Evaluation of antifungal and apoptotic effects of linalool, citral, and carvacrol separately and in combination with nystatin against clinical isolates of Pichia kudriavzevii

Pichia kudriavzevii (formerly Candida krusei) poses a significant threat to immunocompromised patients due to its inherent resistance to various antifungal drugs. This study explored the anticandidal potential of citral, linalool, and carvacrol in combination with nystatin against P. kudriavzevii strains.Using the microdilution method following CLSI guidelines, Minimum Inhibitory Concentrations (MICs) and fungicidal concentrations (MFCs) were determined. Citral exhibited MIC values ranging from 50 to 100 µg/ml, averaging 70.24 ± 16.99 µg/ml, while carvacrol had MIC values of 50 to 100 µg/ml, averaging 86.90 ± 16.99 µg/ml. Linalool demonstrated weaker antifungal activity, with MIC values between 100 and 200 µg/ml, averaging 150 ± 38.73 µg/ml. The study assessed the synergistic effectsof these phenols with nystatin through fractional inhibitory concentration indices (FICIS). In addition, flow cytometry was employed to assess apoptosis induction in P. kudriavzevii cells.Carvacrol displayed a remarkable synergistic effect in combination with nystatin against all 21 isolates tested. Conversely, linalool showed synergy in 17 isolates, while citral exhibited synergy in only 2 isolates. These findings highlight distinct patterns of synergy between the different compounds and nystatin against P. kudriavzevii. Also, Carvacrol emerged as the most potent inducer of apoptosis across all P. kudriavzevii strains, followed by citral and linalool. This suggests that carvacrol not only possesses a stronger antifungal effect but also has a more pronounced ability to trigger programmed cell death in P. kudriavzevii. In conclusion, the study supports the potential of carvacrol, citral and linalool, as anticandidal agents, suggesting their supplementation with nystatin for treating P. kudriavzevii infections.

Surface Modifications and Antifungal Efficacy of Origanum Oil Incorporation in Denture-based Materials: An In Vitro Study

AIM

This study aimed to assess if the addition of origanum oil to denture materials could decrease microorganisms counts and biofilm formation without changing their mechanical/surface properties.

MATERIALS AND METHODS

A total of 66 resilient denture liner discs (SoftConfort, Dencril Comércio de Plásticos Ltda, SP, Brazil) were prepared with fixed dimensions of 10 × 3 mm for biofilm assay (n = 36) and 12 × 2 mm for sorption-solubility tests (n = 30) containing three oil concentrations - 0, 2.5 and 5%, thereby n = 12 per each group samples for biofilm assay and n = 10 per each group for sorption-solubility test respectively. While the microcosm biofilms of Streptococcus mutans, Candida species, and total microorganisms formed on denture liner were counted and expressed as colony-forming units per disc surface area, the water sorption (WS) and solubility (SL), was calculated by weighing the samples with an analytical balance at different intervals after storing them in a desiccator and distilled water alternatively. Data was recorded and statistically analyzed.

RESULTS

Surface roughness increased in all groups after biofilm formation (p < 0.001), with the most significant change observed in the 2.5% oil group. The tested oil concentrations did not result in sorption changes, but a 5% oil concentration resulted in higher solubility (p < 0.001). A reduction of total microorganisms and S. mutans was seen after 24 hours for all concentrations (p < 0.05). No significant reduction was found for Candida (C.) albicans after 24 hours, whilst 2.5% oil concentration presented lower counts of C. albicans in comparison to the 5% group after 24 hours (p < 0.05).

CONCLUSIONS

Incorporating 2.5% origanum essential oil into resilient denture liners seems to reduce microorganisms count in a complex biofilm model. These results need to be confirmed in future studies.

CLINICAL SIGNIFICANCE

The addition of natural products like origanum oil into denture-based materials can help manage biofilm onset and development while offering a simple and effective approach for maintaining denture hygiene. This strategy enhances the antimicrobial properties of denture liners without significantly altering their mechanical and surface characteristics, potentially improving patient outcomes. How to cite this article: Feitosa MÁL, Poletto-Neto V, Maske TT, et al. Surface Modifications and Antifungal Efficacy of Origanum Oil Incorporation in Denture-based Materials: An In Vitro Study. J Contemp Dent Pract 2024;25(9):878-884.

New thymol-derived triazole exhibits promising activity against Trichophyton rubrum

Fungal infections have emerged worldwide, and azole antifungals are widely used to control these infections. However, the emergence of antifungal resistance has been compromising the effectiveness of these drugs. Therefore, the objective of this study was to evaluate the antifungal and cytotoxic activities of the nine new 1,2,3 triazole compounds derived from thymol that were synthesized through Click chemistry. The binding mode prediction was carried out by docking studies using the crystallographic structure of Lanosterol 14α-demethylase G73E mutant from Saccharomyces cerevisiae. The new compounds showed potent antifungal activity against Trichophyton rubrum but did not show relevant action against Aspergillus fumigatus and Candida albicans. For T. rubrum, molecules nº 5 and 8 showed promising results, emphasizing nº 8, whose fungicidal and fungistatic effects were similar to fluconazole. In addition, molecule nº 8 showed low toxicity for keratinocytes and fibroblasts, concluding that this compound demonstrates promising characteristics for developing a new drug for dermatophytosis caused by T. rubrum, or serves as a structural basis for further research.

Antifungal chemosensitization through induction of oxidative stress: A model for control of candidiasis based on the Lippia origanoides essential oil

In this work, evaluated the antifungal chemosensitizing effect of the Lippia origanoides essential oil (EO) through the induction of oxidative stress. The EO was obtained by hydrodistillation and analyzed by GC-MS. To evaluate the antifungal chemosensitizing effect through induction of oxidative stress, cultures of the model yeast Saccharomyces cerevisiae ∆ycf1 were exposed to sub-inhibitory concentrations of the EO, and the expression of genes known, due be overexpressed in response to oxidative and mutagenic stress was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) method. Carvacrol and thymol were identified as the main components. The EO was effective in preventing or reducing the growth of the microorganisms tested. The gene expression profiles showed that EO promoted changes in the patterns of expression of genes involved in oxidative and mutagenic stress resistance. The combined use of the L. origanoides EO with fluconazole has been tested on Candida yeasts and the strategy resulted in a synergistic enhancement of the antifungal action of the azolic chemical product. Indeed, in association with EO, the fluconazole MICs dropped. Thus, the combinatorial use of L. origanoides EO as a chemosensitizer agent should contribute to enhancing the efficiency of conventional antifungal drugs, reducing their negative side effects.

