Anticandidal activity of the essential oils of Thymus maroccanus and Thymus broussonetii and their synergism with amphotericin B and fluconazol

Antibacterial Activity of Essential Oils Combinations based on Thymus broussonnetii, and Their Synergism with some Antibiotics

The present study aimed to evaluate the antibacterial activity of the essential oil (EO) of Moroccan endemic Thymus broussonnetii alone, and in combination with EOs obtained from selected medicinal plants, namely Myrtus communis, Artemisia herba alba, Thymus pallidus, Thymus satureioides, Teucrium polium, and Rosmarinus officinalis. The synergistic interactions between the most effective combinations based on T. broussonnetii EO with two conventional antibiotics (streptomycin and ciprofloxacin) were also investigated. T. broussonnetii EO possessed a higher inhibitory activity against tested pathogenic bacteria with inhibition zone diameter (IZ) ranging from 21.61 ± 0.03 to 40.09 ± 0.02 mm, and MIC values between 0.140 mg/mL and 0.280 mg/mL. M. communis, A. herba alba, T. pallidus, T. satureioides, T. polium, and R. officinalis EOs showed moderate to weak antibacterial activity. Among tested EO mixtures, the highest synergistic antibacterial effect was recorded with the EO combination of T. broussonnetii and T. pallidus against S. aureus, E. coli, and S. enterica (FICI = 0.258). This EO combination was also the most effective mixture to synergistically enhance the antibacterial activity of the two antibiotics with up to a 128-fold increase, particularly against the gram-negative E. coli. These findings suggest that T. broussonnetii EO may be an interesting source of natural antimicrobials, for use in combination therapies with other plant EOs, and with conventional antimicrobial drugs to tackle the emergence of multidrug-resistant bacteria.

Thymus atlanticus: A Source of Nutrients with Numerous Health Benefits and Important Therapeutic Potential for Age-Related Diseases

Thymus atlanticus (Lamiaceae) is a plant endemic to the Mediterranean basin that is found in significant quantities in the arid regions of Morocco. Thymus atlanticus is used in traditional medicine to treat infectious and non-infectious diseases. It is also used for the isolation of essential oils and for the seasoning of many dishes in the Mediterranean diet. The major constituents of Thymus atlanticus are saponins, flavonoids, tannins, alkaloids, various simple and hydroxycinnamic phenolic compounds, and terpene compounds. Several of these compounds act on signaling pathways of oxidative stress, inflammation, and blood sugar, which are parameters often dysregulated during aging. Due to its physiochemical characteristics and biological activities, Thymus atlanticus could be used for the prevention and/or treatment of age-related diseases. These different aspects are treated in the present review, and we focused on phytochemistry and major age-related diseases: dyslipidemia, cardiovascular diseases, and type 2 diabetes.

Chemical Composition, Antioxidant and Antibacterial Activities of Thymus broussonetii Boiss and Thymus capitatus (L.) Hoffmann and Link Essential Oils

Thymus capitatus and Thymus broussonnetii are two Moroccan endemic medicinal plants used traditionally by the local population. The present study aims to investigate their essential oil chemical composition, antioxidant and antibacterial activities. The chemical composition of the essential oils was determined using the GC-MS analysis, the antioxidant activity assessed using DPPH and FRAP methods while the antimicrobial activity was evaluated against nine bacteria species tested (Enterococcus faecalis, Serratia fonticola, Acinetobacter baumannii, Klebsiella oxytoca, sensitive Klebsiella pneumoniae, sensitive Escherichia coli, resistant Escherichia coli, resistant Staphylococcus aureus and Enterobacter aerogenes). The major identified compounds of T. capitatus essential oil where carvacrol (75%) and p-cymene (10.58%) while carvacrol (60.79%), thymol (12.9%), p-cymene (6.21%) and γ-terpinene (4.47%) are the main compounds in T. broussonnetii essential oil. The bioactivity of the essential oils of the two species of thyme was explained by their richness in oxygenated monoterpenes known for their great effectiveness with an IC₅₀ of 3.48 ± 0.05 and 4.88 ± 0.04 μL/mL and EC₅₀ of 0.12 ± 0.01 and 0.20 ± 0.02 μL/mL in the DPPH and FRAP assays, respectively, with an important antibacterial activity. These results encourage the use of these plants as a source of natural antioxidants, and antibacterial additives, to protect food from oxidative damage and to eliminate bacteria that are responsible for nosocomial infections.

A review on Moroccan Thymus species: Traditional uses, essential oils chemical composition and biological effects

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Thymus is among the most important genera in the Lamiaceae family with 215 species and is widely distributed globally, mainly in the Mediterranean region. The genus contains many medicinal plants used in traditional Moroccan medicine for a long time in treating diverse diseases.

