antibacterial compounds isolated from S. officinalis leaves, potentiate the effects of aminoglycosides on methicillin-resistant S. aureus (Horiuchi et al., 2007, Pavić et al., 2019).

inhibited at MIC/MBC of 0.156/0.315 μL/mL (Čabarkapa et al., 2019). Thyme essential oil has also been shown to act against methicillin resistant S. aureus (MIC 18.50 μg/mL) (Tohidpour et al., 2010). The most intense antibacterial activity of this essential oil was observed against blaCTX-M-1-producing E. coli S22 / 12 and ESBL-producing Klebsiella pneumoniae S34 / 15 with a MIC of 2.87 μg / mL. In addition, E. coli producing blaCTX-M-1 was more sensitive than E. coli producing blaSHV-12 (Benameur et al.,

2019). Even thyme essential oil vapors are highly effective against respiratory tract pathogens (Inouye

et al., 2006). The antimicrobial properties are mainly attributed to monoterpenic phenols, thymol and carvacrol, strong anti-infective agents, but also to geraniol, linalool alcohols. Experimental studies have suggested that a higher content of phenolic terpene compounds results in a higher inhibitory activity (Fani et al., 2017). In addition to thymol and carvacrol, phenolic acids, polyphenolic carboxylic acids

μg/mL) and Gram-negative bacteria (MIC between 2 and 60 μg / mL) as opposed to the aqueous extract which showed low activity, the study indicating a synergistic action of the compounds in the methanolic extract. The antibacterial potential of rosemary was also observed in a clinical study, which evaluated the efficacy of a mouthwash containing hydroalcoholic extracts of Zingiber officinale, R. officinalis and Calendula officinalis, concluding that the preparation was effective in patients with gingivitis, and the effectiveness was comparable to chlorhexidine mouthwash. (Mahyari et al., 2016).

Tea tree is a shrub or tree from Myrtaceae family, native to Australia. It has been used by Australians in traditional medicine as antiseptic and anti-inflammatory to treat various infections for almost 100 years. Tea tree essential oil contains terpinene-4-ol, α-terpinene, γ-terpinene, α-terpineol, 1,8-cineole, ρ-cymene, terpinolene, and limonene, as major constituents and exerts a strong antioxidant and antibac­terial activity, as confirmed by many in vitro tests.

Zhang et al. (2018) noticed that the essential oil of M. alternifolia displayed significant antimicrobial activity on Gram-positive and Gram-negative bacteria as Staphylococcus aureus, Pseudomonas aerugi- nosa, P. italicum, P. digitatum and Escherichia coli strains, with a MIC raging between 2 and 24 mg/mL. According to these authors, ” the hydrophobic terpenes from the essential oil interact with the membrane lipids of the pathogenic microorganisms, which affect the permeability of the membrane, leading to a deficit in the production of cellular energy caused by the decrease in ATP generation, and cellular lyses due to leakage or coagulation of the cytoplasm” (Zhang et al., 2018). Ferrini et al. (2006) found that from terpien-4-ol, from the tea tree essential oil has an efficient antibacterial activity on Staphylococ- cus aureus, even for the antibiotic resistant strains. Another in vitro study performed by Kokina et al. (2019) showed the inhibition of tea tree essential oil on the bacterial growth of Staphylococcus aureus and Salmonella Typhimurium with a MIC of 10, respectively > 10 μg/mL.

Many in vitro studies demonstrated the antibacterial effect of garlic extracts against Gram positive and Gram-negative bacteria, including those resistant to antibiotics, such as Staphylococcus aureus, Pseu- domonas, Klebsiella, Salmonella typhi, Enterococcus faecalis, Proteus, and Escherichia coli (Bakri & Douglas, 2005; Yadav et al., 2015; Rawat, 2015; Petropoulos et al., 2018; Ismail et al., 2020; Parham et al., 2020; Pancu et al., 2021). The antibacterial effect of Allium sativum was proved using different extracts: crude extracts, powder, various solvents extracts, and also the biocompounds isolated from this plant. The aqueous and alcoholic extract of garlic contain organosulfur compounds as S-allyl cysteine, S-methyl cysteine, and S-allylmercapto- that garlic distilled oil with diallyl disulfide and diallyl trisulfide is effective on different Gram-positive and negative bacteria cultures (S. aureus, B. subtilis, P. aeruginosa and E. coli). The mechanism of action consists in binding to the thiol groups of enzymes in bacteria, which leads to the microbial inactivation.