Nanoformulated herbal compounds: enhanced antibacterial efficacy of camphor and thymol-loaded nanogels

Herbal components are highly useful assets for the advancement of novel antibacterial drugs. Nanotechnology holds great promise as an approach to enhance the effectiveness and develop the composition of these substances. The study developed nanogels incorporating camphor, thymol, and a combination derived from the initial nanoemulsions with particle sizes of 103, 85, and 135 nm, respectively. The viscosity of nanogels and the successful loading of compounds in them were examined by viscometery and ATR-FTIR studies. The bactericidal properties of the nanogels were examined against four bacterial strains. The nanogel containing camphor and thymol at 1250 µg/mL concentration exhibited complete growth suppression against Pseudomonas aeruginosa and Staphylococcus aureus. The thymol nanogel at 1250 µg/mL and the camphor nanogel at 2500 µg/mL exhibited complete inhibition of growth on Listeria monocytogenes and Escherichia coli, respectively. Both nanogels showed favorable effectiveness as antibacterial agents and could potentially examine a wide range of pathogens and in vivo studies.

Interactions of naturally occurring compounds with antimicrobials

Antibiotics are among the most often used medications in human healthcare and agriculture. Overusing these substances can lead to complications such as increasing antibiotic resistance in bacteria or a toxic effect when administering large amounts. To solve these problems, new solutions in antibacterial therapy are needed. The use of natural products in medicine has been known for centuries. Some of them have antibacterial activity, hence the idea to combine their activity with commercial antibiotics to reduce the latter's use. This review presents collected information on natural compounds (terpenes, alkaloids, flavonoids, tannins, sulfoxides, and mycotoxins), of which various drug interactions have been observed. Many of the indicated compounds show synergistic or additive interactions with antibiotics, which suggests their potential for use in antibacterial therapy, reducing the toxicity of the antibiotics used and the risk of further development of bacterial resistance. Unfortunately, there are also compounds which interact antagonistically, potentially hindering the therapy of bacterial infection. Depending on its mechanism of action, each compound can behave differently in combination with different antibiotics and when acting against various bacterial strains.

Assessment of thyme honey oral gel for the prevention of adriamycin and cyclophosphamide chemotherapy-induced oral mucositis in patients with breast cancer

PURPOSE

Oral mucositis (OM) is a common complication of cancer treatment that has an impact on a patient's quality of life and the outcome of cancer therapy. This trial evaluated the effect of thyme honey oral gel for the prevention of chemotherapy-induced OM.

METHODS

One hundred ten breast cancer patients who received their first cycle of chemotherapy with adriamycin (60 mg/m2) and cyclophosphamide (600 mg/m2) were randomly recruited into two groups: group A were patients who followed general oral hygiene recommendations and rinsing saline 3 times a day, and group B were patients with similar protocol but supplied with our formulated oral gel to be applied 2 to 4 times a day. Patients were assessed by the World Health Organization (WHO) oral mucositis grading scales and self-assessment daily questionnaire.

RESULTS

The use of thyme honey was associated with diminishing incidence of OM grade ≥ 2 (95% CI, 0.12 to 0.90; P = 0.030), duration of OM (- 3.36 days; 95% CI, - 5.50 to - 1.22; P = 0.037) and delayed occurrence of OM grade ≥ 2 (95% CI, 0.10 to 0.80; P = 0.017).

CONCLUSION

Thyme honey can be considered as a prophylactic agent for OM and decrease the severity of its symptoms.

TRIAL REGISTRATIONS

This protocol was registered at the Iranian Registry of Clinical Trials: registration number IRCT201506063106N25, on June 12, 2015; approved by the institutional review board at the Deputy of Research, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran; and approved by the Ethics Committee of Medical Researches of Pharmaceutical Sciences Branch of Islamic Azad University, Tehran, Iran-reference number 5936, on August 17, 2014.

Atypical changes in Candida albicans cells treated with the Venetin-1 complex from earthworm coelomic fluid

In the present research, the effect of a protein-polysaccharide complex Venetin-1 obtained from the coelomic fluid of Dendrobaena veneta earthworm on Candida albicans cells was characterized. The compound destroyed fungal cells without showing cytotoxicity to human skin fibroblasts, which was demonstrated in earlier studies. Since it had an effect on the fungal cell wall and membrane, this complex was compared with the known antifungal antibiotic fluconazole. Both preparations disturbed the division of yeast cells and resulted in the formation of aggregates and chains of unseparated cells, which was illustrated by staining with fluorochromes. Fluorescent staining of the cell wall with Calcofluor white facilitated comparison of the types of aggregates formed after the action of both substances. The analysis performed with the use of Congo red showed that Venetin-1 exposed deeper layers of the cell wall, whereas no such effect was visible after the use of fluconazole. The FTIR analysis confirmed changes in the mannoprotein layer of the cell wall after the application of the Venetin-1 complex. Staining with Rhodamine 123 and the use of flow cytometry allowed comparison of changes in the mitochondria. Significantly elongated mitochondria were observed after the Venetin-1 application, but not after the application of the classic antibiotic. Phase contrast microscopy revealed vacuole enlargement after the Venetin-1 application. The flow cytometry analysis of C. albicans cells treated with Venetin-1 and fluconazole showed that both substances caused a significant decrease in cell viability.

In vitro and in silico analysis of Thymus serpyllum essential oil as bioactivity enhancer of antibacterial and antifungal agents

Wild thyme (Thymus serpyllum L.) of family Laminaceae is an unexplored perennial medicinal shrub. Aerial part of this plant is traditionally used for the treatment of respiratory and gastrointestinal problems. The current study was designed to evaluate the GC-MS, antimicrobial and synergistic potential of T. serpyllum essential oil (TEO). Chemical characterization of TEO showed the presence of thymol (15.79%), Phenol, 2-(1,1-dimethylethyl) (11.55%), o-Cymene (10.96%) as major phytocompounds. Antimicrobial activity of TEO in terms zone of inhibition (ZOI) varied from 13.66 ± 0.58 mm to 33.66 ± 1.52 mm, while, thymol (10%, v/v) showed ZOI ranged from 15.5 ± 0.5 mm to 26.33 ± 2.08 mm against tested bacterial and fungal species. MIC of TEO was 0.039% to 0.078% against tested bacterial and fungal species, whereas, thymol showed 1.25% to 2.5% MIC against tested bacterial and fungal species. Different combinations of TEO (2MIC to ½MIC) and thymol (2MIC to ½MIC) with antibacterial and antifungal antibiotics (2MIC to ½MIC) were found to increase the efficacy of antibiotics by 4-130 folds against bacterial and fungal pathogens. Molecular docking showed the good binding of thymol with both bacterial and fungal targets. Whereas MD simulation showed the stability of thymol complexed with target proteins over 100 ns time scale. Thymol also fulfills the Lipinski rule and showed characteristics similar to that of drugs. Therefore, it can be concluded from the present study that TEO and its major phytocompound, thymol can act as a bioactivity enhancer of antibacterial and antifungal antibiotics and could be used as a potential candidate to fight against antimicrobial drug resistance.Communicated by Ramaswamy H. Sarma.

