Tetraclinis articulata (Vahl) Mast. essential oil as a promising source of bioactive compounds with antimicrobial, antioxidant, anti-inflammatory and dermatoprotective properties: In vitro and in silico evidence

Tetraclinis articulata is a known traditional medicinal plant used to manage various ailments, such as diabetes, rheumatism and infectious diseases. This study aims to determine the chemical constituents of T. articulata essential oil (EO) and to evaluate its in vitro antibacterial, anti-candidal, antioxidant, anti-inflammatory and dermatoprotective properties. In addition, a computational docking approach was used to predict the potential antioxidant, antibacterial, antifungal, anti-inflammatory, and cytotoxic properties of the identified compounds. The volatile oil obtained by hydrodistillation was characterized using gas chromatography-mass spectrometry (GC-MS). The antioxidant activity of T. articulata EO was investigated using three complementary assays: DPPH, ABTS and FRAP. Lipoxygenase (5-LOX) and tyrosinase enzymes were used to assess the anti-inflammatory and dermatoprotective effects of this oil. Moreover, disc-diffusion technique, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were employed for the antimicrobial screening. The GC-MS analysis revealed that bornyl acetate (41.80 %), α-pinene (17.97 %) and camphor (15.97 %) are the major components of the studied EO. Moreover, T. articulata EO has exhibited promising antioxidant effect on FRAP, DPPH, and ABTS experiments. It also significantly inhibited 5-LOX (IC50 = 67.82 ± 0.03 μg/mL) and tyrosinase (IC50 = 211.93 ± 0.02 μg/mL). The results of MIC and MBC assays indicated that T. articulata EO is able to inhibit the growth of all tested bacteria (Gram + and Gram -) and Candida species. The ratio of tolerance level indicated that the tested oil was bactericidal against the Gram + bacteria and Candida species, whereas it has a bacteriostatic behavior against the Gram- bacteria. In light of these findings, T. articulata EO may be suggested as a potential pharmaceutical agent to prevent inflammation and skin problems and may serve as a natural antimicrobial and antioxidant alternative for sustainable application in food products.

Phenotypic, molecular, and symbiotic characterization of the rhizobial symbionts isolated from Acacia saligna grown in different regions in Morocco: a multivariate approach

The introduced species Acacia saligna is a very promiscuous host as it can be efficiently nodulated with a wide range diversity of rhizobia taxa, including both fast and slow-growing strains. Fourteen nitrogen (N)-fixing bacteria were isolated from root nodules of wild Acacia saligna growing in distinct geographic locations in Morocco and were examined for their symbiotic efficiency and phenotypic properties. Multivariate tools, such as principal component analysis (PCA) and hierarchical clustering analysis (HCA), were used to study the correlation between phenotypic and symbiotic variables and discriminate and describe the similarities between different isolated bacteria with respect to all the phenotypic and symbiotic variables. Phenotypic characterization showed a variable response to extreme temperature, salinity and soil pH. At the plant level, the nodulation, nitrogen fixation, and the shoot and root dry weights were considered. The obtained results show that some of the tested isolates exhibit remarkable tolerances to the studied abiotic stresses while showing significant N2 fixation, indicating their usefulness as effective candidates for the inoculation of acacia trees. The PCA also allowed showing the isolates groups that present a similarity with evaluated phenotypic and symbiotic parameters. The genotypic identification of N2-fixing bacteria, carried out by the 16S rDNA approach, showed a variable genetic diversity among the 14 identified isolates, and their belonging to three different genera, namely Agrobacterium, Phyllobacterium and Rhizobium.

