Chemical Composition and Antimicrobial Activity of the Essential Oil of Ruta chalepensis L. Growing Wild in Lebanon

The essential oils (EOs) isolated from the fresh aerial parts of Ruta chalepensis L. collected in North Lebanon were obtained by solvent‐free microwave extraction (Milestone®), yielding 0.12% EO from both the leaves and a mixture of stems and leaves. The EOs were characterized by GC/MS analysis, and 27 components were identified, which were primarily ketones (88.0–93.2%). The main components were nonan‐2‐one and undecan‐2‐one. The antimicrobial activity of the EOs against a Gram‐positive and a Gram‐negative bacterium, a yeast, and a dermatophyte was evaluated using the broth‐microdilution technique and expressed as minimal inhibitory concentration (MIC). The EOs revealed moderate in vitro antifungal activity against Trichophyton rubrum and Candida albicans.     

Chemical Composition and Antimicrobial Activity of the Essential Oil of Juniperus excelsa M.Bieb. Growing Wild in Lebanon

The essential oils (EOs) isolated from the leaves and twigs of Juniperus excelsa M.Bieb . growing wild in Lebanon were characterized, and their antimicrobial activity and antiradical capacity were evaluated. The EOs were obtained by hydrodistillation using a Clevenger‐type apparatus and characterized by GC and GC/MS analyses. The antimicrobial activity was evaluated by determining minimal inhibitory concentrations (MICs) against a Gram‐positive and a Gram‐negative bacterium, a yeast, and a dermatophyte with the broth microdilution technique. A total of 28 constituents was identified and accounted for 90.1 and 95.6% of the twig and leaf EO composition, respectively. Both EOs were essentially composed of monoterpene hydrocarbons (46.7 and 59.6% for twig and leaf EOs, resp.) and sesquiterpenes (39.4 and 32.1%, resp.). The main components were α‐pinene, α‐cedrol, and δ‐car‐3‐ene. The J. excelsa EOs did not show any antiradical potential, but revealed interesting in vitro antimicrobial activities against Staphylococcus aureus and Trichophyton rubrum (MICs of 64 and 128 μg/ml, resp.). The three major compounds were tested separately and in combination according to their respective amounts in the oil. δ‐Car‐3‐ene was the most active component and is undoubtedly one of the constituents driving the antifungal activity of J. excelsa essential oil, even though synergies are probably involved.     

Composition and Antimicrobial Activity of the Essential Oils of Laserpitium latifolium L. and L. ochridanum Micevski (Apiaceae)

The chemical composition and antimicrobial activity of essential oils of Laserpitium latifolium and L. ochridanum were investigated. The essential oils were isolated by steam distillation and characterized by GC‐FID and GC/MS analyses. All essential oils were distinguished by high contents of monoterpenes, and α‐pinene was the most abundant compound in the essential oils of L. latifolium underground parts and fruits (contents of 44.4 and 44.0%, resp.). The fruit essential oil was also rich in sabinene (26.8%). Regarding the L. ochridanum essential oils, the main constituents were limonene in the fruit oil (57.7%) and sabinene in the herb oil (25.9%). The antimicrobial activity of these essential oils as well as that of L. ochridanum underground parts, whose composition was reported previously, was tested by the broth‐microdilution method against four Gram‐positive and three Gram‐negative bacteria and two Candida albicans strains. Except the L. latifolium underground‐parts essential oil, the other investigated oils showed a high antimicrobial potential against Staphylococcus aureus, S. epidermidis, Micrococcus luteus, or Candida albicans (minimal inhibitory concentrations of 13.0–73.0 μg/ml), comparable to or even higher than that of thymol, which was used as reference compound.     

Antifungal and Herbicidal Effects of Fruit Essential Oils of Four Myrtus communis Genotypes

The chemical composition of the essential oils isolated by hydrodistillation from the fruits of four selected Myrtus communis L. genotypes from Turkey was characterized by GC‐FID and GC/MS analyses. 1,8‐Cineole (29.20–31.40%), linalool (15.67–19.13%), α‐terpineol (8.40–18.43%), α‐pinene (6.04–20.71%), and geranyl acetate (3.98–7.54%) were found to be the major constituents of the fruit essential oils of all M. communis genotypes investigated. The oils were characterized by high amounts of oxygenated monoterpenes, representing 73.02–83.83% of the total oil compositions. The results of the fungal growth inhibition assays showed that the oils inhibited the growth of 19 phytopathogenic fungi. However, their antifungal activity was generally lower than that of the commercial pesticide benomyl. The herbicidal effects of the oils on the seed germination and seedling growth of Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense (L.) Scop ., Lactuca serriola L., and Rumex crispus L. were also determined. The oils completely or partly inhibited the seed germinations and seedling growths of the plants. The findings of the present study suggest that the M. communis essential oils might have potential to be used as natural herbicides as well as fungicides.     