In Vitro Activity of Essential Oils Distilled from Colombian Plants against Candidaauris and Other Candida Species with Different Antifungal Susceptibility Profiles

Multi-drug resistant species such as Candida auris are a global health threat. This scenario has highlighted the need to search for antifungal alternatives. Essential oils (EOs), or some of their major compounds, could be a source of new antifungal molecules. The aim of this study was to evaluate the in vitro activity of EOs and some terpenes against C. auris and other Candida spp. The eleven EOs evaluated were obtained by hydro-distillation from different Colombian plants and the terpenes were purchased. EO chemical compositions were obtained by gas chromatography/mass spectrometry (GC/MS). Antifungal activity was evaluated following the CLSI standard M27, 4th Edition. Cytotoxicity was tested on the HaCaT cell line and fungal growth kinetics were tested by time–kill assays. Candida spp. showed different susceptibility to antifungals and the activity of EOs and terpenes was strain-dependent. The Lippia origanoides (thymol + p-cymene) chemotype EO, thymol, carvacrol, and limonene were the most active, mainly against drug-resistant strains. The most active EOs and terpenes were also slightly cytotoxic on the HaCaT cells. The findings of this study suggest that some EOs and commercial terpenes can be a source for the development of new anti-Candida products and aid the identification of new antifungal targets or action mechanisms.

Relapsing Vulvovaginal Candidiasis: Treatment with Oxygen Therapy and Hyaluronic Acid

OBJECTIVE. The aim of our open, anecdotical, retrospective, spontaneous trial has been to evaluate the efficacy of the association between high concentration oxygen and hyaluronic acid for treatment of relapsing candidiasis.METHODS. 45 women (30.9 ±4.4 years) with relapsing candidiasis, and complaining of dryness, dyspareunia, pain, appealing to our Second Opinion Medical Consultation Network, signed an informed consent form and were treated with oxygen/hyaluronic acid therapy treatment, once a week, for a total of five weeks at the outpatient clinic (Healthy Center, Sirio, Fidenza, Italy). The physicians of the Second Opinion Network followed up weekly from remote (WhatsApp, Skype) each treated patient as to state the effectiveness, tolerability, and side effects of the treatment.RESULTS. The mean VAS and VuAS scores measured at first visit were 2,660 and 2,622 and significantly (p<0,0001) reduced to 1,311 and 0,77 at last visit. The measurements of the vaginal pH and of the vaginal swab after the last treatment session confirmed significantly (p<0.0001) the absence of candidiasis. Three months later in the follow-up, the percentage of patients who had had only one VVC relapse was 4,44% (2/45), a percentage that increased just to 8,8% at six months (4/45). The elastography index was significantly (p<0.0001) increased after the last treatment session (2,55 ± 0,545 vs 4,48 ± 0,505).CONCLUSIONS. The combined oxygen therapy with hyaluronic acid gave definite therapeutic benefits in this cohort of relapsing candidiasis in the acute phase of the infection. The 6-month follow up, also detected a lower reinfection rate compared with the historical available data. The procedure is totally painless with excellent compliance by patients and no untoward effects.

Novel one-pot synthesis of a library of 2-aryloxy-1,4-naphthoquinone derivatives. Determination of antifungal and antibacterial activity

The development of new antibiotics and inexpensive antifungals is an important field of research. Based on the privileged pharmacophore of lawsone, a series of phenolic ether derivatives of 1,4-naphthoquinone were synthesized easily in one step in reasonable yields. All the new compounds were characterized and tested as potential antifungal and antibacterial agents against Candida albicans, Escherichia coli and Staphylococcus aureus. Compound 55 has significant antibacterial action (as good as or better than the controls) against E. coli and S. aureus. Against C. albicans, compounds 38, 46, 47 and 60 were the best candidates as antifungals. Using a qualitative structure–activity analysis, a correlation between molar mass and antimicrobial activity was identified, regardless of the substituent group on the phenolic moiety, except for 55 and 63, where electronic effects seem more important. An in silico evaluation of the absorption, distribution, metabolism and excretion (ADME) for 37, 50, 55 and 63 was made, indicating that the classic Lipinski's rule of five applies in all cases.

The development of new antibiotics and inexpensive antifungals is an important field of research. Based on the privileged pharmacophore of lawsone, a series of phenolic ether derivatives of 1,4-naphthoquinone were synthesized easily in one step in reasonable yields.

Thymol and carvacrol supplementation in poultry health and performance

BACKGROUND

Thymol and carvacrol as natural essential oils and phenol compounds are components derived from some medicinal plants, such as thyme and oregano species.

OBJECTIVES

The increasing demands in organic and healthy meat and egg consumption in human society have made it necessary to consider alternative natural compounds for the replacement of chemical compounds in poultry production. The chemical compounds can remain in meat and eggs and cause complications in human health. Therefore, these natural compounds can be fed with a higher safety in poultry production with specific effects. In this regard, the role of thymol and carvacrol as natural compounds in the poultry production has been discussed in the review.

METHODS

In this study, by searching for keywords related to thymol and carvacrol in poultry production in Google Scholar database, the articles related to different aspects of the biological effects of these two phytogenes in poultry production were selected and analyzed.

RESULTS

A review of previous studies has shown that thymol and carvacrol possess a wide range of biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, modulating of immunity response and regulating of the gut microbial population. Also, in meat type chickens can promote growth and influence feed utilization. The beneficial effect of this compound was evaluated in hepatic toxicity and demonstrated as a hepatoprotective compound in chickens. Furthermore, these compounds can affect the behavior of layers and influence egg composition, eggshell thickness, and the sensory quality of eggs.

CONCLUSION

It seems that with the increasing demand for healthy protein products, these compounds can be used to improve performance as a substitute alternative for chemical compounds in healthy poultry farms.

Qualitative and quantitative phytochemical composition, antimicrobial activity, and brine shrimp cytotoxicity of different solvent extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans

Background

The root, root bark, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans are used for managing bacterial and fungal infections among the Luo community of Kisumu East Sub County in Kenya. However, data on the efficacy of these plants against common bacterial and fungal pathogens is not available. The safety of these plants is also not known. This study aimed to investigate the phytochemical composition, antimicrobial properties, and safety of different solvent extracts of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. The broth microdilution method evaluated the antimicrobial activities of the root, root bark, and root tuber extracts (water, acetone, and methanol) of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. Gram-positive (Bacillus cereus, Staphylococcus aureus), gram-negative (Escherichia coli), and fungal (Candida albicans) microorganisms were used in the evaluation. The safety of the extracts was evaluated in Artemia salina. The phytochemical composition of the extracts was determined using qualitative and quantitative assays.

Results

In general, the extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans displayed poor antimicrobial properties relative to conventional antimicrobial agents including Amoxicillin, Gentamicin, and Nystatin. The aqueous extract of Acanthus polystachyus and the aqueous, acetone, and methanol extracts of Keetia gueinzii were safe in Artemia salina but all other extracts were cytotoxic to Artemia salina.

