Helichrysum italicum (Roth) G. Don essential oil: composition and potential anti-tumour, anti-inflammatory, antimicrobial, and antibiofilm effects

Chemical profile and eco-safety evaluation of essential oils and hydrolates from Cistus ladanifer, Helichrysum italicum, Ocimum basilicum and Thymbra capitata

The biofilm formation of bacteria in different parts of the human body can influence the success of antibiotic therapy. Essential oils (EOs) and their components are becoming increasingly popular in point of view of medicinal applications, because of their antibacterial efficacy. The immortelle EO has been used traditionally as an expectorant; however, there are no studies summarizing its antibacterial effect against respiratory tract bacteria. Our aim was to investigate the antibacterial and biofilm inhibitory activity of immortelle (Helichrysum italicum) EO against respiratory tract pathogens such as Haemophilus influenzae, H. parainfluenzae, Pseudomonas aeruginosa and Streptococcus pneumoniae. In order to prove the antibacterial effect of the immortelle EO, broth microdilution and biofilm inhibition tests, and membrane damage assay were investigated. Scanning electron microscopy was used to identify the structural modifications in bacterial cells. Our results showed that immortelle EO has antibacterial and anti-biofilm effects against respiratory tract bacteria used in this study. H. parainfluenzae was the most sensitive to each treatment, however, P. aeruginosa was the most resistant bacteria. In conclusion, the studied EO may have a role in the treatment of respiratory tract infections due to their antibacterial and anti-biofilm activity.

Spanish marjoram (Thymus mastichina) and cardamom (Elettaria cardamomum) are traditional aromatic plants with which several pharmacological properties have been associated. In this study, the volatile composition, antioxidative and antimigratory effects on human breast cancer (MDA-MB-468 cell line), antimicrobial activity, and antibiofilm effect were evaluated. Results obtained via treatment of human breast cancer cells generally indicated an inhibitory effect of both essential oils (EOs) on cell viability (after long-term treatment) and antioxidative potential, as well as the reduction of nitric oxide levels. Antimigratory effects were revealed, suggesting that these EOs could possess significant antimetastatic properties and stop tumor progression and growth. The antimicrobial activities of both EOs were determined using the disc diffusion method and minimal inhibition concentration, while antibiofilm activity was evaluated by means of mass spectrometry. The best antimicrobial effects of T. mastichina EO were found against the yeast Candida glabrata and the G+ bacterium Listeria monocytogenes using the disc diffusion and minimal inhibitory concentration methods. E. cardamomum EO was found to be most effective against Pseudomas fluorescens biofilm using both methods. Similarly, better effects of this oil were observed on G− compared to G+ bacterial strains. Our study confirms that T. mastichina and E. cardamomum EOs act to change the protein structure of older P. fluorescens biofilms. The results underline the potential use of these EOs in manufactured products, such as foodstuffs, cosmetics, and pharmaceuticals.

The essential oils of five Vietnamese Syzygium species (Syzygium levinei, S. acuminatissimum, S. vestitum, S. cumini, and S. buxifolium) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography–flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good–excellent antimicrobial activities against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the yeast Candida albicans. S. levinei leaf essential oil, rich in bicyclogermacrene (25.3%), (E)-β-elemene (12.2%), (E)-caryophyllene (8.2%), and β-selinene (7.4%), as well as S. acuminatissimum fruit essential oil containing (E)-caryophyllene (14.2%), α-pinene (12.1%), caryophyllene oxide (10.9%), β-selinene (10.8%), α-selinene (8.0%), and α-humulene (5.7%), established the same MIC value of 8 µg/mL against E. faecalis and B. cereus, which were much better than the positive control streptomycin (MIC 128–256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC50 values of less than 50 µg/mL against the growth of Culex quinquefasciatus and Aedes aegypti larvae. Especially, S. buxifolium leaf essential oil strongly inhibited Ae. aegypti larvae with 24 and 48 h LC50 values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC90 values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese Syzygium essential oils might have potential for use as supplemental antibacterial agents or as “green” alternatives for the control of mosquitoes.

