Enhanced antifungal activity of ketoconazole by Euphorbia characias latex against Candida albicans

Euphorbia characias: Phytochemistry and Biological Activities

The aim of this review is to summarize all the compounds identified and characterized from Euphorbia characias, along with the biological activities reported for this plant. Euphorbia is one of the greatest genera in the spurge family of Euphorbiaceae and includes different kinds of plants characterized by the presence of milky latex. Among them, the species Euphorbia characias L. is an evergreen perennial shrub widely distributed in Mediterranean countries. E. characias latex and extracts from different parts of the plant have been extensively studied, leading to the identification of several chemical components such as terpenoids, sterol hydrocarbons, saturated and unsaturated fatty acids, cerebrosides and phenolic and carboxylic acids. The biological properties range between antioxidant activities, antimicrobial, antiviral and pesticidal activities, wound-healing properties, anti-aging and hypoglycemic properties and inhibitory activities toward target enzymes related to different diseases, such as cholinesterases and xanthine oxidase. The information available in this review allows us to consider the plant E. characias as a potential source of compounds for biomedical research.

Eucalyptus camaldulensis, Citrus aurantium, and Citrus sinensis Essential Oils as Antifungal Activity against Aspergillus flavus, Aspergillus niger, Aspergillus terreus, and Fusarium culmorum

Several molds are able to colonize wood and many building products or solid wood causing losses for their valuable uses. Essential oils (EOs) from aromatic plants can be used as an ecofriendly biofungicide against the growth of several molds. EOs from Eucalyptus camaldulensis, Citrus aurantium, and C. sinensis have a broad-spectrum antimicrobial activity. EOs from of E. camaldulensis air-dried aerial parts, C. aurantium leaf and C. sinensis peel, and their combinations (1:1 v/v) were evaluated for their antifungal activity against the growth of four common mold fungi (Aspergillus flavus, A. niger, A. terreus, and Fusarium culmorum). The chemical compositions of the EOs were analyzed with GC/MS. The main compounds in EO from E. camaldulensis were spathulenol (20.84%), eucalyptol (12.01%), and sabinene (9.73%); in C. aurantium were linalyl acetate (42.29%), and linalool (29.76%); and in C. sinensis were D-limonene (73.4%) and γ-terpinene (22.6%). At 50 µL/mL, C. sinensis EO showed the highest fungal mycilial growth inhibition (FMGI) percentage (86.66%) against A. flavus. C. sinensis, E. camaldulensis, and E. camaldulensis/C. sinensis showed FMGI values of 96%, 91.66%, and 75.66% respectively, against A. niger. EOs from C. aurantium and C. sinensis showed potent activity against A. terreus (100% FMGI), while C. aurantium/E. camaldulensis and E. camaldulensis/C. sinensis showed FMGI values of 74.33% and 70.66%, respectively. Potent activity against F. culmorum with 100% was observed as the application of E. camaldulensis and C. sinensis EOs at 50 µL/mL, while E. camaldulensis/C. sinensis (50 µL/mL) showed FMGI value of 65.66%. The results suggest using the EOs and their combinations from E.camaldulensis, C. aurantium, and C. sinensis as a biofungicide against molds. The potent properties of EOs offer the possibility of using them as eco-friendly, safe, and cost-effective antimicrobials for molds that could cause discoloration of the wood packaging or food spoilage.

In vivo wound-healing activity of Euphorbia characias subsp. wulfenii: Isolation and quantification of quercetin glycosides as bioactive compounds

ETHNOPHARMACOLOGICAL RELEVANCE

The latex and the aerial parts of Euphorbia characias L. (Euphorbiaceae) have been used as medicinal plant to treat wounds and warts in traditional medicine.

AIM OF THE STUDY

The effect of the plant extract was tested in vivo and in vitro with experimental models to find scientific evidence for traditional use in wound healing. Potentially active wound-healer compounds were isolated from the active fraction using fractionation procedures under the guidance of biological assay and the possible role of the compounds in the wound healing process was also determined.

MATERIAL AND METHODS

N-hexane, ethyl acetate, and methanol extracts were successively prepared from the aerial parts of E. characias subsp. wulfenii. The extracts were tested with linear incision, circular excision wound models and the hydroxyproline assay method to assess the wound-healing activity. The inhibition of the increase in capillary permeability induced by acetic acid, an acute inflammation model, was used to assay the anti-inflammatory activity. Different chromatographic separation techniques on sephadex and silica gel columns, and bioassay guided assay techniques have been used to isolate the active compounds of the plant. Moreover, hyaluronidase, collagenase and elastase enzymes inhibitory effect of active principle were investigated in vitro to find out the mechanism of action.

