Structure-guided design of Cryptococcus neoformans protein farnesyltransferase inhibitors with antifungal activity

Background:In both the developed and developing world, the mortality rates of people afflicted with cryptococcosis are unacceptably high despite the availability of antifungal therapy. The disease is caused by Cryptococcus neoformans (predominantly in immunocompromised individuals) and by Cryptococcus gattii. Globally the disease is estimated to cause around 600,000 deaths annually. Antifungal therapy is available, but in the developing world, may be unaffordable to many people, there is an increasing threat of resistance to the available drugs and our repertoire of antifungal drugs is very limited. Consequently, more research has been focusing on the use of medicinal plants as therapeutic agents. The originality of the current study is that although Tulbaghia violacea is a well-documented medicinal plant, the chemical composition of aqueous extracts and their antifungal potential against pathogenic yeasts are unknown. This is the first study that evaluates the chemical constituents of aqueous T. violacea root, leaf, rhizome and tuber extracts and their corresponding antifungal activities against C. neoformans and C. gattii.Objectives:The study aimed to investigate the phytochemical composition and antifungal potential of Tulbaghia violacea root, leaf, rhizome and tuber extracts against Cryptococcus neoformans and Cryptococcus gattii.Methods:Roots, leaves, rhizomes and tubers were extracted with water only for 48 h at room temperature with continuous shaking. Extracts were filter sterilized, freeze-dried and, chemically analyzed for saponin, flavonol, phenolic and tannin content. Chemical constituents of each extract were also identified by GC-MS analysis. The Minimum Inhibitory Concentration (MIC) of suitably diluted extracts of each plant part were also performed against C. neoformans and C. gattii, yeast pathogens commonly associated with HIV/AIDS sufferers.Results:Phytochemical analysis showed different concentrations of saponins (between 1023 and 2896.73 µg/ml), phenolics (between 16.48 and 51.58 µg/ml) and tannins (between 122.30 and 543.07 µg/ml) present in the different extracts. No flavonols were detected. GC-MS analysis identified a complex mixture of phytochemicals composed predominantly of sulphide, pyran, furan and ketone containing compounds to be present in the different plant parts. All extracts were dominated by the presence of 4 H-pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl, a pyran known to have antifungal properties. Although the root, leaf, rhizome and tuber extracts exhibited antifungal activities against both fungi, the rhizome and tuber extract were found to possess the lowest MIC’s of 1.25 mg/ml and 2.5 mg/ml against Cryptococcus neoformans and Cryptococcus gattii respectively.Conclusion:T. violacea extracts have a complex constituent of phytochemicals and each plant part exhibited a strong antifungal activity against C. neoformans and C. gattii. The rhizome and tuber extracts showed the highest antifungal activity against C. neoformans and C. gattii respectively. Thus, T. violacea aqueous extracts are strong candidates for further development into an antifungal chemotherapeutic agent.

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Antifungal activity of dendritic cell lysosomal proteins against Cryptococcus neoformans

Scientific Reports ◽

10.1038/s41598-021-92991-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Benjamin N. Nelson ◽

Savannah G. Beakley ◽

Sierra Posey ◽

Brittney Conn ◽

Emma Maritz ◽

...

Keyword(s):

Antifungal Activity ◽

Cryptococcus Neoformans ◽

Mammalian Cells ◽

Cysteine Proteases ◽

Dependent Manner ◽

Life Threatening ◽

Opportunistic Fungal Pathogen ◽

Dose Dependent ◽

Lysosomal Proteins

AbstractCryptococcal meningitis is a life-threatening disease among immune compromised individuals that is caused by the opportunistic fungal pathogen Cryptococcus neoformans. Previous studies have shown that the fungus is phagocytosed by dendritic cells (DCs) and trafficked to the lysosome where it is killed by both oxidative and non-oxidative mechanisms. While certain molecules from the lysosome are known to kill or inhibit the growth of C. neoformans, the lysosome is an organelle containing many different proteins and enzymes that are designed to degrade phagocytosed material. We hypothesized that multiple lysosomal components, including cysteine proteases and antimicrobial peptides, could inhibit the growth of C. neoformans. Our study identified the contents of the DC lysosome and examined the anti-cryptococcal properties of different proteins found within the lysosome. Results showed several DC lysosomal proteins affected the growth of C. neoformans in vitro. The proteins that killed or inhibited the fungus did so in a dose-dependent manner. Furthermore, the concentration of protein needed for cryptococcal inhibition was found to be non-cytotoxic to mammalian cells. These data show that many DC lysosomal proteins have antifungal activity and have potential as immune-based therapeutics.

