Antifungal Activities of L-Methionine and L-Arginine Treatment In Vitro and In Vivo against Botrytis cinerea

Gray mold caused by Botrytis cinerea is a common postharvest fungal disease in fruit and vegetables. The prevention and treatment of postharvest gray mold has been one of the hot research issues addressed by researchers. This study aimed to investigate the effect of L-methionine and L-arginine on Botrytis cinerea in vitro and on cherry tomato fruit. The results of the in vitro experiment showed that L-methionine and L-arginine had significant inhibitory effects on the mycelial growth and spore germination of Botrytis cinerea, and the inhibitory effects were enhanced with increasing L-methionine or L-arginine concentration. In addition, L-methionine and L-arginine treatment increased the leakage of Botrytis cinerea electrolytes, proteins and nucleic acids. The experiment involving propidium iodide staining and malondialdehyde content assay also confirmed that L-methionine and L-arginine treatment could lead to cell membrane rupture and lipid peroxidation. The results of scanning electron microscopy further verified that the morphology of hyphae was damaged, deformed, dented and wrinkled after treatment with L-methionine or L-arginine. Fruit inoculation experiments displayed that L-methionine and L-arginine treatments significantly inhibited the occurrence and development of gray mold in postharvest cherry tomato. Therefore, treatment with L-methionine or L-arginine might be an effective means to control postharvest gray mold in fruit and vegetables.

Formulation and Development of a Herbal Antifungal Gel Containing Origanum vulgare and Syzygium aromaticum Essential Oils Against Oral Candida albicans

Background Oral candidiasis is the most prevalent oral fungal infection, and existing antifungal agents have side effects such as drug intolerance, resistance, and toxicity. Herbal essential oils are emerging as an alternative therapeutic approach for treating fungal infections. Origanum vulgare (O. vulgare), commonly known as oregano, and Syzygium aromaticum (S. aromaticum), commonly known as clove, are known to have antifungal properties and are effective against fluconazole-resistant strains. A combination of essential oils has a synergistic effect and aids in achieving effective antifungal activity at sufficiently low concentrations, which could lead to reduced side effects and resistance. Aim of the study This study aimed to formulate and develop an herbal antifungal gel containing O. vulgare and S. aromaticum and evaluate its synergistic antifungal efficacy against oral Candida albicans (C. albicans). Methodology Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) determinations of O. vulgare and S. aromaticum essential oils were performed individually and in combination to assess the antifungal activity against C. albicans. Based on the obtained MIC and MFC of essential oils in combination, an herbal antifungal gel was formulated. Further, to determine the biocompatible nature of the gel, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed. Results We found that a combination of O. vulgare and S. aromaticum essential oils showed antifungal activity at a lesser concentration, with a MIC of 0.19 μl/ml and MFC of 0.39 μl/ml when compared to their individual concentrations. Based on our results, an antifungal herbal gel comprising a concentration of 0.6 μl/ml of both essential oils was developed to achieve synergistic antifungal activity against oral C. albicans. The MTT assay of the herbal gel did not show any cytotoxicity. Conclusion The novel herbal antifungal gel containing O. vulgare and S. aromaticum is biocompatible in nature and provides an alternative therapeutic approach for treating oral candidiasis.

Evaluation of the Antifungal Effect of Rhus verniciflua Stokes Extract for Oral Application Potential

Background and Objectives: This study confirms the possibility of using Rhus verniciflua Stokes (RVS) extract as a natural treatment for oral candidiasis. Materials and Methods: RVS was extracted with 70% ethanol to examine the antioxidant activity through polyphenol, flavonoid content, and DPPH (1,1-diphenyl-2-picrylhydrazyl). To evaluate the antifungal effect against Candida albicans (C. albicans; KCTC 7965/ATCC 10231) and evaluate the stability of RVS, a water-soluble tetrazolium salt (WST-1) assay was performed in human keratinocytes (HaCaT). Results: The findings revealed that RVS extract has fairly high antioxidant activity. The clear zones of the RVS extract against C. albicans increased in diameter due to the inhibition of fungal growth at higher concentrations. Treatment with the 1.25 mg/mL RVS extract had a more than 99% antifungal effect against C. albicans, and the 20 mg/mL RVS extract had a 100% antifungal effect. The WST-1 assay showed that the RVS extract induced low cell viability in the HaCaT cells, which inhibited their proliferation, and the RVS extract is also toxic to normal cells. Conclusions: Although the RVS extract with high antioxidant activity showed clear antifungal activity against C. albicans, it exhibited a low survival rate. Therefore, the development of a safe natural antibiotic is necessary.

against Magnaporthe oryzae

BACKGROUND

Rice blast caused by Magnaporthe oryzae is one of the most devastating diseases of rice, and novel fungicides for controlling rice blast are needed owing to the problem of resistance to commonly used control agents. We previously found that methanol extract of Lycoris radiata (L'Her.) Herb. showed an excellent inhibitory effect on mycelial growth of M. oryzae, indicating its potential for developing control agents against M. oryzae. In this study, we aim to investigate the antifungal effects of different Lycoris spp. against M. oryzae, and clarify the main active components.

RESULTS

Extracts from bulbs of seven Lycoris spp. showed excellent inhibitory effects on mycelial growth and spore germination of M. oryzae at 400 mg L^-1 . Liquid chromatography-tandem mass spectrometry was employed to analyze the components of the extracts, and heatmap clustering analysis with Mass Profiler Professional software revealed that lycorine and narciclasine may be the main active components. Lycorine and narciclasine, together with three other amaryllidaceous alkaloids (AAs), were then isolated from bulbs of Lycoris spp. Antifungal assays showed that lycorine and narciclasine had good inhibitory activities against M. oryzae in vitro, but the other three AAs showed no antifungal activities under test concentrations. In addition, lycorine and the ethyl acetate part of L. radiata showed good antifungal effects against M. oryzae in vivo, but narciclasine showed phototoxicity on rice when used alone.

CONCLUSION

Extracts of test Lycoris spp. and the main active component lycorine have excellent antifungal activities against M. oryzae, and are good candidates for developing control agents against M. oryzae. © 2023 Society of Chemical Industry.

Anti-Candida and Anti-Inflammatory Properties of a Vaginal Gel Formulation: Novel Data Concerning Vaginal Infection and Dysbiosis

Vaginal ecosystem is a unique environment where, in physiological conditions, lactobacilli dominate. However, pathogenic microbial species responsible for vaginitis and vaginosis can also harbor vaginal microbiota. To extend our previously published data, we analyzed here both the anti-Candida and anti-inflammatory properties of the vaginal gel formulation, Respecta^® Balance Gel (RBG), commercialized as an adjuvant to treat vaginitis and vaginosis. We evaluated its activity by an in vitro model where a monolayer of A-431 vaginal epithelial cells was infected by Candida albicans in the presence of RBG or the placebo formulation (pRBG). Specifically, we tested the RBG capacity to counteract C. albicans virulence factors and their anti-inflammatory properties. Our results show that, unlike the placebo, RBG reduces C. albicans adhesion, its capacity to form hyphae and C. albicans-induced vaginal cell damage. Interestingly, both RBG and pRBG reduce LPS-induced IL-8 secretion (with RBG being the most effective), demonstrating that also the placebo retains anti-inflammatory properties. From our experimental approach, we highlighted the possible role of farnesol on such effects, but we would like to point out that lactic acid, polydextrose and glycogen too must be relevant in the actual application. In summary, our results show that RBG impairs C. albicans virulence and is able to reduce the inflammation in the vaginal environment, ultimately allowing the establishment of a balanced vaginal ecosystem.