RESULTS

The methanol (MeOH-ex) extract of the aerial parts of E. characias subsp. wulfenii showed significant wound healing activity (linear incision wound model: 43.04%; circular excision wound model 65.24%) and anti-inflammatory activity (34.74%). The methanol extract was separated into its fractions by column chromatography for isolation of efficient compounds. Biological activity of the fractions were assessed and further isolation and purification processes have been carried out in the active fraction. Isolation studies were carried out from the MeOH-ex fraction to obtain active constituents and their structures were elucidated to be quercetin-3-O-rhamnoside (quercitrin), quercetin-3-O-galactoside (hyperoside), and quercetin-3-O-arabinoside (guaijaverin). Further in vitro and in vivo assays showed that quercetin derivatives were responsible for the wound-healing activity of the plant, and also found to be significant anti-elastase and anti-collagenase activities. The amounts of three compounds, isolated from active fraction, were determined by using high performance liquid chromatography. Calibration equation was calculated with dilutions, prepared from pure substances, and assay was performed in total extract, prepared from E. characias subsp. wulfenii. It was detected that the plant had 1.22% quercitrin, 0.35% hyperoside, and 0.11% guaijaverin. The validation of the analytical method was performed by linearity, precision, limit of detection, and limit of quantification parameters.

CONCLUSION

Present study supported the traditional use of the aerial parts E. characias subsp. wulfenii as wound healer and quercetin derivatives were isolated as active components from the active fraction by using bioassay-guided fractionation technique.

Comparative nutritional value and antimicrobial activities between three Euphorbia species growing in Saudi Arabia

Plants are excellent sources of nutrition and highly bioactive substances that might use in the development of new drugs and pharmaceutical agents. Three species of the Genus Euphorbia (Family Euphorpiaceae), namely; Euphorbia granulata Forssk, Euphorbia helioscobia L., and Euphorbia hirta Linn growing in Ryiadh, KSA were air-dried, powdered, and their active materials were extracted with alcohol. The nutritional value phytochemical constituents and antimicrobial activity of the plants were determined. The chemical contents were similar in the three species; however, lipid profile of the plants showed that the stearic acid and lignoceric acid were detected only in E. helioscopia and E. hirta, while palmitoleic acid was detected only in E. hirta. The percentage of unsaturated fatty acid methyl esters were 52.48%, 69.39% and 66.52% in Euphorbia granulate, Euphorbia helioscobia, E. hirta, respectively. Three compounds, 1-ethoxypentacosane, heptacosan-1-ol and β-sitosterol were isolated from the three plant extracts and identified using different spectroscopic analysis. The percentage of crude protein was 43.65%, 25.00% and 18.75% in E. granulata, E. helioscobia, and E. hirta, respectively. The free amino acids and amino acid composition were quantitatively determined using amino acid analyzer. All the plant extracts were active against bacterial and fungal test organisms, however, the antimicrobial activity were varied according to both the Euphorbia species and the test organism.

The In Vitro Antimicrobial Effects of Lavandula angustifolia Essential Oil in Combination with Conventional Antimicrobial Agents

The paper focuses on the in vitro antimicrobial activity of Lavandula angustifolia Mill. (lavender) essential oil in combination with four commercial antimicrobial agents. Stock solutions of chloramphenicol, ciprofloxacin, nystatin, and fusidic acid were tested in combination with L. angustifolia essential oil. The antimicrobial activities of the combinations were investigated against the Gram-positive bacterial strain Staphylococcus aureus (ATCC 6538) and Gram-negative Pseudomonas aeruginosa (ATCC 27858) and Candida albicans (ATCC 10231) was selected to represent the yeasts. The antimicrobial effect was performed using the minimum inhibitory concentration (MIC) microdilution assay. Isobolograms were constructed for varying ratios. The most prominent interaction was noted when L. angustifolia essential oil was combined with chloramphenicol and tested against the pathogen P. aeruginosa (ΣFIC of 0.29). Lavendula angustifolia essential oil was shown in most cases to interact synergistically with conventional antimicrobials when combined in ratios where higher volumes of L. angustifolia essential oil were incorporated into the combination.

Anti-dermatophyte efficacy and environmental safety of some essential oils commercial and in vitro extracted pure and combined against four keratinophilic pathogenic fungi

AIM

Establish new biocontrol practices with low persistence in the environment against dermatophyte causing mycosis.