AIM OF THE REVIEW

This review describes the traditional uses, biological activities and chemical composition of essential oils (EOs) obtained from Thymus species growing in Morocco.

MATERIALS AND METHODS

Information related to the traditional uses, essential oils chemical composition and biological activities on Moroccan Thymus species were obtained using the electronic databases Web of science, Scopus, SciFinder, Pubmed and Google Scholar.

RESULTS

Moroccan Thymus species have been used in treatment of several diseases, namely diabetes, digestive, circulatory, genital, nervous, urinary, skin and respiratory diseases. Diverse biological activities of Moroccan Thymus species EOs have been reported, such as antibacterial, antifungal, antioxidant, anti-proliferative, anti-tumoral, insecticidal, larvicidal, nematicide, anti-inflammatory, anti-cyanobacterial and anti-acetylcholinesterase. The chemical compositions of Thymus EOs is primarily composed of monoterpenes.

New Insight into the Chemical Composition, Antimicrobial and Synergistic Effects of the Moroccan Endemic Thymus atlanticus (Ball) Roussine Essential Oil in Combination with Conventional Antibiotics

This study reported the volatile profile, the antimicrobial activity and the synergistic potential of essential oil (EO) from the Moroccan endemic Thymus atlanticus (Ball) Roussine, in combination with the antibiotics ciprofloxacin and fluconazole for the first time, to the best of our knowledge. The EO chemical composition was determined by gas chromatography coupled to mass spectrometry (GC-MS) analysis and the antimicrobial activity assessed by the disc diffusion method against three Gram positive (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and one clinical isolate, Klebsiella pneumonia). The antifungal activity was evaluated in four pathogenic yeasts (Candida albicans, C. glabrata, C. krusei and C. parapsilosis). The minimum inhibition concentration (MIC) and the synergistic effect with ciprofloxacin and fluconazole were determined by the two-fold dilution technique and checkerboard test, respectively. Twenty-one constituents were identified by GC-MS in the EO, including carvacrol (21.62%) and borneol (21.13%) as the major components. The EO exhibited a significant antimicrobial activity with inhibition zones ranging from 0.7 mm to 22 mm for P. aeruginosa and B. subtilis, respectively, and MIC values varying from 0.56 mg/mL to 4.47 mg/mL. The fractional inhibitory concentration index (FICI) values ranged from 0.25 to 0.50 for bacteria and from 0.25 to 0.28 for yeasts. The maximum synergistic effect was observed for K. pneumonia with a 256-fold gain of antibiotic MIC. Our results have suggested that EO from T. atlanticus may be used alone or in association with antibiotics as a new potential alternative to prevent and control the emergence of resistant microbial strains both in the medical field and in the food industry.

Phytochemistry and Pharmacology of Thymus broussonetii Boiss

Thymus broussonetii Boiss (T. broussonetii) is a rare medicinal and aromatic plant. It is widely used in traditional medicine to treat several diseases, including diarrhea, fever, cough, irritation, skin diseases, rheumatism, respiratory ailments, influenza, and digestion problems. In this review, we have critically summarized previous data on T. broussonetii about its phytochemistry, botanical and geographical distribution, toxicological investigation, and pharmacological properties. Using scientific research databases such as Wiley Online, SciFinder, ScienceDirect, PubMed, SpringerLink, Web of Science, Scopus Wiley Online, and Google Scholar, the data on T. broussonetii were collected and discussed. The presented data regrouped bioactive compounds and biological activities of T. broussonetii. The findings of this work showed that essential oils and extracts of T. broussonetii exhibited numerous pharmacological activities (in vitro and in vivo), particularly antibacterial, antifungal, antioxidant, anticancer, anti-inflammatory, insecticidal, antipyretic, antinociceptive, and immunological and behavioral effects. While toxicological studies of T. broussonetii essential oils and extracts are lacking, modern scientific tools revealed the presence of different classes of secondary metabolites such as terpenoids, alkaloids, flavonoids, tannins, coumarins, quinones, carotenoids, and steroids. T. broussonetii essential oils, especially from the aerial parts, exhibited potent antibacterial, antifungal, and antioxidant effects. An in-depth toxicological investigation is needed to validate the efficacy and safety of T. broussonetii extracts and essential oils and their secondary metabolites. However, further pharmacokinetic and pharmacodynamic studies should be performed to validate its bioavailability.