Potential Succinate Dehydrogenase Inhibitors Bearing a Novel Pyrazole-4-sulfonohydrazide Scaffold: Molecular Design, Antifungal Evaluation, and Action Mechanism

Aiming to develop novel antifungal agents with a distinctive molecular scaffold targeting succinate dehydrogenase (SDH), 24 N'-phenyl-1H-pyrazole-4-sulfonohydrazide derivatives were first devised, synthesized, and verified by ¹H NMR, ¹³C NMR, high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction analysis. The bioassays revealed that the target compounds possessed highly efficient and broad-spectrum antifungal activities against four tested plant pathogenic fungi Rhizoctonia solani (R. solani), Botrytis cinerea, Fusarium graminearum, and Alternaria sonali. Strikingly, compound B6 was assessed as the selective inhibitor against R. solani, with an in vitro EC₅₀ value (0.23 μg/mL) that was similar to that of thifluzamide (0.20 μg/mL). The in vivo preventative effect of compound B6 (75.76%) at 200 μg/mL against R. solani was roughly comparable to thifluzamide (84.31%) under the same conditions. The exploration of morphological observations indicated that compound B6 could strongly damage the mycelium morphology, obviously increase the permeability of the cell membrane, and dramatically increase the number of mitochondria. Compound B6 also significantly inhibited SDH enzyme activity with an IC₅₀ value of 0.28 μg/mL, and its fluorescence quenching dynamic curves were similar to that of thifluzamide. Molecular docking and molecular dynamics simulations demonstrated that compound B6 could strongly interact with similar residues around the SDH active pocket as thifluzamide. The present study revealed that the novel N'-phenyl-1H-pyrazole pyrazole-4-sulfonohydrazide derivatives are worthy of being further investigated as the promising replacements of traditional carboxamide derivatives targeting SDH of fungi.

Antimicrobial Diterpenes from Rough Goldenrod (Solidago rugosa Mill.)

Solidago rugosa is one of the goldenrod species native to North America but has sporadically naturalized as an alien plant in Europe. The investigation of the root and leaf ethanol extracts of the plant using a bioassay-guided process with an anti-Bacillus assay resulted in the isolation of two antimicrobial components. Structure elucidation was performed based on high-resolution tandem mass spectrometric and one- and two-dimensional NMR spectroscopic analyses that revealed (-)-hardwickiic acid (Compound 1) and (-)-abietic acid (Compound 2). The isolates were evaluated for their antimicrobial properties against several plant pathogenic bacterial and fungal strains. Both compounds demonstrated an antibacterial effect, especially against Gram-positive bacterial strains (Bacillus spizizenii, Clavibacter michiganensis subsp. michiganensis, and Curtobacterium flaccumfaciens pv. flaccumfaciens) with half maximal inhibitory concentration (IC₅₀) between 1 and 5.1 µg/mL (5-20 times higher than that of the positive control gentamicin). In the used concentrations, minimal bactericidal concentration (MBC) was reached only against the non-pathogen B. spizizenii. Besides their activity against Fusarium avenaceum, the highest antifungal activity was observed for Compound 1 against Bipolaris sorokiniana with an IC₅₀ of 3.8 µg/mL.

cubense

Fusarium wilt of banana (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), especially tropical race 4 (TR4), presents the foremost menace to the global banana production. Extensive efforts have been made to search for efficient biological control agents for disease management. Our previous study showed that Streptomyces sp. XY006 exhibited a strong inhibitory activity against several phytopathogenic fungi, including F. oxysporum. Here, the corresponding antifungal metabolites were purified and determined to be two cyclic lipopeptide homologs, lipopeptin A and lipopeptin B. Combined treatment with lipopeptin complex antagonized Foc TR4 by inhibiting mycelial growth and conidial sporulation, suppressing the synthesis of ergosterol and fatty acids and lowering the production of fusaric acid. Electron microscopy observation showed that lipopeptide treatment induced a severe disruption of the plasma membrane, leading to cell leakage. Lipopeptin A displayed a more pronounced antifungal activity against Foc TR4 than lipopeptin B. In pot experiments, strain XY006 successfully colonized banana plantlets and suppressed the incidence of FWB, with a biocontrol efficacy of up to 87.7%. Additionally, XY006 fermentation culture application improved plant growth parameters and induced peroxidase activity in treated plantlets, suggesting a possible role in induced resistance. Our findings highlight the potential of strain XY006 as a biological agent for FWB, and further research is needed to enhance its efficacy and mode of action in planta.

Evaluation of the Fungicidal Effect of Some Commercial Disinfectant and Sterilizer Agents Formulated as Soluble Liquid against Sclerotium rolfsii Infected Tomato Plant

Globally, root rot disease of tomato plants caused by Sclerotium rolfsii is a severe disease leading to the death of infected plants. The effect of some commercial antiseptics and disinfectant agents, such as chloroxylenol (10%), phenic (10%) and formulated phenol (7%) on the control of root rot pathogen and its impact on growth and chemical constituents of tomato seedlings cv. Castle Rock were investigated in vitro and in vivo. The antifungal activity was measured in vitro following the poisoned food technique at different concentrations of 1000, 2000, 3000 and 4000 µL/L. Disinfectant agents and atrio (80%) were tested in vivo by soaking 20-day-old tomato seedlings in four concentrations of 125, 250, 500 and 1000 µL/100 mL water for 5 min and thereafter planting in soil infested by S. rolfsii. Fresh and dry weight, shoot and root length, and chemical constituents of tomato seedlings infected by S. rolfsii were investigated at 35 days after planting (DAP). Experimental results indicated that chloroxylenol (10%) was the most effective on fungus in vitro, recorded an effective concentration (EC₅₀ = 1347.74 µL/L) followed by phenic (10%) (EC₅₀ = 1370.52 µL/L) and formulated phenol (7%) (EC₅₀ = 1553.59 µL/L). In vivo, atrio (80%) and disinfectant agents at different concentrations significantly (p ≤ 0.05) reduced disease incidence, increased shoot and root lengths and increased dry and fresh weight. Additionally, it significantly increased chlorophyll a, chlorophyll b, total carotenoids, total carbohydrates, total proteins, and total phenols. The highest reduction of root rot incidence and increase tomato growth parameters, as well as chemical compositions, were recorded on tomato seedlings treated with atrio (80%) as well as formulated phenol (7%) at different concentrations, followed by chloroxylenol (10%) at 125 and 250 µL/100 mL, whereas phenic (10%) was found to be the least effective treatment. Therefore, the application of formulated phenol (7%) could be commercially used to control tomato root rot diseases and increase the quality and quantity of tomato plants since it is promising against the pathogen, safe, and less expensive than fungicides.