METHODS

Antimycotic activity of twenty-six plant-derived commercial essential oils (EOs) was evaluated against four dermatophyte keratinophilic fungi (Microsporum canis, Epidermophyton floccosum, Trichophyton rubrum and Trichophyton mentagrophytes). Commercial EOs which showed the strongest mycelial growth inhibitions were selected and re-extracted in vitro from fresh plant samples. Minimal inhibition concentration (MIC) and antifungal index (AI) of pure and combined extracted oils and were evaluated. All samples were collected and examined during the year of 2014.

RESULTS

The results revealed that commercial EOs of Prunus armeniaca, Prunus dulcis var. amara, Olea europaea and Mentha piperita were the most potent antidermatophyte. The mixture of the extracted four oils was the strongest fungicides followed by the alternative two-oil combined extractions then pure extracted oils. MIC was at 50, 25 and 12.5 μg/disc for pure oils, two-oil combinations and four-oil mixture, respectively. Achieved values of AI were found variable.

CONCLUSION

Using of natural products like plant-derived EOs instead of chemotherapy on pathogens can be regarded as an environmental safety mode of diseases control.

Synergistic effect of Myrtus communis L. essential oils and conventional antibiotics against multi-drug resistant Acinetobacter baumannii wound isolates

Acinetobacter baumannii is a rapidly emerging, highly resistant clinical pathogen with increasing prevalence. In recent years, the limited number of antimicrobial agents available for treatment of infections with multi-drug resistant (MDR) strains reinforced tendency for discovery of novel antimicrobial agents or treatment strategies. The aim of the study was to determine antimicrobial effectiveness of three Myrtus communis L. essential oils, both alone and in combination with conventional antibiotics, against MDR A. baumannii wound isolates. The results obtained highlighted the occurrence of good antibacterial effect of myrtle oils when administered alone. Using checkerboard method, the combinations of subinhibitory concentrations of myrtle essential oils and conventional antibiotics, i.e. polymixin B and ciprofloxacine were examined. The results proved synergism among M. communis L. essential oils and both antibiotics against MDR A. baumannii wound isolates, with a FIC index under or equal 0.50. Combination of subinhibitory concentrations of essential oils and ciprofloxacin most frequently reduced bacterial growth in synergistic manner. The similar has been shown for combination with polymyxin B; furthermore, the myrtle essential oil resulted in re-sensitization of the MDR wound isolates, i.e. MICs used in combination were below the cut off for the sensitivity to the antibiotic. Time-kill curve method confirmed efficacy of myrtle essential oil and polymyxin B combination, with complete reduction of bacterial count after 6h. The detected synergy offers an opportunity for future development of treatment strategies for potentially lethal wound infections caused by MDR A. baumannii.

Anti-Candida, anti-enzyme activity and cytotoxicity of 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides

Because of the need for more effective and less harmful antifungal therapies, and interest in the synthesis of new carboximidamides, the goal of this study was to determine the antifungal and anti-enzyme activities of some new pyrazole carboximidamides and their cytotoxicity. For this purpose, tests were performed to evaluate: minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC); production of proteinases and phospholipase, and cytotoxicity of the extracts. Data were analyzed by ANOVA and Tukey Tests (α = 5%). The results were: MIC and MFC ≥ 62.5 μg/mL (C. albicans, C. parapsilosis, C. famata, C. glabrata, and Rhodotorula mucillaginosa) and MIC and MFC ≥ 15.6 μg/mL (C. lipolytica). The values of proteinase and phospholipase (Pz) of C. albicans before and after exposure to the compounds were: 0.6 (±0.024) and 0.2 (±0.022) and 0.9 (±0.074) and 0.3 (±0.04), respectively. These proteinase results were not significant (p = 0.69), but those of phospholipase were (p = 0.01), and 15.6 μg/mL was the most effective concentration. The cytotoxicity means were similar among the tests (p = 0.32). These compounds could be useful as templates for further development through modification or derivatization to design more potent antifungal agents. Data from this study provide evidence that these new pyrazole formulations could be an alternative source for the treatment of fungal infections caused by Candida. However, a specific study on the safety and efficacy of these in vivo and clinical trials is still needed, in order to evaluate the practical relevance of the in vitro results.

