Ayoub Kasrati

Essential oil composition and antimicrobial activity of wild and cultivated mint timija (Mentha suaveolens subsp. timija (Briq.) Harley), an endemic and threatened medicinal species in Morocco

The hydro-distilled essential oils obtained from aerial parts of the wild (w) and cultivated (c) mint timija (Mentha suaveolens subsp. timija), an endemic medicinal species of Morocco, have been analyzed by GC–MS and screened for antimicrobial activity. In total, 35 compounds representing more than 98% of the oils were identified. Menthone (39.4(w)–10.8(c)%), pulegone (62.3(c)–34.3(w)%) and isomenthone (9.3(c)–7.8(w)%) were found as the main components for the two oils. The volatiles of the wild and cultivated material differed significantly in both the percentage of the main components and antimicrobial effect. Pulegone was more dominant in cultivated mint timija (62.3%) than in wild one (34.3%), while menthone was more abundant in the wild material (39.4%). In the antimicrobial assays, both oils displayed good to excellent activity against all microorganisms tested with the oil of the cultivated form being more active.

Chemical characterization and insecticidal properties of essential oils from different wild populations of Mentha suaveolens subsp. timija (BRIQ.) HARLEY from Morocco

The present study is the first investigation of the volatile‐oil variability and insecticidal properties of the endemic Moroccan mint Mentha suaveolens subsp. timija (mint timija). The yield of essential oils (EOs) obtained from different wild mint timija populations ranged from 0.20±0.02 to 1.17±0.25% (v/w). GC/MS Analysis revealed the presence of 44 oil constituents, comprising 97.3–99.9% of the total oil compositions. The main constituents were found to be menthone (1.2–62.6%), pulegone (0.8–26.6%), cis‐piperitone epoxide (2.9–25.5%), piperitone (0.3–35.5%), trans‐piperitone epoxide (8.1–15.7%), piperitenone (0.2–9.6%), piperitenone oxide (0.5–28.6%), (E)‐caryophyllene (1.5–11.0%), germacrene D (1.0–15.7%), isomenthone (0.3–7.7%), and borneol (0.2–7.3%). Hierarchical‐cluster analysis allowed the classification of the EOs of the different mint timija populations into four main groups according to the contents of their major components. This variability within the species showed to be linked to the altitude variation of the mint timija growing sites. The results of the insecticidal tests showed that all samples exhibited interesting activity against adults of Tribolium castaneum, but with different degrees. The highest toxicity was observed for the EOs belonging to Group IV, which were rich in menthone and pulegone, with LC50 and LC90 values of 19.0–23.4 and 54.9–58.0 μl/l air in the fumigation assay and LC50 and LC90 values of 0.17–0.18 and 0.40–0.52 μl/cm2 in the contact assay.

Insecticidal properties and chemical composition of essential oils of some aromatic herbs from Morocco

The essential oils (EOs) of Artemisia herba alba, Rutachalepensis and Satureja calamintha aerial parts were analysed by GC/MS and the EOs were tested for their toxicity against two flour beetles, Tribolium castaneum and Tribolium confusum. EO composition showed that the major compounds were pulegone, menthone and menthol for S. calamintha, camphor and β-thujone for A. herba alba and 2-undecanone for R. chalepensis. Contact bioassay showed that all EOs were toxic to adults of T. castaneum and T. confusum. Higher toxicity was found with the EOs from S. calamintha and R. chalepensis (LD50 of 0.09–0.13 μL/cm2 and LD90 of 0.17–0.29 μL/cm2). In fumigant toxicity test, A. herba alba and S. calamintha EOs produced insecticidal activity with S. calamintha EO being more toxic with LD50 and LD90 values of 10.5 and 19.1 μL/L air, respectively, for T. confusum against 7.8 and 17.4 μL/L air, respectively, for T. castaneum.

Acaricidal properties of essential oils from Moroccan plants against immature ticks of Hyalomma aegyptium (Linnaeus, 1758); an external parasite of the spur-thighed tortoise (Testudo graeca)

ABSTRACT Hyalomma aegyptium (Linnaeus, 1758) is a hard-tick species of the Ixodidae family with the main adult hosts being Palearctic tortoises of the genus Testudo. In Morocco, it is commonly found infecting Testudo graeca that has a wide geographic distribution and is subject to protection through international illegal trade legislation. This tortoise tick has been reported as an important vector of various human and animal pathogens. Unfortunately, to date, there are no strategies to control this hematophagous ectoparasite. The present study was conducted in laboratory to evaluate the acaricidal activity of essential oils (EOs) extracted from six plants of Moroccan origin as an alternative against H. aegyptium. All EOs tested displayed toxic effects on different life stages of H. aegyptium. Mentha suaveolens subsp. timija (LC50 = 0.910 µL/mL and LC90 = 1.465 µL/mL) and Satureja calamintha EOs (LC50 = 0.927 µL/mL and LC90 = 1.347 µL/mL) exhibited higher activity against hatching eggs, whereas Chenopodium ambrosioides EO was comparatively more toxic to larvae (LC50 = 0.444 µL/mL and LC90 = 0.918 µL/mL). Juniperus thurifera var. africana (LC50 = 0.0045 mL/cm2 and LC90 = 0.0118 mL/cm2) and Lavandula pedunculata subsp. atlantica EOs (LC50 = 0.0036 mL/cm2 and LC90 = 0.0110 mL/cm2) caused high mortality in nymphs. The effect of different EOs is discussed according to their chemical composition and bioactive components.

