Superior Antifungal Activity Research Articles

Medicinal and culinary herbs as environmentally safe inhibitors of dangerous toxinogenic plant and human fungal pathogens

The need for new antifungal substances and alternative antifungal treatments is becoming more and more obvious. One of the most promising and ecologically safe possibilities could be based on taking advantage of a plant’s natural antifungal properties. This work presents the results of extensive screening experiments focused on the antifungal inhibitory effect of 49 plant species against 6 dangerous toxinogenic plant and human fungal pathogens: Fusarium oxysporum, F. verticillioides, Penicillium expansum, P. brevicompactum, Aspergillus flavus and A. fumigatus. 14 plant species with the most significant antifungal effect were then compared according to their MIC50 values. The most sensitive target fungus was the toxinogenic and human pathogenic species A. fumigatus. Superior antifungal activity was finally proved in the case of Chenopodium bonus henricus, Origanum dictamnus and O. vulgare. All three superior effective species are non-toxic to mammals, and they are also frequently used as culinary and medicinal plants. They could be seriously considered as a promising source for the future, with a great potential as bioactive components of environmentally safe botanical fungicides. In addition, this is the first study describing the antifungal effect of Chenopodium bonus henricus. Key words: Pathogenic fungi, toxinogenic fungi, botanical fungicide, antifungal activity,Aspergillus fumigatus, alternative treatment.

In vitro antifungal effect of mouth rinses containing chlorhexidine and thymol

Background/purpose In this in vitro study, we assessed the antifungal effect of mouth rinses containing chlorhexidine and thymol. Materials and methods The fungistatic activities of chlorhexidine- and thymol-containing mouth rinses were assessed by means of the minimum inhibitory concentration (MIC) and the fungicidal activity was determined by a time-kill assay. Results The chlorhexidine-containing mouthwash was able to kill all strains of Candida albicans and Candida tropicalis in shorter times compared to the thymol-containing mouthwash. Hexidine showed an MIC of 1:32 for both Candida species, whereas Listerine respectively showed MICs of 1:8 and 1:16 for C. albicans and C. tropicalis. Conclusions Antimicrobial agents used in the study had good in vitro activity against the two Candida species. Mouth rinses containing chlorhexidine showed superior antifungal and fungicidal activities compared to the thymol-containing mouth rinse. Both antimicrobial agents may be suggested for use as topical antifungal agents.

Antimicrobial activities of Conyzolide and Conyzoflavone from Conyza canadensis

Antibacterial and antifungal activities of the two isolated compounds from Conyza canadensis have been reported in the current study. The two isolated compounds i.e. Conyzolide (1) and Conyzoflavone (2) were tested against six bacterial and five fungal strains, employing hole diffusion and macrodilution methods. Both the compounds showed significant activities against the tested pathogens with special reference to E. coli, P. aeruginosa, S. aureus, Trichophytom longifusus, C. albicans, and C. glaberata. Conyzolide revealed comparatively better antibacterial activity against E. coli (minimum inhibitory concentration (MIC): 25 µg/mL) in comparison to Conyzoflavone. However, in case of antifungal activities, Conyzoflavone exhibited superior antifungal activity against C. albicans (MIC: 10 µg/mL) as compared to Conyzolide.

Antifungal effect of Pimenta dioica essential oil against dangerous pathogenic and toxinogenic fungi

Essential oils from 25 species of medicinal plants were tested as mycelial growth inhibitors against six important pathogenic and toxinogenic fungal species. An agar dilution method was used for determination of the inhibitory effect namely on Fusarium oxysporum, Fusarium verticillioides, Penicillium expansum, Penicillium brevicompactum, Aspergillus flavus and Aspergillus fumigatus. All essential oils used in our experiment evidently affected growth of these fungi. Minimum inhibitory concentration (MIC) was evaluated in the case of five essential oils showing the most significant antifungal activity. The superior antifungal activity was finally proved on the base of MIC values in the case of Pimenta dioica. The chemical composition of P. dioica essential oil was determined by means of GC–MS analysis.