Conclusions

These findings suggest that the use of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans is limited by poor antimicrobial efficacy and cytotoxicity.

Volatile phenolics: A comprehensive review of the anti-infective properties of an important class of essential oil constituents

Historically, essential oils and their lead molecules have been extensively recognised for their anti-infective properties. In this context, certain volatile phenolics (VPs) have emerged as important antimicrobial compounds with excellent inhibitory activity against pathogenic bacteria and fungi, which further extends to drug-resistant and biofilm-forming micro-organisms. In this review, we aim to collate and discuss a number of published papers on the anti-infective activities of naturally occurring VPs with special emphasis on eugenol, isoeugenol, thymol and carvacrol, using Scopus Web of Science and PubMed databases. The biosynthesis and extraction of these VPs are discussed, while particular attention is given to their broad-spectrum antimicrobial activity and the mechanisms of action. We highlight combinational studies of the VPs with other phytocompounds and with commercially available drugs, which may be a promising and a rewarding future approach to combat antimicrobial resistance. These VPs alone, or concomitantly with other compounds or drugs, have the potential to be incorporated into different formulations for biomedical applications. An in-depth assessment of 2310 articles retrieved from the Scopus database spanning a 35-year period indicated 23.1% increase in global publication growth in VPs anti-infective research, with authors from Italy, Portugal and Austria dominating the research landscape. The dominant areas of investigations are identified as antimicrobial activity, antibacterial mechanism of action, antifungal mechanism of action, extraction methods and phytochemistry, use in the food industry, and for oral and dental anti-infective activity. Specific research areas, which require future attention include; antituberculosis research, nanoparticle formulation of antimicrobial active VP molecules, preclinical and clinical trials. The antimicrobial testing of isoeugenol was found to be the least studied of the VPs and this requires further attention.

Thymol as an Interesting Building Block for Promising Fungicides against Fusarium solani

The semisynthesis of 15 new thymol derivatives was achieved through Williamson synthesis and copper-catalyzed azide-alkyne cycloaddition (CuAAC) approaches. The reaction of CuAAC using the "Click Chemistry" strategy, in the presence of an alkynyl thymol derivative and commercial or prepared azides, provided nine thymol derivatives under microwave irradiation. This procedure reduces reaction time and cost. All molecular entities were elucidated by ¹H and ¹³C NMR, IR, and HRMS data. These derivatives were evaluated in vitro for their fungicidal activity against Fusarium solani sp. Among the nine triazolic thymol derivatives obtained, seven of them were found to have moderated antifungal activity. In contrast, naphthoquinone/thymol hybrid ether 2b displayed activity comparable with that of the commercial fungicide thiabendazole. The structure-activity relationship for the most active compound 2b was discussed, and the mode of action was predicted by a possible binding to the fungic ergosterol and interference of osmotic balance of K⁺ into the extracellular medium.

Whole transcriptome analysis of schinifoline treatment in Caenorhabditis elegans infected with Candida albicans

Candida albicans is an opportunistic fungal human pathogen that has been causing an increasing number of deaths each year. Due to the widespread use of broad-spectrum antibiotics and immunosuppressants, C. albicans resistance to these therapies has increased. Thus, natural plant inhibitors are being investigated for treating C. albicans infections. Schinifoline is a 4-quinolinone alkaloid with antibacterial, insecticidal, antitumor, and other biological activities. Here, we explored the effects of schinifoline on C. albicans in C. elegans and extracted RNA from uninfected C. elegans, C. elegans infected with C. albicans, and C. elegans infected with C. albicans and treated with 100 mg/l schinifoline. Our results showed that there were significant differences among the three groups. The GO and KEGG pathway analysis suggested that the pathogenicity of C. albicans to C. elegans was caused by abnormal protein function. Schinifoline regulates lysosomal pathway related genes that accelerate the metabolism and degradation of abnormal proteins, thereby inhibiting the negative effects of C. albicans in vivo. These findings advance our understanding of the molecular mechanisms underlying schinifoline inhibition of C. albicans.

In vitro activities of Traganum nudatum and Mentha pulegium extracts combined with amphotericin B against Candida albicans in production of hydrolytic enzymes

Background and Purpose :

Candida albicans is an important microorganism in the normal flora of a healthy subject; however, it has an expedient pathogenic character that induces hydrolytic virulence. Regarding this, the present study aimed to find an in vitro alternative that could reduce the virulence of this yeast.

Materials and Methods:

For the purpose of the study, the effect of amphotericin B (AmB) combined with the extract of Traganum nudatum (E1) or Mentha pulegium (E2) was evaluated against the hydrolytic activities of esterase, protease, and phospholipase. This effect was determined by calculating the minimum inhibitory concentration (MIC), used to adjust the extract/AmB mixtures in culture media.

Results:

The evaluated Pz values, which corresponded to the different enzymatic activities, showed a decrease in the hydrolytic activities of C. albicans strains after the addition of E1/AmB and E2/AmB combinations at descending concentrations (lower than the obtained MICs).

Conclusion:

Based on the findings, it would be possible to reduce the pathogenesis of this species without destabilizing the balance of the flora.

Trachyspermum ammi aromatic water: A traditional drink with considerable anti-Candida activity

BACKGROUND AND PURPOSE

Aromatic waters (AWs) are therapeutic distillates, which harbor both essential oil and water-soluble components of a plant. Due to the dispersion of the light amount of essence through the AWs, they have their specific pleasant smell, taste, and medicinal properties. In Iranian traditional medicine, Trachyspermum ammi AW is used to treat gastrointestinal disorders. The present study was conducted to determine the chemical composition of the essential oil extracted from T. ammi AW and its antifungal activities against Candida species.

MATERIALS AND METHODS

The composition of the essential oil extracted from T. ammi AW was analyzed by gas chromatography-mass spectrometry. In addition, the evaluation of the antifungal activity of AW against Candida species was performed using broth microdilution methods as recommended by the Clinical Laboratory Standard Institute. Moreover, the biofilm formation inhibition, antioxidant properties, and experimental activity of AW were determined in an animal model.

RESULTS

According to the results, thymol (78.08%) was the major compound of EO, followed by carvacrol (8.20%) and carvotanacetone (6.50%). Furthermore, T. ammi AW exhibited antifungal activities against the examined fungi and inhibited the biofilm formation of C. albicans at a concentration of up to 0.25 V/V. Histopathological analyses revealed that Candida colonization declined in the mice following the administration ofT. ammi AW in a therapeutic trial.

CONCLUSION

It seems that the presence of phenolic monoterpenes in AW has resulted in antifungal effects. Pleasant odor and antioxidant properties are extra bonuses to the antimicrobial effects of this plant. Based on the findings, AW might have the potential to be used in the management of alimentary candidiasis or oral hygienic products.