Variation of the Chemical Composition and Antimicrobial Activity of the Essential Oils of Natural Populations of Tunisian Daucus carota L. (Apiaceae)

The essential oils of Daucus carota L. (Apiaceae) seeds sampled from ten wild populations spread over northern Tunisia were characterized by GC‐FID and GC/MS analyses. In total, 36 compounds were identified in the D. carota seed essential oils, with a predominance of sesquiterpene hydrocarbons in most samples (22.63–89.93% of the total oil composition). The main volatile compounds identified were β‐bisabolene (mean content of 39.33%), sabinene (8.53%), geranyl acetate (7.12%), and elemicin (6.26%). The volatile composition varied significantly across the populations, even for oils of populations harvested in similar areas. The chemometric principal component analysis and the hierarchical clustering identified four groups, each corresponding to a composition‐specific chemotype. The in vitro antimicrobial activity of the isolated essential oils was preliminarily evaluated, using the disk‐diffusion method, against one Gram‐positive (Staphylococcus aureus) and two Gram‐negative bacteria (Escherichia coli and Salmonella typhimurium), as well as against a pathogenic yeast (Candida albicans). All tested essential oils exhibited interesting antibacterial and antifungal activities against the assayed microorganisms.     

Myrtus communis berry color morphs: a comparative analysis of essential oils, fatty acids, phenolic compounds, and antioxidant activities

Extracts of mature dark blue and white berries from two Tunisian Myrtus communis morphs growing at the same site were assessed for their essential‐oil and fatty‐acid compositions, phenolic contents, and antioxidant activities. The GC and GC/MS analyses of the essential oils allowed the identification of 33 constituents. The oils from the dark blue fruits showed high percentages of α‐pinene (11.1%), linalool (11.6%), α‐terpineol (15.7%), methyl eugenol (6.2%), and geraniol (3.7%). Myrtenyl acetate (20.3%) was found to be the major compound in the oils from white berries. GC Analysis of the pericarp and seed fatty acids showed that the polyunsaturated fatty acids constituted the major fraction (54.3–78.1%). The highest percentages of linoleic acid (78.0%) and oleic acid (20.0%) were observed in the seeds and the pericarps of the white fruits, respectively. The total phenol, flavonoid, and flavonol contents and the concentration of the eight anthocyanins, identified by HPLC analysis, were significantly higher in the dark blue fruits. All extracts showed a substantial antioxidant activity, assessed by the free radical‐scavenging activity and the ferric reducing power, with the dark blue fruit extracts being more effective.     

Chemical Compositions,Antioxidant and Antimicrobial Activities of Essential Oils of Psidium guajava L. Leaves from Different Geographic Regions in China

Hydrodistilled essential oils (EO) of Psidium guajava L. leaves from different regions in China were analyzed by GC and GC/MS. The samples from Guangdong Province displayed high EO yields (0.61 – 0.75%, v/w). A total of 50 components, representing over 98.00% of the EOs, were identified and semi‐quantitatived. The major constituents of EOs included β‐caryophyllene (17.17 – 31.38%), γ‐gurjunene (9.17 – 15.22%), τ‐cadinol (1.35 – 10.02%) and calamenene (2.13 – 7.80%). The terpenoids in all sample oils were dominated by sesquiterpenes hydrocarbons (70.18 – 84.35%), followed by oxygenated sesquiterpenes (9.89 – 22.19%). The similarities and differences among EOs from different samples were evaluated by hierarchical cluster analysis and principal component analysis methods. The IC₅₀ values of EOs from different regions were between 18.52 – 33.72 mg/ml (DPPH) and 13.12 – 25.15 mg/ml (ABTS⁺). The FRAP value of EO from Guangdong Province was 7.34 – 9.13 mmol Vc/g DM, while the FRAP value of EO from Taiwan Province was 2.29 – 2.36 mmol Vc/g DM. The antimicrobial tests revealed that EO had a higher antimicrobial activity against all Gram‐positive bacteria and two fungi. Moreover, EO from P. guajava leaves of Guangdong Province showed the highest antimicrobial activity. These properties can be considered in the design of industrial products and for further application in the food, pharmaceutical and cosmetic industries.     