Traditionally, the Algerian medicinal plant Elaeosilenum thapsioides (Desf.) Maire has been used for many diseases. The present research work aims to explore the chemical and biological characterization of its essential oil. The essential oils were obtained by hydrodistillation of different Elaeosilenum thapsioides (Apiaceae) aerial parts samples collected from two different regions (Mahouane and Megres) from Setif, Eastern Algeria. The chemical characterization of the obtained essential oils is reported here for the first time. Besides, they were evaluated for their in vitro Acetylcholinesterase (AChE) inhibitory activity involved in Alzheimer's disease using Ellman's spectrophotometric method. Additionally, their in vitro antimicrobial activity was assessed by the disc diffusion method. Both activities were performed at various oil concentrations. The GC/MS analysis of the essential oils from aerial parts (leaves, stems, flowers, and seeds) of E. thapsioides identified 47 constituents. Monoterpene hydrocarbons were the main components, ranging from 72.78 to 99.13%. Oxygenated monoterpenes and oxygenated sesquiterpenes ranged between 1.37 and 17.25% and 0.12 and 3.53% in essential oils from leaves and stems. Sesquiterpene hydrocarbons were present in small to large quantities in the essential oils of both populations, ranging from 0.69 to 13.44%. The presence of m-Methoxybenzyl isothiocyanate was recorded in stems essential oils from Mahouane and leaves essential oils from Merges, which was 9.73% and 3.72%, respectively. The stems essential oils obtained from plants collected in Mahouane showed the highest AChE inhibitory activity. The highest anti-bacterial activity was shown by the essential oil obtained from Megres leaves against Bacillus cereus ATCC 11778. The oils exhibited a moderate inhibitory activity in both tests.

Background Only a few studies have investigated the bioactivity of the essential oils (EOs) of Chamaecyparis formosensis and C. obtusa var. formosana, which are endemic to Taiwan. The wood and leaf EOs extracted from C. obtusa var. formosana had anti-inflammatory and antitermitic effects, respectively, and the twig EO extracted from C. formosensis inhibited the growth of Fusarium oxysporum, Pestalotiopsis funerea, and Ganoderma australe. Methods A poisoned food technique was used to evaluate the antifungal effects of wood and leaf EOs extracted from C. formosensis and C. obtusa var. formosana on brown rot fungus, white rot fungus, and mold. A phytatray chamber assay was conducted to investigate the antifungal activities of the EOs in the vapor phase. Gas chromatography-mass spectrometry was used to examine the chemical constituents of both EOs. Results The leaf EO extracted from C. formosensis primarily contained monoterpene hydrocarbons, whereas the leaf EO extracted from C. obtusa var. formosana primarily contained monoterpene and sesquiterpene hydrocarbons. The wood EOs extracted from C. formosensis and C. obtusa var. formosana primarily contained sesquiterpene hydrocarbons and oxygenated sesquiterpenes. These results indicated that the wood EOs had higher antifungal activity in the liquid phase, whereas the leaf EOs had higher antifungal activity in the vapor phase. Conclusion Wood EOs extracted from C. formosensis and C. obtusa var. formosana have strong antifungal effects against Gloeophyllum trabeum, Lenzites betulina, Trametes versicolor, and Trichoderma sp. Compared with wood EOs, leaf EOs have a greater inhibitory effect on mycelial growth in the vapor phase. In both the liquid and vapor phases, the EOs extracted from C. formosensis and C. obtusa var. formosana serve as effective antifungal agents against pathogenic fungi. Further research is required to elucidate the mechanisms underlying the antifungal activities of EOs in different phases and explore their potential applications.