Improved efficacy of antifungal drugs in combination with monoterpene phenols against Candida auris

Emergence of Candida auris has been described as a global health threat due to its ability to cause invasive infections with high mortality rate and multidrug resistance. Novel drugs and therapies are required to target this organism and its pathogenicity. Anti-virulence approach and combination therapy have been proposed as alternatives in recent years. This study evaluated the virulence factors in C. auris, combination antifungal activity of phenolic compounds with antifungal drugs and determined effect of the most active compound on positive pathogenicity markers of C. auris. Antifungal susceptibility profile of 25 clinical isolates of C. auris against antifungal agents as well as against phenolic compounds was obtained using CLSI guidelines. Combination of the most active phenolic compound with antifungal drugs was determined. Effect of carvacrol on the virulence factors was also studied. Carvacrol was the most active phenol with median MIC of 125 µg/ml and its combination with fluconazole, amphotericin B, nystatin and caspofungin resulted synergistic and additive effects in 68%, 64%, 96% and 28%, respectively. Combination also reduced the MIC values of the drugs. All test strains showed adherence ability to epithelial cells and 96% of strains produced proteinase. None of the strains produced hyphae and phospholipase. At low concentrations, carvacrol significantly inhibited the adherence ability and proteinase production (both p < 0.01). Carvacrol has antifungal and anti-virulence activity against C. auris. It also showed an enhanced antifungal activity in combination with antifungal agents. Therefore it has potential to be developed into a novel antifungal agent.

Unusual and Highly Bioactive Sesterterpenes Synthesized by Pleurotus ostreatus during Coculture with Trametes robiniophila Murr

Candida albicans and Cryptococcus neoformans, human-pathogenic fungi found worldwide, are receiving increasing attention due to high morbidity and mortality in immunocompromised patients. In the present work, 110 fungus pairs were constructed by coculturing 16 wood-decaying basidiomycetes, among which coculture of Trametes robiniophila Murr and Pleurotus ostreatus was found to strongly inhibit pathogenic fungi through bioactivity-guided assays. A combination of metabolomics and molecular network analysis revealed that 44 features were either newly synthesized or produced at high levels in this coculture system and that 6 of the features that belonged to a family of novel and unusual linear sesterterpenes contributed to high activity with MICs of 1 to 32 μg/ml against pathogenic fungi. Furthermore, dynamic ¹³C-labeling analysis revealed an association between induced features and the corresponding fungi. Unusual sesterterpenes were ¹³C labeled only in P. ostreatus in a time course after stimulation by the coculture, suggesting that these sesterterpenes were synthesized by P. ostreatus instead of T. robiniophila Murr. Sesterterpene compounds 1 to 3 were renamed postrediene A to C. Real-time reverse transcription-quantitative PCR (RT-qPCR) analysis revealed that transcriptional levels of three genes encoding terpene synthase, farnesyl-diphosphate farnesyltransferase, and oxidase were found to be 8.2-fold, 88.7-fold, and 21.6-fold higher, respectively, in the coculture than in the monoculture, indicating that biosynthetic gene cluster 10 was most likely responsible for the synthesis of these sesterterpenes. A putative biosynthetic pathway of postrediene A to postrediene C was then proposed based on structures of sesterterpenes and molecular network analysis.IMPORTANCE A number of gene clusters involved in biosynthesis of secondary metabolites are presumably silent or expressed at low levels under conditions of standard laboratory cultivation, resulting in a large gap between the pool of discovered metabolites and genome capability. This work mimicked naturally occurring competition by construction of an artificial coculture of basidiomycete fungi for the identification of secondary metabolites with novel scaffolds and excellent bioactivity. Unusual linear sesterterpenes of postrediene A to C synthesized by P. ostreatus not only were promising lead drugs against human-pathogenic fungi but also highlighted a distinct pathway for sesterterpene biosynthesis in basidiomycetes. The current work provides an important basis for uncovering novel gene functions involved in sesterterpene synthesis and for gaining insights into the mechanism of silent gene activation in fungal defense.

Inhibitory effects of thymol on the cytotoxicity and inflammatory responses induced by Staphylococcus aureus extracellular vesicles in cultured keratinocytes

Staphylococcus aureus extracellular vesicles (EVs) deliver effector molecules to host cells and induce host cell pathology. This study investigated the disruption of S. aureus EVs by thymol along with its inhibitory effects on the cytotoxicity and inflammatory responses induced by EVs derived from two different S. aureus strains in cultured keratinocytes. Membrane disruption of the S. aureus EVs treated with thymol was determined using transmission electron microscopy. Human keratinocyte HaCaT cells were incubated with either intact or thymol-treated S. aureus EVs and then analyzed for cytotoxicity and pro-inflammatory cytokine gene expression. Thymol inhibited the growth of S. aureus strains and disrupted the membranes of the S. aureus EVs. The cytotoxicity and the expression levels of the pro-inflammatory cytokine genes towards HaCaT cells differed between the EVs derived from two S. aureus strains. Thymol-treated S. aureus EVs inhibited the cytotoxicity and the expression of the pro-inflammatory cytokine genes when compared to intact S. aureus EVs. Thymol-treated S. aureus EVs delivered lesser amounts of the EV component to host cells than intact EVs. Our results suggest that the thymol-induced disruption of the S. aureus EVs inhibits the delivery of effector molecules to host cells, resulting in the suppression of cytotoxicity and inflammatory responses in keratinocytes. Thymol may attenuate the host cell pathology induced by an S. aureus infection via both the antimicrobial activity against the bacteria and the disruption of the secreted EVs.

Anti-Candida Biofilm Activity of Pterostilbene or Crude Extract from Non-Fermented Grape Pomace Entrapped in Biopolymeric Nanoparticles

Polymeric nanoparticle-based carriers are promising agents to deliver drugs to cells. Vitis vinifera phenolic compounds are known for their antifungal activity against Candida albicans. The aim of the present study was to investigate the antifungal activity of pterostilbene or crude extracts from non-fermented grape pomace, entrapped in poly(lactic-co-glycolic) acid nanoparticles (NPs), with diameters of 50 and 150 nm, on Candida biofilm. The fluorescent probe coumarin 6 was used to study the uptake of poly(lactic-co-glycolic)acid (PLGA) NPs in planktonic cells and biofilm. The green fluorescent signal of coumarin 6 was observed in Candida biofilm after 24 and 48 hours. Both pterostilbene and crude pomace extract entrapped in NPs exerted a significantly higher anti-biofilm activity compared to their free forms. The entrapment efficiency of both pterostilbene and crude pomace extract in PLGA NPs was ~90%. At 16 µg/mL, pterostilbene loaded in PLGA NPs reduced biofilm formation of 63% and reduced mature biofilm of 50%. Moreover, at 50 µg/mL, the pomace extract loaded in NPs reduced mature biofilm of 37%. These results strongly suggest that PLGA NPs are promising nanodevices for the delivery of antifungal drugs as the crude grape pomace extract, a by-product of white wine making.