Synergistic Anticandidal Effects of Six Essential Oils in Combination with Fluconazole or Amphotericin B against Four Clinically Isolated Candida Strains

The development of opportunistic pathogenic Candida strains insensitive to several classes of antifungals has emerged as a major health care problem during the last years. Combinational therapy of natural products (e.g., essential oils, EOs) with conventional antifungals has been suggested as a promising alternative to overcome this medical problem. The present study investigates the potential antifungal activity of EOs extracted from some selected medicinal plants, alone and in combination with two common conventional antifungals (fluconazole and amphotericin B) against four clinical Candida isolates. MIC assays indicated that EOs induced strong anticandidal activities with MIC values ranging from 0.162 to 4.950 mg/mL. The combination of amphotericin B with Thymus leptobotrys, Origanum compactum and Artemisia herba alba EOs provided a synergistic effect against C. krusei only, with MIC gain of four-fold, and additive effect against remaining strains (MIC gain = two-fold). Interesting synergistic interactions were observed by combining all studied EOs with fluconazole, with reduction rates of their MICs ranging from 16 to 512-fold. This synergistic effect was very pronounced with the combination of T. leptobotrys EO and fluconazole. These findings indicate that studied EOs can be used as anti-candidals in combination with antifungals, particularly fluconazole, to counteract the emergence of resistant Candida spp.

Herbal Products and Their Active Constituents Used Alone and in Combination with Antifungal Drugs against Drug-Resistant Candida sp

Clinical isolates of Candida yeast are the most common cause of opportunistic fungal infections resistant to certain antifungal drugs. Therefore, it is necessary to detect more effective antifungal agents that would be successful in overcoming such infections. Among them are some herbal products and their active constituents.The purpose of this review is to summarize the current state of knowledge onherbal products and their active constituents havingantifungal activity against drug-resistant Candida sp. used alone and in combination with antifungal drugs.The possible mechanisms of their action on drug-resistant Candida sp. including (1) inhibition of budding yeast transformation into hyphae; (2) inhibition of biofilm formation; (3) inhibition of cell wall or cytoplasmic membrane biosynthesis; (4) ROS production; and (5) over-expression of membrane transporters will be also described.

Colombian Essential Oil of Ruta graveolens against Nosocomial Antifungal Resistant Candida Strains

Drug resistance in antifungal therapy, a problem unknown until a few years ago, is increasingly assuming importance especially in immunosuppressed patients and patients receiving chemotherapy and radiotherapy. In the past years, the use of essential oils as an approach to improve the effectiveness of antifungal agents and to reduce antifungal resistance levels has been proposed. Our research aimed to evaluate the antifungal activity of Colombian rue, Ruta graveolens, essential oil (REO) against clinical strains of Candida albicans, Candida parapsilopsis, Candida glabrata, and Candida tropicalis. Data obtained showed that C. tropicalis and C. albicans were the most sensitive strains showing minimum inhibitory concentrations (MIC) of 4.1 and 8.2 µg/mL of REO. Time–kill kinetics assay demonstrated that REO showed a fungicidal effect against C. tropicalis and a fungistatic effect against C. albicans. In addition, an amount of 40% of the biofilm formed by C. albicans was eradicated using 8.2 µg/mL of REO after 1 h of exposure. The synergistic effect of REO together with some antifungal compounds was also investigated. Fractional inhibitory concentration index (FICI) showed synergic effects of REO combined with amphotericin B. REO Lead a disruption in the cellular membrane integrity, consequently resulting in increased intracellular leakage of the macromolecules, thus confirming that the plasma membrane is a target of the mode of action of REO against C. albicans and C. tropicalis.

Effect of LongZhang Gargle on Dual-Species Biofilm of Candida albicans and Streptococcus mutans

Bioactive natural products have become a hot spot for oral disease treatments. At the present study, LongZhang Gargle was investigated for its effects on single-species biofilms of Candida albicans and dual-species biofilms of Candida albicans and Streptococcus mutans. Two different models of single and dual-species biofilms were grown in YNBB medium under appropriate conditions. Biofilm biomass, biofilm architecture, and cell activity in biofilms were assessed using Crystal Violet Staining, MTT, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Significant reductions of biofilm biomass and fungus activity were obtained when treated with LongZhang Gargle at 2% (P < 0.05), 4% (P < 0.05), and 8% (P < 0.05) in single-species biofilms of C. albicans, and at 4% (P < 0.05) and 8% (P < 0.05) in double-species biofilms. Suppression of density, thickness, and the proportion of hyphae and fungal spores were obtained under SEM and CLSM. In conclusion, LongZhang Gargle affects single and dual-species biofilms by inhibiting biofilm biomass, cell activity, and formation of hyphae, but it does not affect the production of Extracellular polysaccharides (EPS). We speculate that LongZhang Gargle would be a promising natural drug, which can be used in treatment against C. albicans and S. mutans in oral diseases.

Synergistic potential of Citrus aurantium L. essential oil with antibiotics against Candida albicans

ETHNOPHARMACOLOGICAL RELEVANCE

Citrus aurantium L. is used in traditional medicine in India for treating stomach ache, vomiting, blood pressure, dysentery, diarrhea, cardiovascular analeptic, sedative, boils and urinary tract infections. Its essential oil from fruit peels has antioxidant, antimicrobial, antifungal, antiparasitic, and anti-inflammatory activities.