Chemical Composition Profiling and Antifungal Activity of Saffron Petal Extract

Numerous fungal plant pathogens can infect fresh fruits and vegetables during transit and storage conditions. The resulting infections were mainly controlled by synthetic fungicides, but their application has many drawbacks associated with the threatened environment and human health. Therefore, the use of natural plants with antimicrobial potential could be a promising alternative to overcome the side effects of fungicides. In this regard, this study aimed at evaluating the antifungal activity potential of saffron petal extract (SPE) against three mains important fungal pathogens: Rhizopus stolonifer, Penicillium digitatum and Botritys cinerea, which cause rot decay on the tomato, orange and apple fruits, respectively. In addition, the organic composition of SPE was characterized by attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy and its biochemical, and gas chromatography-mass spectrometry (GC-MS) analyses were carried out. The obtained results highlighted an increased inhibition rate of the mycelial growth and spore germination of the three pathogenic fungi with increasing SPE concentrations. The mycelial growth and spore germination were completely inhibited at 10% of the SPE for Rhizopus stolonifer and Penicillium digitatum and at 5% for B. cinerea. Interestingly, the in vivo test showed the complete suppression of Rhizopus rot by the SPE at 10%, and a significant reduction of the severity of grey mold disease (37.19%) and green mold, when applied at 5 and 10%, respectively. The FT-IR spectra showed characteristic peaks and a variety of functional groups, which confirmed that SPE contains phenolic and flavonoid components. In addition, The average value of the total phenolic content, flavonoid content and half-maximal inhibitory concentration (IC₅₀) were 3.09 ± 0.012 mg GAE/g DW, 0.92 ± 0.004 mg QE/g DW and 235.15 ± 2.12 µg/mL, respectively. A volatile analysis showed that the most dominant component in the saffron petal is 2(5H)-Furanone (92.10%). Taken together, it was concluded that SPE could be used as an alternative to antioxidant and antifungal compounds for the control of postharvest diseases in fruits.

Nonthermal Plasma Effects on Fungi: Applications, Fungal Responses, and Future Perspectives

The kingdom of Fungi is rich in species that live in various environments and exhibit different lifestyles. Many are beneficial and indispensable for the environment and industries, but some can threaten plants, animals, and humans as pathogens. Various strategies have been applied to eliminate fungal pathogens by relying on chemical and nonchemical antifungal agents and tools. Nonthermal plasma (NTP) is a potential tool to inactivate pathogenic and food-contaminating fungi and genetically improve fungal strains used in industry as enzyme and metabolite producers. The NTP mode of action is due to many highly reactive species and their interactions with biological molecules. The interaction of the NTP with living cells is believed to be synergistic yet not well understood. This review aims to summarize the current NTP designs, applications, and challenges that involve fungi, as well as provide brief descriptions of underlying mechanisms employed by fungi in interactions with the NTP components.

Potential for Biological Control of Pythium schmitthenneri Root Rot Disease of Olive Trees (Olea europaea L.) by Antagonistic Bacteria

Several diseases affect the productivity of olive trees, including root rot disease caused by Pythium genera. Chemical fungicides, which are often used to manage this disease, have harmful side effects on humans as well as environmental components. Biological management is a promising control approach that has shown its great potential as an efficient eco-friendly alternative to treating root rot diseases. In the present study, the antagonistic activity of ten bacterial isolates was tested both in vitro and in planta against Pythium schmitthenneri, the causal agent of olive root rot disease. These bacterial isolates belonging to the genera Alcaligenes, Pantoea, Bacillus, Sphingobacterium, and Stenotrophomonas were chosen for their potential antimicrobial effects against many pathogens. Results of the in vitro confrontation bioassay revealed a high reduction of mycelial growth exceeding 80%. The antifungal effect of the volatile organic compounds (VOCs) was observed for all the isolates, with mycelial inhibition rates ranging from 28.37 to 70.32%. Likewise, the bacterial cell-free filtrates showed important inhibition of the mycelial growth of the pathogen. Overall, their efficacy was substantially affected by the nature of the bacterial strains and their modes of action. A greenhouse test was then carried out to validate the in vitro results. Interestingly, two bacterial isolates, Alcaligenes faecalis ACBC1 and Bacillus amyloliquefaciens SF14, were the most successful in managing the disease. Our findings suggested that these two antagonistic bacterial isolates have promising potential as biocontrol agents of olive root rot disease.

GroEL protein from the potential biocontrol agent Rhodopseudomonas palustris enhances resistance to rice blast disease

BACKGROUND

GroEL, which is a chaperone, plays a key role in maintaining protein homeostasis and, among other functions, serves to prevent protein misfolding and aggregation. In addition, the GroEL protein also has a significant effect on enhancing plant resistance and inhibiting plant diseases. However, the function of the GroEL protein in the inhibition of rice blast remains unknown.

RESULTS

Field experiment results show that photosynthetic bacteria PSB-06 have a good control effect on Magnaporthe oryzae. PSB-06 also can promote rice growth and enhance stress resistance. A GroEL protein which was separated and purified from photosynthetic bacteria had a significant antagonistic effect on appressorial formation and pathogenicity of Magnaporthe oryzae, meanwhile transcriptional analysis demonstrated that the GroEL protein could improve the expression of defense gene of rice.

CONCLUSION

Our results show that the photosynthetic bacteria Rhodopseudomonas palustris significantly controls rice blast disease. Its action involves an extracellular GroEL protein, which inhibits appressoria formation, antagonizes the pathogenicity of Magnaporthe oryzae and promotes a host defense response. The research results provide evidence of the potential of this photosynthetic bacterium as a biocontrol agent at least for rice blast control. © 2021 Society of Chemical Industry.

Engineered Nanomaterials Suppress the Soft Rot Disease (Rhizopus stolonifer) and Slow Down the Loss of Nutrient in Sweet Potato

About 45% of the world’s fruit and vegetables are wasted, resulting in postharvest losses and contributing to economic losses ranging from $10 billion to $100 billion worldwide. Soft rot disease caused by Rhizopus stolonifer leads to postharvest storage losses of sweet potatoes. Nanoscience stands as a new tool in our arsenal against these mounting challenges that will restrict efforts to achieve and maintain global food security. In this study, three nanomaterials (NMs) namely C₆₀, CuO, and TiO₂ were evaluated for their potential application in the restriction of Rhizopus soft rot disease in two cultivars of sweet potato (Y25, J26). CuO NM exhibited a better antifungal effect than C₆₀ and TiO₂ NMs. The contents of three important hormones, indolepropionic acid (IPA), gibberellic acid 3 (GA-3), and indole-3-acetic acid (IAA) in the infected J26 sweet potato treated with 50 mg/L CuO NM were significantly higher than those of the control by 14.5%, 10.8%, and 24.1%. CuO and C₆₀ NMs promoted antioxidants in both cultivars of sweet potato. Overall, CuO NM at 50 mg/L exhibited the best antifungal properties, followed by TiO₂ NM and C₆₀ NM, and these results were further confirmed through scanning electron microscope (SEM) analysis. The use of CuO NMs as an antifungal agent in the prevention of Rhizopus stolonifer infections in sweet potatoes could greatly reduce postharvest storage and delivery losses.

Influence of TiO2 Nanoparticles on the Resistance of Cementitious Composite Materials to the Action of Fungal Species

The development of mold films on the cement surfaces of buildings is a health and safety problem for the population, aesthetic but also in terms of their durability. The use of specific performance of cementitious composites containing TiO₂ nanoparticles, photoactivated by UV radiation, can be a viable solution to mitigate to eliminate these problems. The experimental studies presented aim to analyze the capacity to inhibit the development of mold type Aspergillus and Penicillium on the surface of composite materials with nano-TiO₂ content and the identification of the optimal range of nanomaterial addition. The identification and analysis of the inhibition halo (zone with a biological load of maximum 1–10 colonies of microorganisms) confirmed the biocidal capacity of the cementitious composites, but also indicated the possibility that an excess of TiO₂ nanoparticles in the mixture could induce a development of cell resistance, which would be unfavorable both in terms of behavior and in terms of cost.

The antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy

Introduction: Candida species have been regarded as global health threats due to their ability to cause invasive infections. It is challenging to treat Candida bloodstream infections, which are associated with high mortality levels. Monotherapy with antifungals is sometimes not effective against severe Candida infections, and combination therapy is needed in clinical practice.Areas covered: This review was undertaken based on data from a PubMed search for English language reports published before March 2021 by using the terms 'caspofungin,' 'Candida species,' 'combination therapy,' 'antifungal effect,' and 'novel antifungal agent.'Expert opinion: Combination therapy is an empirical strategy for treating refractory Candida infections. Caspofungin has been recommended to treat candidaemia. Caspofungin in combination therapy has some applications, while the efficacy of combination therapy in the treatment of refractory Candida infections needs more study, such as randomized controlled trials. In addition, novel compounds or drugs with potential antifungal activities have been examined, and some of them exhibit synergistic interactions with caspofungin. Thus, the antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy is summarized.

Antibiofilm activity of selected plant essential oils from the Lamiaceae family against Candida albicans clinical isolates

INTRODUCTION

The virulence of Candida albicans is conditioned by several virulence factors, one of which is the formation of biofilm which reduces the sensitivity of the yeast to conventional antimycotics. This study determines the antifungal and antibiofilm activity of five essential oils (EOs) of the Lamiaceae family: Salvia officinalis, Thymus vulgaris, Rosmarinus officinalis, Origanum vulgare, and Hyssopus officinalis.

MATERIAL AND METHODS

In the preliminary research, the antifungal effect of eachof the EOs was tested in the concentration range of 200-0.4 mg/mL on planktonic Candida albicans (C. albicans) cells. A total of 13 C. albicans clinical isolates and one reference strain were evaluated on biofilm formation.

RESULTS

Nine isolates (69.2%) showed weak biofilm production and four strains (30.8%) were detected as moderate biofilm producers. The EOs of Thymus vulgaris and Origanum vulgare were seen as effective antifungal agents on planktonic cells with the MIC 0.4 mg/mL. The highest average MIC values were recorded in Salvia officinalis EO (24.0 and 14.8 mg/mL). All isolates were used to determine EOs efficacy on the inhibition of adherence phase and biofilm formation. The biofilm production of C. albicans after exposition by EOs was quantitatively examined by crystal violet dye.

CONCLUSIONS

The most effective for adherence phase and biofilm formation were EOs of Origanum vulgare (0.1 mg/mL and 0.3 mg/mL) and Thymus vulgaris (0.1 mg/mL and 0.4 mg/mL). The obtained results show that EOs of Thymus vulgaris and Origanum vulgare are potential agents for antifungal treatment or prophylaxis by reducing the resistance of pathogen.

Synergistic antifungal effects of curcumin derivatives as fungal biofilm inhibitors with fluconazole

Lack of novel antifungal agents and severe drug resistance has led to high incidence and associated mortality of invasive fungal infections. To tackle the challenges, novel antifungal agents with anti-resistant potency are highly desirable. Thus, derivatives of curcumin were synthesized to restore the effectiveness of fluconazole (FLC) against FLC-resistant Candida spp. and structure-activity relationships were then discussed. Some novel derivatives showed promising features as novel antifungal lead compounds. Of them, compound 4 showed good alone or synergistic antifungal activity against FLC-resistant Candida spp. Moreover, compound 4 was proven as a potent inhibitor of Candida albicans biofilm formation and yeast-to-hypha morphological transition whether used alone or in combination with FLC, which was further confirmed by the inhibitory effect on cellular surface hydrophobicity of C. albicans. Compound 4 also inhibits intracellular ATP production of C. albicans and disrupts membrane permeability of C. albicans when used in combination with FLC. The results highlighted the potential of curcumin derivatives to overcome fluconazole-related and biofilm-related drug resistance.

Anti-Inflammatory, Antimicrobial and Insecticidal Properties of Daucus Gracilis Steinh Flowers Essential Oil

BACKGROUND

Daucus gracilis Steinh belongs to the Apiaceae family. The flowers of this plant have been used by the population of western Algeria for the treatment of mouth ulcers. However, very few studies exist concerning the biological properties of essential oil of Daucus gracilis Steinh flowers.

OBJECTIVES

The purpose of this work was to study the chemical composition of the essential oil of Daucus gracilis flowers and to evaluate their antimicrobial, insecticidal and anti-inflammatory properties.

METHODS

The distilled essential oil was analyzed by GC and GC-MS. The antimicrobial activity of the essential oil was evaluated using two methods i) diffusion method, and ii) micro dilution technique. The insecticidal activity of essential oil was evaluated against adults of Tribolium confusum by fumigant test. The in vitro assessment of the anti-inflammatory property of essential oil was assessed by the protein denaturation method.

RESULTS

Daucus gracilis flowers essential oil mainly represented oxygenated monoterpenes such as geranyl acetate (18.3%), lavandulyl acetate (15.2%), lavandulyl isobutyrate (13.6%) and citronellyl isobutyrate (6.8%). According to the results of antimicrobial activity, the essential oil of flowers presented prominent inhibitory action against Aspergillus flavus (0.06 μg/mL), followed by Staphylococcus aureus, Escherichia faecalis, Bacillus cereus and Candida albicans with MIC values of 0.125 μg/mL. The Daucus gracilis essential oil flowers proved to be very biocidal toward adults of Tribolium confusum; mortality of 100% of the population was noted with a dose of 2 μl/L air after 24 hours of exposure. Furthermore, the oil has shown a very good inhibition of protein denaturation comparable to Diclofenac at a concentration of 30 μL/mL.

CONCLUSION

Daucus gracilis essential oil can be used as a pharmacological tools for inflammatory, antimicrobial and insecticidal properties.

Antibacterial and Antifungal Activities of PMMAs Implanted Fluorine and/or Silver Ions by Plasma-Based Ion Implantation with Argon

The purpose of this study was to examine the anti-oral microorganism effects of fluorine and/or silver ions implanted into acrylic resin (PMMA) using plasma-based ion implantation (PBII) with argon gas. The experimental PMMA specimens were implanted with F and Ag ions alone or simultaneously by the PBII method using Ar or Ar/F₂ gases and Ag mesh. The surface characteristics were evaluated by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM). Moreover, the antibacterial activity against Streptococcus mutans (S. mutans) and the antifungal activity against Candida albicans (C. albicans) were examined by the adenosine-5'-triphosphate (ATP) emission luminescence method. XPS spectra of the modified specimens revealed peaks due to F in the Ar/F and the Ar/F+Ag groups, and due to Ag in the Ar+Ag and the Ar/F+Ag groups. The water contact angle increased significantly due to the implantation of Ar, F, and Ag. In the AFM observations, the surface roughness of the Ar/F and the Ar/F+Ag groups increased significantly by less than 5 nanometers. The presence of F and Ag was found to inhibit S. mutans growth in the Ar+Ag and the Ar/F+Ag groups. However, this method provided no significant antifungal activity against C. albicans.

Removal Ability and Resistance to Cinnamic and Vanillic Acids by Fungi

Twelve fungal strains were assayed to investigate their resistance to cinnamic and vanillic acids and their ability to remove these compounds from a liquid medium. In a first step, the effect of the two aromatic acids (1 g/L) on the fungal growth kinetic was studied. The results were modelled through a logistic like function (Dantigny equation) to estimate τ, which is the time to the half-maximum colony diameter. The key findings of this part were as follows: (i) generally, cinnamic acid exerted a stronger effect than vanillic acid; (ii) aromatic acids exerted a delay on the growth of some fungi and only one strain (Athelia rolfsii) was completely inhibited. In the second part, fungi were assayed to investigate their ability to remove cinnamic and vanillic acids (ca. 350 mg/kg) from liquid media at pH 3.5. The results indicated that the most efficient fungi were Aspergillus niger and Lasiodiplodia theobromae.