Synthesis, determination of the lipophilicity, anticancer and antimicrobial properties of some fused 1,2,4-triazole derivatives

3-Unsubstituted and 3-substituted-7-aryl-5 H-6,7-dihydroimidazo[2,1- c][1,2,4]triazoles ( 1– 14) were designed and obtained from biologically active 1-aryl-2-hydrazonoimidazolidines by cyclocondensation reaction with triethyl orthoformates ( 1– 4), phenoxyacetic acid derivatives ( 5– 13) and carbon disulfide ( 14), respectively. Their chemical structures were confirmed by IR, 1H NMR, 13C NMR, MS spectra and elemental analysis. In the high performance liquid chromatographic series of experiments, fourteen synthesized compounds ( 1– 14) were chromatographed on octadecyl silica adsorbent and their lipophilicity parameter (log k W) was determined using various aqueous systems: mixture of water and organic modifiers (methanol – MeOH, acetonitrile – MeCN or dioxane – DX). Compounds 7 and 12 were evaluated for their cytotoxic activity against three cancer cell lines: human Caucasian colon adenocarcinoma cell line – LS180 (ECACC 87021202), human uterus carcinoma cell line – SiHa (ECACC 85060701) and human breast carcinoma cell line – T47D (ECACC 85102201). Compound 12 was found to be the most effective in vitro against human colon adenocarcinoma cell line (LS180). Moreover, the distinctly marked lower cytotoxicity of compounds 7 and 12 against the normal cell line – human skin fibroblasts (HSF) and almost several-fold higher against the examined cancer cell lines was ascertained. The cytotoxic effect of imidazotriazole 7 was noticed on DNA structure of breast cancer cell line (T47D) by using the comet assay. Compound 7 in concentration of 29.3 μM was found to possess efficiency for DNA strand breakage. In particular, this led to cutting of the DNA strands and formation of small fragments of DNA – two higher and one lighter in comparison with control DNA. Moreover, significant viability decreases in the human leukaemic RPMI 8226 cells treated with different concentrations of imidazotriazoles 8– 12 were observed, suggesting their antiproliferative properties. Besides, three tested compounds ( 9, 13, 14) revealed significant antimicrobial activities with MIC values in the range of 30.9–44.0 μM. Compound 13 showed superior antibacterial activity to ampicillin and chloramphenicol in vitro, whereas 14 displayed superior antifungal activity to miconazole.

Significant Improvement of Antifungal Activity of Polyene Macrolides by Bisalkylation of the Mycosamine

[reaction: see text] New derivatives of Amphotericin B (AmB) were synthesized through a double reductive alkylation of the mycosamine. These derivatives of AmB displayed superior antifungal activity against Saccharomyces cerevisiae wild-type strain and especially in the case of an AmB-resistant Candida albicans strain. Moreover, these compounds are potential drug candidates because of significantly reduced hemotoxicity compared to AmB. Furthermore, the same mycosamine modification can be applied to other polyene macrolides such as Nystatin and Pimaricin to improve their antifungal activity.

The novel azole R126638 is a selective inhibitor of ergosterol synthesis in Candida albicans, Trichophyton spp., and Microsporum canis.

