Chemical composition and antifungal activity of the essential oil of Thymbra capitata

Effect of Thymbra capitata (L.) Cav. on Inflammation, Senescence and Cell Migration

Aromatic plants are reported to display pharmacological properties, including anti-aging. This work aims to disclose the anti-aging effect of the essential oil (EO) of Thymbra capitata (L.) Cav., an aromatic and medicinal plant widely used as a spice, as well as of the hydrodistillation residual water (HRW), a discarded by-product of EO hydrodistillation. The phytochemical characterization of EO and HRW was assessed by GC-MS and HPLC-PDA-ESI-MSⁿ, respectively. The DPPH, ABTS, and FRAP assays were used to disclose the antioxidant properties. The anti-inflammatory potential was evaluated using lipopolysaccharide-stimulated macrophages by assessing NO production, iNOS, and pro-IL-1β protein levels. Cell migration was evaluated using the scratch wound assay, and the etoposide-induced senescence was used to assess the modulation of senescence. The EO is mainly characterized by carvacrol, while the HRW is predominantly characterized by rosmarinic acid. The HRW exerts a stronger antioxidant effect in the DPPH and FRAP assays, whereas the EO was the most active sample in the ABTS assay. Both extracts reduce NO, iNOS, and pro-IL-1β. The EO has no effect on cell migration and presents anti-senescence effects. In opposition, HRW reduces cell migration and induces cellular senescence. Overall, our study highlights interesting pharmacological properties for both extracts, EO being of interest as an anti-aging ingredient and HRW relevant in cancer therapy.

Phytochemical Composition, Antioxidant and Antifungal Activity of Thymus capitatus, a Medicinal Plant Collected from Northern Morocco

Thymus capitatus is a Mediterranean endemic plant commonly known as "Zaïtra" in northern Morocco. As T. capitatus is widely used in traditional medicine and food, this present work aims to investigate the chemical compositions and biological activities of the T. capitatus leaves essential oil (TcLEO), acetonic (TcLAE), and methanolic extract (TcLME). The spectrophotometric determination demonstrated that T. capitatus is a natural source rich in phenolic contents (TPC) and flavonoid contents (TFC) and that TcLME revealed the highest TPC and TFC than TcLAE and TcLEO. The LC-MS analysis of phenolic compounds showed that paraben acid was predominant in both TcLME and TcLAE, followed by cinnamic acid and p-hydroxybenzoic acid. GC-MS analysis of the TcLEO revealed the presence of a total of 10 compounds, which were predominated by carvacrol. The antioxidant activity by ORAC was observed to be significantly higher in TcLEO and TcLAE than in TcLME. All samples used to assess DNA degradation effectively prevented DNA oxidation and, at the same time, had a prooxidant effect. The genotoxicity test showed that the T. capitatus were devoid of any mutagenic activity. Concerning antifungal activity, all samples were able to inhibit the growth of all microorganisms tested at low concentrations. TcLAE showed higher activity than TcLME, and in general, dermatophytes were more susceptible, being Microsporum canis the most sensitive one. Overall, the results obtained from this study confirm the wide uses of T. capitatus. Furthermore, the finding results suggest that the T. capitatus essential oil and extracts can be highly useful for pharmaceutical industries.

Six Bacterial Vaginosis-Associated Species Can Form an In Vitro and Ex Vivo Polymicrobial Biofilm That Is Susceptible to Thymbra capitata Essential Oil

Bacterial vaginosis (BV) is associated with serious gynaecologic and obstetric complications. The hallmark of BV is the presence of a polymicrobial biofilm on the vaginal epithelium, but BV aetiology is still a matter of debate. We have previously developed an in vitro biofilm model that included three BV-associated species, but, up to now, no studies are available whereby more bacterial species are grown together to better mimic the in vivo situation. Herein, we characterized the first polymicrobial BV biofilm consisting of six cultivable BV-associated species by using both in vitro and ex vivo vaginal tissue models. Both models revealed that the six species were able to incorporate the polymicrobial biofilm, at different bacterial concentrations. As it has been thought that this polymicrobial biofilm may increase the survival of BV-associated species when exposed to antibiotics, we also assessed if the Thymbra capitata essential oil (EO), which has recently been shown to be highly bactericidal against several Gardnerella species, could maintain its anti-biofilm activity against this polymicrobial biofilm. Under our experimental conditions, T. capitata EO exhibited a high antibacterial effect against polymicrobial biofilms, in both tested models, with a significant reduction in the biofilm biomass and the number of culturable cells. Overall, this study shows that six BV-associated species can grow together and form a biofilm both in vitro and when using an ex vivo model. Moreover, the data obtained herein should be considered in further applications of T. capitata EO as an antimicrobial agent fighting BV.