AIM OF THE STUDY

The aim of the study was to characterize the antifungal activity and synergistic potential of essential oil extracted from leaves of Citrus aurantium L. of North-Western Himalayas against Candida albicans.

MATERIALS AND METHODS

Citrus aurantium essential oil (CAEO) was extracted from leaves and characterized by GC-MS. The antifungal activity and synergistic potential of CAEO against C. albicans was studied by agar well diffusion, and broth microdilution assay. The anti-fungal potential of the phytoconstituents of CAEO was studied by in silico interaction with two fungal drug targets, N-myristoyl transferase (NMT) and Cytochrome P450 14 Alpha-sterol Demethylase (CYP51).

RESULTS

CAEO exhibited strong antifungal activity against two strains of C. albicans, with fungicidal effect. The MIC of CAEO against C. albicans strains was 0.15 - 0.31% (v/v). CAEO exhibited synergistic potential with fluconazole and amphotericin B against C. albicans and enhanced the antifungal efficacy of the clinical drugs by 8.3 to 34.4 folds. The GC-MS analysis of CAEO identified at least ten compounds, with 2-β pinene, δ-3 Carene and D-limonene as the major compounds. In silico molecular docking of the three major phytocompounds of CAEO with NMT and CYP51 revealed their potential to interact with both targets. δ-3 Carene showed best binding (E_total of -131.13 kcal/mol) with NMT, while D-limonene exhibited highest binding energy (E_total of -175.23 kcal/mol) with CYP51. ADME/T analysis showed that 2-β pinene, δ-3 Carene and D-limonene exhibit drug likeliness and ideal toxicity profiles for their use as drug candidates.

CONCLUSIONS

Thus, the essential oil from leaves of C. aurantium and its phytocomponents can be used as sustainable and natural therapeutic to treat candidiasis as well as a resource to enhance the potency of clinical antibiotics, which have lost efficacy due to emergence of drug resistance in C. albicans.

Anti-Candida Activity of Essential Oils from Lamiaceae Plants from the Mediterranean Area and the Middle East

Extensive documentation is available on plant essential oils as a potential source of antimicrobials, including natural drugs against Candida spp. Yeasts of the genus Candida are responsible for various clinical manifestations, from mucocutaneous overgrowth to bloodstream infections, whose incidence and mortality rates are increasing because of the expanding population of immunocompromised patients. In the last decade, although C. albicans is still regarded as the most common species, epidemiological data reveal that the global distribution of Candida spp. has changed, and non-albicans species of Candida are being increasingly isolated worldwide. The present study aimed to review the anti-Candida activity of essential oils collected from 100 species of the Lamiaceae family growing in the Mediterranean area and the Middle East. An overview is given on the most promising essential oils and constituents inhibiting Candida spp. growth, with a particular focus for those natural products able to reduce the expression of virulence factors, such as yeast-hyphal transition and biofilm formation. Based on current knowledge on members of the Lamiaceae family, future recommendations to strengthen the value of these essential oils as antimicrobial agents include pathogen selection, with an extension towards the new emerging Candida spp. and toxicological screening, as it cannot be taken for granted that plant-derived products are void of potential toxic and/or carcinogenic properties.

Alternative therapy to manage otitis media caused by multidrug-resistant fungi

During the last few decades, the increase in the incidence of multidrug-resistant (MDR) fungal infections has become an emerging threat to public health. Therefore, it is important to illuminate the usage of alternative therapy to treat MDR fungal infection. This study was carried out to elucidate the usage of plant extract and essential oil, either alone or with other antifungal drugs to treat otitis media caused by MDR fungi. Medicinal plant is a safe and cheap source when compared with chemical antifungal drugs. Twenty-one fungal isolates out of 104 ear swabs from patients suffering from otitis media were characterized using both phenotypic and genotypic methods. The antibiogram typing was used to determine the MDR isolates. The sensitivity of MDR fungal isolates was tested against several plant extracts and essential oils, either alone or with other antifungal drugs. Thyme oil and clove extracts proved to have synergistic effects suggesting their use in the treatment of fungal infections, especially otitis media caused by MDR fungi. The ultrastructure of MDR fungal isolates exhibited a complete destruction post exposure to the used materials when observed under the transmission microscope (TEM). Thyme oil and clove extract were found to be the most effective agents against MDR fungal isolates and they constitute a promising tool for the management of fungal infection causing the otitis media.