R126638 is a novel triazole with in vitro activity similar to that of itraconazole against dermatophytes, Candida spp., and Malassezia spp. In animal models of dermatophyte infections, R126638 showed superior antifungal activity. R126638 inhibits ergosterol synthesis in Candida albicans, Trichophyton mentagrophytes, Trichophyton rubrum, and Microsporum canis at nanomolar concentrations, with 50% inhibitory concentrations (IC(50)s) similar to those of itraconazole. The decreased synthesis of ergosterol and the concomitant accumulation of 14 alpha-methylsterols provide indirect evidence that R126638 inhibits the activity of CYP51 that catalyzes the oxidative removal of the 14 alpha-methyl group of lanosterol or eburicol. The IC(50)s for cholesterol synthesis from acetate in human hepatoma cells were 1.4 microM for itraconazole and 3.1 microM for R126638. Compared to itraconazole (IC(50) = 3.5 microM), R126638 is a poor inhibitor of the 1 alpha-hydroxylation of 25-hydroxyvitamin D(3) (IC(50) > 10 microM). Micromolar concentrations of R126638 and itraconazole inhibited the 24-hydroxylation of 25-hydroxyvitamin D(3) and the conversion of 1,25-dihydroxyvitamin D(3) into polar metabolites. At concentrations up to 10 microM, R126638 had almost no effect on cholesterol side chain cleavage (CYP11A1), 11 beta-hydroxylase (CYP11B1), 17-hydroxylase and 17,20-lyase (CYP17), aromatase (CYP19), or 4-hydroxylation of all-trans retinoic acid (CYP26). At 10 microM, R126638 did not show clear inhibition of CYP1A2, CYP2A6, CYP2D6, CYP2C8, CYP2C9, CYP2C10, CYP2C19, or CYP2E1. Compared to itraconazole, R126638 had a lower interaction potential with testosterone 6 beta hydroxylation and cyclosporine hydroxylation, both of which are catalyzed by CYP3A4, whereas both antifungals inhibited the CYP3A4-catalyzed hydroxylation of midazolam similarly. The results suggest that R126638 has promising properties and merits further in vivo investigations for the treatment of dermatophyte and yeast infections.

Screening of some indigenous Qatari medicinal plants for antimicrobial activity.

Aqueous, ethanol and butanol crude extracts of the aerial parts of ten plants exhibited variable degrees of antimicrobial activity against four bacterial and two fungal species. Aqueous extracts had low antimicrobial activity against E.coli, P.aeruginosa, B. cerreus, S.aureus, C.albicans and A.flavus. Avicennia marina (AM) aqueous extract exhibited a moderate antifungal activity. Ethanol and butanol crude extracts exhibited an improved antimicrobial activity. However, butanol exhibited a superior antimicrobial activity compared with aqueous and ethanol crudes. Compared with the standard antibiotics tested the butanol extract had the highest activity. Butanol extracts at 2000 microg/disc of AM, Lotus halophilus (LA), Pulicaria gnaphaloides (PG) and Capparis spinosa (CS) had a very good antibacterial activity against both gram-positive and -negative bacteria as well as moderate to good antifungal activity against C. albicans and A. flavus. Medicago laciniata (ML), Limonium axillare (LA) and (PG) butanol crude extract compared with standard chloramphenicol, tetracycline and nalidixic acid exhibited a superior antifungal activity.

The essential oil of lemon grass (Cymbopogon citratus) demonstrates a superior antifungal activity compared with tea tree (Melalueca alternifolia) or lavender (Lavandula angustifolia)

The essential oil of lemon grass (<i>Cymbopogon citratus</i>) demonstrates a superior antifungal activity compared with tea tree (<i>Melalueca alternifolia</i>) or lavender (<i>Lavandula angustifolia</i>)

Geotrichosis of oral mucosa

A livid, sharply defined enanthema of the oral mucosa with ulcerations on the soft palate in a patient presenting with de novo acute myeloid leukaemia with prolonged, therapy-induced granulocytopenia (< 0.5 nl-1 for 113 days!) was diagnosed as geotrichosis. Geotrichum capitatum was identified both in vivo and in vitro. Pneumonic infiltrates in the upper lobes of both lungs were treated with amphotericin B infusions. Healing of the aforementioned enanthema was only achieved after addition of 5-fluorocytosine to therapy. Susceptibility determinations with several Geotrichum capitatum isolates led to the conclusion that amphotericin B was unsuitable as a therapeutic agent in this case. 5-Fluorocytosine and itraconazole exhibited superior antifungal and antimycotic activity.

Comparative Susceptibility of Candida albicans to Amphotericin B and Amphotericin B Methyl Ester

The in vitro antifungal activities of amphotericin B (AMB) and amphotericin B methyl ester (AME) were compared against 465 clinical isolates of Candida albicans. AMB and AME possessed comparable activity against half of the strains, but against the remainder of the strains the activity of AME was slightly lower than that of AMB. Rarely did AME show superior antifungal activity to AMB.