Synthesis of Thymol Derivatives as Potential Non-Irritant Antimicrobial and Insecticidal Agents

Background:

Thymol has been reported to have a variety of antimicrobial and insecticidal activities but it has irritation side effect due to its phenolic nature.

Methods:

A new series of potential non-irritant non-phenolic thymol derivatives were designed to hybridize the well-known biologically active thymol scaffold with various five membered heterocyclic antimicrobial and insecticidal pharmacophores like 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,4-triazole, thiazole and 4-thiazolidinone through different spacers. The target compounds were biologically evaluated for their in vitro antibacterial, antifungal and insecticidal activities.

Results:

Compounds 4b and 9c showed weak antibacterial activity against S. aureus and B.subtilis with the inhibition zone diameters ranging from 2 to 7 mm and 4 mm respectively compared with ciprofloxacin with the inhibition zone diameter of 21 mm. Compounds 9a, 7d and 13b showed weak antibacterial compounds against B. subtilis with inhibition zone diameters 4, 4 and 6 mm respectively. Compounds 12b, 9c and 7a showed 20% insecticidal activity at a concentration of 0.157 mg/cm2 for each compound against Tribolium castaneum (Herbst) and Sitophilus oryzae (L.). Compound 6 showed moderate larvicidal activity against Culex pipiens with 40% mortality at a concentration of 1000 ppm.

Conclusion:

Compound 9c showed weak dual antimicrobial and insecticidal activities.

Investigation of the Antifungal Activity and Mode of Action of Thymus vulgaris, Citrus limonum, Pelargonium graveolens, Cinnamomum cassia, Ocimum basilicum, and Eugenia caryophyllus Essential Oils

The antimicrobial activity of plant oils and extracts has been recognized for many years. In this study the activity of Thymus vulgaris, Citrus limonum, Pelargonium graveolens, Cinnamomum cassia, Ocimumbasilicum, and Eugenia caryophyllus essential oils (EOs) distributed by Pollena Aroma (Nowy Dwór Mazowiecki, Poland) was investigated against a group of 183 clinical isolates of C. albicans and 76 isolates of C. glabrata. All of the oils exhibited both fungistatic and fungicidal activity toward C. albicans and C. glabrata isolates. The highest activity was observed for cinnamon oil, with MIC (Minimum Inhibitory Concentration) values in the range 0.002⁻0.125% (v/v). The MIC values of the rest of the oils were in the range 0.005% (or less) to 2.5% (v/v). In most cases MFC (Minimum Fungicidal Concentration) values were equal to MIC or twice as high. Additionally, we examined the mode of action of selected EOs. The effect on cell wall components could not be clearly proved. Three of the tested EOs (thyme, lemon, and clove) affected cell membranes. At the same time, thyme, cinnamon, and clove oil influenced potassium ion efflux, which was not seen in the case of lemon oil. All of the tested oils demonstrated the ability to inhibit the transition of yeast to mycelium form, but the effect was the lowest in the case of cinnamon oil.

Thymol attenuates the worsening of atopic dermatitis induced by Staphylococcus aureus membrane vesicles

Staphylococcus aureus membrane vesicles (MVs) aggravate atopic dermatitis (AD) through the delivery of bacterial effector molecules to host cells and the stimulation of inflammatory responses. This study investigated the inhibitory effect of thymol, a phenolic monoterpene found in essential oils derived from plants, on the worsening of AD induced by S. aureus MVs both in vitro and in vivo. The sub-minimal inhibitory concentrations of thymol disrupted S. aureus MVs. Intact S. aureus MVs induced the expression of pro-inflammatory cytokine (interleukin (IL)-1β, IL-6, and tumor necrosis factor-α) and chemokine (IL-8 and monocyte chemoattractant protein-1) genes in cultured keratinocytes, whereas thymol-treated S. aureus MVs did not stimulate the expression of these genes. Topical application of thymol-treated S. aureus MVs or treatment with thymol after intact S. aureus MVs to AD-like skin lesions diminished the pathology of AD. This included decreases in epidermal/dermal thickness and infiltration of eosinophils/mast cells, and inhibited expression of pro-inflammatory cytokine and chemokine genes in mouse AD model. Moreover, thymol significantly suppressed the Th1, Th2, and Th17-mediated inflammatory responses in AD-like skin lesions induced by S. aureus MVs, and reduced the serum levels of immunoglobulin (Ig) G2a, mite-specific IgE, and total IgE. In summary, thymol disrupts S. aureus MVs and suppresses inflammatory responses in AD-like skin lesions aggravated by S. aureus MVs. Our results suggest that thymol is a possible candidate for the management of AD aggravation induced by S. aureus colonization or infection in the lesions.

Potential effect of 2-isopropyl-5-methylphenol (thymol) alone and in combination with fluconazole against clinical isolates of Candida albicans, C. glabrata and C. krusei

Limitations of antifungals used in the treatment of candidiasis, as the development of resistant strains, are known by the scientific community. In this context, the aim of this study was to investigate the activity of 2-isopropyl-5-methylphenol (thymol) in combination with fluconazole (FLZ) against clinical Candida strains. The antifungal activity of thymol along with FLZ was evaluated by the Clinical Laboratory Standards Institute (CLSI) M27-A2 broth microdilution method. In addition, synergism was observed for clinical strains of Candida spp. with combination of thymol-FLZ evaluated by the chequerboard microdilution method. The mean of minimum inhibitory concentration (MIC) values of thymol and FLZ were 49.37 and 0.475μg/ml for C. albicans, 51.25 and 18.80μg/ml for C. glabrata and 70 and 179.20μg/ml for C. krusei strains, respectively. Thymol in combination with FLZ exhibited the synergistic effects against all species of Candida tested. FICI values for thymol plus FLZ ranged from 0.366 to 0.607 for C. albicans strains, 0.367 to 0.482 for C. glabrata strains, and 0.375 to 0.563 for C. krusei strains. No antagonistic activity was seen in the strains tested. Thymol was found to have a fungicidal effect on Candida species and a synergistic effect when combined with FLZ.

Antifungal Compounds against Candida Infections from Traditional Chinese Medicine

Infections caused by Candida albicans, often refractory and with high morbidity and mortality, cause a heavy burden on the public health while the current antifungal drugs are limited and are associated with toxicity and resistance. Many plant-derived molecules including compounds isolated from traditional Chinese medicine (TCM) are reported to have antifungal activity through different targets such as cell membrane, cell wall, mitochondria, and virulence factors. Here, we review the recent progress in the anti-Candida compounds from TCM, as well as their antifungal mechanisms. Considering the diverse targets and structures, compounds from TCM might be a potential library for antifungal drug development.

Plant phenolics and terpenoids as adjuvants of antibacterial and antifungal drugs

BACKGROUND

The intensive use of antibacterial and antifungal drugs has dramatically increased the microbial resistance and has led to a higher number of difficult-to-eradicate infections. Combination therapy with two or more antimicrobial drugs has emerged some years ago to overcome the issue, but it has proven to be not completely effective. Natural secondary metabolites of MW ≤ 500 represent promising adjuvants for antimicrobials and have been the object of several researches that have increased in the last two decades.