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Protein Farnesyltransferase Inhibitors

Frontiers in Medicinal Chemistry - Online ◽

10.2174/1567204043396695 ◽

2004 ◽

Vol 1 (1) ◽

pp. 97-128

Author(s):

Semiramis Ayral-Kaloustian ◽

Edward J. Salaski

Keyword(s):

Farnesyltransferase Inhibitors ◽

Protein Farnesyltransferase

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The "in vitro" antifungal activity evaluation of propolis G12 ethanol extract on Cryptococcus neoformans

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652007000200005 ◽

2007 ◽

Vol 49 (2) ◽

pp. 93-95 ◽

Cited By ~ 17

Author(s):

Fabrício Freitas Fernandes ◽

Amanda Latercia Tranches Dias ◽

Cíntia Lacerda Ramos ◽

Masaharu Ikegaki ◽

Antonio Martins de Siqueira ◽

...

Keyword(s):

Antifungal Activity ◽

Cryptococcus Neoformans ◽

Ethanol Extract ◽

Inhibitory Effect ◽

Biological Properties ◽

Standard Strain ◽

Antiviral Activities ◽

Prolonged Antibiotic Therapy ◽

In Vitro Antifungal Activity

Cryptococcosis is a worldwide disease caused by the etiological agent Cryptococcus neoformans. It affects mainly immunocompromised humans. It is relatively rare in animals only affecting those that have received prolonged antibiotic therapy. The propolis is a resin that can present several biological properties, including antibacterial, antifungal and antiviral activities. The standard strain C. neoformans ATTC 90112 was used to the antifungal evaluation. The tests were realized with propolis ethanol extract (PEE) G12 in concentrations from 0.1 to 1.6 mg mL-1. The evaluation of MIC and MFC were done according to DUARTE (2002)5. The inhibitory effect of PEE G12 on the fungal growing was seen at the concentration of 0.2 mg mL-1 and 1.6 mg mL-1 was considered a fungicidal one.

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Highly improved antiparasitic activity after introduction of an N-benzylimidazole moiety on protein farnesyltransferase inhibitors

European Journal of Medicinal Chemistry ◽

10.1016/j.ejmech.2015.12.045 ◽

2016 ◽

Vol 109 ◽

pp. 173-186 ◽

Cited By ~ 11

Author(s):

Damien Bosc ◽

Elisabeth Mouray ◽

Sandrine Cojean ◽

Caio Haddad Franco ◽

Philippe M. Loiseau ◽

...

Keyword(s):

Farnesyltransferase Inhibitors ◽

Antiparasitic Activity ◽

Protein Farnesyltransferase

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Novel Antifungal Compounds Discovered in Medicines for Malaria Venture’s Malaria Box

mSphere ◽

10.1128/msphere.00537-17 ◽

2018 ◽

Vol 3 (2) ◽

Cited By ~ 7

Author(s):

Eric H. Jung ◽

David J. Meyers ◽

Jürgen Bosch ◽

Arturo Casadevall

Keyword(s):

Candida Albicans ◽

Antifungal Activity ◽

Cryptococcus Neoformans ◽

Fungal Pathogens ◽

Pathogenic Fungi ◽

Cryptococcus Gattii ◽

Antifungal Drugs ◽

Resistant Bacteria ◽

Animal Cells ◽

Malaria Box

ABSTRACTSimilarities in fungal and animal cells make antifungal discovery efforts more difficult than those for other classes of antimicrobial drugs. Currently, there are only three major classes of antifungal drugs used for the treatment of systemic fungal diseases: polyenes, azoles, and echinocandins. Even in situations where the offending fungal organism is susceptible to the available drugs, treatment courses can be lengthy and unsatisfactory, since eradication of infection is often very difficult, especially in individuals with impaired immunity. Consequently, there is a need for new and more effective antifungal drugs. We have identified compounds with significant antifungal activity in the Malaria Box (Medicines for Malaria Ventures, Geneva, Switzerland) that have higher efficacy than some of the currently used antifungal drugs. Our best candidate, MMV665943 (IUPAC name 4-[6-[[2-(4-aminophenyl)-3H-benzimidazol-5-yl]methyl]-1H-benzimidazol-2-yl]aniline), here referred to as DM262, showed 16- to 32-fold-higher activity than fluconazole againstCryptococcus neoformans. There was also significant antifungal activity in other fungal species with known antifungal resistance, such asLomentospora prolificansandCryptococcus gattii. Antifungal activity was also observed against a common fungus,Candida albicans. These results are important because they offer a potentially new class of antifungal drugs and the repurposing of currently available therapeutics.IMPORTANCEMuch like the recent increase in drug-resistant bacteria, there is a rise in antifungal-resistant strains of pathogenic fungi. There is a need for novel and more potent antifungal therapeutics. Consequently, we investigated a mixed library of drug-like and probe-like compounds with activity inPlasmodiumspp. for activity against two common fungal pathogens,Cryptococcus neoformansandCandida albicans, along with two less common pathogenic species,Lomentospora prolificansandCryptococcus gattii. We uncover a previously uncharacterized drug with higher broad-spectrum antifungal activity than some current treatments. Our findings may eventually lead to a compound added to the arsenal of antifungal therapeutics.

