Melilotus albus Medic. and Dorycnium herbaceum Vill. (Fabaceae) acetone, ethyl acetate, and ethanol extracts were investigated for their in vitro antimicrobial, antibiofilm, and antioxidant activity ...with quantification of phenolic compound contents. In general, D. herbaceum extracts showed better antibacterial and antioxidant activity than M. albus extracts. Bacteria Bacillus subtilis, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa, and Proteus mirabilis were the most susceptible with the minimum inhibitory concentrations (MICs), determined by microdilution method, between 1.25–10 mg/mL. Antifungal activity was lower with the detectable MICs at 10 mg/mL and 20 mg/mL. The plant extracts, using the crystal violet assay, inhibit P. aeruginosa biofilm formation in concentration range from 5 mg/mL to 20 mg/mL whereas the effect on mature bacterial biofilm was lower. The antioxidant activity was evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging and reducing power model systems. The intensity of DPPH radicals scavenging activity, expressed as half maximal effective concentration (EC50) values, was from 84.33 μg/mL to >1000 μg/mL. The extracts demonstrated reduced power in a concentration-dependent manner, with ethanol extract as the most active. The total phenols, flavonoids, and proanthocyanidins were determined spectrophotometrically while total extractable tannins were obtained by precipitation method. The phenolic compounds showed differences in their total contents depending on solvents polarities and plant species. Although the plants M. albus and D. herbaceum have not yet been fully explored, these results contribute better understanding of their biotic properties and potential application as antimicrobial and antioxidant agents.
The antioxidative, antimicrobial and antiproliferative potentials of the methanol extracts of the lichen species Parmelia sulcata, Flavoparmelia caperata, Evernia prunastri, Hypogymnia physodes and ...Cladonia foliacea were evaluated. The total phenolic content of the tested extracts varied from 78.12 to 141.59 mg of gallic acid equivalent (GA)/g of extract and the total flavonoid content from 20.14 to 44.43 mg of rutin equivalent (Ru)/g of extract. The antioxidant capacities of the lichen extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging. Hypogymnia physodes with the highest phenolic content showed the strongest DPPH radical scavenging effect. Further, the antimicrobial potential of the lichen extracts was determined by a microdilution method on 29 microorganisms, including 15 strains of bacteria, 10 species of filamentous fungi and 4 yeast species. A high antimicrobial activity of all the tested extracts was observed with more potent inhibitory effects on the growth of Gram (+) bacteria. The highest antimicrobial activity among lichens was demonstrated by Hypogymnia physodes and Cladonia foliacea. Finally, the antiproliferative activity of the lichen extracts was explored on the colon cancer adenocarcinoma cell line HCT-116 by MTT (3-4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide) viability assay and acridine orange/ethidium bromide staining. The methanol extracts of Hypogymnia physodes and Cladonia foliacea showed a better cytotoxic activity than the other extracts. All lichen species showed the ability to induce apoptosis of HCT-116 cells.
In this study, the antibiofilm activity of ethanol, acetone, and ethyl acetate extracts of Lamium album was evaluated against nine clinical strains from human wound swabs and two reference strains. ...The extracts of L. album exhibited significant antibiofilm activity. The extracts inhibited cell attachment and subsequent biofilm formation. The activity was dose-and strain-dependent, which was confirmed by fluorescence microscopy. The effects on mature biofilms were lower. In addition, the results showed a decrease in bacterial auto-aggregation in the presence of the extracts and no motility reduction. Phytochemical analysis and identification of functional groups by using Fourier Transform Infrared Spectroscopy were also performed. The results obtained in this study provide a basis for further research on this plant species.
This study deals with a quantitative and qualitative analysis of indoor airborne microbiota and estimation of microbiological quality of indoor air in faculty's rooms during the summer semester of ...2017/18 school year. The concentration of bacteria was significantly higher than the concentration of fungi. The species that belong to human skin microbiota or of environmental origin were identified. According to indoor air quality breakpoints, low to medium/high level of bacterial and fungal air contaminations was noticed.
In this study, the extraction of plant species Taraxacum officinale (F. H. Wigg) was optimized providing the maximum extraction of phenolic compounds using Response Surface Methodology (RSM). The ...optimum extraction parameters were as follows: extraction temperature of 60°C, extraction time of 30 min and 1:32.7 g/mL solid-liquid ratio for ethanol extract, and 60°C, 30 min, 1:14.2 g/mL ratio for acetone extract. The optimized extracts exhibited different biological activities. Ethanol extract showed better DPPH radicals scavenging activity and reducing power compared to acetone extract. The extracts had low antibacterial activity. In addition, the extracts had no effect on the healthy MRC-5 cell line, while acetone extract reduced the viability of HCT-116 carcinoma cells. This paper provides a basis for further research on the optimization of dandelion extraction under different conditions and testing the bioactivity of this medicinal plant.