Dittrichia graveolens (L.) Greuter Essential Oil: Chemical Composition,Multivariate Analysis,and Antimicrobial Activity

The chemical composition and in vitro antimicrobial activities of Dittrichia graveolens (L.) Greuter essential oil was studied. Moreover, using agglomerative hierarchical cluster (AHC) and principal component analyses (PCA), the interrelationships of the D. graveolens essential‐oil profiles characterized so far (including the sample from this study) were investigated. To evaluate the chemical composition of the essential oil, GC‐FID and GC/MS analyses were performed. Altogether, 54 compounds were identified, accounting for 92.9% of the total oil composition. The D. graveolens oil belongs to the monoterpenoid chemotype, with monoterpenoids comprising 87.4% of the totally identified compounds. The major components were borneol (43.6%) and bornyl acetate (38.3%). Multivariate analysis showed that the compounds borneol and bornyl acetate exerted the greatest influence on the spatial differences in the composition of the reported oils. The antimicrobial activity against five bacterial and one fungal strain was determined using a disk‐diffusion assay. The studied essential oil was active only against Gram‐positive bacteria.     

The Genus Myrtus L. in Algeria: Composition and Biological Aspects of Essential Oils from M. communis and M. nivellei: A Review

The genus Myrtus L. (Myrtaceae family) comprises two species, Myrtus communis L. (known as common myrtle) growing wild all around the Mediterranean basin and Myrtus nivellei Batt . and Trab . (known as Saharan myrtle), found in central Sahara. Only one country, Algeria, hosts both species, M. communis in the North and M. nivellei in the South. The aim of this review was to collect, summarize, and compare the main results reported relative to the essential oils isolated from aerial parts of both species: botanical aspects, habitat, traditional use, chemical composition, new compounds, antimicrobial activity, antioxidant activity, anti‐inflammatory effect, and insecticidal activity. Both essential oils have potential applications in human health.     

Chemical Composition and Antipathogenic Activity of Artemisia annua Essential Oil from Romania

The essential oil extracted by hydrodistillation from Romanian Artemisia annua aerial parts was characterized by GC/MS analysis, which allowed the identification of 94.64% of the total oil composition. The main components were camphor (17.74%), α‐pinene (9.66%), germacrene D (7.55%), 1,8‐cineole (7.24%), trans‐β‐caryophyllene (7.02%), and artemisia ketone (6.26%). The antimicrobial activity of this essential oil was evaluated by determining the following parameters: minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), minimal fungicidal concentration (MFC), and minimal biofilm eradication concentration (MBEC). Moreover, the soluble virulence factors were quantified with different biochemical substrates incorporated in the culture media. The reference and resistant, clinical strains proved to be susceptible to the A. annua oil, with MICs ranging from 0.51 to 16.33 mg/ml. The tested essential oil also showed good antibiofilm activity, inhibiting both the initial stage of the microbial cell adhesion to the inert substratum and the preformed mature biofilm. When used at subinhibitory concentrations, the essential oil proved to inhibit the phenotypic expression of five soluble virulence factors (hemolysins, gelatinase, DNase, lipases, and lecithinases). Briefly, the present results showed that the A. annua essential oil contained antimicrobial compounds with selective activity on Gram‐positive and Gram‐negative bacterial strains as well as on yeast strains and which also interfere with the expression of cell‐associated and soluble virulence factors.     