Stability-Indicating Validated Novel RP-HPLC Method for Simultaneous Estimation of Methylparaben, Ketoconazole, and Mometasone Furoate in Topical Pharmaceutical Dosage Formulation

A simple, specific, precise, and accurate RP-HPLC method has been developed and validated for simultaneous estimation of Methylparaben (MP), Ketoconazole (KT), and Mometasone Furoate (MF) topical pharmaceutical dosage formulation. The separation was achieved by Waters X Terra C18 column using mobile phase consisting of buffer (triethyl amine in water, pH adjusted to 6.5 with glacial acetic acid)-acetonitrile (40 : 60, v/v) at a flow rate of 1.5 mL/min and detection at 250 nm. The method showed linearity with correlation coefficient <0.9999 over the range of 0.12–15.2 μg/mL, 0.67–149.4 μg/mL, and 0.42–7.6 μg/mL for MP, KT, and MF, respectively. The mean recoveries were found to be in the range of 99.9–101.1% for all the components. The method was validated as per the ICH guidelines for linearity, limit of detection, limit of quantification, accuracy, precision, robustness and solution stability. Stability indicating capability of the developed method was established by analyzing forced degradation of samples in which spectral purity of MP, KT, and MF along with separation of degradation products from analytes peak was achieved. The method can be successfully applied for routine analysis of quantitative determination of MP, KT, and MF in pharmaceutical dosage form.

Anti-ulcerative colitis activity of compounds from Euphorbia granuleta Forssk

The aim of the present study was to evaluate the anti-ulcerative colitis (UC) activity of the total alcohol extracts of Euphorbia granuleta Forssk. (Euphorpiaceae), isolate and identify the active compounds that could be responsible for the activity, in addition to determination of the possible mechanism of action. Six compounds were isolated and identified from this plant: three phenolic compounds (kampferol, kampferol-3-glucoside and kampferol-3-galactoside) in addition to three steroidal compounds (1-ethoxypentacosane, heptacosan-1-ol and β-sitosterol). Three compounds (heptacosan-1-ol, β-sitosterol and kampferol-3-galactoside) were found to be responsible for the anti-UC activity of E. granuleta extract. The anti-UC activity of these compounds may be explained by reducing the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α), in addition to reduction of colonic malondialdehyde (MDA) contents. No side effects were reported on liver and kidney functions. The active compounds reduced both serum TNF-α and mucosal MDA levels.

Chemosensitization as a means to augment commercial antifungal agents

Antimycotic chemosensitization and its mode of action are of growing interest. Currently, use of antifungal agents in agriculture and medicine has a number of obstacles. Foremost of these is development of resistance or cross-resistance to one or more antifungal agents. The generally high expense and negative impact, or side effects, associated with antifungal agents are two further issues of concern. Collectively, these problems are exacerbated by efforts to control resistant strains, which can evolve into a treadmill of higher dosages for longer periods. This cycle in turn, inflates cost of treatment, dramatically. A further problem is stagnation in development of new and effective antifungal agents, especially for treatment of human mycoses. Efforts to overcome some of these issues have involved using combinations of available antimycotics (e.g., combination therapy for invasive mycoses). However, this approach has had inconsistent success and is often associated with a marked increase in negative side effects. Chemosensitization by natural compounds to increase effectiveness of commercial antimycotics is a somewhat new approach to dealing with the aforementioned problems. The potential for safe natural products to improve antifungal activity has been observed for over three decades. Chemosensitizing agents possess antifungal activity, but at insufficient levels to serve as antimycotics, alone. Their main function is to disrupt fungal stress response, destabilize the structural integrity of cellular and vacuolar membranes or stimulate production of reactive oxygen species, augmenting oxidative stress and apoptosis. Use of safe chemosensitizing agents has potential benefit to both agriculture and medicine. When co-applied with a commercial antifungal agent, an additive or synergistic interaction may occur, augmenting antifungal efficacy. This augmentation, in turn, lowers effective dosages, costs, negative side effects and, in some cases, countermands resistance.

Identification of major degradation products of ketoconazole

Analytical methods were developed for the identification of major degradation products of Ketoconazole, an antifungal agent. The stressed degradation of Ketoconazole drug substance was performed under acid, base, thermal, photo and oxidative stress conditions. The major degradation was observed under acid, base and oxidative stress conditions. The degradation study was performed on Inertsil ODS-3V, length 100 X diameter 4.6 mm, particle size 3 μm column using gradient method. These degradants were identified by LC-MS technique.