Essential Oils of Lamiaceae Family Plants as Antifungals

The incidence of fungal infections has been steadily increasing in recent years. Systemic mycoses are characterized by the highest mortality. At the same time, the frequency of infections caused by drug-resistant strains and new pathogens e.g., Candida auris increases. An alternative to medicines may be essential oils, which can have a broad antimicrobial spectrum. Rich in the essential oils are plants from the Lamiaceae family. In this review are presented antifungal activities of essential oils from 72 Lamiaceae plants. More than half of these have good activity (minimum inhibitory concentrations (MICs) < 1000 µg/mL) against fungi. The best activity (MICs < 100) have essential oils from some species of the genera Clinopodium, Lavandula, Mentha, Thymbra, and Thymus. In some cases were observed significant discrepancies between different studies. In the review are also shown the most important compounds of described essential oils. To the chemical components most commonly found as the main ingredients include β-caryophyllene (41 plants), linalool (27 plants), limonene (26), β-pinene (25), 1,8-cineole (22), carvacrol (21), α-pinene (21), p-cymene (20), γ-terpinene (20), and thymol (20).

Dermatophyte Resistance to Antifungal Drugs: Mechanisms and Prospectus

Dermatophytes comprise pathogenic fungi that have a high affinity for the keratinized structures present in nails, skin, and hair, causing superficial infections known as dermatophytosis. A reasonable number of antifungal drugs currently exist on the pharmaceutical market to control mycoses; however, their cellular targets are restricted, and fungi may exhibit tolerance or resistance to these agents. For example, the stress caused by antifungal and cytotoxic drugs in sub-inhibitory concentrations promotes compensatory stress responses, with the over-expression of genes involved in cellular detoxification, drug efflux, and signaling pathways being among the various mechanisms that may contribute to drug tolerance. In addition, the ATP-binding cassette transporters in dermatophytes that are responsible for cellular efflux can act synergistically, allowing one to compensate for the absence of the other, revealing the complexity of drug tolerance phenomena. Moreover, mutations in genes coding for target enzymes could lead to substitutions in amino acids involved in the binding of antifungal agents, hindering their performance and leading to treatment failure. The relevance of each one of these mechanisms of resistance to fungal survival is hard to define, mainly because they can act simultaneously in the cell. However, an understanding of the molecular mechanisms involved in the resistance/tolerance processes, the identification of new antifungal targets, as well as the prospective of new antifungal compounds among natural or synthetic products, are expected to bring advances and new insights that facilitate the improvement or development of novel strategies for antifungal therapy.

In vitro susceptibility of Trypanosoma brucei brucei to selected essential oils and their major components

Aiming for discovering effective and harmless antitrypanosomal agents, 17 essential oils and nine major components were screened for their effects on T. b. brucei. The essential oils were obtained by hydrodistillation from fresh plant material and analyzed by GC and GC-MS. The trypanocidal activity was assessed using blood stream trypomastigotes cultures of T. b. brucei and the colorimetric resazurin method. The MTT test was used to assess the cytotoxicity of essential oils on macrophage cells and Selectivity Indexes were calculated. Of the 17 essential oils screened three showed high trypanocidal activity (IC₅₀ < 10 μg/mL): Juniperus oxycedrus (IC₅₀ of 0.9 μg/mL), Cymbopogon citratus (IC₅₀ of 3.2 μg/mL) and Lavandula luisieri (IC₅₀ of 5.7 μg/mL). These oils had no cytotoxic effects on macrophage cells showing the highest values of Selectivity Index (63.4, 9.0 and 11.8, respectively). The oils of Distichoselinum tenuifolium, Lavandula viridis, Origanum virens, Seseli tortuosom, Syzygium aromaticum, and Thymbra capitata also exhibited activity (IC₅₀ of 10-25 μg/mL) but showed cytotoxicity on macrophages. Of the nine compounds tested, α-pinene (IC₅₀ of 2.9 μg/mL) and citral (IC₅₀ of 18.9 μg/mL) exhibited the highest anti-trypanosomal activities. Citral is likely the active component of C. citratus and α-pinene is responsible for the antitrypanosomal effects of J. oxycedrus. The present work leads us to propose the J. oxycedrus, C. citratus and L. luisieri oils as valuable sources of new molecules for African Sleeping Sickness treatment.