Antimicrobial Activity of 4-Chlorocinnamic Acid Derivatives

The microbial resistance of fungi and bacteria is currently considered a major public health problem. Esters derived from cinnamic acid have a broad spectrum of pharmacological properties that include antimicrobial activity. In this study, a collection of structurally related 4-chlorocinnamic acid esters was prepared using Fischer esterification reactions, alkyl or aryl halide esterification, and Mitsunobu and Steglich reactions. All of the esters were submitted to antimicrobial tests against strains of the species Candida albicans, Candida glabrata, Candida krusei, Candida guilliermondii, Pseudomonas aeruginosa, and Staphylococcus aureus. The compounds also were subjected to molecular docking study with the enzyme 14α-demethylase. Twelve esters derived from 4-chlorocinnamic acid were obtained, with yields varying from 26.3% to 97.6%, three of which were unpublished. The ester methyl 4-chlorocinnamate (1) presented activity against S. aureus at the highest concentration tested. In the antifungal evaluation, all of the esters were bioactive, but methoxyethyl 4-chlorocinnamate (4) and perillyl 4-chlorocinnamate (11) were the most potent (MIC = 0.13 and 0.024 μmol/mL, respectively). The data of molecular docking suggested that all the compounds present good affinity towards the active site related to antifungal activity. Therefore, the esters tested may be inhibitors of the enzyme 14α-demethylase. In addition, the results demonstrate that substituents of short alkyl chains with presence of heteroatom, such as oxygen, or those with a perillyl type terpenic substructure promote better antifungal profiles.

Evaluation of the antimicrobial and antioxidant activity of 7-hydroxy-4', 6-dimethoxy-isoflavone and essential oil from Myroxylon peruiferum L.f

This study evaluated the antibacterial, antifungal, and antioxidant effect of 7-hydroxy-4',6-dimethoxy-isoflavone and essential oil of Myroxylon peruiferum. The compound was isolated and its structure elucidated by NMR. The chemical composition of essential oil determined by GC-MS analysis. To evaluation of antimicrobial activity, the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC) were performed. In addition to analysis of antioxidant activity, DPPH radical scavenging tests, iron chelating assay (FIC), antioxidant reducing power assay (FRAP) and β-carotene bleaching assay (BCB) were performed. For the essential oil were identified 24 organized compounds having as main constituents; Germacrene D (17.2%), α-pinene (14.8%) and E-caryophyllene (10.8%). The results showed that isoflavone (2000 to 156 μg/mL) and essential oil (5.0 to 1.25%) present antibacterial and antifungal activity against Gram-positive bacteria and filamentous fungi. The isoflavone and the essential oil also presented antioxidant activity in all the tests, mainly on inhibition of the oxidation of β-carotene test concentrations ranging from 60 to 100%. In conclusion, isoflavone and essential oil from M. peruiferum present an antimicrobial alternative against Gram-positive bacteria, especially of the genus Staphylococcus and dermatophyte fungi of the genus Trichophyton, as well as a natural compound antioxidant.

Commercial Essential Oils as Potential Antimicrobials to Treat Skin Diseases

Essential oils are one of the most notorious natural products used for medical purposes. Combined with their popular use in dermatology, their availability, and the development of antimicrobial resistance, commercial essential oils are often an option for therapy. At least 90 essential oils can be identified as being recommended for dermatological use, with at least 1500 combinations. This review explores the fundamental knowledge available on the antimicrobial properties against pathogens responsible for dermatological infections and compares the scientific evidence to what is recommended for use in common layman's literature. Also included is a review of combinations with other essential oils and antimicrobials. The minimum inhibitory concentration dilution method is the preferred means of determining antimicrobial activity. While dermatological skin pathogens such as Staphylococcus aureus have been well studied, other pathogens such as Streptococcus pyogenes, Propionibacterium acnes, Haemophilus influenzae, and Brevibacterium species have been sorely neglected. Combination studies incorporating oil blends, as well as interactions with conventional antimicrobials, have shown that mostly synergy is reported. Very few viral studies of relevance to the skin have been made. Encouragement is made for further research into essential oil combinations with other essential oils, antimicrobials, and carrier oils.

Comparison of aglycon and glycosidic saponin extracts of Cyclamen coum tuber against Candida spp

BACKGROUND AND PURPOSE

Candidiasis, an important fungal infection, is considered the fourth most common nosocomial blood stream infection. Nowadays, because of increased fungal resistance to antibiotics, the use of herbal medicine has gained particular attention. Cyclamen species are medicinal plants containing triterpenoid saponins, which are shown to have antimicrobial properties.

MATERIALS AND METHODS

Three species of Candida including C.albicans, 10231 C.tropicalis 0750 ,and C.krusei and nine clinical samples were cultured on Sabouraud dextrose agar. Active substances of the tubers were extracted by fractionation method. Susceptibility of Candida to Cyclamencoum tuber extracts was evaluated via minimum inhibitory concentration) MIC( and minimum fungicidal concentration (MFC.(.