Antifungal Activity of Gentamicin B1 Against Systemic Plant Mycoses

BACKGROUND

Gentamicin is a broad-spectrum aminoglycoside antibiotic produced by Micromonospora purpurea bacteria, effective against Gram-negative bacterial infections. Major fractions of the gentamicin complex (C1, C1a, C2, C2a) possess weak antifungal activity and one of the minor components (A, A1-A4, B, B1, X), gentamicin B1 was found to be a strong antifungal agent.

METHODS

This work uses in vitro and in vivo dilution methods to compare the antifusarial, antiaspergillic and anticryptococcal effects of gentamicin derivatives and structurally-related congeners.

RESULTS

The in vitro antifusarial activity of gentamicin B1 (minimum inhibitory concentration (MIC) 0.4 μg/mL) and structurally-related compounds (MIC 0.8-12.5 μg/mL) suggests that the purpuroseamine ring substituents are responsible for the specific antimycotic effect. The functional groups of the garoseamine and 2-deoxystreptamine rings of gentamicin derivatives are identical in gentamicin compounds and are unlikely to exert a significant antifungal effect. Among soil dermatophytes, Microsporum gypseum was more susceptible to gentamicin B1 (MIC 3.1 µg/mL) than Trichophyton gypseum (MIC 25 µg/mL). The in vitro antifungal effect of gentamicin B1 against plant pathogenic fungi was comparable to primary antifungal agents.

CONCLUSION

Gentamicin is already in medical use. In vitro and preclinical in vivo synergisms of gentamicin B1 with amphotericin B suggest immediate clinical trials starting with subtoxic doses.

Antifungal activity of silver salts of Keggin-type heteropolyacids against Sporothrix spp

Sporotrichosis is a chronic and subacute mycosis causing epidemiological outbreaks involving sick cats and humans in southeastern Brazil. The systemic disease prevails in cats, and in humans, the symptoms are restricted to skin in immunocompetent individuals. Under these conditions, the prolonged treatment of animals and cases of recurrence justify the discovery of new treatments for sporotrichosis. This work addresses the antifungal activity of silver salts of Keggin-type heteropolyacid salts (Ag-HPA salts) such as Ag₃[PW₁₂O₄₀], Ag₆[SiW₁₀V₂O₄₀], Ag₄[SiW₁₂O₄₀] and Ag₃[PMo₁₂O₄₀] and interactions with the antifungal drugs itraconazole (ITC), terbinafine (TBF) and amphotericin B (AMB) on the yeast and mycelia forms of Sporothrix spp. Sporothrix spp. yeast cells were susceptible to Ag-HPA salts at minimum inhibitory concentration (MIC) values ranging from 8 to 128 μg/mL. Interactions between Ag₃[PW₁₂O₄₀] and Ag₃[PMo₁₂O₄₀] with itraconazole and amphotericin B resulted in higher antifungal activity with a reduction in growth and melanization. Treated cells showed changes in cell membrane integrity, vacuolization, cytoplasm disorder, and membrane detachment. Promising antifungal activity for treating sporotrichosis was observed for the Ag-HPA salts Ag₃[PMo₁₂O₄₀] and Ag₃[PW₁₂O₄₀], which have a low cost, high yield and activity at low concentrations. However, further evaluation of in vivo tests is still required.

Antifungal Activity of an Original Amino-Isocyanonaphthalene (ICAN) Compound Family: Promising Broad Spectrum Antifungals

: Multiple drug resistant fungi pose a serious threat to human health, therefore the development of completely new antimycotics is of paramount importance. The in vitro antifungal activity of the original, 1-amino-5-isocyanonaphthalenes (ICANs) was evaluated against reference strains of clinically important Candida species. Structure-activity studies revealed that the naphthalene core and the isocyano- together with the amino moieties are all necessary to exert antifungal activity. 1,1-N-dimethylamino-5-isocyanonaphthalene (DIMICAN), the most promising candidate, was tested further in vitro against clinical isolates of Candida species, yielding a minimum inhibitory concentration (MIC) of 0.04-1.25 µg/mL. DIMICAN was found to be effective against intrinsically fluconazole resistant Candida krusei isolates, too. In vivo experiments were performed in a severly neutropenic murine model inoculated with a clinical strain of Candida albicans. Daily administration of 5 mg/kg DIMICAN intraperitoneally resulted in 80% survival even at day 13, whereas 100% of the control group died within six days. Based on these results, ICANs may become an effective clinical lead compound family against fungal pathogens.

Cytotoxic Action of Artemisinin and Scopoletin on Planktonic Forms and on Biofilms of Candida Species

We investigated the antifungal activities of purified plant metabolites artemisinin (Ar) and scopoletin (Sc) including inhibition, effects on metabolic activities, viability, and oxidative stress on planktonic forms and on preformed biofilms of seven Candida species. The characteristic minimum inhibitory concentration (MIC90) of Ar and Sc against Candida species ranged from 21.83-142.1 µg/mL and 67.22-119.4 µg/mL, respectively. Drug concentrations causing ≈10% CFU decrease within 60 minutes of treatments were also determined (minimum effective concentration, MEC10) using 100-fold higher CFUs than in the case of MIC90 studies. Cytotoxic effects on planktonic and on mature biofilms of Candida species at MEC10 concentrations were further evaluated with fluorescent live/dead discrimination techniques. Candida glabrata, Candida guilliermondii, and Candida parapsilosis were the species most sensitive to Ar and Sc. Ar and Sc were also found to promote the accumulation of intracellular reactive oxygen species (ROS) by increasing oxidative stress at their respective MEC10 concentrations against the tested planktonic Candida species. Ar and Sc possess dose-dependent antifungal action but the underlying mechanism type (fungistatic and fungicidal) is not clear yet. Our data suggest that Ar and Sc found in herbal plants might have potential usage in the fight against Candida biofilms.

Production of antifungal saponins in an airlift bioreactor with a cell line transformed from Solanum chrysotrichum and its activity against strawberry phytopathogens

Biotechnology through plant cell cultures in bioreactors is a tool that allows increasing the production of secondary metabolites of commercial interest. The hydrodynamic characterization, in addition to the transfer (OTR) and uptake (OUR) of oxygen through the dynamic method with different aeration rate, were used to see their influence on the production of biomass and saponins. The culture poisoning technique was used to determine the antifungal activity of the SC-2 and SC-3 saponins in vitro. Likewise, the shear or hydrodynamic stress of 273.6 mN/m² were calculated based on the Reynolds Number. The oxygen supply (OTR) was always greater than the demand (OUR) for all the aeration rate evaluated. Dry weight values of 8.6 gDW/L and a concentration of 2.7 mg/L and 187.3 mg/L of the saponins SC-2 and SC-3 respectively were obtained with an air flow of 0.1 vvm. In addition, it was possible to inhibit the growth of phytopathogenic fungi in vitro by up to 93%, while in vivo it was possible to reduce the infections of strawberry seeds inoculated with phytopathogens, obtaining up to 94% of germinated seeds. This information will facilitate the rational operation of the bioreactor culture system that produces secondary metabolites.

In Planktonic and Biofilm Conditions

Purpose

Antifungal resistance associated with the extensive use of antifungals and biofilm formation presents major clinical challenges. Thus, new therapeutic strategies for fungal infections are urgently required. This study aimed to evaluate the in vitro antifungal effects of the natural bioactive alkaloid berberine against Candida spp. in planktonic and biofilm conditions.