Carvacrol is highly disruptive against coagulase-negative staphylococci in in vitro biofilms

AIM

To evaluate the antimicrobial activity of carvacrol against stationary-phase planktonic and biofilm cells of coagulase-negative staphylococci and comparison to traditional antistaphylococcal antibiotics.

MATERIALS & METHODS

The antimicrobial effect of carvacrol and antibiotics against planktonic and biofilm cells were assessed through quantification of the number of culturable and/or viable cells. Confocal laser scanning microscopy was used to evaluate the effect of carvacrol on the biofilm structure.

RESULTS

A concentration of 4 mM of carvacrol demonstrated a potent antimicrobial effect, vastly superior than ciprofloxacin, rifampicin, gentamicin and vancomycin, both in planktonic and biofilm cells.

CONCLUSION

Carvacrol is a potential antimicrobial agent, which applicability for the prevention and/or treatment of coagulase-negative staphylococci biofilm-associated infections is worthwhile investigating in more detail.

Thymbra capitata essential oil as potential therapeutic agent against Gardnerella vaginalis biofilm-related infections

Aim: To evaluate the antibacterial activity of Thymbra capitata essential oil and its main compound, carvacrol, against Gardnerella vaginalis grown planktonically and as biofilms, and its effect of vaginal lactobacilli. Materials & methods: Minimal inhibitory concentration, minimal lethal concentration determination and flow cytometry analysis were used to assess the antibacterial effect against planktonic cells. Antibiofilm activity was measured through quantification of biomass and visualization of biofilm structure by confocal laser scanning microscopy. Results: T. capitata essential oil and carvacrol exhibited a potent antibacterial activity against G. vaginalis cells. Antibiofilm activity was more evident with the essential oil than carvacrol. Furthermore, vaginal lactobacilli were significantly more tolerant to the essential oil. Conclusion: T. capitata essential oil stands up as a promising therapeutic agent against G. vaginalis biofilm-related infections.

Natural Products: An Alternative to Conventional Therapy for Dermatophytosis?

The increased incidence of fungal infections, associated with the widespread use of antifungal drugs, has resulted in the development of resistance, making it necessary to discover new therapeutic alternatives. Among fungal infections, dermatophytoses constitute a serious public health problem, affecting 20-25 % of the world population. Medicinal plants represent an endless source of bioactive molecules, and their volatile and non-volatile extracts are clearly recognized for being the historical basis of therapeutic health care. Because of this, the research on natural products with antifungal activity against dermatophytes has considerably increased in recent years. However, despite the recognized anti-dermatophytic potential of natural products, often advantageous face to commercial drugs, there is still a long way to go until their use in therapeutics. This review attempts to summarize the current status of anti-dermatophytic natural products, focusing on their mechanism of action, the developed pharmaceutical formulations and their effectiveness in human and animal models of infection.

Hydrosol of Thymbra capitata Is a Highly Efficient Biocide against Salmonella enterica Serovar Typhimurium Biofilms

Salmonella is recognized as one of the most significant enteric foodborne bacterial pathogens. In recent years, the resistance of pathogens to biocides and other environmental stresses, especially when they are embedded in biofilm structures, has led to the search for and development of novel antimicrobial strategies capable of displaying both high efficiency and safety. In this direction, the aims of the present work were to evaluate the antimicrobial activity of hydrosol of the Mediterranean spice Thymbra capitata against both planktonic and biofilm cells of Salmonella enterica serovar Typhimurium and to compare its action with that of benzalkonium chloride (BC), a commonly used industrial biocide. In order to achieve this, the disinfectant activity following 6-min treatments was comparatively evaluated for both disinfectants by calculating the concentrations needed to achieve the same log reductions against both types of cells. Their bactericidal effect against biofilm cells was also comparatively determined by in situ and real-time visualization of cell inactivation through the use of time-lapse confocal laser scanning microscopy (CLSM). Interestingly, results revealed that hydrosol was almost equally effective against biofilms and planktonic cells, whereas a 200-times-higher concentration of BC was needed to achieve the same effect against biofilm compared to planktonic cells. Similarly, time-lapse CLSM revealed the significant advantage of the hydrosol to easily penetrate within the biofilm structure and quickly kill the cells, despite the three-dimensional (3D) structure of Salmonella biofilm.