RESULTS

Our results demonstrated that ethyl acetate extract had no inhibitory effect on Candida strains, whereas the aqueous and n-butanolic extracts showed considerable activity. MIC and MFC of these extracts varied within the range of 2-32 µg/mL of saponin for different Candida samples. Aglyconic aqueous phase of the extract had the most effective anticandida activity. Glycosidic and aglyconic aqueous extracts were less active on C. albicans strains and C. Tropicalis, respectively.

CONCLUSION

Tuber extract of Cyclamen was rich in triterpenoid saponins and had antifungal effect. Sugar chain structure, as well as type and concentration of the aglycones were effective in this activity.

Quercetin and rutin as potential agents antifungal against Cryptococcus spp

Amphotericin B is a fungicidal substance that is treatment of choice for most systemic fungal infections affecting as cryptococcosis the immunocompromised patients. However, severe side effects have limited the utility of this drug. The aim of this study was to evaluate the antifungal effect of the combination of amphotericin B with quercetin or rutin and as a protective of citotoxic effect. The antifungal activity to amphotericin B, quercetin and rutin alone and in combination was determined in Candida sp and Cryptococcus neoformans strains. Cytotoxicity test on erythrocytes was performed by spectrophotometric absorbance of hemoglobin. The amphotericin B MIC was reduced when used in combination with quercetin or rutin to C. neoformans ATCC strain and reduced when combined with rutin to a clinical isolate of C. neoformans. In addition, the combination of quercetin with amphotericin B may reduce the toxicity of amphotericin B to red blood cells. Our results suggest that quercetin and rutin are potential agents to combine with amphotericin B in order to reduce the amphotericin dose to lessen side effects and improve antifungal efficacy.

Newer patents in antimycotic therapy

There has been a global upsurge in fungal infections due to rise in immunodeficiencies, debilitation and situations of violated anatomical barriers. The available antifungal repertoire has limited activity and is fraught with toxicity concerns. Drug resistance has also shown a rapid upward trend. This has resulted in increased treatment failures, mortality and health care costs. Novel effective and safe antimycotics are needed. Analogues of existing antifungal compounds and new molecules are being developed. New targets are being explored for their putative role in curtailing fungal infections. Newer antigens as vaccine candidates are being researched into. Focused efforts in this direction have yielded encouraging results. This review illuminates the various antifungal strategies which hold promise for the future.

Potent Synergy between Spirocyclic Pyrrolidinoindolinones and Fluconazole against Candida albicans

A spiroindolinone, (1S,3R,3aR,6aS)-1-benzyl-6'-chloro-5-(4-fluorophenyl)-7'-methylspiro[1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-3,3'-1H-indole]-2',4,6-trione, was previously reported to enhance the antifungal effect of fluconazole against Candida albicans. A diastereomer of this compound was synthesized, along with various analogues. Many of the compounds were shown to enhance the antifungal effect of fluconazole against C. albicans, some with exquisite potency. One spirocyclic piperazine derivative, which we have named synazo-1, was found to enhance the effect of fluconazole with an EC50 value of 300 pM against a susceptible strain of C. albicans and going as low as 2 nM against some resistant strains. Synazo-1 exhibits true synergy with fluconazole, with an FIC index below 0.5 in the strains tested. Synazo-1 exhibited low toxicity in mammalian cells relative to the concentrations required for antifungal synergy.

Review of Ethnobotanical, Phytochemical, and Pharmacological Study of Thymus serpyllum L

Thymus serpyllum L. (wild thyme) is a perennial shrub, native to areas of northern and central Europe. Its aerial parts are most frequently used in ethnomedicine (mainly for treating illnesses and problems related to the respiratory and gastrointestinal systems), although recently its essential oils are becoming more popular as an important plant-derived product. The composition of these oils is affected by geographic region, the development stage of the plant, the harvest season, habitat, and climatic conditions. Wild thyme essential oil has an ever-growing number of uses in contemporary medicine due to its pharmacological properties: antioxidative, antimicrobial, and anticancerogenic activities. The antioxidative and antimicrobial properties of the essential oil are related to the synergistic and cumulative effect of its components. In terms of antitumor and cytotoxic activity, further research into the effects of essential oil is necessary, aimed at improving its cytotoxic effects, on the basis of which appropriate medicines can be formulated. Due to its pharmacological properties, the essential oil of wild thyme, a plant used in traditional medicine, represents an important natural resource for the pharmaceutical industry. In addition, it can be a source of natural antioxidants, nutritional supplements, or components of functional foods in the food industry.