Synergistic effects of three Moroccan thyme essential oils with antibiotic cefixime

The association of essential oils (EOs) with antibiotics provides a promising solution towards combating resistant bacteria. Thus, the aim of this study was to examine for the first time the possible synergistic interaction between EOs of three Moroccan thymes, namely Thymus leptobotrys (carvacrol [79.1%]), Thymus pallidus (γ-terpinene [29.6%], thymol [26.8%] and p-cymene [18.9%]) and Thymus ciliatus (carvacrol [26.2%], p-cymene [19.6%], thymol [17.3%] and γ-terpinene [14.6%]) and the antibiotic cefixime against selected pathogenic bacteria. The results showed that all thyme EOs presented interesting antibacterial potency and important synergistic effects with cefixime. Thymus leptobotrys EO showed the strongest efficacy against all tested bacteria (minimum inhibitory concentration values 0.14 mg/mL to 73.92 mg/mL), and the best synergistic effect (fractional inhibitor concentration indices: 0.26 to 0.5; gain: 4- to 130-fold). This synergistic interaction between the studied thyme EOs and cefixime may provide a basis for future applications for the control of antibiotic-resistant bacteria.RésuméLa combinaison des huiles essentielles (HEs) avec les antibiotiques constitue une solution prometteuse pour surmonter les problèmes de l’émergence de la résistance des bactéries aux antibiotiques. Ainsi, ce travail a pour objectif principal d’évaluer pour la première fois la synergie entre les HEs de trois espèces de thyms marocaines, à savoir Thymus leptobotrys (carvacrol [79,1 %]), Thymus pallidus (γ-terpinène [29,6 %], thymol [26,8 %], p-cymène [18,9 %]) et Thymus ciliatus (carvacrol [26,2 %], p-cymène [19,6 %], thymol [17,3 %], γ-terpinène [14,6 %]) et l’antibiotique céfixime sur quelques bactéries pathogènes. Les résultats obtenus ont montré que toutes les HEs de thyms étudiées ont présenté un pouvoir antibactérien très intéressant, ainsi qu’un effet synergique important en combinaison avec l’antibiotique céfixime. L’HE extraite de Thymus leptobotrys a montré l’activité inhibitrice la plus forte sur toutes les souches testées (CMI: 0,14 à 73,92 mg/ml). Cette HE combinée avec la céfixime a montré aussi l’effet synergique le plus important (indices de concentration inhibitrice fractionnaire (FICIs): 0,26 et 0,5; gain: 4 à 130 fois). Ces interactions synergiques entre les HEs de thyms étudiées et la céfixime peuvent présenter une plateforme pour le développement de nouvelles applications dans le contrôle de la résistance des bactéries aux antibiotiques.

Chemical Characterization and Biological Activities of Essential Oil Obtained from Mint Timija Cultivated under Mineral and Biological Fertilizers

Cultivation of mint timija (Mentha suaveolens subsp. timija (Briq.) Harley) constitutes a promising solution to the conservation and sustainable utilization of this Moroccan endemic and threatened species. Optimized agronomic practices require mineral and/or biological fertilizer applications. The aim of this study was to determine the effects of application of a complete (N, P, and K) mineral fertilizer and vesicular arbuscular mycorrhizae (VAM) inoculation on the composition, antioxidant, and insecticidal properties of mint timija essential oils (EOs). The GC-MS analyses identified 27 components representing more than 99.9% of the total oils. Menthone (40.7–49.3%), pulegone (31.3–36.5%), and isomenthone (2.5–4.4%) were found to be the main constituents. Cultivation of mint timija with mineral fertilizer and VAM inoculation induced an increase in menthone content and a parallel decrease of pulegone. Both treatments enhanced the antioxidant activity of the investigated EOs in all assays (IC50 ranged from 2.34 ± 0.03 mg/mL to 6.82 ± 0.25 mg/mL), while no significant difference in the toxicities of these oils against Tribolium confusum du Val. has been observed. Overall, we conclude that cultivation using complete mineral fertilizer and VAM inoculation could be useful in modulating the chemical composition and enhancing the antioxidant activity of the EO of this endemic Moroccan species.

Antibacterial activity of essential oils of some moroccan aromatic herbs against selected food-related bacteria

Abstract The present study evaluates the antibacterial activity of essential oils (EOs) of some widely used Moroccan aromatic herbs namely, Thymus satureioides, Achillea ageratum, Cotula cinerea, Salvia officinalis, and Salvia aucheri subsp. blancoana. The chemical composition was characterized by means of GC-MS and a total of 47 components were identified accounting for more than 96.5% of the total oils. A. ageratum oil was particularly rich in terpene alcohol which included artemisyl acetate (70.1%), yomogi alcohol (12.4%) and artemisia alcohol (7.1%). The T. satureioides EO was characterized by high contents of carvacrol (24.1%), borneol (18.1%), p-cymene (7.0%), camphene (6.8%) and γ-terpinene (6.5%). The C. cinerea EO contained trans-thujone (41.4%), cis-verbenyl acetate (24.7%) and santolina triene (7.2%) as major constituents. S. officinalis EO had a high content of trans-thujone (20.2%), 1,8-cineole (19.2%), camphor (14.7%), while the S. aucheri subsp. blancoana EO was characterized by camphor (34.7%), followed by camphene (19.9%) and α-pinene (18.7%) as main constituents. EOs were evaluated for antibacterial activity against seven bacteria of significant importance for food hygiene. According to the results, most EOs studied were effective against Gram-positive bacteria with MIC/MBC values of 1.71 mg/mL to 74.32 mg/mL. The greatest effectiveness was achieved with T. satureioides oil (MIC = 2.25-4.50 mg/mL), while the weakest potency was displayed by the A. ageratum EO (MIC = 4.64-74.32 mg/mL). Of the EOs tested, only those obtained from T. satureioides and C. cinerea were able to control the Gram-negative bacteria, with the exception of Pseudomonas aeroginosa.