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Antifungal Activity of the Essential Oil of Echinops kebericho Mesfin: An In Vitro Study

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2020/3101324 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Tamirat Bekele Beressa ◽

Serawit Deyno ◽

Paul E. Alele

Keyword(s):

Candida Albicans ◽

Antifungal Activity ◽

Essential Oil ◽

Cryptococcus Neoformans ◽

Antioxidant Properties ◽

Pathogenic Fungi ◽

Diffusion Method ◽

Potential Candidate ◽

Standard Drug

Background. Echinops kebericho is an endemic medicinal plant in Ethiopia widely used in the treatment of infectious and noninfectious diseases. Essential oils are known for their antibacterial, antifungal, antiviral, insecticidal, and antioxidant properties. This study evaluated the antifungal activity of essential oil from E. kebericho against four common pathogenic fungi and two standard strains. Methods. The essential oil was obtained by hydrodistillation. The antifungal screening was done by agar well diffusion method. Minimal inhibitory concentrations (MICs) were determined by broth microdilution. Minimal fungicidal concentrations (MFCs) were determined by subculturing fungal strains with no visible growth onto a Sabouraud dextrose agar (SDA) plate. Results. Candida albicans and Cryptococcus neoformans were highly sensitive while Aspergillus flavus did not show sensitivity up to 1 mg/ml of essential oil; MICs ranged from 0.083 mg/ml to 0.208 mg/ml. Concentration and fungal species showed significant dose-dependent associations ( p < 0.0001 ) with antifungal activity. The MICs of essential oil were comparable to those of the standard drug (fluconazole) against C. glabrata and C. krusei. The lowest MFC of the essential oil was observed against Candida parapsilosis (0.145 mg/ml) while the highest MFC was against Candida krusei (0.667 mg/ml). Conclusion. Echinops kebericho essential oil showed noteworthy antifungal activity against Cryptococcus neoformans, Candida albicans, and Candida glabrata and could be a potential candidate for further antifungal drug development.

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Screening and Antifungal Activity of a β-Carboline Derivative against Cryptococcus neoformans and C. gattii

International Journal of Microbiology ◽

10.1155/2019/7157845 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Kátia Santana Cruz ◽

Emerson Silva Lima ◽

Marcia de Jesus Amazonas da Silva ◽

Erica Simplício de Souza ◽

Andreia Montoia ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Antifungal Activity ◽

Cryptococcus Neoformans ◽

Active Compound ◽

Cell Walls ◽

Human Fibroblasts ◽

Lead Compound ◽

Fungal Cell ◽

Fungal Cell Walls

Background. Cryptococcosis is a fungal disease of bad prognosis due to its pathogenicity and the toxicity of the drugs used for its treatment. The aim of this study was to investigate the medicinal potential of carbazole and β-carboline alkaloids and derivatives against Cryptococcus neoformans and C. gattii. Methods. MICs were established in accordance with the recommendations of the Clinical and Laboratory Standards Institute for alkaloids and derivatives against C. neoformans and C. gattii genotypes VNI and VGI, respectively. A single active compound was further evaluated against C. neoformans genotypes VNII, VNIII, and VNIV, C. gattii genotypes VGI, VGIII, and VGIV, Candida albicans ATCC 36232, for cytotoxicity against the MRC-5 lineage of human fibroblasts and for effects on fungal cells (cell wall, ergosterol, and leakage of nucleic acids). Results. Screening of 11 compounds revealed 8-nitroharmane as a significant inhibitor (MIC 40 μg/mL) of several C. neoformans and C. gattii genotypes. It was not toxic to fibroblasts (IC50 > 50 µg/mL) nor did it alter fungal cell walls or the concentration of ergosterol in C. albicans or C. neoformans. It increased leakage of substances that absorb at 260 nm. Conclusions. The synthetic β-carboline 8-nitroharmane significantly inhibits pathogenic Cryptococcus species and is interesting as a lead compound towards new therapy for Cryptococcus infections.

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