PURPOSE

The purpose of this Review is to do a literature search of the natural compounds that showed high enhancing capacity of antibacterials' and antifungals' effects against planktonic bacteria and fungi and to analyze which are the natural products most used in combination with a focus on polyphenols and terpenoids.

RESULTS

One hundred of papers were collected for reviewing. Fifty six (56) of them deal with combinations of low MW natural products with antibacterial drugs against planktonic bacteria and forty four (44) on natural products with antifungal drugs against planktonic fungi. Of the antibacterial adjuvants, 41 (73%) were either polyphenols (27; 48%) or terpenes (14; 25%). The remaining 15 papers (27%), deal with different class of natural products. Since most natural potentiators belong to the terpene or phenolic structural types, a more detailed description of the works dealing with these type of compounds is provided here. Bacterial and fungal resistance mechanisms, the modes of action of the main classes of antibacterial and antifungal drugs and the methodologies most used to assess the type of interactions in the combinations were included in the Review too.

CONCLUSIONS AND PERSPECTIVES

Several promising results on the potentiation effects of antifungals' and antibacterials' activities by low MW natural products mainly on polyphenols and terpenes were reported in the literature and, in spite of that most works included only in vitro assays, this knowledge opens a wide range of possibilities for the combination antimicrobial therapy. Further research including in vivo assays and clinical trials are required to determine the relevance of these antimicrobial enhancers in the clinical area and should be the focus of future studies in order to develop new antimicrobial combination agents that overpass the drawbacks of the existing antibiotics and antifungals in clinical use.

Thymol has antifungal activity against Candida albicans during infection and maintains the innate immune response required for function of the p38 MAPK signaling pathway in Caenorhabditis elegans

The Caenorhabditis elegans model can be used to study Candida albicans virulence and host immunity, as well as to identify plant-derived natural products to use against C. albicans. Thymol is a hydrophobic phenol compound from the aromatic plant thyme. In this study, the in vitro data demonstrated concentration-dependent thymol inhibition of both C. albicans growth and biofilm formation during different developmental phases. With the aid of the C. elegans system, we performed in vivo assays, and our results further showed the ability of thymol to increase C. elegans life span during infection, inhibit C. albicans colony formation in the C. elegans intestine, and increase the expression levels of host antimicrobial genes. Moreover, among the genes that encode the p38 MAPK signaling pathway, mutation of the pmk-1 or sek-1 gene decreased the beneficial effects of thymol's antifungal activity against C. albicans and thymol's maintenance of the innate immune response in nematodes. Western blot data showed the level of phosphorylation of pmk-1 was dramatically decreased against C. albicans. In nematodes, treatment with thymol recovered the dysregulation of pmk-1 and sek-1 gene expressions, the phosphorylation level of PMK-1 caused by C. albicans infection. Therefore, thymol may act, at least in part, through the function of the p38 MAPK signaling pathway to protect against C. albicans infection and maintain the host innate immune response to C. albicans. Our results indicate that the p38 MAPK signaling pathway plays a crucial role in regulating the beneficial effects observed after nematodes infected with C. albicans were treated with thymol.

Effect of Addition of Antifungal Agents on Physical and Biological Properties of a Tissue Conditioner: An In-Vitro Study

Purpose: Tissue conditioners are used for healing of abused oral tissues. They may harbour microorganisms causing oral diseases such as candidiasis compromising the health of the patient. Also, addition of antifungal agents into tissue conditioner may alter its properties. This study compares the anti-fungal property and mechanical properties of tissue conditioner containing different antifungal agents.

Methods: Three antifungal agents, one synthetic – fluconazole, and two natural - oregano oil and virgin coconut oil were added into the tissue conditioner (Viscogel) in different concentrations. The antifungal property, tensile bond strength and viscoelasticity of Viscogel containing these antifungal agents were assessed after 24 hours, three days and seven days.

Results: While, the highest antifungal activity was shown by Viscogel containing fluconazole, the maximum tensile bond strength was found to be of Viscogel alone (control). Although Viscogel alone and in combination of fluconazole showed deterioration in viscoelasticity, Viscogel in combination of natural agents showed no significant changes over the period of seven days.

Conclusion: Incorporation of the natural agents in the tissue conditioner can be used as an effective alternative to systemic or topical synthetic antifungal agents.

Antifungal effects of phytocompounds on Candida species alone and in combination with fluconazole

Invasive fungal infections caused by Candida spp. remain the most predominant nosocomial fungal infections. Owing to the increased use of antifungal agents, resistance of Candida spp. to antimycotics has emerged frequently, especially to fluconazole (FLC). To cope with this issue, new efforts have been dedicated to discovering novel antimycotics or new agents that can enhance the susceptibility of Candida spp. to existing antimycotics. The secondary metabolites of plants represent a large library of compounds that are important sources for new drugs or compounds suitable for further modification. Research on the anti-Candida activities of phytocompounds has been carried out in recent years and the results showed that a series of phytocompounds have anti-Candida properties, such as phenylpropanoids, flavonoids, terpenoids and alkaloids. Among these phytocompounds, some displayed potent antifungal activity, with minimum inhibitory concentrations (MICs) of ≤8 µg/mL, and several compounds were even more effective against drug-resistant Candida spp. than FLC or itraconazole (e.g. honokiol, magnolol and shikonin). Interestingly, quite a few phytocompounds not only displayed anti-Candida activity alone but also synergised with FLC against Candida spp., even leading to a reversal of FLC resistance. This review focuses on summarising the anti-Candida activities of phytocompounds as well as the interactions of phytocompounds with FLC. In addition, we briefly overview the synergistic mechanisms and present the structure of the antimycotic phytocompounds. Hopefully, this analysis will provide insight into antifungal agent discovery and new approaches against antifungal drug resistance.

Antifungal adjuvants: Preserving and extending the antifungal arsenal

As the rates of systemic fungal infections continue to rise and antifungal drug resistance becomes more prevalent, there is an urgent need for new therapeutic options. This issue is exacerbated by the limited number of systemic antifungal drug classes. However, the discovery, development, and approval of novel antifungals is an extensive process that often takes decades. For this reason, there is growing interest and research into the possibility of combining existing therapies with various adjuvants that either enhance activity or overcome existing mechanisms of resistance. Reports of antifungal adjuvants range from plant extracts to repurposed compounds, to synthetic peptides. This approach would potentially prolong the utility of currently approved antifungals and mitigate the ongoing development of resistance.