Anti-oxidant studies and anti-microbial effect of Origanum vulgare Linn in combination with standard antibiotics

BACKGROUND

Origanum is one of the over 200 genera in the Lamiaceae (mint family), and this genus includes culinary, fragrant, and medicinal properties. The plant is reported to contain anti-microbial properties, but it lacks combination studies with that of synthetic antibiotics.

AIM

To investigate the anti-oxidant and anti-microbial interaction studies of Origanum vulgare with standard drugs against Bacillus species of bacteria and Aspergillus niger.

MATERIALS AND METHODS

The anti-oxidant properties of phenolic, non-phenolic fractions of chloroform extract and volatile oil were evaluated by free radical-scavenging, hydrogen peroxide radical-scavenging assay, reducing power, and metal chelating assays.

RESULTS

The minimum inhibitory concentration and fractional inhibitory concentration index were determined which demonstrates the behavior of volatile oil, phenolic, and non-phenolic fractions of volatile oil with that of ciprofloxacin and fluconazole. The IC50 value for volatile oil was found to be 15, 30, and 30 μg/ml and that of phenolic fraction was 60, 120, and 120 μg/ml for free radical-scavenging, hydrogen peroxide-scavenging, and metal chelating assays respectively. Non-phenolic fraction was found to act antagonistically along with ciprofloxacin against B. cereus and B. subtilis, while the phenolic fraction exhibited indifferent activity along with ciprofloxacin against both the bacterial strains.

CONCLUSION

This combination of drug therapy will not only prove effective in antibiotic resistance, but these natural constituents will also help in preventing body from harmful radicals which lead to fatal diseases.

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.

Antibacterial activities of Origanum vulgare alone and in combination with different antimicrobials against clinical isolates of Salmonella typhi

Background:

Typhoid fever continues to remain a major public health problem especially in the areas where there is problem of sanitation and hygiene. The emergence of multidrug resistance of Salmonella typhi, the bacteria responsible for Typhoid to ampicillin, chloramphenicol, and cotrimoxazole has further complicated the treatment and management of enteric fever. One strategy for the treatment of the multidrug resistant bacteria is to use herbs in combination with conventional drugs. The present study was done to find out the interaction effect of phenolic, nonphenolic fractions, and volatile oil of Origanum vulgare with ciprofloxacin.

Materials and Methods:

The minimum inhibitory concentration (MIC) by microdilution method for individual phytoconstituents and in combination with ciprofloxacin was compared for clinically isolated bacteria from patients infected with S. typhi. Fractional inhibitory concentration (FIC) and Fractional inhibitory concentration index (FICI) were also calculated.

Results:

The MIC declined to a significant level indicating synergistic relationship between ciprofloxacin and phenolic, nonphenolic fractions and volatile oil in vitro. The FICI exhibits synergistic effect for all the three samples while indifferent and antagonistic for samples and for phenolic and nonphenolic fractions.

Conclusions:

Present study shows that not only the formulation using O. vulgare and ciprofloxacin can overcome multidrug resistance but also will reduce the toxic effects of ciprofloxacin.

Combination Studies of Oreganum Vulgare Extract Fractions and Volatile Oil along with Ciprofloxacin and Fluconazole against Common Fish Pathogens

PURPOSE

The study is aimed at finding new antibiotic therapy for aquaculture due to potential of bacteria to develop resistance to the existing therapies. Use of large quantities of synthetic antibiotics in aquaculture thus has the potential to be detrimental to fish health, to the environment and wildlife and to human health.

METHODS

Antimicrobial potential of volatile oil and fractions of chloroform extract of Oreganum vulgare was evaluated alone and in the presence of standard antimicrobials against common fish pathogens by disc-diffusion, agar well assay and two fold microdilution method by nanodrop spectrophotometric method.

RESULTS

The best results were represented by volatile oil followed by phenolic fraction by disc-diffusion, agar well and microdilution assays (Minimum inhibitory concentration). By the interaction studies, it was observed that the volatile oil and phenolic fraction were able to inhibit the pathogens at very low concentration compared to standard drugs. The fractional inhibitory concentration index (FICI) was calculated and volatile oil and phenolic fractions were found to be synergistic against Pseudomonas fluorescens and Candida albicans.

CONCLUSION

The experimental data suggests the use of volatile oil and phenolic fraction in combination with standard antimicrobials to maintain healthy aquaculture with lesser adverse effects as compared to synthetic antibiotic therapy.