IMPORTANCE

The results of this paper highlight the significant antimicrobial action of a natural compound, hydrosol of Thymbra capitata, against both planktonic and biofilm cells of a common foodborne pathogen. Hydrosol has numerous advantages as a disinfectant of food-contact surfaces. It is an aqueous solution which can easily be rinsed out from surfaces, it does not have the strong smell of the essential oil (EO) and it is a byproduct of the EO distillation procedure without any industrial application until now. Consequently, hydrosol obviously could be of great value to combat biofilms and thus to improve product safety not only for the food industries but probably also for many other industries which experience biofilm-related problems.

Antioxidant, Anti-inflammatory and Anti-hyperglycaemic Activities of Essential Oils from Thymbra capitata, Thymus albicans, Thymus caespititius, Thymus carnosus, Thymus lotocephalus and Thymus mastichina from Portugal

The in vitro antioxidant, anti-inflammatory, anti-hyperglycaemic, and anti-acetylcholinesterase activities of the essential oils (EOs) isolated from six Lamiaceae species ( Thymbra capitata, Thymus albicans, Th. caespititius, Th. carnosus, Th. lotocephalus and Th. mastichina) grown in Portugal, were evaluated. Th. caespititius and T. capitata carvacrol/thymol-rich EOs showed the best capacity for preventing lipid peroxidation, and scavenging the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and peroxyl free radicals, as well as for inhibiting lipoxygenase and α-amylase. However, Th. caespititius and Th. lotocephalus 1,8-cineole and linalool rich EOs were the best inhibitors of α-glucosidase. T. capitata, Th. lotocephalus and Th. albicans EOs were the most active for inhibiting acetylcholinesterase. Th. caespititius and Th. mastichina EOs were the main scavengers of nitric oxide (NO) radicals. The comparison between the present data with a survey of the existing literature on the in vitro biological activities of the essential oils isolated from the same species from Portuguese origin, using other methodologies, showed some differences. For instance the use of two oxidizable substrates (egg yolk and lecithin liposomes) led to distinct results mainly for those samples with relatively low activity. In addition, the EOs capacity for scavenging peroxyl radicals was also influenced by the presence of cyclodextrins, as a synergism seemed to occur between EOs and those carbohydrates.

Plant essential oils as active antimicrobial agents

Essential oils derived from plants have been recognized for decades to exhibit biological activities, including antioxidant, anticancer, and antimicrobial attributes. Antimicrobial activities of these natural plant materials have been intensively explored in recent years, mainly in response to the overwhelming concern of consumers over the safety of synthetic food additives. Gram-negative organisms are believed to be slightly less sensitive to essential oils than Gram-positive bacteria. Generally, a higher concentration is required to obtain the same efficacy in foods than in synthetic media. The combinations of different types of essential oils or with other food additives have been found to potentially exhibit synergistic if not additive effects. This suggests a cost-efficient and wholesome alternative to both food industry and consumers, at the same time adhering to the hurdle technology in inhibiting proliferation of foodborne pathogens. This review aims to examine the conventional methods commonly used for assessment of antimicrobial activities of essential oils and phytochemicals, the use of these substances as antimicrobials in food products, factors that affect their efficacy, synergism between components or with available food preservatives as well as the challenges and future directions of using essential oils and phytochemicals as natural food preservatives.

Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitata Essential Oil with Its Preservative Effect against Listeria monocytogenes Inoculated in Minced Beef Meat

The chemical composition, antioxidant and antimicrobial activities, and the preservative effect of Thymus capitata essential oil against Listeria monocytogenes inoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89%) of the oil. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid) with IC50 values of 44.16 and 0.463 μ g/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15-80 mm) and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) essential oil of T. capitata to minced beef significantly reduced the L. monocytogenes population when compared to those of control samples (P-value  <0.01).

Ethnopharmacological study of medicinal plants used in the treatment of CNS disorders in Sinai Peninsula, Egypt

ETHNOPHARMACOLOGICAL RELEVANCE

To provide ethnopharmacological information on the use of medicinal plants for central nervous system (CNS) disorders in the Sinai Peninsula region (Egypt). To collect, analyze and evaluate the ethnobotanical knowledge about these medicinal plants in the Sinai Peninsula region with 61,000 km (2) and 379,000 inhabitants.