Methods

Using the CLSI M27-A3 reference method for broth dilution antifungal susceptibility testing of yeasts, the MICs for five standard strains comprised of Candida albicans (ATCC 10231, ATCC 90028), Candida krusei (ATCC 6258), Candida glabrata (ATCC 90030), Candida dubliniensis (MYA 646), and six clinical isolates (CLC1–CLC6) were tested. The 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay was used to evaluate the inhibitory effects of berberine against Candida biofilms. The optical density value at 490 nm was measured and illustrated using concentration-absorbance curves. Finally, the effects were quantified by confocal laser scanning microscopy (CLSM), and 3-dimensional reconstruction was performed. The viability inhibition rates, biofilm formation, and thickness decrease rates were tested and analyzed using independent-samples t-test. The differences among the five Candida strains were analyzed using one way ANOVA.

Results

The MICs for the five standard strains described above were 80, 160, 10, 20, and 40 μg/mL, respectively, which was similar to that of the clinical isolates, suggesting the stable, broad-spectrum antifungal activity of berberine. Berberine exerted concentration-dependent inhibitory effects against Candida biofilms, which were enhanced with the maturation of Candida biofilms. Berberine decreased the viability of Candida biofilms, with inhibition rates by CLSM ranging from 19.89 ± 0.57% to 96.93 ± 1.37%. Following 3-dimensional reconstruction, the biofilms of the berberine-treated group displayed a poorly developed architecture, and the biofilm thickness decrease rates ranged from 15.49 ± 8.45% to 30.30 ± 15.48%.

Conclusion

Berberine exhibited significant antifungal activity in Candida spp. The results provide a useful reference for multiple Candida infections and biofilm infections associated with antifungal resistance. Therefore, berberine might have novel therapeutic potential as an antifungal agent or a major active component of antifungal drugs.

Fungicidal Activity of Essential Oils from Cinnamomum cassia against the Pathogenic Fungi of Panax notoginseng Diseases

The frequent disease of Panax notoginseng caused by the pathogenic fungi in field cultivation has become the major threaten to the sustainable development of it. The present study was conducted to find natural agent with potential inhibition against pathogen. Therefore, the inhibitory effects of Cinnamomum cassia (L.) J.Presl essential oils (EOs) against P. notoginseng associated pathogenic fungi were conducted both in vitro and in vivo experiments. The results of the Oxford cup test revealed that C. cassia dry bark EO (50 mg/mL) had significant inhibitory activity on the growth of all tested fungi, and the growth of various pathogens was completely inhibited, except for that of Fusarium solani. Therefore, the constituents of C. cassia EOs were analyzed by GC/MS, and the research demonstrated that the main constituents of C. cassia dry bark EO were trans-cinnamaldehyde (75.65 %), (E)-2-methoxycinnamaldehyde (6.08 %), cinnamaldehyde (3.47 %) and cinnamyl acetate (1.02 %). The MIC results showed that C. cassia dry bark EO and the main compounds had good antifungal effect on the tested strains, and the inhibitory effect was similar to that of hymexazol (chemical pesticide). By analyzing the value of the fraction inhibitory concentration index (FICI), additive effects, irrelevant effects and synergistic effects were observed after the mixture of hymexazol against various pathogens. Moreover, in vivo model showed that C. cassia dry bark EO could reduce the occurrence of anthrax in P. notoginseng. To widen the resources of C. cassia available, the compositions of both C. cassia fresh bark and leaf EOs were also tested and many common compositions existed among them. Taken together, it was concluded that C. cassia EO had the potential use in the field to reduce the pathogenic disease.

Bacillus subtilis CF-3 Volatile Organic Compounds Inhibit Monilinia fructicola Growth in Peach Fruit

In this study, we evaluated the effects of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 in inhibiting Monilinia fructicola in vitro and in vivo. In the in vitro experiments, the effect of VOCs on the growth of the pathogenic fungi was explored by using plate enthalpy test; mycelial morphology was studied by scanning electron and transmission electron microscopy; and fatty acid contents in the cell membrane were assessed by gas chromatography-mass spectrometry (GC-MS). The results indicated that treatment with benzothiazole and CF-3 for 24 h, in the form of a fermentation broth (24hFB), significantly inhibited the germination of fungal spores, modified hyphal and cell morphology, and decreased the cell membrane fluidity and integrity. In the in vivo experiments, the effect of VOCs on the defense mechanism of peach fruit toward M. fructicola was studied, and we found that benzothiazole and CF-3 24hFB inhibited the activity of the pathogenic enzymes (pectinase, cellulase) secreted by M. fructicola to reduce the decomposition of plant tissues, activate the antioxidant enzymes (peroxidase, polyphenol oxidase, catalase, and superoxide dismutase) in the fruit to eliminate excessive reactive oxygen species in order to reduce plant cell damage, and trigger the disease-resistant enzymes (phenylalanine ammonia-lyase, chitinases, and β-1,3-glucanase) to enhance the resistance of peach fruit to M. fructicola and inhibit its growth. This study suggests that CF-3 VOCs could activate disease-resistant enzymes to prevent the invasion of pathogenic fungi and induce resistance in peach, thereby providing a theoretical basis for future applications.

Silver Nanoparticles with High Loading Capacity of Amphotericin B: Characterization, Bactericidal and Antifungal Effects

The purpose of this study was to evaluate the most appropriate conditions to generate silver nanoparticles (AgNPs) loaded with a potent antimycotic drug like amphotericin B (AmB), characterize the physicochemical properties, and to evaluate the cytotoxic effect and biological activity of these new nanostructures as a potential nanocarrier for hydrophobic drugs. It was determined that the optimal molar ratio between Ag and AmB is 1/1 given the uniformity of size around 170 nm of the nanoparticles generated as well as their strongly negative ζ potential of -35 mV, a condition that favors repulsions between AgNPs and inhibiting their aggregation. In this condition, only 0.8 mg.mL-1 of Ag is needed to solubilize 5 mg.mL-1 of AmB, a concentration currently used in commercial formulations. It is important to emphasize that the loading capacity (w/w) of this nanostructure is much higher than that of micellar and liposomal formulations. These AgNP-AmB nanoparticles retain both the bactericidal effect of silver and the cytotoxic and antifungal effect of AmB. However, it was shown that these nanoparticles are spontaneously associated with plasma lipoproteins (LDL and HDL), inhibiting their cytotoxic effects on red blood cells and on at least two cell lines, Vero and H1299 and slightly reducing its bactericidal effect on P. aeruginosa. In contrast, the antifungal effect of the formulation is maintained and is even higher than that when the nanoparticle is not associated with lipoproteins, indicating that this association is of the reversible type. The characterization of these nanoparticles is discussed as a potential new model formulation able to improve the antifungal therapeutic efficiency of AmB.

Comparative study of antifungal effect of green and chemically synthesised silver nanoparticles in combination with carbendazim, mancozeb, and thiram

This study reports synthesis and characterisation of silver nanoparticles and their effect on antifungal efficacy of common agricultural fungicides. Silver nanoparticles were synthesised using biological and chemical reduction methods employing Elettaria cardamomum leaf extract and sodium citrate, respectively. Nanoparticles were then characterised using UV-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). While XRD assigned particles size of 31.86 nm for green and 41.91 nm for chemical silver nanoparticles with the help of the Debye-Scherrer formula, DLS specified monodisperse nature of both suspensions. Nanoparticles were tested individually and in combination with fungicides (carbendazim, mancozeb, and thiram) against fungal phytopathogens. Silver nanoparticles exhibited good antifungal activity and minimum inhibitory concentration (MIC) was observed in the range of 8-64 µg/ml. Also, they positively influenced the efficacy of fungicides. The mean MIC value (mean ± SD) for combination of all three fungicides with green AgNPs was 1.37 ± 0.6 µg/ml and for chemical AgNPs was 1.73 ± 1.0 µg/ml. Hence, it could be concluded that green AgNPs performed better than chemical AgNPs. Synergy was observed between green AgNPs and fungicides against Fusarium oxysporum. In conclusion, this study reports synthesis of monodisperse silver nanoparticles which serve as efficient antifungal agents and also enhance the fungicidal action of reported agricultural fungicides in combination studies.

