Antifungal, antimicrobial, insecticidal and antioxidant activities of Origanum vulgare L. provide the basis for suggesting that oregano plant extracts may be useful for prevention and treatment of many infection. The main goal of this study was to determine antimicrobial and antioxidant activities of methanolic and aqueous extracts from the leaves and flowers of Origanum vulgare. Antimicrobial testing of plant extracts was done using well diffusion method. Activity of extracts were tested against Gram positive bacteria: Staphylococcus aureus ATCC 25923, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 33591, Bacillus subtilis ATCC 6633, Enterococcus faecalis ATCC 29212 and five Gram-negative bacteria: Salmonella abony ATCC 6017, Salmonella enterica serovar Enteritidis ATCC 31194, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 25922, extended-spectrum β-lactamase (ESBL) producing Escherichia coli ATCC 35218 and fungi Candida albicans ATCC 1023. Antibiotics ampicillin, streptomycin and antimycotic nystatin were used as positive controle. The antioxidant activity was determined by using the DPPH (1,1-diphenyl-2-picrylhydrazyl) method. The highest values for inhibition zone for methanolic and aqueous extracts were recorded for Gram positive Bacillus subtilis, Staphylococcus aureus and MRSA. Methanolic extracts exhibited antibacterial activity against tested Gram negative bacteria in variable degree while the growth of these bacteria was not inhibited by aqueous extracts. Tested fungi Candida albicans was not susceptible to investigated oregano extracts. All the extracts showed moderate to potent antioxidant activity, among which the methanolic flower extract demonstrated the strongest antioxidant activity with the IC50 value of 0.205 mg/mL. Therefore it can be concluded that flower and leaf oregano extracts have great antibacterial and antioxidant potential.

Abstract Detailed analysis of phenolic composition and antioxidant and antimicrobial activities of Verbascum glabratum subsp. bosnense (K. Malý) Murb., an endemic species of southeastern Dinaric Alps was performed for the first time. The phenolic composition measured via UHPLC-MS/MS of four extract with different polarity suggested this plant species is very rich in both phenolic acids and flavonoids. Ethanol extract was chemically the most versatile containing 12 compounds with quercitrin and rosmarinic acid as the majors, while water extracts were rich in 4-hydroxybenzoic acid, salicylic acid, morin, and apigenin. All extracts showed high antioxidant potential measured spectrophotometrically with IC50 values ranging 0.139 - 0.021 mg/mL. Antimicrobial testing using agar diffusion test showed that ethanol extract was the most potent against all tested organisms. Also, these activities are correlated with the content of phenolic compounds, which suggest they are active ingredients of the extracts. Graphical Abstract

Introduction: The objective of the present study was to evaluate the antimicrobial and cytotoxic activities of water extracts of leaves and barks from Alnus glutinosa (L.) Gaertn., A. incana (L.) Moench, and A. viridis (Chaix) DC.Methods: The antimicrobial activities of extracts were tested against gram-negative and gram-positive bacteria as well as yeast strains by the agar diffusion method. The cell viability was determined by the Trypan blue dye exclusion method.Results: The largest diameters of inhibition zone (DIZ) were recorded with Staphylococcus aureus ATCC 6538 and Bacillus subtilis 168M. The highest percentage of cell viability was observed with water bark extracts of A. glutinosa (97.46%).Conclusions: Potential antimicrobial properties of A. glutinosa, A. incana, and A. viridis demonstrated in this study, as well as their low levels of toxicity, make them an interesting subject for further studies.