Composition, and antimicrobial and remarkable antiprotozoal activities of the essential oil of rhizomes of Aframomum sceptrum K. Schum. (Zingiberaceae)

The essential oil from the rhizomes of Aframomum sceptrum (Zingiberaceae) was analyzed by GC/MS, and its major constituents were found to be β‐pinene (12.7%), caryophyllene oxide (10.0%), and cyperene (6.0%). The oil was also evaluated for antimicrobial activities, in comparison with β‐pinene, caryophyllene oxide, and the leaf essential oil of Melaleuca alternifolia (Myrtaceae). The A. sceptrum essential oil exhibited bacteriostatic activity against the Gram‐positive bacteria Bacillus subtilis, Staphylococcus epidermidis, and S. aureus, but not against Gram‐negative bacteria. Moreover, it showed mild fungicidal activity against Candida albicans and Aspergillus fumigates, and remarkable antiprotozoal activity against Trypanosoma brucei brucei (MLC of 1.51 μl/ml) and Trichomonas vaginalis (IC₅₀ of 0.12±0.02 and MLC of 1.72 μl/ml).     

Volatile‐Oils Composition,and Bioactivity of the Essential Oils of Plectranthus barbatus,P. neochilus,and P. ornatus Grown in Portugal

Volatile‐oils chemical composition and bioactivity of the essentail oils from Plectranthus barbatus, P. neochilus, and P. ornatus (Lamiaceae) were assessed. Aerial parts from these three related Plectranthus species were collected from cultivated plants grown in Portugal, during vegetative and flowering phases. Volatiles, isolated by distillation? extraction, were analyzed by GC and GC/MS. Monoterpene hydrocarbons (12–74%) and sesquiterpene hydrocarbons (4–45%) constituted the main fractions in all volatiles. α‐Pinene ( 3 ; 12–67%), oct‐1‐en‐3‐ol ( 6 ; traces–28%), β‐pinene ( 7 ; 0.1–22%), and β‐caryophyllene ( 50 ; 7–12%) dominated P. barbatus volatiles. P. neochilus major volatile components were α‐terpenyl acetate ( 41 ; traces–48%), α‐thujone ( 2 ; 2–28%), β‐caryophyllene ( 50 ; 2–28%), β‐pinene ( 7 ; 1–25%), and α‐pinene ( 3 ; 1–19%). Oct‐1‐en‐3‐ol ( 6 ; 13–31%), β‐pinene ( 7 ; 11–24%), α‐pinene ( 3 ; 11–19%), and β‐caryophyllene ( 50 ; traces–11%) were the main constituents from P. ornatus volatiles. These chemical compositions were rather different from those previously found for specimens harvested in Africa and Brazil. Moreover, the volatiles from the flowers are herewith reported for the first time. Essential oils, isolated by hydrodistillation from leaves and stems, showed a yellowish color and unpleasant odor, with yields ranging from 0.08% to 0.84% (v/dry weight). Antioxidant and antimicrobial activities of the essential oils were evaluated by DPPH^. and TBARS assays, and agar disc‐diffusion method, respectively. Results showed low or moderate antioxidant capacity and significant antimicrobial activity against Gram‐positive bacteria.     

Chemical Characteristics,Antimicrobial, and Cytotoxic Activities of the Essential Oil of Egyptian Cinnamomum glanduliferum Bark

The essential oil isolated from the bark of Cinnamomum glanduliferum (Wall ) Meissn grown in Egypt was screened for its composition as well as its biological activity for the first time. The chemical composition was analyzed by GC and GC/MS. The antimicrobial activity of the oil was assessed using agar‐well diffusion method toward representatives for each of Gram‐positive bacteria, Gram‐negative bacteria, and fungi. The cytotoxic activity was checked using three human cancer cell lines. Twenty seven compounds were identified, representing 99.07% of the total detected components. The major constituents were eucalyptol (65.87%), terpinen‐4‐ol (7.57%), α‐terpineol (7.39%). The essential oil possessed strong antimicrobial activities against Escherichia coli, with an activity index of one and minimum inhibitory concentration (MIC) equaling to 0.49 μg/ml. The essential oil possessed good antimicrobial activities against methicillin‐resistant Staphylococcus aureus, Geotrichum candidum, Pseudomonas aeruginosa, Bacillus subtilis, Helicobacter pylori, Aspergillus fumigatus (MIC: 7.81, 1.95, 7.81, 0.98, 31.25, and 32.5 μg/ml, respectively). A considerable activity was reported against S. aureus and Mycobacterium tuberculosis (MIC; 32.5 and 31.25 μg/ml, respectively). The extracted oil was cytotoxic to colon (HCT‐116), liver (HepG2), and breast (MCF‐7) carcinoma cell lines with IC₅₀ of 9.1, 42.4, and 57.3 μg/ml, respectively. These results revealed that Egyptian Cinnamomum glanduliferum bark oil exerts antimicrobial and cytotoxic activities mainly due to eucalyptol and other major compounds.     