Development of coating formulation with silica-titania core-shell nanoparticles against pathogenic fungus

In the present study, we developed an antifungal coating formulation using silica, titania and silica-titania core-shell nanoparticles individually. The idea behind the synthesis of core-shell nanoparticles was to use the mechanical strength of silica and the antimicrobial property of TiO₂ together. These nanoparticles were characterized by dynamic light scattering, transmission electron microscopy, scanning electron microscopy, EDX, FTIR and X-ray diffraction. Silica nanoparticles of 92 nm were prepared by the sol-gel process, while TiO₂ nanoparticles and nano-core-shells were prepared through the peptization process with a size of 77 and 144 nm separately. The antifungal effect of the prepared nanoparticles was observed in potato dextrose agar media using the concentration of nanoparticles at 1 wt%. These nanoparticles were incorporated in two types of binder, polyurethane and polyacrylic, with the same concentration of nanoparticles. Coatings were applied on tiles, dried and tested against pathogenic fungus, and fungus growth reduction was observed up to 7-10 days. Coatings developed with TiO₂ nanoparticles have shown good growth reduction of pathogenic fungus, but coatings formulated with silica-titania core-shell nanoparticles killed the fungus fusarium completely and have shown around 90% growth reduction for acremonium species also.

Progress on the Antimicrobial Activity Research of Clove Oil and Eugenol in the Food Antisepsis Field

As potential and valuable antiseptics in the food industry, clove oil and its main effective composition eugenol show beneficial advantages on antibacterial and antifungal activity, aromaticity, and safety. Researches find that both clove oil and eugenol express significantly inhibitory effects on numerous kinds of food source microorganisms, and the mechanisms are associated with reducing the migratory and adhesion and inhibiting the synthesis of biofilm and various virulence factors of these microorganisms. Clove oil and eugenol are generally regarded as safe in vivo experiments. However, they may express certain cytotoxicity on fibroblasts and other cells in vitro. Studies on the quality and additive standard of clove oil and eugenol should be strengthened to promote the antiseptic effects of them in the food antiseptic field.

Evaluation of antifungal effect of iron‐oxide nanoparticles against different Candida species

Iron‐oxide nanoparticles (IONPs) have been widely favoured due to their biodegradable, low cytotoxic effects and having reactive surface which can be altered with biocompatible coatings. Considering various medical applications of IONPs, the authors were encouraged to study whether IONPs could be effective against fungal infections caused by Candida species. In this study, IONPs were characterised by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The goal of this study was to evaluate the antifungal activity of IONPs against different Candida spp. compared with fluconazole (FLC). IONPs were spherical with the size of 30–40 nm. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of IONPs ranged from 62.5 to 500 µg/ml and 500 to 1000 μg/ml, respectively. The MIC and MFC of FLC were in range of 16–128 μg/ml and 64–512 μg/ml, respectively. The growth inhibition value indicated that Candida tropicalis , Candida albicans and Candida glabrata spp. were most susceptible to IONPs. The finding showed that the IONPs possessed antifungal potential against pathogenic Candida spp. and could inhibit the growth of all the tested Candida spp. Further studies, both in vitro and in vivo (including susceptibility, toxicity, Probability of kill (PK) and efficacy studies) are needed to determine whether IONPs are suitable for medicinal purposes.

Antifungal and Ichthyotoxic Sesquiterpenoids from Santalum album Heartwood

In our continuing study on a survey of biologically active natural products from heartwood of Santalum album (Southwest Indian origin), we newly found potent fish toxic activity of an n-hexane soluble extract upon primary screening using killifish (medaka) and characterized α-santalol and β-santalol as the active components. The toxicity (median tolerance limit (TLm) after 24 h at 1.9 ppm) of α-santalol was comparable with that of a positive control, inulavosin (TLm after 24 h at 1.3 ppm). These fish toxic compounds including inulavosin were also found to show a significant antifungal effect against a dermatophytic fungus, Trichophyton rubrum. Based on a similarity of the morphological change of the immobilized Trichophyton hyphae in scanning electron micrographs between treatments with α-santalol and griseofulvin (used as the positive control), inhibitory effect of α-santalol on mitosis (the antifungal mechanism proposed for griseofulvin) was assessed using sea urchin embryos. As a result, α-santalol was revealed to be a potent antimitotic agent induced by interference with microtubule assembly. These data suggested that α-santalol or sandalwood oil would be promising to further practically investigate as therapeutic agent for cancers as well as fungal skin infections.

Antibacterial and Antifungal Activities of Spices

Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices-such as clove, oregano, thyme, cinnamon, and cumin-possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens, pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives.

Antibiofilm peptides against oral biofilms

The oral cavity is a major entry point for bacteria and other microorganisms. Oral biofilms are formed by mixed communities of microorganisms embedded in an exopolysaccharide matrix. Biofilms forming on dental hard or soft tissue are the major cause of caries and endodontic and periodontal disease. Human oral biofilms exhibit high resistance to antimicrobial agents. Antibiofilm peptides constitute a diverse class of host-defense molecules that act to combat invasion and infection with biofilms. Different in vitro and in vivo biofilm models with quantitative analysis have been established to provide predictable platforms for the evaluation of the antibiofilm effect of oral antibiofilm peptides. These peptides have engendered considerable interest in the past decades as potential alternatives to traditional disinfecting agents due to their ability to target bacterial biofilms specifically, leading to the prevention of biofilm formation and destruction of pre-existing biofilms by Gram-positive and -negative bacterial pathogens and fungi. At the same time, challenges associated with the application of these antibiofilm peptides in dental practice also exist. The production of effective, nontoxic, and stable antibiofilm peptides is desired in both academic and industrial fields. This review focuses on the antibiofilm properties of current synthetic peptides and their application in different areas of dentistry.

Preparation, characterization, and evaluation of amphotericin B-loaded MPEG-PCL-g-PEI micelles for local treatment of oral Candida albicans

Fatal Candida albicans infections in the mucosal system can occur in association with immune-compromised diseases and dysbacteriosis. Currently, amphotericin B (AmB) is considered to be the most effective antibiotic in the treatment of C. albicans infections, but its clinical application is limited by side effects and poor bioavailability. In order to use AmB in the local treatment of oral C. albicans infections, AmB/MPEG-PCL-g-PEI (monomethoxy poly(ethylene glycol)-poly(epsilon-caprolactone)-graft-polyethylenimine, MPP) micelles were prepared. A series of characterizations were performed. The micelles allowed a sustained in vitro release in both normal oral conditions (pH 6.8) and C. albicans infection conditions (pH 5.8). Then, buccal tablets containing freeze-dried powder of AmB/MPP micelles were produced by direct compression process and evaluated as regards to weight variation, hardness, and friability. In vitro drug release of the buccal tablets was measured in both the United States Pharmacopeia dissolution apparatus and the dissolution rate test apparatus, which was previously designed for simulating in vivo conditions of the oral cavity. The buccal tablets could sustainably release within 8 h and meet the antifungal requirements. Regarding safety assessment of AmB/MPP micelles, in vivo histopathological data showed no irritation toward buccal mucosa of the rats in both optical microscopy and ultrastructure observation of the tissues. MTT experiment proved that AmB/MPP micelles reduced the cytotoxicity of AmB. The micelles delivered through the gastrointestinal route were also found to be non-systemic toxicity by liquid chromatography-mass spectrometry analysis. Furthermore, the antifungal action of AmB/MPP micelles was evaluated. Although AmB/MPP had no obvious improvement as compared to AmB alone in the antifungal effect on planktonic C. albicans, the micelles significantly enhanced the antifungal activity against the biofilm state of C. albicans. Thus, it was concluded that AmB/MPP micelles represent a promising novel drug delivery system for the local treatment of oral C. albicans infections.