Antibacterial activity of Thymus maroccanus and Thymus broussonetii essential oils against nosocomial infection - bacteria and their synergistic potential with antibiotics

The aim of this study was to evaluate the antibacterial effect of the association between conventional antibiotics and essential oils (EOs) of endemic Moroccan thyme species, Thymus maroccanus and T. broussonetii, on antibiotic-resistant bacteria involved in nosocomial infections. Synergistic interactions between antibiotics (ciprofloxacin, gentamicin, pristinamycin, and cefixime) and EOs, and between T. maroccanus and T. Broussonetii EOs were determined by the checkerboard test. Serial dilutions of two antimicrobial agents were mixed together so that each row (and column) contained a fixed amount of the first agent and increasing amounts of the second one. The results indicate that the oils had a high inhibitory activity against tested bacteria, except for Pseudomonas aeruginosa. In parallel with the increase of cellular killing, the release of 260nm-absorbing materials from bacterial cells, treated with EOs, increased in response to oil concentration. Out of 80 combinations tested between EOs and antibiotics, 71% showed total synergism, 20% had partial synergistic interaction and 9% showed no effect. Combination with carvacrol, the major constituent of T. maroccanus and T. broussonetii, showed also an interesting synergistic effect in combination with ciprofloxacin. The effect on Gram-positive bacteria was more important than on Gram-negative bacteria. These findings are very promising since the use of these combinations for nosocomial infections treatment is likely to reduce the minimum effective dose of the antibiotics, thus minimizing their possible toxic side effects and treatment cost. However, further investigations are needed to assess the potential for therapeutic application.

Chemical Composition and Anticandidal Properties of the Essential Oil Isolated from Aerial parts of Cotula cinerea: A Rare and Threatened Medicinal Plant in Morocco

The chemical composition and anticandidal properties of the essential oil of Moroccan Cotula cinerea aerial parts have been examined. GC-MS data were used to identify 24 constituents. Oxygenated monoterpenes constituted the main fraction with trans-thujone (41.4%), cis-verbenyl acetate (24.7%), 1,8-cineole (8.2%) and camphor (5.5%) as the major components. The anticandidal activity of the essential oil was evaluated using a panel of human pathogenic fungi (Candida albicans CCMM L4 and CCMM L5, C. krusei CCMM L10, C. glabrata CCMM L7 and C. parapsilosis CCMM L18). The oil showed high anticandidal activity against all investigated strains with minimal inhibitory concentrations of 3.2 to 4.7 mg/mL depending on the tested yeast and 5.9 mg/mL as a minimal candidicidal concentration value. These findings add significant information to the pharmacological activity of Cotula cinerea essential oil, which may present a good alternative to antibiotics for the treatment of resistant strains of Candida.

Essential oils from Moroccan plants as potential chemosensitisers restoring antibiotic activity in resistant Gram-negative bacteria

Bacterial drug resistance is a worrying public health problem. Antibiotic efflux is a major non-specific resistance mechanism used by bacteria, and efflux pumps are involved in the low-level susceptibility of various important Gram-negative pathogens. Use of molecules that can block bacterial pumps is an attractive strategy, but several studies report only partial efficacy owing to limits of these molecules (stability, selectivity, bioavailability, toxicity, etc.). The objective of this study was to search for natural sources of molecules able to inhibit efflux pump systems of resistant Gram-negative bacteria (Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Salmonella enterica serotype Typhimurium and Pseudomonas aeruginosa). The results indicate that the studied essential oils exhibit interesting activity against the tested bacteria. This activity was significantly enhanced in the presence of an efflux pump inhibitor such as phenylalanine arginyl β-naphthylamide (PAβN). The role of lipopolysaccharide (LPS) structure in the effect of essential oils was also reported in Salmonella LPS deep-rough mutants. In addition, essential oils of Thymus maroccanus and Thymus broussonetii, used at a low concentration (a fraction of the minimum inhibitory concentration), are able to significantly increase chloramphenicol susceptibility of several resistant isolates. These results demonstrate that these essential oils can alter efflux pump activity and may be attractive candidates to develop new drugs for chemosensitising multidrug-resistant strains to clinically used antibiotics.

Preliminary phytochemical analysis, antibacterial, antifungal and anticandidal activities of successive extracts of Crossandra infundibuliformis

OBJECTIVE

To investigate the phytochemical, antibacterial, antifungal and anticandidal activity of successive extracts of Crossandra infundibuliformis (Acanthaceae) leaves.

METHODS

Preliminary screening on the presence of alkaloids, saponins, phytosterols, phenolic compounds, flavanoids, tannins, carbohydrates, terpenoids, oils and fats were carried out by phytochemical analysis. The antibacterial, antifungal and anticandidal activities were done by agar well diffusion technique.

RESULTS

The successive extracts have an array of chemical constituents and the MIC values of antibacterial activity ranges from 0.007 8 to 0.015 0 μg/mL. In case of antifungal and anticandidal activities the MIC values were between 0.125 and 0.250 μg/mL.

CONCLUSIONS

These findings demonstrate that the leaf extracts of C. infundibuliformis presents excellent antimicrobial activities and thus have great potential as a source for natural health care products.