Synergism between natural products and antibiotics against infectious diseases

Antibiotics have been effective in treating infectious diseases, but resistance to these drugs has led to the emergence of new and the reemergence of old infectious diseases. One strategy employed to overcome these resistance mechanisms is the use of combination of drugs, such as beta-lactams together with beta-lactamase inhibitors. Several plant extracts have exhibited synergistic activity against microorganisms. This review describes in detail, the observed synergy and mechanism of action between natural products including flavonoids and essential oils and synthetic drugs in effectively combating bacterial, fungal and mycobacterial infections. The mode of action of combination differs significantly than that of the same drugs acting individually; hence isolating a single component may lose its importance thereby simplifying the task of pharma industries.

Antibacterial effect of some essential oils administered alone or in combination with Norfloxacin

The objective of the present study was that of verifying a possible synergistic antibacterial effect between Pelargonium graveolens [Lis-Balchin, M., Deans, S.G., Hart, S., 1996. Bioactive Geranium oils from different commercial sources. J. Essential Oil Res. 8, 281-290.] essential oil (and its main components) and Norfloxacin antibiotic. As a first step growth inhibition by some types of essential oils was assessed in five microbial species. The antimicrobial effects of P. graveolens oil, as well as those of its components, were evaluated by means of the agar dilution method (ADM) against Bacillus cereus ATCC 11778, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 6538 and S. aureus ATCC 29213. The results obtained highlighted the occurrence of a pronounced synergism between P. graveolens essential oil and Norfloxacin against three of the five bacterial species under study with a FIC index in the 0.37-0.50 range. Such antibacterial effects were also shown to increase, although to a lesser extent, when Norfloxacin was given with the main components of P. graveolens essential oil.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combination of Norfloxacin with either P. graveolens essential oil, or with some of the main components of this latter, in the treatment of infections caused by some bacterial species is likely to reduce the minimum effective dose of Norfloxacin thus minimizing the side effects of the antibiotic.

Antifungal effects of the volatile oils from Allium plants against Trichophyton species and synergism of the oils with ketoconazole

In an attempt to develop stable and safe antifungal agents from natural products (daily foodstuffs in particular), the activities of essential oils from Allium sativum for. pekinense, A. cepa, and A. fistulosum against three Trichophyton species responsible for severe mycoses in humans were investigated and compared with activity of allicin in this study. The fungistatic activities of Allium oils were evaluated by the broth dilution method and disk diffusion assay. The combined effects of Allium oils with ketoconazole were tested by the checkerboard titer test. Among the tested oils, A. sativum for. pekinense oil exhibited the strongest inhibition of growth of T. rubrum, T. erinacei, and T. soudanense with MICs (minimum inhibiting concentrations) of 64microg/ml, while the activities of A. cepa and A. fistulosum were relatively mild. The inhibiting activities of the oils on Sabouraud agar plates were dose dependent against Trichophyton species. Additionally, these oils showed significant synergistic antifungal activity when combined with ketoconazole in the checkerboard titer test and disk diffusion test.

Anti-Candida effects of estragole in combination with ketoconazole or amphotericin B

The anti-Candida effects of estragole combined with amphotericin B or ketoconazole, commonly used antifungal drugs for treatment of candidasis, were evaluated in this study. The fractional inhibitory concentration (FIC) indices of both estragole combined with ketoconazole against C. albicans and C. utilis calculated from the checkerboard microtiter assay were 0.28 and 0.50 respectively, indicating significant synergism. These drug combinations exhibited additive effects against C. tropicalis, with FIC index of 0.75. Consistent for the most part with the results from the checkerboard titer tests, the time-kill curves of the tested samples also indicated significant synergism or additive effect between ketoconazole and estragole against the Candida species evaluated. In contrast, amphotericin B showed antagonism in combination with estragole in most experiments of this study. Thus, we have shown the synergistic combination effects between estragole and ketoconazole, which may be effective combinations for the treatment of Candida infections.

Antifungal effects of herbal essential oils alone and in combination with ketoconazole against Trichophyton spp

AIMS

To determine the effects of herbal essential oils on Trichophyton spp. growth and to evaluate the effects of Pelargonium graveolens oil and its main components citronellol and geraniol combined with ketoconazole against Trichophyton spp.

METHODS AND RESULTS

Growth inhibition of six Trichophyton spp. by herbal essential oils was accessed and the combined effects of P. graveolens oil and its main components citronellol and geraniol were evaluated using a checkerboard microtitre assay against T. schoenleinii, T. erinacei and T. soudanense. The essential oil fraction of P. graveolens and its main components, geraniol and citronellol, exhibited strong synergism with ketoconazole against T. schoenleinii and T. soudanense, with fractional inhibitory concentration (FIC) indices in the range of 0.18-0.38.