METHODOLOGY

Field work was concluded between March 2006 and May 2011, using semi-structured questionnaire with 700 informants (mean age: 59; 100% men) from 117 settlements of 17 Bedouin tribes. Transects walks in wild herbal plant collection areas and bibliographical review on the collected plants were also conducted. The Interview/ Inhabitant index (I/P), relative importance value of the species and informant consensus factor (FIC) were calculated.

RESULTS

More than 300 species were traditionally used in folk medicine in the Sinai Peninsula; 101 of these species belonging to 40 families were reported as useful in different CNS disorders. Only 5 species are endemic of the studied area. All different part plants were used, leaves and aerial parts being the most frequent. Most of the remedies were prepared as infusion or decoction, while oral administration was the most common way to be used. Gastrointestinal (67.3%) and respiratory disorders (42.57%) were also reported as frequently treated by Bedouins with herbal remedies.

CONCLUSIONS

Only a few species were found where the traditional use is supported by pharmacological studies (Acacia nilotica, Achillea fragrantissima, Ajuga iva or Mentha longifolia). No bibliographical references in the scientific literature were found for 22 species (21.78%); finally, several studies were published with different pharmacological activities than those provided by Bedouins.

Antifungal mechanism of essential oil from Anethum graveolens seeds against Candida albicans

This work studied the antifungal mechanism of dill seed essential oil (DSEO) against Candida albicans. Flow cytometric analysis and inhibition of ergosterol synthesis were performed to clarify the mechanism of action of DSEO on C. albicans. Upon treatment of cells with DSEO, propidium iodide penetrated C. albicans through a lesion in its plasma membrane. DSEO also significantly reduced the amount of ergosterol. These findings indicate that the plasma membrane of C. albicans was damaged by DSEO. The effect of DSEO on the functions of the mitochondria in C. albicans was also studied. We assayed the mitochondrial membrane potential (mtΔψ) using rhodamine 123 and determined the production of mitochondrial dysfunction-induced reactive oxygen species (ROS) via flow cytometry. The effects of the antioxidant l-cysteine (Cys) on DSEO-induced ROS production and the antifungal effect of DSEO on C. albicans were investigated. Exposure to DSEO increased mtΔψ. Dysfunctions in the mitochondria caused ROS accumulation in C. albicans. This increase in the level of ROS production and DSEO-induced decrease in cell viability were prevented by the addition of Cys, indicating that ROS are an important mediator of the antifungal action of DSEO. These findings indicate that the cytoplasmic membrane and mitochondria are the main anti-Candida targets of DSEO.

Wild Thymbra Capitata from Western Rif (Morocco): Essential Oil Composition, Chemical Homogeneity and Yield Variability

Essential oils (EO, 15 collective samples and 47 individual samples) of Thymbra capitata collected from Moroccan Western Rif were analyzed using gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC-SM) and 13C NMR spectroscopy. Twenty components were identified. Carvacrol (68.2%–85.9 %) was by far the major component of all the samples, while the content of thymol (0.1-0.3%) was very low. Other components present in appreciable amounts were γ-terpinene (up to 8.9%), p-cymene (up to 7.1%), linalool (up to 4.4%) and ( E)- β-caryophyllene (up to 4.1%). In contrast, the yield of EO varied drastically from sample to sample (0.5–3.7%). No correlation could be established between yield of EO and altitude, pH, chemical composition and granularity of the soil. Cultivation under controlled conditions is suggested to improve the quantitative characteristics of carvacrol-rich Moroccan T. capitata.

The anti-Candida activity of Thymbra capitata essential oil: effect upon pre-formed biofilm

ETHNOPHARMACOLOGICAL RELEVANCE

[corrected] Thymbra capitata essential oil is traditionally considered to exhibit powerful antiseptic properties, thus being used to treat cutaneous infections. The aim of the present study was to evaluate the effect of Thymbra capitata essential oil upon pre-formed biofilm of different Candida strains while comparing it with the activity against planktonic cells.

MATERIALS AND METHODS

Fifteen Candida isolates were included, corresponding to clinical and collection type strains. Essential oil was obtained by hydrodistillation and its composition analysed by GC/MS. Activity upon planktonic cells was evaluated according to M27-A3 macromethod. Its effect upon 24h preformed biofilm biomass was determined using the crystal violet procedure and the metabolic activity was studied applying the XTT/menadione technique.