Combination of Chemically-Characterized Essential Oils from Eucalyptus polybractea, Ormenis mixta, and Lavandula burnatii: Optimization of a New Complete Antibacterial Formulation Using Simplex-Centroid Mixture Design

This study aims to identify the volatile profile of three essential oils obtained from Eucalyptus polybractea cryptonifera (EPEO), Ormenis mixta (OMEO), and Lavandula burnatii briquet (LBEO) and to examine their combined antibacterial activity that affords the optimal inhibitory ability against S. aureus and E. coli using simplex-centroid mixture design and checkerboard assay. Essential oils (EOs) were isolated by hydrodistillation and characterized using gas chromatography-mass spectrometry (GC-MS) and gas chromatography coupled with flame-ionization detector (GC-FID). The antibacterial activity was performed using disc diffusion and microdilution assays. The chemical analysis revealed that 1,8-cineole (23.75%), p-cymene (22.47%), and α-pinene (11.20%) and p-menthane-1,8-diol (18.19%), α-pinene (10.81%), and D-germacrene (9.17%) were the main components detected in E. polybractea and O. mixta EOs, respectively. However, L. burnatii EO was mainly represented by linalool (24.40%) and linalyl acetate (18.68%). The EPEO, LBEO, and OMEO had a strong antibacterial effect on S. aureus with minimal inhibitory concentrations (MICs) values ranging from 0.25 to 0.5% (v/v). Furthermore, the combination of 1/2048 MICEPEO + 1/4 MICLBEO showed a synergistic antibacterial effect on S. aureus with a FIC index of 0.25, while the formulation of 1/4 MICEPEO + 1/4 MICOMEO demonstrated an antibacterial synergistic activity on E. coli with a FIC index of 0.5. Moreover, the simplex-centroid mixture design reported that the most effective combinations on E. coli and S. aureus correspond to 32%/28%/40% and 35%/30%/35% of E. polybractea, O. mixta, and L. burnatii, respectively. Presented information highlights the action of antibacterial formulations of these EOs and suggests their potential applications as alternatives to commercialized drugs to contract the development of bacteria causing serious infections and food deterioration.

Antioxidant, Volatile Compounds; Antimicrobial, Anti-Inflammatory, and Dermatoprotective Properties of Cedrus atlantica (Endl.) Manetti Ex Carriere Essential Oil: In Vitro and In Silico Investigations

Cedrus atlantica (Endl.) Manetti ex Carriere is an endemic tree possessing valuable health benefits which has been widely used since time immemorial in international traditional pharmacopoeia. The aim of this exploratory investigation is to determine the volatile compounds of C. atlantica essential oils (CAEOs) and to examine their in vitro antimicrobial, antioxidant, anti-inflammatory, and dermatoprotective properties. In silico simulations, including molecular docking and pharmacokinetics absorption, distribution, metabolism, excretion, and toxicity (ADMET), and drug-likeness prediction were used to reveal the processes underlying in vitro biological properties. Gas chromatography-mass spectrophotometry (GC-MS) was used for the chemical screening of CAEO. The antioxidant activity of CAEO was investigated using four in vitro complementary techniques, including ABTS and DPPH radicals scavenging activity, ferric reductive power, and inhibition of lipid peroxidation (β-carotene test). Lipoxygenase (5-LOX) inhibition and tyrosinase inhibitory assays were used for testing the anti-inflammatory and dermatoprotective properties. GC-MS analysis indicated that the main components of CAEO are β-himachalene (28.99%), α-himachalene (14.43%), and longifolene (12.2%). An in vitro antimicrobial activity of CAEO was examined against eleven strains of Gram-positive bacteria (three strains), Gram-negative bacteria (four strains), and fungi (four strains). The results demonstrated high antibacterial and antifungal activity against ten of them (>15 mm zone of inhibition) using the disc-diffusion assay. The microdilution test showed that the lowest values of MIC and MBC were recorded with the Gram-positive bacteria in particular, which ranged from 0.0625 to 0.25 % v/v for MIC and from 0.5 to 0.125 % v/v for MBC. The MIC and MFC of the fungal strains ranged from 0.5 to 4.0% (MIC) and 0.5 to 8.0% v/v (MFC). According to the MBC/MIC and MFC/MIC ratios, CAEO has bactericidal and fungicidal activity. The results of the in vitro antioxidant assays revealed that CAEO possesses remarkable antioxidant activity. The inhibitory effects on 5-LOX and tyrosinase enzymes was also significant (p < 0.05). ADMET investigation suggests that the main compounds of CAEO possess favorable pharmacokinetic properties. These findings provide scientific validation of the traditional uses of this plant and suggest its potential application as natural drugs.