Chemical Composition and Antimicrobial Activity of Essential Oils from Scabiosa arenaria Forssk. Growing Wild in Tunisia

The essential oils isolated from three organs, i.e., fruits, stems and leaves, and flowers, of the endemic North African plant Scabiosa arenaria Forssk . were screened for their chemical composition, as well as their possible antibacterial, anticandidal, and antifungal properties. According to the GC‐FID and GC/MS analyses, 61 (99.26% of the total oil composition), 79 (98.43%), and 51 compounds (99.9%) were identified in the three oils, respectively. While α‐thujone (34.39%), camphor (17.48%), and β‐thujone (15.29%) constituted the major compounds of the fruit oil, chrysanthenone (23.43%), together with camphor (12.98%) and α‐thujone (10.7%), were the main constituents of the stem and leaf oil. In the case of the flower oil, also chrysanthenone (38.52%), camphor (11.75%), and α‐thujone (9.5%) were identified as the major compounds. Furthermore, the isolated oils were tested against 16 Gram‐positive and Gram‐negative bacteria, four Candida species, and nine phytopathogenic fungal strains. It was found that the oils exhibited interesting antibacterial and anticandidal activities, comparable to those of thymol, which was used as positive control, but no activity against the phytopathogenic fungal strains was observed.     

Campanula portenschlagiana Roem. et Schult.: Chemical and Antimicrobial Activities

The phytochemical profile and the antimicrobial effects of the volatile oil and the aqueous extract of Campanula portenschlagiana, a wild growing plant endemic to Croatia, were described. In the volatile oil, 53 compounds were identified by GC‐FID and GC/MS analyses. Diterpene alcohols constituted the major compound class with labda‐13(16),14‐dien‐8‐ol as the main compound. The aqueous extract was characterized by the total phenolic content. The antimicrobial potential of the volatile oil and the aqueous extract was evaluated against a diverse range of microorganisms comprising food‐spoilage and food‐borne pathogens. The volatile oil exhibited interesting and promising antimicrobial effects against the tested species, which were generally more pronounced against Gram‐negative bacteria. In addition, the inhibitory effect of this volatile oil was also evaluated against eleven extended‐spectrum β‐lactamase (ESBL)‐producing isolates. The results suggest that the C. portenschlagiana volatile oil might be used as antimicrobial agent against ESBL‐producing isolates and Gram‐negative bacteria.     

Volatile Compounds in Fruits of Peucedanum cervaria (Lap.) L.

The volatile compounds from Peucedanum cervaria (Lap. ) L. were obtained by hydrodistillation (HD) and headspace solid‐phase microextraction techniques (HS‐SPME), and then analyzed by GC/MS methods. The composition of samples from a botanical garden was compared with plants collected in the wild. The main compounds of the essential oils of P. cervaria were identified as α‐pinene, sabinene, and β‐pinene (more than 80% of oil). The content of β‐myrcene, limonene+β‐phellandrene, and germacrene D was higher than 1%. The in vitro antibacterial activity of the essential oil was evaluated by the agar dilution method against ten reference strains of Gram‐positive and Gram‐negative bacteria.     

Anthelmintic Effects of the Essential Oil of Fennel (Foeniculum vulgare Mill., Apiaceae) against Schistosoma mansoni

Foeniculum vulgare Mill . (Apiaceae), known as fennel, is a widespread aromatic herbaceous plant, and its essential oil is used as additive in the food, pharmaceutical, cosmetic, and perfume industries. The in vitro antischistosomal activity and cytotoxic effects against V79 cells of the essential oil of F. vulgare cultivated in southeastern Brazil (FV‐EO) was investigated. The FV‐EO was obtained by hydrodistillation and characterized by GC‐FID and GC/MS analyses. (E)‐Anethole (69.8%) and limonene (22.5%) were identified as the major constituents. Its anthelmintic activity against Schistosoma mansoni was evaluated at concentrations of 10, 50, and 100 μg/ml, and it was found to be active against adult S. mansoni worms, although it was less effective than the positive control praziquantel (PZQ) in terms of separation of the coupled pairs, mortality, and decreased motor activity. However, FV‐EO elicited an interesting dose‐dependent reduction in the number of S. mansoni eggs. On their own, (E)‐anethole and the limonene enantiomers were much less effective than FV‐EO and PZQ. An XTT‐cytotoxicity‐based assay evidenced no FV‐EO cytotoxicity against V79 cells. In summary, FV‐EO displayed moderate in vitro schistosomicidal activity against adult S. mansoni worms, exerted remarkable inhibitory effects on the egg development, and was of low toxicity.     