Arctostaphylos uva-ursi L., from the Ericaceae family, is an evergreen shrub that grows in the northern hemisphere, abounds in the Arctic regions, and only at high altitudes in the temperate and Mediterranean area. For a long time, the leaves of this plant have been used in traditional medicine to combat and treat urinary tract diseases, like infections such as cystitis or urethritis, as a diuretic and anti-inflammatory agent for various diseases of the urogenital tract.

Anukk et al., (1999) reported that aqueous bearberry leaf extracts show remarkable bacteriostatic activ- ity on H. pylori strains. This activity could be related to the ability of the aqueous extract to modulate the hydrophobicity of the cell surface and to increase the aggregation of cells, an effect determined by the high content of tannins. Various extracts (aqueous, ethanolic and ethyl acetate) from A. uva - ursi leaves were tested on strains of Enterococcus faecalis and strains of Escherichia coli, etiological agents of urinary tract infections. In vitro results concluded that the aqueous extract has a stronger antibacte­rial effect on E. coli (MIC 0.625-5 mg/mL) compared to ethanolic and ethyl acetate extracts (MIC 10 mg/mL), while the effect on Enterococcus faecalis was similar for the three types of extracts. It should be noted that the extracts showed stronger antibacterial activity against Gram-positive strains (Vučić et al., 2013). Arbutin metabolites (hydroquinone, hydroquinone glucuronide, hydroquinone sulfate) are considered to be the compounds responsible for the urinary antiseptic activity of the plant. They exert antimicrobial action on a wide range of pathogens involved in the infectious pathology of the urinary tract, E. coli, Proteus vulgaris, Acinetobacter baumanii, Ataphylococcus aures, Bacillus subtilis, Entero- coccus faecalis, Neisseria gonorrhoeae (Ștefănescu et al., 2019). Although it was initially thought that hydroquinone could be released from arbutin only by alkalizing urine, more recent research challenges this hypothesis. Hydroquinone deconjugation is now thought to be catalyzed by intracellular enzymes present in the bacterial cytoplasm. Alkalization of urine does not appear to be a prerequisite for the release of hydroquinone from arbutin (Quintus et al., 2005). The pharmacology of the whole plant has also been shown to be different from that of arbutin alone. Crude plant extracts are more medically effective than isolated arbutin (Asensio et al., 2020). In addition, A. uva - ursi extracts have been shown to be helpful in increasing the susceptibility of antibiotic-resistant bacteria such as beta-lactams. A group of Japanese researchers studied the effect of corilagin, a polyphenolic compound isolated from A. uva - ursi, against methicillin-resistant Staphylococcus aureus. Corilagin reduced the minimum inhibitory concentration of oxacillin and other beta-lactam antibiotics by 100 to 2000 times, the effect of corilagin and oxacillin being synergistic (Shimizu et al., 2001).

responsible for the sweet taste), and flavonoids (liquiritigenin and isoliquiritigenin) are the most impor­tant constituents (Pastorino et al., 2018).

Gupta et al., 2008 and Wang et al., 2015 showed the antimicrobial action of G. glabra extract on Gram‐ positive and Gram‐negative bacteria cultures, as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis (Gupta et al., 2008; Wang et al., 2015). Responsible for the

Avato et al., 2004 tested the microbiological activity of various extracts against Gram-positive bacteria (Bacillus subtilis, B. cereus, Staphylococcus aureus, Enterococcus) as well as Gram-negative (Pseudo-

mechanisms of antimicrobial action of biological compounds from plants must be completely elucidated, and additionally, their toxicity on humans should be evaluated.

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Bhatwalkar, S. B., Mondal, R., Krishna, S., Adam, J. K., Govender, P., & Anupam, R. (2021). Antibacte­rial Properties of Organosulfur Compounds of Garlic (Allium sativum). Frontiers in Microbiology, 12,

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