The chemical composition and the antimicrobial and antioxidant activity of essential oils from two Helichrysum italicum (Roth) G.Don subspecies grown in Bulgaria were investigated. As a result, 95 compounds with concentrations above 0.05% were detected by GC/MS and 46 of them, mainly mono- and sesquiterpenes, representing 79.81% and 85.51% of the total content of the samples, were identified. The main constituents of the essential oil from Helichrysum italicum subsp. microphyllum (plant origin from Bosnia) were monoterpene alpha-pinene (20.84%) and sesquiterpene gamma-curcumene (16.53%), followed by beta-selinene (5.59%), ar-curcumene (4.39%), trans-caryophyllene (4.35%), beta-diketone italidione I (4.32%), alpha-selinene (4.28%), and neryl acetate (3.81%). The sesquiterpene hydrocarbons were the dominant groups of chemical constituents in the essential oil, followed by the oxygenated aliphatic hydrocarbons. The main constituents in the H. italicum essential oil (plant origin from France) were neryl acetate (33.87%), gamma-curcumene (8.84%), rosifoliol (5.46%), geranyl propionate (4.98%), alpha r-curcumene (4.31%), italidione I (3.56%), alpha-eudesmol (3.19%), and limonene (3.02%). The main class of chemical compounds was the oxygenated monoterpenes, followed by sesquiterpene hydrocarbons. H. italicum essential oil from France showed more pronounced antimicrobial activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, and the fungus Aspergillus brasiliensis, as well as stronger antioxidant potential.

The current study describes chemical compositions and antimicrobial activity of essential oils from the rhizome of two Vietnamese ginger plants Newmania orthostachys N.S. Lý & Škorničk. and Newmania serpens N.S. Lý & Škorničk. 49 compounds (98.4%) were identified in N. orthostachys rhizome oil, whereas 54 compounds (93.4%) were identified in N. serpens rhizome oil. N. orthostachys rhizome essential oil was dominated by monoterpene hydrocarbons (74.2%), in which β-pinene (35.7%), α-pinene (13.4%), sabinene (8.0%), camphene (6.7%), and limonene (5.1%) were characteristic compounds. Monoterpene hydrocarbons (33.5%) and sesquiterpene hydrocarbons (44.1%) represented N. serpens rhizome essential oil, as well as β-pinene (18.5%), bicyclogermacrene (12.4%), β-selinene (8.2%) were the principal compounds. In an antimicrobial assay against three tested Gram-positive bacteria Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579, both two essential oils showed the minimum inhibitory concentration (MIC) values of 16-64 µg/mL lower than those of positive control Streptomycin (MIC 128-256 µg/ml). These two essential oils with the MIC values of 8-16 µg/mL are also better than the positive control cycloheximide (MIC 32 µg/mL) against the yeast Candida albicans ATCC 10231.

The extracts of five invasive plants were investigated for antifungal and antibiofilm activities against Candida albicans, C. glabrata, C. krusei, and C. parapsilosis. The antifungal activity was evaluated using the microdilution assay and the antibiofilm effect by measurement of the metabolic activity. Ethanol and ethanol-water extracts of Reynoutria japonica leaves inhibited 50 % of planktonic cells at 250 μg mL-1 and 15.6 μg mL-1 , respectively. Ethanol and ethanol-water extracts of Baccharis halimifolia inhibited >75 % of the mature biofilm of C. albicans at 500 μg mL-1 . The essential oil (EO) of B. halimifolia leaves was the most active (50 % inhibition (IC50 ) at 4 and 74 μg mL-1 against the maturation phase and 24 h old-biofilms of C. albicans, respectively). Oxygenated sesquiterpenes were the primary contents in this EO (62.02 %), with β-caryophyllene oxide as the major component (37 %). Aromadendrene oxide-(2), β-caryophyllene oxide, and (±)-β-pinene displayed significant activities against the maturation phase (IC50 =9-310 μ mol l-1 ) and preformed 24 h-biofilm (IC50 =38-630 μ mol l-1 ) of C. albicans with very low cytotoxicity for the first two compounds. C. albicans remained the most susceptible species to this EO and its components. This study highlighted for the first time the antibiofilm potential of B. halimifolia, its EO and some of its components.