The presence, biochemical and physiological characteristics of Lactobacillus and Lactococcus species isolated from traditionally made cheese from Southeastern Serbia (Sokobanja), was investigated. ...The screening of their antimicrobial potentials, using agar‐well diffusion method, and the ability of biofilm formation, using crystal violet method, was evaluated. The cheese samples, from different households, were obtained during the summer and the autumn. Chemical characteristics of cheese samples were examined. The members of genus Lactobacillus were: Lb. fermentum, Lb. brevis, and Lb. plantarum. The members of genus Lactococcus were: Lc. lactis subsp. lactis and Lc. lactis subsp. lactis biovar. diacetylactis. The antagonism of Lactobacillus and Lactococcus isolates on the growth of some Gram‐negative bacteria, isolated from the same cheese, was examined. The zones of growth inhibition ranged from 10 to 26 mm. The ability of biofilm formation of isolates was strains‐specific. Lactobacillus (KGPMF 28, KGPMF 29, KGPMF 35) and Lactococcus (KGPMF 23 and KGPMF 26) isolates demonstrated the potential for further investigation in natural preservation of food.
Practical applications
Lactic acid bacteria, which can be found in traditional dairy products, presents unique and autochthonous microflora responsible for fermentation and quality of dairy products. These bacteria often have a great potential in natural food preservation, but their number and diversity are depending of season, vegetation, and the nutrition of animals. In this paper, the seasonal differences in bacterial community (especially community of lactobacilli and lactococci) between cheese samples, were investigated. In addition, the antagonism against some enterobacteria, which can affect the hygienic safety of cheese, was screened. Also, it was showed that some isolates had the ability of biofilm formation. Further investigation need to include the potential of isolates to be uses like probiotic or starter cultures.
Traditional fermented foods are a significant source of starter and/or non‐starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The ...potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health‐promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.
Curcuma longa L. (turmeric) and Urtica dioica L. (common nettle) are well-known medicinal plants. In recent decades, due to its excellent biological activity and low toxicity, significant efforts ...have been made to research the potential application of these plants. Accordingly, the aim of this study was to investigate the combined effects of preservatives (potassium nitrite and sodium nitrite) and ethanol, acetone, and ethyl acetate extracts of C. longa and U. dioica emphasizing their join, synergistic effects. The eight isolates of foodborne pathogenic bacteria and two reference strains were used. The interactions were tested by the checkerboard method and expressed as fractional inhibitory concentration (FIC) index. FIC index was ranged in intervals from 0.25 to 2.0. The extracts of C. longa showed better synergistic effect with preservatives than U. dioica extracts. Synergism was observed in relation to Staphylococcus aureus ATCC 25923, S. aureus, Bacillus subtilis, and Salmonella typhimurium. In the presence of subinhibitory concentrations (1/4 MIC, 1/8 MIC) of the extracts, the MICs of preservatives have decreased up to 8-fold. In addition, the contents of phenolic compounds (total phenols, flavonoids, tannins, and proanthocyanidins) were determined spectrophotometrically. The higher concentration of phenolic compounds was detected in C. longa extracts than in U. dioica extracts.
The research aimed to optimize the ultrasound-assisted extraction of secondary metabolites and the antibacterial activity of the plant species Geranium robertianum. The phytochemical profiles of the ...optimized extracts, as well as their antibacterial and synergistic activity with an antibiotic and their potential mechanisms of action and cytotoxicity, were examined.
Response Surface Methodology was used to optimize extraction conditions. Optimized ethanol and acetone extracts were tested via microdilution, checkerboard, time-kill kinetics, and cell membrane permeability methods. The extracts displayed broad antibacterial activity with minimum inhibitory concentrations ranging from 1.25 to 20 mg ml-1. In addition, the extract synergistically reacted with gentamicin against gentamicin-resistant strains of Escherichia coli and Staphylococcus aureus, enhancing the efficacy of the antibiotic up to 32-fold. The extracts demonstrated strain-dependent bactericidal activity in a 24-h time interval. They increase the permeability of the cell membrane, thus disrupting its normal functioning. The cytotoxic concentration (CC50) on human keratinocytes was 1771.24 ± 5.78 µg ml-1 for ethanol extract, and 958.01 ± 6.14 µg ml-1 for acetone extract. Kaempferol, ellagic acid, quercetin, and rutin were recognized as the main components in both extracts.
The findings of this study indicate that the extracts of G. robertianum can be considered as potential natural antibacterial agents in the control of microorganisms.
Synergistic activity of Salvia officinalis and Cichorium intybus extracts and commonly used antibiotics, amoxicillin and chloramphenicol, were evaluated. Interactions between plant extracts and ...antibiotics were tested by checkerboard method and interpreted as FIC index. Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and clinical isolates Staphylococcus aureus, Bacillus subtilis, Enterobacter cloacae, Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis were used. Salvia officinalis showed better synergistic capacity than Cichorium intybus. Synergistic interactions were observed between amoxicillin and acetone or ethyl acetate extract of Salvia officinalis and between chloramphenicol and ethyl acetate extract of Salvia officinalis. In the presence of sub-inhibitory concentration (1/4 MIC to 1/32 MIC) of sage extracts, the MIC values of antibiotics were decreased by 2- to 10-fold. Synergism was observed against all test bacteria, except Escherichia coli. The combinations of acetone and ethyl acetate extract from Cichorium intybus and antibiotics resulted in additive and indifferent effects against tested bacteria.
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