RESULTS

Biofilm biomass and metabolic activity of all tested species were reduced up to 50% at MIC values. The effect was more pronounced at double MIC values, achieving >80% reduction, except for Candida albicans that presented a more resistant profile (62%).

CONCLUSION

Thymbra capitata essential oil presented an important effect upon Candida biofilms. It is proposed as a valuable antifungal product to be used in an appropriate pharmaceutical formulation for the management of resistant mucocutaneous candidosis.

Chemical composition and antifungal activity of essential oils and supercritical CO2 extracts of Apium nodiflorum (L.) Lag

Aerial parts of Apium nodiflorum collected in Portugal and Italy were submitted to hydrodistillation; also a supercritical fluid extract was obtained from Italian plants. The extracts were analyzed by GC and GC/MS. Both essential oils, obtained from Portuguese and Italian plants, posses high content of phenylpropanoids (51.6 vs. 70.8%); in the former, the percentage split in myristicin (29.1%) and dillapiol (22.5%), whereas in the latter, the total percentage is only of dillapiol (70.8%). The co-occurrence of myristicin and dillapiol is frequent because dillapiol results from enzymatic methoxylation of myristicin. Antimicrobial activity of phenylpropanoids has been patented, what suggest the potential of plants with high amounts of these compounds. Minimal inhibitory concentration (MIC) and minimal lethal concentration, determined according to NCCLS, were used to evaluate the antifungal activity of the essential oils against yeasts, Aspergillus species and dermatophytes. Essential oils exhibited higher antifungal activity than other Apiaceae against dermatophytes, with MIC ranging from 0.04 to 0.32 μl/ml. These results support the potential of A. nodiflorum oil in the treatment of dermatophytosis and candidosis.

Effects of Essential Oils on the Growth of Giardia lamblia Trophozoites

Giardia lamblia is one of the most important worldwide causes of intestinal infections produced by protozoa. Current therapy for giardiasis is unsatisfactory due to high incidence of undesirable side effects and significant failure in clearing parasites from the gastrointestinal tract. In the search for new therapeutic agents, we report on the effect of several essential oils on G. lamblia growth. Among eighteen tested essential oils, those with phenolic compositions were the most active, particularly if containing high contents of carvacrol, such as Thymbra capitata and Origanum virens (IC50 values of 71 and 85 μg.mL−1, respectively). The oils from Syzygium aromaticum and Thymus zygis subsp. sylvestris (IC50 values from 100 to 200 μg.mL−1), as well as, those from Mentha x piperita and Lippia graveolens (IC50 values over 200 μg.mL−1) were less active. Results support the concept that several essential oils or some of their constituents may be useful in the clinical management of Giardia infections.

Antifungal effects of essential oils from oregano and fennel onSclerotinia sclerotiorum

AIMS

The antifungal effects of essential oils of oregano (Origanum syriacum var. bevanii) and fennel (Foeniculum vulgare) were evaluated against Sclerotinia sclerotiorum. Effects of the essential oils on morphological structures of hyphae and sclerotia were studied under light and scanning electron microscopes (SEM).

METHODS AND RESULTS

Inhibitory effects of volatile and contact phases of the essential oils used were determined on hyphae and sclerotia. Both essential oils have a marked antifungal effect against S. sclerotiorum. Soil amendment with essential oils has significant effect on reducing sclerotial viability. Both essential oils significantly inhibited the fungal growth in soil, thereby increasing the number of surviving tomato seedling by 69.8% and 53.3%, respectively. Light and SEM observations on pathogen hyphae and sclerotia revealed considerable morphological alterations in hyphae and sclerotia.

CONCLUSIONS

The significant reduction in the mycelial growth and germination of sclerotia would greatly reduce the pathogen inoculum source. This may influence the rate of disease development in soil.

SIGNIFICANCE AND IMPACT OF THE STUDY

Considering the reduction in the number of diseased plants in infested soil amended with essential oils, we concluded that oregano and fennel essential oils could be used as possible bio fungicides alternative to synthetic fungicides against phytopathogenic fungi.

Antifungal activity of essential oils against filamentous fungi determined by broth microdilution and vapour contact methods

AIMS

The in vitro activity of some essential oils (EO) (thyme red, fennel, clove, pine, sage, lemon balm and lavender) against clinical and environmental fungal strains was determined.