The essential oil from the aerial parts of Leucas mollissima Wall. ex Benth growing wild in the Himalayan region of Uttarakhand, India was isolated by steam distillation method and analyzed by capillary GC and GC-MS. The oil was found to be rich in sesquiterpene hydrocarbons (64.1 %) followed by monoterpene hydrocarbons (13.7 %). Total thirty-five compounds were identified accounting for 87.1 % of the total oil composition. Germacrene D (16.0 %), valencene (15.6 %), β-caryophyllene (14.9 %), bicyclogermacrene (8.5 %), β-phellandrene (6.0 %) and ρ-cymene (4.6 %) were identified as the major constituents. The in vitro antibacterial activity of the oil was assessed using disc-diffusion method against ten bacterial strains. The oil showed significant activity against Gram-negative bacterium Agrobacterium tumefaciens and Gram-positive bacterium Bacillus subtilis. Minimum inhibitory concentration value was observed at 31.25 μL/mL against A. tumefaciens and B. subtilis.

From hydro-distillation and GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis, chemical compositions in essential oils of two Vietnamese Piper plants Piper pendulispicum C. DC. and P. hymenophyllum Miq. were identified. Essential oils of P. pendulispicum leaf and stem are highlighted with the predominant amount of sesquiterpene hydrocarbons (73.21-78.06%), in which bicyclogermacrene (12.17-12.54%) and β-caryophyllene (12.10-14.51%) were the principal compounds. Monoterpene hydrocarbons (87.44%) are the main chemical class of P. hymenophyllum leaf oil, in which α-pinene (52.92%) and β-pinene (26.65%) are the principal compounds. These obtained essential oils with the MIC (minimum inhibitory concentration) values of 16-128 μg/mL are better than the positive control streptomycin ((MIC 128-256 μg/mL) in antimicrobial assay against three Gram-positive bacteria Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Bacillus cereus ATCC 14579. P. pendulispicum essential oils (MIC 16-32 μg/mL) are also comparable to the other standard cycloheximide (MIC 32 μg/mL) against the yeast Candida albicans ATCC 10231. In general, P. pendulispicum essential oil is better than P. hymenophyllum leaf oil for antimicrobial treatment.

This study aimed to investigate the chemical composition and some biological activities of the essential oils (EOs) from needles of Pinus canariensis, P. jeffreyi, and P. taeda cultivated in Tunisia. The chemical composition of the EOs revealed the presence of 119 components, with monoterpene hydrocarbons (in EOs of P. canariensis and P. taeda) and sesquiterpene hydrocarbons (in P. jeffreyi EO) being the main chemical classes. The EOs showed significant inhibitory effects on the germination and seedling and radical growth of the weeds, Sinapis arvensis, Lolium rigidum, and Trifolium campestre. The EO of P. jeffreyi exhibited the highest phytotoxicity, while T. campestre was the most tolerant seed. The EOs showed antibiofilm activity against Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli) pathogenic bacterial strains, depending on the EO, and the concentration tested. Overall, the EOs displayed efficacy against mature biofilms and were effective also against the metabolism of the sessile cells in the biofilm. These findings provide valuable insights into the potential applications of these EOs in phytotoxic and antibiofilm strategies, for agriculture, food and pharmaceutical fields.

Biofilms represent a serious problem for food industries due to their persistence in processing surfaces, from which they can cause food spoilage or, even worse, lead to foodborne diseases. Microorganisms immersed in biofilms are more resistant to biocides. The search for natural effective alternatives for the prevention and the control of biofilms has increased lately. The aim of this research was to test the antibacterial and the anti-biofilm activities of cinnamon, onion, and garlic essential oils against Listeria monocytogenes. The methodology highlighted first the effect of these essential oils on L. monocytogenes using disc diffusion and minimum inhibitory concentration (MIC) methods and then on initial cell attachment and six hours preformed biofilms. The inhibition of biofilms was assessed by crystal violet assay. Sulfides were the most abundant compounds present in onion and garlic essential oils, while cinnamaldehyde was predominant in cinnamon essential oil. MIC values were of 0.025 mg mL−1 for onion essential oil and 0.100 mg mL−1 for cinnamon and garlic. Onion essential oil inhibited initial cell attachment by 77% at 0.5 of the MIC dose, while at MIC, cinnamon and garlic essential oils inhibited the initial microbial adhesion completely. All three essential oils completely inhibited initial cell attachment when applied at 2 MIC. On the contrary, preformed biofilms were more resistant, and the inhibition rate ranged from 33% to 78%. In summary, this investigation revealed that the essential oils of garlic, onion, and cinnamon show an effective antibiofilm activity against L. monocytogenes and are promising natural antimicrobial alternatives for food processing facilities.