Phytochemical analysis and evaluation of antimicrobial, antioxidant, and antidiabetic activities of essential oils from Moroccan medicinal plants: Mentha suaveolens, Lavandula stoechas, and Ammi visnaga

Mentha suaveolens, Lavandula stoechas, and Ammi visnaga are widely used in Moroccan folk medicine against several pathological disorders, including diabetes and infectious diseases. This work was designed to determine the chemical profile of M. suaveolens (MSEO), L. stoechas (LSEO), and A. visnaga (AVEO) essential oils and assess their antimicrobial, antioxidant, and antidiabetic effects. The volatile components of LSEO, AVEO, and MSEO were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The in vitro antidiabetic activity was assessed using α-amylase and α-glucosidase enzymes, while DPPH, FRAP, and β-carotene/linoleic acid methods were used to determine the antioxidant capacity. The antimicrobial activities were investigated using disc diffusion and broth-microdilution assays. GC-MS investigation revealed that the main components were fenchone (29.77 %) and camphor (24.9 %) for LSEO, and linalool (38.29 %) for AVEO, while MSEO was mainly represented by piperitenone oxide (74.55 %). The results of the antimicrobial evaluation showed that all examined essential oils (EOs) had noticeable antimicrobial activity against both bacteria and yeast, especially Micrococcus luteus and Bacillus subtilis. The MIC, MBC, and MFC values were ranged from 0.015 % to 0.5 %. The MBC/MIC and MFC/MIC ratios were less than or equal to 4.0 % (v/v), indicating their noticeable bactericidal and candidacidal efficacy. Moreover, the three EOs showed significant inhibitory effects on α-amylase and α-glucosidase (p < 0.05). It also exerted remarkable activity on FRAP, β-carotene, and DPPH radicals. These findings demonstrated that the tested plants have promising biological activities, validating their ethnomedicinal value and providing potential applications as natural drugs.

Simplex-centroid design as innovative approach in the optimization of antimicrobial effect of Thymus satureioides, Myrtus communis and Artemisia herba alba essential oils against Escherichia coli, Staphylococcus aureus and Candidatropicalis

Essential Oils (EOs) known since Antiquity, and initially obtained by maceration of aromatic plants, are used as diseases' remedies because they contain valuable therapeutic components. Antimicrobial effect's evaluation of formulations established by an augmented centered mixing plan for three Moroccan medicinal and aromatic plants' essential oils (EOs): Thymus satureioides (T. satureioides), Myrtus communis (M. communis) and Artemisia herba alba (A. herba alba) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida tropicalis (C. tropicalis). The identification of E.Os chemical compounds was made using Gaz chromatography (GC) and Gaz chromatography coupled to Mass spectrometry (GC/MS).Whereas, the optimization of their antimicrobial effect was performed by experimental design methodology (mixture design) coupled to microdilution method based on Minimal Inhibitory Concentrations (MICs) determination. Results showed that the main components are borneol (34.26%) and α-pinene (31.21%); borneol (27.15%) and 1,8-cineole (21.33%); camphor (14.67%), chrysanthenone (14.10%), and β-thujone (12.60%) for T. satureioides, M. communis and A. herba alba respectively. Optimal mixtures composed of 60% and 40% of T. satureioides and M. communis E.Os; 72% and 28% of T. satureioides and A. Herba alba E.Os; 75% of thyme E.O and 25% of mugwort E.O; predicted the highest antimicrobial effect against E. coli, S. aureus and C. tropicalis, respectively. This study highlights the antimicrobial effect of EOs tertiary mixtures through using mixture design methodology, which may contribute to a successful application in pharmaceutical, food, or cosmetic industries.