METHODS AND RESULTS

The minimal inhibitory concentrations were determined by a microdilution method in RPMI 1640 and by a vapour contact assay. The composition of oils was analysed by gas chromatography (GC) and GC/mass spectrometry. The results indicated that the oils antifungal activity depended on the experimental assay used. The inhibiting effects of EO in vapour phase were generally higher than those in liquid state. According to both methods thyme red and clove were found to be the oils with the widest spectrum of activity against all fungi tested.

CONCLUSIONS

Despite the differences between the two methods, our results demonstrate that some EO are very active on dermatophytes and dematiaceous fungi. However, more data will be necessary to confirm this good in vitro efficacy.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study could identify candidates of EO for developing alternative methods to control environmental and clinically undesirable filamentous fungi.

Antifungal activity of the essential oil of Thymus pulegioides on Candida, Aspergillus and dermatophyte species

The composition of the essential oil of Thymus pulegioides and its antifungal activity on Candida, Aspergillus and dermatophyte fungal strains were studied. Essential oil from the aerial parts of the plant was obtained by hydrodistillation and analysed by GC and GC-MS. The oil showed high contents of carvacrol and thymol. The MIC and minimal lethal concentration were used to evaluate the antifungal activity against Candida (seven clinical isolates and four ATCC type strains), Aspergillus [five clinical isolates, and two Colección Española de Cultivos Tipo (CECT) and two ATCC type strains] and five clinical dermatophyte strains. Antifungal activity was evaluated for the essential oil and for its main components. To clarify its mechanism of action on yeasts and filamentous fungi, flow-cytometric studies of cytoplasmic membrane integrity were performed, and the effect on the amount of ergosterol was investigated. Results showed that T. pulegioides essential oil exhibited a significant activity against clinically relevant fungi, mainly due to lesion formation in the cytoplasmic membrane and a considerable reduction of the ergosterol content. The present study indicates that T. pulegioides essential oil has considerable antifungal activity, deserving further investigation for clinical applications.

Anticandidal low molecular compounds from higher plants with special reference to compounds from essential oils

The most active low molecular weight compounds from higher plants against Candida species are compiled from a database of antimicrobials (Amicbase) to find out new hints on their mechanism of action. The selected compounds possess strong inhibitory activities in vitro against Candida species either in the agar diffusion test, bioautography, agar dilution test, serial dilution test, or activity in the vapour phase. The test conditions are listed thoroughly and aspects of the different methods and recent developments in the testing of anticandidal drugs are discussed. The anticandidal spectra of drugs, antiseptics, and disinfectants licensed on the major markets are given for comparison of activities with compounds from natural sources. So far known mechanisms of action are described and some new structure-activity relationships are deduced from relationships between biological activities and chemical and physical parameters. Main specific targets of natural anticandidals are the ergosterol pathway, respiratory chain, and chitin biosynthesis.

Antifungal activity of Juniperus essential oils against dermatophyte, Aspergillus and Candida strains

AIMS

The increasing resistance to antifungal compounds and the reduced number of available drugs led us to search therapeutic alternatives among aromatic plants and their essential oils, empirically used by antifungal proprieties. In this work the authors report on the antifungal activity of Juniperus essential oils (Juniperus communis ssp. alpina, J. oxycedrus ssp. oxycedrus and J. turbinata).

METHODS AND RESULTS

Antifungal activity was evaluated by determination of MIC and MLC values, using a macrodilution method (NCCLS protocols), on clinical and type strains of Candida, Aspergillus and dermatophytes. The composition of the oils was ascertained by GC and GC/MS analysis. All essential oils inhibited test dermatophyte strains. The oil from leaves of J. oxycedrus ssp. oxycedrus is the most active, with MIC and MLC values ranging from 0.08-0.16 microl ml(-1) to 0.08-0.32 microl ml(-1), respectively. This oil is mainly composed of alpha-pinene (65.5%) and delta-3-carene (5.7%).

CONCLUSIONS

J. oxycedrus ssp. oxycedrus leaf oil proved to be an emergent alternative as antifungal agent against dermatophyte strains. delta-3-Carene, was shown to be a fundamental compound for this activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results support that essential oils or some of their constituents may be useful in the clinical management of fungal infections, justifying future clinical trials to validate their use as therapeutic alternatives for dermatophytosis.