Potential Use of Phenolic Acids as Anti-Candida Agents: A Review

There has been a sharp rise in the occurrence of Candida infections and associated mortality over the last few years, due to the growing body of immunocompromised population. Limited number of currently available antifungal agents, undesirable side effects and toxicity, as well as emergence of resistant strains pose a considerable clinical challenge for the treatment of candidiasis. Therefore, molecules that derived from natural sources exhibiting considerable antifungal properties are a promising source for the development of novel anti-candidal therapy. Phenolic compounds isolated from natural sources possess antifungal properties of interest. Particularly, phenolic acids have shown promising in vitro and in vivo activity against Candida species. However, studies on their mechanism of action alone or in synergism with known antifungals are still scarce. This review attempts to discuss the potential use, proposed mechanisms of action and limitations of the phenolic acids in anti-candidal therapy.

[Effects of Blending Oil of Lavender and Thyme on Oxidative Stress, Immunity, and Skin Condition in Atopic Dermatitis Induced Mice]

PURPOSE

The purpose of this study was to evaluate the effects of essential oil on oxidative stress, immunity, and skin condition in atopic dermatitis (AD) induced mice.

METHODS

This study was a 3×3 factorial design. Factors were oil type (Lavender, Thyme, and 2:1 mixture of lavender and thyme oil [blending oil]) and treatment period (0 day, 7 days, and 21 days). The samples were 45 mice with AD and randomly assigned to nine groups of five mice per group. The dependent variables such as superoxide radical, IgE, degranulated mast cells, and epidermal thickness were measured. Data were collected from February to April in 2014. Descriptive statistics, One-way ANOVA, Two-way ANOVA, and Tukey's HSD test were performed using the SPSS WIN 20.0 program.

RESULTS

Dependent variables were not statistically significantly different by the three oil types (p>.05). Essential oils such as lavender, thyme, and blending oil were all effective in reducing AD symptoms and especially 2:1 blending oil were most effective. There were statistically significant differences by the three treatment periods in all dependent variables (p<.001). There were statistically significant interactions between oil types and treatment periods in all dependent variables (p<.01). For decreasing superoxide radical, degranulated mast cells, and epidermal thickness, 2:1 mixed oil should be applied for at least 21 days. Otherwise to reduce IgE, 2:1 mixed oil should be used for at least 7 days.

CONCLUSION

These findings provide bases for developing effective interventions for AD patients to manage their AD symptoms.

Sensitization of Candida albicans biofilms to fluconazole by terpenoids of plant origin

Infections associated with the biofilms of Candida albicans are a challenge to antifungal treatment. Combinatorial therapy involving plant molecules with antifungal drugs would be an effective complementary approach against drug-resistant Candida biofilms. The aim of this study was to evaluate the efficacy of three bioactive terpenoids (carvacrol, eugenol and thymol) in combination with fluconazole against planktonic cells, biofilm development and mature biofilms of C. albicans. Activities of the selected molecules were tested using a microplate-based methodology, while their combinations with fluconazole were performed in a checkerboard format. Biofilms were quantitated by XTT-metabolic assay and confirmed by microscopic observations. Combinations of carvacrol and eugenol with fluconazole were found synergistic against planktonic growth of C. albicans, while that of thymol with fluconazole did not have any interaction. Biofilm development and mature biofilms were highly resistant to fluconazole, but susceptible to three terpenoids. Sensitization of cells by sub-inhibitory concentrations of carvacrol and eugenol resulted in prevention of biofilm formation at low fluconazole concentrations, i.e. 0.032 and 0.002 mg ml(-1), respectively. Addition of thymol could not potentiate activity of fluconazole against biofilm formation by C. albicans. Fractional inhibitory concentration indices (FICI) for carvacrol-fluconazole and eugenol-fluconazole combinations for biofilm formation were 0.311 and 0.25, respectively. The FICI value of 1.003 indicated a status of indifference for the combination of thymol and fluconazole against biofilm formation. Eugenol and thymol combinations with fluconazole did not have useful interaction against mature biofilms of C. albicans, but the presence of 0.5 mg ml(-1) of carvacrol caused inhibition of mature biofilms at a significantly low concentration (i.e. 0.032 mg ml(-1)) of fluconazole. The study indicated that carvacrol and eugenol combinations with fluconazole would be a potential alternative strategy for prevention and control of biofilm-associated C. albicans infections.

Inhibition of acid sphingomyelinase by tricyclic antidepressants and analogons

Amitriptyline, a tricyclic antidepressant, has been used in the clinic to treat a number of disorders, in particular major depression and neuropathic pain. In the 1970s the ability of tricyclic antidepressants to inhibit acid sphingomyelinase (ASM) was discovered. The enzyme ASM catalyzes the hydrolysis of sphingomyelin to ceramide. ASM and ceramide were shown to play a crucial role in a wide range of diseases, including cancer, cystic fibrosis, diabetes, Alzheimer's disease, and major depression, as well as viral (e.g., measles virus) and bacterial (e.g., Staphylococcus aureus, Pseudomonas aeruginosa) infections. Ceramide molecules may act in these diseases by the alteration of membrane biophysics, the self-association of ceramide molecules within the cell membrane and the ultimate formation of larger ceramide-enriched membrane domains/platforms. These domains were shown to serve the clustering of certain receptors such as CD95 and may also act in the above named diseases. The potential to block the generation of ceramide by inhibiting the ASM has opened up new therapeutic approaches for the treatment of these conditions. Since amitriptyline is one of the longest used clinical drugs and side effects are well studied, it could potentially become a cheap and easily accessible medication for patients suffering from these diseases. In this review, we aim to provide an overview of current in vitro and in vivo studies and clinical trials utilizing amitriptyline to inhibit ASM and contemplate possible future applications of the drug.

IgE-mediated mast cell responses are inhibited by thymol-mediated, activation-induced cell death in skin inflammation

BACKGROUND

Mast cells play a critical role in inflammatory skin diseases through releasing proinflammatory mediators; however, few therapies directly target these cells. In 1878, the use of topical thymol, a now recognized potent agonist for transient receptor potential channels, was first described to treat eczema and psoriasis.

OBJECTIVE

We sought to determine the mechanisms through which thymol can alter skin inflammation.

METHODS

We examined the effect of topical thymol on IgE-dependent responses using a mast cell-dependent passive cutaneous anaphylaxis (PCA) model, as well as in vitro-cultured mast cells.

RESULTS

Thymol dose-dependently inhibited PCA when administered topically 24 hours before antigen challenge but provoked an ear-swelling response directly on application. This direct effect was associated with local mast cell degranulation and was absent in histamine-deficient mice. However, unlike with PCA responses, there was no late-phase swelling. In vitro thymol directly triggered calcium flux in mast cells through transient receptor potential channel activation, along with degranulation and cytokine transcription. However, no cytokine protein was produced. Instead, thymol induced a significant increase in apoptotic cell death that was seen both in vitro and in vivo.

CONCLUSIONS

We propose that the efficacy of thymol in reducing IgE-dependent responses is through promotion of activation-induced apoptotic cell death of mast cells and that this likely explains the clinical benefits observed in early clinical reports.