Ethnobotany, phytochemistry and pharmacological activities of Celtis australis: A review

Celtis australis is a deciduous plant used worldwide in folk medicine to treat various ailments, such as stomach disorders, cough, pimples, joint pain, amenorrhoea, rheumatism, menstrual disorders, and herpes. The present review aims to document and summarize different works regarding the ethnomedicinal uses, phytochemistry, and biological activities of different parts (fruits, barks, leaves, and seeds) of this medicinal plant. For data collection, Google scholar, Science direct, Scopus, PubChem, and PubMed databases were used. This study shows that C. australis contains several bioactive compounds, exhibiting various pharmacological activities mainly hepatoprotective, analgesic, anti-inflammatory, cytotoxic, antioxidant, and antimicrobial properties. Thus, C. australis is a promising plant that can be exploited in the treatment of various diseases.

Incidence of surgical site infections and prediction of risk factors in a hospital center in Morocco

INTRODUCTION

Surgical site infections (SSIs) remain the major cause of morbidity and mortality in the postoperative period and are important surgical and hospital quality indicators. In this context, our study aims to identify SSIs associated risk factors and to develop a predictive model.

METHODOLOGY

2521 patients who underwent surgery, between June 2018 and May 2019, in four surgery departments, at the Taza Provincial Hospital (Morocco) were diagnosed for SSI according to the standards of the Center for Disease Control and Prevention. The SSIs' risk factors were assessed by univariate statistical analysis and logistic regression using the Scikit Learn function of Python.

RESULTS

The average age of the studied population was 35 ± 1 years. The overall SSI incidence was 6.3% (17.95%, 6.86%, 6.67% and 3.16% respectively in child, female, male and gynaecological-obstetrical surgeries. The univariate statistical analysis has shown a highly significant (p < 0.001) and a very significant (p < 0.01) relationship between SSIs and almost all risk factors; and the logistic regression model has revealed a strong association between SSI and people who have had previous surgery, urinary catheter, antibiotic use duration, co-morbidity, American Society of Anesthesiologists (ASA) score, duration of intervention, emergency preoperative and postoperative durations, service, specialty and age range. The prediction score exceeds 96% which justifies our model's quality.

CONCLUSIONS

SSIs are generally frequent among postoperative patients. Therefore, pre-operative preparation, post-operative surveillance and the environment quality of the wards are necessary to reduce SSI rates in the hospital.

Ruta montana (L.) L.: An insight into its medicinal value, phytochemistry, biological properties, and toxicity

Ruta montana (RM) is a medicinal and aromatic plant (MAP) used in folk medicine, especially in North Africa, to treat digestive, infectious, respiratory, neurological, gynecological, and diabetic diseases. The current work aims to review the scientifically validated ethno-medicinal usage, bioactivities and phytochemistry of RM, in order to provide data support for further investigations. Data were procured from PubMed, Scopus, Google Scholar, Web of Science, ScienceDirect, and PubChem. The present study revealed that RM could be used to manage many diseases involved in public health problems, such as diabetes, hypertension, neurological disorders, infections, reproductive system disorders, and cancer. It might also replace chemical insecticides and fungicides since it exhibits antifungal, insecticidal, and larvicidal properties. RM extracts also contain mainly coumarins and alkaloids. The volatile oil of RM is characterized by an abundance of ketone compounds and 2-undecanone as major constituents. In the case of a high-dose administration, RM infusion can cause poisoning through the oral path. Thus, in-depth in vivo pharmacological studies and clinical trials are needed to transmute the traditional applications of RM into scientific-based information.

The Relationship between Nasal Carriage of Staphylococcus aureus and Surgical Site Infections in a Hospital Center in Morocco

BACKGROUND

Surgical site infection is a major public health problem in the world. Nasal carriage is a major risk factor for the development of nosocomial Staphylococcus aureus infection, especially methicillin-resistant Staphylococcus aureus (MRSA). Our work aims to determine the prevalence of Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and the associated risk factors and to evaluate their sensitivity to 27 antibiotics.