Antifungal, optical, and mechanical properties of polymethylmethacrylate material incorporated with silanized zinc oxide nanoparticles

Background

Fungal infected denture, which is typically composed of polymethylmethacrylate (PMMA), is a common problem for a denture wearer, especially an elderly patient with limited manual dexterity. Therefore, increasing the antifungal effect of denture by incorporating surface modification nanoparticles into the PMMA, while retaining its mechanical properties, is of interest.

Aim of the study

This study aimed to evaluate antifungal, optical, and mechanical properties of heat-cured PMMA incorporated with different amounts of zinc oxide nanoparticles (ZnOnps) with or without methacryloxypropyltrimethoxysilane modification.

Materials and methods

Specimens made from heat-cured PMMA containing 1.25, 2.5, and 5% (w/w) nonsilanized (Nosi) or silanized (Si) ZnOnps were evaluated. Specimens without filler served as control. The fungal assay was performed placing a Candida albicans suspension on the PMMA surface for 2 h, then Sabouraud Dextrose Broth was added, and growth after 24 h was determined by counting colony forming units on agar plates. A spectrophotometer was used to measure the color in L* (brightness), a* (red-green), b* (yellow-blue) and opacity of the experimental groups. Flexural strength and flexural modulus were determined using a three-point bending test on universal testing machine after 37°C water storage for 48 h and 1 month.

Results

The antifungal, optical, and mechanical properties of the PMMA incorporated with ZnOnps changed depending on the amount. With the same amount of ZnOnps, the silanized groups demonstrated a greater reduction in C. albicans compared with the Nosi groups. The color difference (ΔE) and opacity of the Nosi groups were greater compared with the Si groups. The flexural strength of the Si groups, except for the 1.25% group, was significantly greater compared with the Nosi groups.

Conclusion

PMMA incorporated with Si ZnOnps, particularly with 2.5% Si ZnOnps, had a greater antifungal effect, less color differences, and opacity compared with Nosi ZnOnps, while retaining its mechanical properties.

Triclosan Demonstrates Synergic Effect with Amphotericin B and Fluconazole and Induces Apoptosis-Like Cell Death in Cryptococcus neoformans

Objectives:Cryptococcus neoformans is an opportunistic fungus that causes fatal meningoencephalitis especially in AIDS patients. There is an increasing need for discovery of new anti-cryptococcal drugs due to emergence of resistance cases in recent years. In this study, we aim to elucidate the antifungal effect of triclosan against C. neoformans.

Methods: Minimal inhibitory concentration (MIC) of triclosan in different C. neoformans strains was first examined. The in vitro interactions between triclosan and two standard anti-fungal drugs (amphotericin B and fluconazole) were further evaluated by microdilution checkerboard assay. Mechanism of triclosan fungicidal activity was then investigated by viewing the cell morphology under transmission electron microscope.

Results: We reported that triclosan potently inhibited the growth of C. neoformans. A combination of triclosan with amphotericin B or with fluconazole enhanced their fungicidal effects. Triclosan-treated C. neoformans displayed characteristics such as nuclear chromatin condensation, extensive intracellular vacuolation and mitochondrial swelling, indicating that triclosan triggered apoptosis-like cell death.

Conclusion: In summary, our report suggests triclosan as an independent drug or synergent for C. neoformans treatment.

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.

Toxicology of antimicrobial nanoparticles for prosthetic devices

Advances in nanotechnology are producing an accelerated proliferation of new nanomaterial composites that are likely to become an important source of engineered health-related products. Nanoparticles with antifungal effects are of great interest in the formulation of microbicidal materials. Fungi are found as innocuous commensals and colonize various habitats in and on humans, especially the skin and mucosa. As growth on surfaces is a natural part of the Candida spp. lifestyle, one can expect that Candida organisms colonize prosthetic devices, such as dentures. Macromolecular systems, due to their properties, allow efficient use of these materials in various fields, including the creation of reinforced nanoparticle polymers with antimicrobial activity. This review briefly summarizes the results of studies conducted during the past decade and especially in the last few years focused on the toxicity of different antimicrobial polymers and factors influencing their activities, as well as the main applications of antimicrobial polymers in dentistry. The present study addresses aspects that are often overlooked in nanotoxicology studies, such as careful time-dependent characterization of agglomeration and ion release.

In vitro antifungal effect and inhibitory activity on biofilm formation of seven commercial mouthwashes

OBJECTIVE

To investigate the antifungal ability of seven over-the-counter mouthwashes against planktonic and sessile Candida albicans and Candida krusei.

MATERIALS AND METHODS

The seven mouthwashes studied were Listerine, compound chlorhexidine solution, povidone iodine solution (PV-I), cetylpyridinium chloride solution, Colgate Plax, Crest Prohealth Mouthwash, and NaHCO3 . The antifungal ability of each mouthwash against ATCC90028, ATCC6258, and 10 clinical C. albicans isolates was tested using disk diffusion tests, the broth microdilution method, and biofilm testing with two different XTT-reduction assays. Fluconazole was used as a positive control, and the experiments were performed in triplicate.

RESULTS

Chlorhexidine and cetylpyridinium chloride had the largest inhibition zones for ATCC90028 and ATCC6258 (18.6 ± 3.5 and 19 ± 1.6 mm, respectively). Cetylpyridinium chloride was the most effective at inhibiting all of the planktonic C. albicans strains and ATCC6258 with the minimum inhibitory concentration (MIC). As the maturity of the biofilms increased, the change in sessile cell MIC of the mouthwashes was much smaller than that of fluconazole. For the mature biofilms, chlorhexidine, PV-I, and cetylpyridinium chloride produced the greatest reductions in metabolism (60-80%).

CONCLUSION

Most of these seven mouthwashes had significant antifungal activity for both planktonic and sessile Candida species.

Cytocompatible antifungal acrylic resin containing silver nanoparticles for dentures

Background

Inhibition of Candida albicans on denture resins could play a significant role in preventing the development of denture stomatitis. The safety of a new dental material with antifungal properties was analyzed in this work.

Methods

Poly(methyl methacrylate) [PMMA] discs and PMMA-silver nanoparticle discs were formulated, with the commercial acrylic resin, Nature-Cryl^TM, used as a control. Silver nanoparticles were synthesized and characterized by ultraviolet-visible spectroscopy, dispersive Raman spectroscopy, and transmission electron microscopy. The antifungal effect was assessed using a luminescent microbial cell viability assay. Biocompatibility tests were carried out using NIH-3T3 mouse embryonic fibroblasts and a Jurkat human lymphocyte cell line. Cells were cultured for 24 or 72 hours in the presence or absence of the polymer formulations and analyzed using three different tests, ie, cellular viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and cell proliferation by enzyme-linked immunosorbent assay BrdU, and genomic DNA damage (Comet assay). Finally, the samples were evaluated mechanically, and the polymer-bearing silver nanoparticles were analyzed microscopically to evaluate dispersion of the nanoparticles.

Results

The results show that PMMA-silver nanoparticle discs significantly reduce adherence of C. albicans and do not affect metabolism or proliferation. They also appear not to cause genotoxic damage to cells.

Conclusion

The present work has developed a new biocompatible antifungal PMMA denture base material.