CONCLUSIONS

The antifungal effects of ketoconazole against Trichophyton spp. are enhanced significantly by administering it in combination with the essential oil fraction of P. graveolens or its main components, because of strong synergism, especially against T. soudanense and T. schoenleinii.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combination of ketoconazole and the essential oil fraction from P. graveolens or its main components for treatment of infections caused by Trichophyton species may reduce the minimum effective dose of ketoconazole, and thus minimize the side-effects of ketoconazole.

Essential oil compounds fromAgastache rugosa as antifungal agents againstTrichophyton species

The antifungal activities of the essential oil from Agastache rugosa and its main component, estragole, combined with ketoconazole, one of the azole antibiotics commonly used to treat infections caused by Trichophyton species, were evaluated in this study. The combined effects were measured by the checkerboard microtiter and the disk diffusion tests, against T. erinacei, T. mentagrophytes, T. rubrum, T. schoenleinii and T. soudanense. Susceptibility of the five Trichophyton species to the oil alone, or ketoconazole alone, differed distinctly. The fractional inhibitory concentration indices (FICI) of ketoconazole combined with estragole or A. rugosa essential oil, against the tested Trichophyton species, were between 0.05 and 0.27, indicating synergistic effects. These drug combinations exhibited the most significant synergism against T. mentagrophytes, with FICIs of 0.05 and 0.09 for estragole and the essential oil fraction from A. rugosa, respectively. Isobolograms based on the data from checkerboard titer tests also indicated significant synergism between ketoconazole and the Agastache oil fraction or estragole, against the Trichophyton species evaluated. Trichophyton susceptibility to ketoconazole was significantly improved by combination with the Agastache rugosa oil fraction or its main component, estragole.

Antifungal activities of nine traditional Mexican medicinal plants

Eighteen plant extracts from nine traditional Mexican medicinal plants were tested for antifungal activity against two dermatophyte fungal species (Trichophyton mentagrophytes and Trichophyton rubrum), one non-dermatophyte (Aspergillus niger), and one yeast (Candida albicans). The strongest effect was manifested by the hexane extracts from Eupatorium aschenbornianum and Sedum oxypetalum, as well as the methanol extracts from Lysiloma acapulcensis and Annona cherimolia.

Anti-Aspergillus activities of plant essential oils and their combination effects with ketoconazole or amphotericin B

The essential oils from Cedrus atlantica, Styrax tonkinensis, Juniperus communis, Lavandula angustifolia, Melaleuca alternifolia, Pelargonium graveolens, Pogesternon patchouli and Rosmarinus officinalis were analyzed by GC-MS. Antifungal activities of the oils were investigated by disk diffusion assay and the broth dilution method against Aspergillus niger and A. flavus. The effects of geraniol and the essential oil fraction from P. graveolens on the antifungal activity of amphotericin B and ketoconazole were examined using a checkerboard microtiter assay against both Aspergillus fungi. Most of the tested essential oils, with the exception of C. atlantica, J. communis, and P. patchouli, significantly inhibited growth of A. niger and to a lesser extent that of A. flavus, with MICs (minimal inhibitory concentrations) in the range 0.78-12.5 mg/mL. The essential oil fraction of P. graveolens and its main components, geraniol and citronellol, exhibited additive effects with amphotericin B and with ketoconazole against both Aspergillus species, resulting in fractional inhibitory concentration (FIC) indices ranging from 0.52 to 1.00.

Antifungal activity of the essential oil of Agastache rugosa Kuntze and its synergism with ketoconazole

AIMS

To evaluate the fungitoxic activity of the essential oil of Agastache rugosa alone and to determine its combination effect with ketoconazole against Blastoschizomyces capitatus.

METHODS AND RESULTS

The antifungal activities of the essential oil of A. rugosa and its main constituent estragole were investigated using the broth microdilution, disk diffusion methods and checkerboard microtitre assay. Both estragole and the essential oil exhibited strong activities against the tested fungi and showed synergism with ketoconazole against B. capitatus.

CONCLUSIONS

Both estragole and the essential oil of A. rugosa have significant growth-inhibiting activities against B. capitatus showing strong synergistic effect with ketoconazole.

SIGNIFICANCE AND IMPACT OF THE STUDY

The essential oil of A. rugosa, combined with ketoconazole, may be particularly useful against B. capitatus, a rare pathogenic fungus documented to cause severe and fatal mycoses in immunocompromised patients.