METHODS

A cross-sectional study was carried out on 100 patients, hospitalized in preoperative care of surgery units at the Taza Provincial Hospital Center in the Fez-Meknes region, from January to June 2019. Samples were taken from the patient's anterior nostril using single-use sterile dry or wet cotton swabs and then analyzed in the Provincial Public Health Laboratory in Taza. The carriage of Staphylococcus aureus was studied by conventional bacteriological methods by spreading nasal swabs on Chapman culture medium, while antibiotic resistance was determined by the Mueller-Hinton agar disc diffusion method according to the recommendations described by the Antibiogram Committee of the French Society of Microbiology 2019 (CA SFM 2019).

RESULTS

Of the 84 patients found to be positive, 45.24% had coagulase-positive Staphylococcus aureus and 54.76% had coagulase-negative Staphylococcus. After surgery in the postoperative phase, 16 patients developed surgical site infections, of which two had a negative nasal culture and 14 had positive nasal culture. Among the Staphylococcus aureus-positive patients, 36.84% were colonized by a methicillin-resistant Staphylococcus aureus (MRSA) and 63.16% by a methicillin-sensitive Staphylococcus aureus (MSSA). Of these, 57.14% of MRSA colonized patients developed an infection of the surgical site and 42.85% showed no sign of SSI, while for patients colonized by MSSA, 16.67% developed SSI and 83.33% showed no sign of SSI. Moreover, children were the most affected by MRSA. Concerning antibiotic sensitivity, multiresistance of MRSA to more than 3 antibiotics has been found.

CONCLUSION

To the best of our knowledge, this is the first study carried out in this hospital center with the aim of knowing the prevalence of nasal carriage of Staphylococcus aureus and MRSA and to identify the risk factors in order to prevent infections related to nasal carriage of Staphylococcus aureus and MRSA.

Main Therapeutic Uses of Some Moroccan Hot Springs' Waters

Morocco has an important groundwater reserve, especially in the Atlas domain, corresponding to its largest water reservoir. This reserve comes from rainwater infiltrated into rocks and sediments to give rise to mineralized waters feeding many springs and having curative properties, which confer each spa-specific therapeutic indications, based on the medicinal properties of its waters. All over the world, mineral waters of thermal springs have interesting therapeutic uses to cure some diseases; unfortunately, such potential is underexploited in Morocco. This narrative review deals with the distribution of thermal springs in Morocco, the classification of their thermal waters, and their health effects, with the aim to enhance them. For this purpose, previous studies' results on different aspects of thermal waters were searched in the most famous scientific databases, by using targeted specific keywords. Literature has shown that Morocco contains several thermal springs, scattered throughout the Middle Atlas, in the South, and in the Rif, which are regarded as waters of high therapeutic quality, whose thermal cures are often recommended to people suffering from rheumatism and locomotor system's diseases, skin diseases such as eczema and psoriasis, cardiovascular diseases, overweight, or respiratory troubles. However, apart from the unique and real thermal station of Moulay Yacoub, the other thermal springs are exploited in an empirical and artisanal way, mainly by a local population. So, as hydrotherapy constitutes a good choice of natural therapy using water components as a complement or alternative to conventional treatments, a better understanding of the thermal springs' distribution in Morocco, their thermal waters' classification, and their potential health effects may enable their valorization through a better use of their waters.

Environmental Impact Assessment of Taza City's Wastewater: Application through Principal Component Analysis

Taza City is among the Moroccan cities which is in full urban expansion, with a daily wastewater discharge volume estimated at 16534 m³/d in 2020, and expected to reach 20056 m³/d by 2030. These waters, collected in a combined sewerage network, are directly released into the natural environment without any treatment. Indeed, a large part of this water is discharged into Oued Defali, the main tributary of Oued Larbâa. In order to manage and better understand these discharges impact on the streams crossing this city, wastewater sampling campaigns were carried out for one year from May 2018 to April 2019 at domestic (S1) and industrial (S2) sites. The wastewater physicochemical characterization revealed that these discharges are highly loaded with organic matter in terms of chemical oxygen demand (S1 avg = 1231.44 mg/l and S2 avg = 933.03 mg/l), biochemical oxygen demand (S1 avg = 511.87 mg/l and S2 avg = 464.35 mg/l), and suspended matter (S1 avg = 744.11 mg/l and S2 avg = 578.13 mg/l). The use of principal component analysis (PCA) has allowed us to collect as much information as possible from the database of the physicochemical analyses performed for the studied parameters.