Background: The altitudinal and geographical variability of the Aurès mountains of Algeria favored the existence of some endemic and rare varieties of medicinal plants. The aim of the present work is to determine the chemical composition, antimicrobial and antibiofilm properties of the essential oils (EOs) from aerial parts of four medicinal plants from Aurès region of Algeria; Juniperus thurifera L., Juniperus oxycedrus L., Salvia officinalis L. and Thymus ciliatus ssp. munbyanus (Boiss. & Reut.) Batt. on coagulase negative staphylococci (CoNS) isolates.
 Methodology: Extraction of EOs from the four plant materials was carried out by hydro-distillation, and the EO yield expressed in gram of the distillate per 100 grams of dry matter. The chemical composition of the EOs was analyzed by gas chromatography-mass spectrometry (GC-MS) method. In vitro antibacterial and antibiofilm activities of the EOs were evaluated against CoNS previously isolated at the Anti-Cancer Center of Batna, Algeria using the agar disc diffusion assay and biofilm inhibition study, respectively. Minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of the EOs of S. officinalis L. and T. ciliatus ssp. munbyanus were determined by the dilution method.
 Results: Twenty-seven and 41 compounds rich in monoterpene hydrocarbons were identified from J. oxycedrus and J. thurifera plants respectively, while 45 and 32 compounds, constituted mainly by oxygenated monoterpenes, were identified from S. officinalis L. and T. ciliatus ssp. munbyanus, respectively. The EOs of T. ciliatus ssp. munbyanus showed the most inhibitory activity of all the four plants on CoNS isolates (n=66) with mean inhibition zone diameter of 24.99±6.29mm, and mean MIC and MBC values of 2.65±3.77mg/ml and 5.31±7.41mg/ml respectively, followed by S. officinalis L., with mean inhibition zone diameter of 13.38± 6.52mm, and mean MIC and MBC values of 27.53±28.2 mg/ml and 31.97±33.19 mg/ml respectively (p<0.0001 by one-way ANOVA). Also, percentage biofilm inhibition of CoNS isolates (n=59) was high for EOs of T. ciliatus ssp. munbyanus (65.63±10.71%) and S. officinalis L. (53.13±5.83%), although was significantly higher for T. ciliatus ssp. munbyanus compared to S. officinalis L. (p<0.0001, t=7.874).
 Conclusion: Essential oils from T. ciliatus ssp. munbyanus and S. officinalis L. could represent an alternative to classical antibiotics against planktonic cells and biofilms of CoNS.

Candidiasis is a common oral and vaginal infection. Some papers have presented that the essential oils of Lamiaceae plants can have antifungal activity. This study aimed to investigate the activity of 7 essential oils of the Lamiaceae family with known phytochemical compositions against Candida fungi. Forty-four strains belonging to six species were tested: C. albicans, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. During this investigation, the following methods were used: determination of the minimal inhibitory concentrations (MICs), biofilm inhibition studies, and in silicotoxicity tests. Essential oils of lemon balm (Melissa officinalis) and oregano (Origanum vulgare) showed the best anti-Candida activity, with MIC values below 3.125 mg/mL. Lavender (Lavandula stoechas), mint (Mentha × piperita), rosemary (Rosmarinus officinalis), and thyme (Thymus vulgaris) essential oils were also very active (0.39 to 6.25 or 12.5 mg/mL). Sage (Salvia officinalis) essential oil presented the lowest activity, with MIC values ranging from 3.125 to 100 mg/mL. In an antibiofilm study using MIC values, oregano and thyme essential oils showed the greatest effect, followed by lavender, mint, and rosemary oils. The weakest antibiofilm activity was observed with the lemon balm and sage oils. In silico toxicity research suggests that most of main compounds of Lamiaceae essential oils probably do not exhibit carcinogenicity, mutagenicity, or cytotoxicity. The obtained results showed that Lamiaceae essential oils have anti-Candida and antibiofilm activity. Further research is required to confirm the safety and efficacy of essential oils in the topical treatment of candidiasis.