A Comparative Study of the in Vitro Antimicrobial and Synergistic Effect of Essential Oils from Laurus nobilis L. and Prunus armeniaca L. from Morocco with Antimicrobial Drugs: New Approach for Health Promoting Products

Abstract

Laurus nobilis L. (laurel, Lauraceae) and Prunus armeniaca L. (apricot, Rosaceae) are important industrial crops and display significant biological properties, including antimicrobial activity. In this work, essential oils (EOs) prepared from the leaves of both species from Morocco were evaluated for the first time for possible synergistic in vitro antibacterial and antifungal effects with some conventional antimicrobial drugs, namely fluconazole, ciprofloxacin and vancomycin. Samples were further evaluated for chemical composition by gas chromatography–mass spectrometry (GC-MS). The main volatile compounds detected in L. nobilis were eucalyptol (40.85%), α-terpinyl acetate (12.64%) and methyl eugenol (8.72%), while P. armeniaca was dominated essentially by (Z)-phytol (27.18%), pentacosane (15.11%), nonacosane (8.76%) and benzaldehyde (7.25%). Regarding antimicrobial activity, both EOs inhibited significantly all the microorganisms tested. The EO from L. nobilis had the highest activity, with minimal inhibitory concentrations (MICs) ranging from 1.39 to 22.2 mg/mL for bacteria and between 2.77 and 5.55 mg/mL for yeasts. Conversely, the combination of the studied EOs with ciprofloxacin, vancomycin and fluconazol resulted in a noteworthy decrease in their individual MICs. In fact, of the 32 interactions tested, 23 (71.87%) demonstrated total synergism and 9 (28.12%) a partial synergistic interaction. The EO from L. nobilis exhibited the highest synergistic effect with all the antibiotics used, with fractional inhibitory concentration (FIC) index values in the range of 0.266 to 0.75 for bacteria, and between 0.258 and 0.266 for yeast. The synergistic interaction between the studied EOs and standard antibiotics may constitute promising anti-infective agents useful for treating diseases induced by antibiotic-resistant pathogens.

Chemical composition and synergistic effect of three Moroccan lavender EOs with ciprofloxacin against foodborne bacteria: a promising approach to modulate antimicrobial resistance

“…Furthermore, eucalyptol (or 1,8‐cineole), found as major constituent in L. angustifolia EO, is known as an antimicrobial agent targeting the bacterial cell membrane (Simsek and Duman 2017; Nafis et al . 2020). Several studies showed that EOs characterized by high amounts of fenchone exhibited a high inhibitory capacity on the microbial cell, especially against pathogenic yeasts like Candida species (Garzoli et al .…”

“…For this reason, our results cannot be compared to other data, but several studies extensively demonstrated the antimicrobial potential of numerous lavender species individually. Nelson (1997) and Alexopoulos et al (2011) showed that the extensively explored L. angustifolia had a remarkable activity against methicillin-resistant Staphylococcus aureus(MRSA). In addition, Kwiatkowski et al (2019) found that the combination of L. angustifolia EO with octenidine dihydrochloride revealed cell wall alterations in MRSA strains; Yang et al (2020) suggested that L angustifolia EO and meropenem induced oxidative stress in K. pneumoniae by oxidation of the outer membrane, production of reactive oxygen species (ROS) and their influx into bacterial cell, ultimately causing cell damage and death.…”

Supercritical Fluid Extraction of Celery and Parsley Fruit-Chemical Composition and Antibacterial Activity

“…Therefore, extracts for topical use, without a pronounced cytotoxic action, are considered as strong antibacterial agents, even if the MIC values are greater than 1 mg/mL [24]. Some authors declared strong activity of some herbal extracts in concentrations greater than 5 mg/mL [25]. Aiming to make our results applicable in the food industry, we have taken into account the fact that excess concentrations of extracts can affect the organoleptic food properties, and therefore, we did not use concentrations higher than 2.56 mg/mL in our study, but also included the lowest concentrations that would be comparable to antibiotics (1.25-40 µg/mL).…”

Effect of Dietary Supplementation of Laurus Nobilis Leaves Meal on Growth Performance, Carcass Traits and Blood Antioxidant Status of Growing NZW Rabbits

“…Similarly, Rebickov et al, (2020) showed that essential oils from bay leaves had a remarkable antimicrobial against many types of harmful bacteria (E.coli, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans) in addition to the antioxidant effect. The synergistic interaction between Laurus nobilis L essential oil and standard antibiotics may constitute encouraging anti-infectious agents useful for antibiotic resistant bacteria (Nafis et al, 2020). In the same way, Tometri et al, (2020) indicated that nano-extract of Laurus nobilis leaves treatment inhibited E. coli and Staphaureus growth and can be used as a natural antibacterial with appropriate antioxidant effects.…”

“…Bay leaf contains many types of flavonoids and glycosides, such as kaempferol, quercetin, apigenin, luteolin, quercetin (Ayoub et al, 2013 andAbu-Dahab et al, 2014). Nafis et al, (2020) indicated that the main essencial oils in bay laurel were eucalyptol, αterpinyl acetate and methyl eugenol representing about 40.85, 12.64 and 8.72% , respectively . Bay leaf has a broad range of biological properties including anti-microbial and antioxidant.…”