Screening and optimization of indole-3-acetic acid production and phosphate solubilization by rhizobacterial strains isolated from Acacia cyanophylla root nodules and their effects on its plant growth

Background

Plant growth-promoting rhizobacteria (PGPR) are known to improve plant growth and are used as biofertilizers, thanks to their numerous benefits to agriculture such as phosphorus solubilization and phytohormone production. In this paper, four rhizospheric bacteria (Phyllobacterium sp., Bacillus sp., Agrobacterium sp., and Rhizobium sp.) isolated from surface-sterilized root nodules of Acacia cyanophylla were tested for their ability to solubilize inorganic phosphate and to produce indole-3-acetic acid (IAA) under laboratory conditions. Then, the best IAA producer (Rhizobium sp.) was selected to test optimized conditions for IAA production. Finally, the effect of the four strains on plant growth for A. cyanophylla was evaluated in vivo.

Results

The results showed that the totality of the tested isolates had solubilized inorganic phosphate (P) in both NBRIP (National Botanical Research Institute Phosphate) and PVK (Pikovskaya) media. Bacillus sp. was a high P-solubilizer and showed maximum solubilization in PVK (519 μg ml^-1) and NBRIP (782 μg ml^-1). The optimization of maximum phosphate solubilization was done using different sources of carbon (1%) and nitrogen (0.1%). Glucose and ammonium sulfate were selected to be the best carbon and nitrogen source for phosphate solubilization by all tested strains, except for Phyllobacterium sp., which recorded the highest phosphate solubilization with ammonium nitrate. The IAA production by the tested strains indicated that Rhizobium sp. produced the highest amount of IAA (90.21 μg ml^-1) in culture media supplemented with L-tryptophan. The best production was observed with L-Trp concentration of 0.2% (116.42 μg ml^-1) and at an initial pH of 9 (116.07 μg ml^-1). The effect of NaCl on IAA production was tested at concentrations of 0 to 5% and the maximum production of  89.43 μg ml^-1 was found at 2% NaCl. The extraction of crude IAA from this strain was done and purity was confirmed with Thin Layer Chromatography (TLC) analysis. A specific spot from the extracted IAA production was found to correspond with a standard spot of IAA with the same Rf value. Finally, the tested PGPR demonstrated growth stimulatory effects on Acacia cyanophylla seedlings in vivo, with a great increase of shoots’ and roots’ dry weights, and shoot length compared to control.

The rhizobacterial isolates were identified by 16S rDNA sequence analysis as Agrobacterium sp. NA11001, Phyllobacterium sp. C65, Bacillus sp. CS14, and Rhizobium sp. V3E1.

Conclusion

This study highlights the importance of the use of phosphate solubilizing and IAA producer microorganisms as biofertilizers to increase crop yields. The studied strains showed a significant phosphate solubilization potential and IAA production. The use of selected strains as inoculants would be interesting, in particular with a view of promoting sustainable agriculture. However, further studies to verify the efficacy of the best isolates in situ is certainly required.

Screening and optimization of indole-3-acetic acid production by Rhizobium sp. strain using response surface methodology

BACKGROUND

The production of indole-3-acetic acid (IAA) is an essential tool for rhizobacteria to stimulate and facilitate plant growth. For this, eighty rhizobial bacteria isolated from root nodules of Acacia cyanophylla grown in different regions of Morocco were firstly screened for their ability to produce IAA. Then, IAA production by a combination of isolates and the inoculation effect on the germination of Acacia cyanophylla seeds was studied using the best performing isolates in terms of IAA production. The best IAA producer bacterial isolate (I69) was selected to optimize IAA production using response surface methodology based on the central composite design.