Chemical Composition of Hydrodistilled Essential Oil of Artemisia incana (L.) Druce and Antimicrobial Activity against Foodborne Microorganisms

The oil obtained by hydrodistillation from the aerial parts of Artemisia incana (L.) Druce from Turkey was analyzed by GC and GC/MS. Sixty‐three compounds were characterized, representing 97.2% of the total components detected, and camphor (19.0%), borneol (18.9%), 1,8‐cineole (14.5%), bornyl acetate (7.8%), camphene (4.9%), and α‐thujone (4.8%) were identified as predominant components. The essential oil was also tested for its antimicrobial activity against 44 different foodborne microorganisms, including 26 bacteria, 15 fungi, and 3 yeast species. The essential oil of A. incana exhibited considerable inhibitory effects against all bacteria, fungi, and yeast species tested. However, the oil showed lower inhibitory activity against the tested bacteria than the reference antibiotics.     

Chemical Profiling of the Essential Oils of Syzygium aqueum,Syzygium samarangense and Eugenia uniflora and Their Discrimination Using Chemometric Analysis

The essential oil compositions of the leaves of three related Myrtaceae species, namely Syzygium aqueum, Syzygium samarangense and Eugenia uniflora, were investigated using GLC/MS and GLC/FID. Altogether, 125 compounds were identified: α‐Selinene (13.85%), β‐caryophyllene (12.72%) and β‐selinene constitute the most abundant constituents in S. aqueum. Germacrene D (21.62%) represents the major compound in S. samarangense whereas in E. uniflora, spathulenol (15.80%) represents the predominant component. Multivariate chemometric analyses were used to discriminate the essential oils using hierarchical cluster analysis (HCA) and principal component analysis (PCA) based on the chromatographic results. The antimicrobial activity of the popularly used E. uniflora essential oil was assessed using broth microdilution method against six Gram‐positive, three Gram‐negative bacteria and two fungi. The oil showed moderate antimicrobial activity against Bacillus licheniformis exhibiting MIC and MMC of 0.63 mg/ml. The cytotoxic activity of E. uniflora essential oil was investigated against Trypanosoma brucei brucei (T. b. brucei) and MCF‐7 cancer cell line using MTT assay. It showed moderate activity against MCF‐7 cells with an IC₅₀ value of 76.40 μg/ml. On the other hand, T. brucei was highly susceptible to E. uniflora essential oil with IC₅₀ of 11.20 μg/ml, and a selectivity index of 6.82.     

Chemical Diversity and Antimicrobial Activity of Salvia multicaulis Vahl Essential Oils

The chemical compositions and antimicrobial activities of the essential oils (EOs) of aerial parts of Salvia multicaulis Vahl , collected during the same week from two different Lebanese regions, were investigated. The EOs were obtained by hydrodistillation using a Clevenger‐type apparatus and characterized by GC and GC/MS analyses. The minimum inhibitory concentrations of these EOs were determined against one Gram‐negative and two Gram‐positive bacteria, one yeast, and five dermatophytes using the broth microdilution technique. One EO was notably active against Staphylococcus aureus, methicillin‐resistant S. aureus, and all of the Trichophyton species tested. Nerolidol was found to be the major compound in the active oil; nerolidol was also absent from the inactive oil. This study demonstrated that nerolidol shows antimicrobial activity and therefore significantly contributes to the antimicrobial potential of the oil. The chemical diversity of worldwide S. multicaulis EOs was analyzed, revealing that the EOs of this study belong to two different chemotypes found in the literature. The nerolidol chemotype appears to be restricted to Lebanon, and it can be used as antimicrobial agent against external bacterial and fungal infections.