasive aspergillosis or candidiasis). Gliotoxin can also affect the invasiveness of fungi and their dissemination from the primary site throughout the organism.

Animals↗