RESULTS

Results showed that the majority of tested isolates were able to produce IAA with a relatively higher concentration of 135 μg/ml for the isolate I69, followed by isolates I22 and I75 with respective concentrations of 116 μg/ml and 105 μg/ml IAA. The IAA production and the seed germination rate were relatively increased by the synergistic effect of I69 and I22. Later, response surface methodology was used to determine optimal operating conditions leading to IAA production optimization. Thus, an incubation temperature of 36 °C, a pH of 6.5, an incubation time of 1 day, and respective tryptophan and NaCl concentrations of 1 g/l and 0.1 g/l were optimal parameters leading to 166 μg/ml IAA which was the maximal produced concentration.

CONCLUSION

The present study highlighted that IAA-producing rhizobacteria could be harnessed to improve plant growth. Furthermore, their production can be easily controlled using response surface methodology, which represents a very useful tool for optimization.

Characterization, antioxidant, antimycobacterial, antimicrobial effcts of Moroccan rosemary essential oil, and its synergistic antimicrobial potential with carvacrol

Thanks to their promising properties, essential oils (EOs) have strong potential to remedy several problems such as microorganisms acquired resistance to antimicrobial agents and chemical antioxidants toxicity. Firstly, this work was conducted to determine chemical composition, antioxydant activity, then antibacterial, antifungal, antimycobacterial properties of Rosmarinus officinalis EO. Secondly, EOs combined antimicrobial effect with carvacrol was assessed. Chemical EO analysis was performed using Gas chromatography/mass spectrometer. 1,1-diphenyl-2-picrylhydrazyl test was used to evaluate in vitro antioxidant rosemary oil effect. The antimicrobial activity against seven bacteria, two fungi, and two mycobacterial strains was screened using the broth microdilution method. Thereafter, the checkerboard essay was used to evaluate the antibacterial effect of this EO and Carvacrol. Chemical EO analysis revealed 1,8-cineole (33.88%), camphor (14.66%), and α-pinene (12.76%) as main constituents. The obtained IC50 value (2.77 mg/mL) showed rosemary EO's radical scavenging power. Moreover, all tested microorganisms showed an important sensitivity to this EO (MIC values: 0.007%–1% (v/v)). Furthermore, results highlighted synergistic and partial synergistic interaction for tested products. The studied EO has both antimicrobial and antioxidant potentials. Combined application showed a remarkable synergistic antibacterial potentiation that can be used as an alternative in pharmaceutical and food processing sectors.

Combined treatment of Thymus vulgaris L., Rosmarinus officinalis L. and Myrtus communis L. essential oils against Salmonella typhimurium: Optimization of antibacterial activity by mixture design methodology

To increase the sensibility of Salmonella typhimurium strain, a mixture of Thymus vulgaris L. (T. vulgaris L.), Rosmarinus officinalis L. (R. officinalis L.) and Myrtus communis L. (M. communis L.) essential oils (EOs) was used in combined treatment by experimental design methodology (mixture design). The chemical composition of EOs was firstly identified by GC and GC/MS and their antibacterial activity was evaluated. The results of this first step have shown that thymol and borneol were the major compounds in T. vulgaris and M. communis L. EOs, respectively, while 1,8-cineole and α-pinene were found as major compounds in R. officinalis L. The same results have shown a strong antibacterial activity of T. vulgaris L. EO followed by an important power of M. communis L. EO against a moderate activity of R. officinalis L. EO. Besides, 1/20 (v/v) was the concentration giving a strain response classified as sensitive. From this concentration, the mixture design was performed and analyzed. The optimization of mixtures antibacterial activities has highlighted the synergistic effect between T. vulgaris L. and M. communis L. essential oils. A formulation comprising 55% of T. vulgaris L. and 45% of M. communis L. essential oils, respectively, can be considered for the increase of Salmonella typhimurium sensibility.