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The aim of the present study was to evaluate antioxidant, antimicrobial, anti-HIV, and cholinesterase inhibitory activities of aqueous and alcoholic extracts from leaves, stems, and flowers of Euphorbia characias. The extracts showed a high antioxidant activity and were a good source of total polyphenols and flavonoids. Ethanolic extracts from leaves and flowers displayed the highest inhibitory activity against acetylcholinesterase and butyrylcholinesterase, showing potential properties against Alzheimer’s disease. Antimicrobial assay showed that leaves and flowers extracts were active against all Gram-positive bacteria tested. The ethanolic leaves extract appeared to have the strongest antibacterial activity against Bacillus cereus with MIC value of 312.5 μg/mL followed by Listeria monocytogenes and Staphylococcus aureus that also exhibited good sensitivity with MIC values of 1250 μg/mL. Moreover, all the extracts possessed anti-HIV activity. The ethanolic flower extract was the most potent inhibitor of HIV-1 RT DNA polymerase RNA-dependent and Ribonuclease H with IC50 values of 0.26 and 0.33 μg/mL, respectively. The LC-DAD metabolic profile showed that ethanolic leaves extract contains high levels of quercetin derivatives. This study suggests that Euphorbia characias extracts represent a good source of natural bioactive compounds which could be useful for pharmaceutical application as well as in food system for the prevention of the growth of food-borne bacteria and to extend the shelf-life of processed foods. [ABSTRACT FROM AUTHOR]

In the present study, six Lactococcus lactis and seven Lactiplantibacillus plantarum strains isolated from artisanal Sardinian dairy products were evaluated for their efficacy in controlling the growth of Listeria monocytogenes during the storage of miniature fresh cheese manufactured on a laboratory scale to exploit their possible use as biopreservatives. The strains were tested for antimicrobial activity and some technological characteristics before using them in miniature fresh cheese to evaluate their in situ antilisterial effect. Our results showed that five strains (L. lactis 16FS16-9/20234-11FS16 and Lpb. plantarum 1/14537-4A/20045) could be considered suitable candidates for use as protective cultures in fresh cheese manufacture since they significantly lowered the pathogen counts by 3–4 log units compared to the control; however, all strains tested were capable of decreasing L. monocytogenes numbers. Our results suggest that the single and combined action of the acidifying power and the production of bacteriocin of these strains was capable of controlling and/or reducing the growth of L. monocytogenes. Considering their technological characteristics, they might be used as starter/adjunct cultures to increase the safety of the products, perhaps in association with other antimicrobial hurdles. [ABSTRACT FROM AUTHOR]

Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. All selected strains maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, well comparable to the values obtained for the probiotic strain Lactobacillus rhamnosus GG, and were able to adhere to Caco-2 cells to various extents (from 3 to 20%). All strains exhibited high aminopeptidase, and absent or very low proteolytic and strong β-galactosidase activities; none was found to be haemolytic or to produce biogenic amines and all were susceptible to tetracycline, chloramphenicol, erythromycin, ampicillin, and amoxicillin/clavulanic acid. Our results indicate that the Lactobacillus strains analyzed could be considered appropriate probiotic candidates, due to resistance to GIT simulated conditions, antimicrobial activity, adhesion to Caco-2 cell-line, and absence of undesirable properties. They could be used as adjunct cultures for contributing to the quality and health related functional properties of dairy products. [ABSTRACT FROM AUTHOR]