ANTIFUNGAL POTENTIAL OF BACTERIAL METABOLITES: ISOLATION, SCREENING AND CHARACTERIZATION (original) (raw)
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Microbial natural products as a source of antifungals
Clinical Microbiology and Infection, 2003
The vast number and variety of chemotherapeutic agents isolated from microbial natural products and used to treat bacterial infections have greatly contributed to the improvement of human health during the past century. However, only a limited number of antifungal agents (polyenes and azoles, plus the recently introduced caspofungin acetate) are currently available for the treatment of life-threatening fungal infections. Furthermore, the prevalence of systemic fungal infections has increased significantly during the past decade. For this reason, the development of new antifungal agents, preferably with novel mechanisms of action, is an urgent medical need. A selection of antifungal agents in early stages of development, produced by microorganisms , is summarized in this review. The compounds are classified according to their mechanisms of action, covering inhibitors of the synthesis of cell wall components (glucan, chitin and mannoproteins), of sphingolipid synthesis (serine palmitoyltransferase, ceramide synthase, inositol phosphoceramide synthase and fatty acid elongation) and of protein synthesis (sordarins). In addition, some considerations related to the chemotaxonomy of the producing organisms and some issues relevant to antifungal drug discovery are also discussed.
Journal of Applied Microbiology, 2005
Aim: To study the antifungal activity and plant beneficial traits of a broad-spectrum antagonistic fluorescent pseudomonad strain, PUPa3. Methods and Results: Strain PUPa3 was isolated from the rhizosphere soil of rice and identified as Pseudomonas aeruginosa on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards phytopathogenic fungi. The antifungal metabolite by PUPa3 was extracted, purified and characterized using nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Production of indole-3-acetic acid (IAA), siderophores, phosphatase and protease in PUPa3 was determined. Strain PUPa3 did not produce hydrogen cyanide, cellulase and pectinase. Conclusion: The antifungal metabolite produced by PUPa3 has been identified as phenazine-1-carboxamide (PCN) on the basis of NMR and MS data. Strain PUPa3 showed a broad-spectrum antifungal activity towards a range of phytopathogenic fungi. This bacterium also showed several plant growth-promoting traits but did not show the traits attributed to deleterious rhizobacteria. Significance and Impact of the Study: Present study reports the production of PCN as well as IAA for the first time by a saprophytic P. aeruginosa strain PUPa3. Because of the production of siderophore, growth hormone, protease and phosphatase and its innate fungicidal potential, this strain can be used as biofertilizer and antagonist against a range of phytopathogenic fungi that infect rice, groundnut, tobacco, chili, mango, sugarcane, tea, cotton and banana.
Secondary metabolites and bioactivity of two fungal strains
Purpose The investigation of two fungal strains isolated from Egyptian habitats, namely, the endophytic Fusarium poae FUN1 and the terrestrial Penicillium italicum FUN2 to illustrate their chemical constituents and their bioactivities. Materials and methods See General instrumental procedures. Results Linoleic acid (1), indole-3-acetic acid methyl ester (2) and Nb-acetyltryptamine (3) were produced by F. poae FUN1, whereas P. italicum FUN2 also delivered linoleic acid (1) in addition to cis-cyclo-(prolyl,valyl) (4). The structures of compounds (1)–(4) were elucidated by 1D and 2D NMR, MS data and through comparison with literature reports. In this article, the taxonomical characterization of both fungal strains, their upscale fermentation and the antimicrobial and cytotoxic activities tested have been described. Conclusion Two different fungal strains, endophytic F. poae FUN1 and terrestrial P. italicum FUN2, were intensively studied biologically and chemically. Four bioactive compounds (1)–(4) were isolated, and structurally confirmed by intensive studies of NMR and MS. The antimicrobial and cytotoxic activities of the fungal extracts and their delivered compounds were studied. This might be helpful for the cure of recent diseases, and drug-resistant phenomena as well as in the development of pharmaceutical, agrochemical and biochemical agents and their lead compounds.
Anticandidal activity of medicinal plants and Pseudomonas aeruginosa strains of clinical specimens
Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi, 2014
This study was designed to investigate the in vitro anticandidal activity of some medicinal plants and Pseudomonas aeruginosa strains against Candida species. The antifungal activity of methanolic extracts of five medicinal plants, namely, Cinnamomumporrectum, Lippia nudiflora, Cestrum nocturnum, Trachyspermum ammi, and Sida carpinifolia were studied. The medicinal characteristics of these plants were compared with commercially used antibiotics. The antimicrobial assay was done by agar well diffusion and the broth dilution method. Among the plants used, T. ammi and C. nocturnum were found to be more potent than the others. Twenty P. aeruginosa strains were isolated from various clinical specimens. The total inhibitions obtained were found to be 47%, 38%, and 36% in blood agar, whereas in Sabouraud dextrose agar (SDA) the inhibitions were 57%, 48%, and 37%, respectively.
Saudi Pharmaceutical Journal
Objective: The present study focused on isolation and identification of endophytic fungi producing antimicrobial compounds and enzymes from a draught resistant medicinal plant. Methods: Endophytic fungi were isolated from fresh live parts of Eucalyptus citriodora and studied their antimicrobial activity against pathogenic microbes and enzyme production. Secondary metabolites assayed for Minimum Bactericidal/ Fungicidal Concentration (MBC/MFC). Active endophytic fungi were identified using rDNA by molecular method. A phylogeny tree for the identified fungi was constructed using online software. Results: Three endophytic fungal isolates inhibited standard microorganisms Pseudomonas aeroginosa, Mycobacterium smegmatis and Candida albicans when tested in dual culture, well and disc diffusion methods. Isolates PECL011 and PECL014 had the best MIC value of 62.5 µg/ml against C.albicans and 125 µg/ml against both P. aeroginosa and M. smegmatis. All the ten fungal isolates were showing activity for at least one of the five enzymes tested qualitatively. The endophytic fungi showing highest inhibition to Candida albicans identified as Aspergillus sp. and Chaetomium sp. by rDNA molecular method. There are 5 isolates belongs to Preussia spp. which are rarely reported and this is the first report from E. citirodora in India. Conclusion: Crude extract of endophytic fungi Aspergillus sp and Chaetomium sp. are very active against fungi and comparable to that of standard antifungal agent flucanazole. Purified compound from this crude extract might be a promising antifungal compound for the treatment of various fungal infections.
Journal of microbiological methods, 2016
In the last decades, the increased number of immunocompromised patients has led to the emergence of many forms of fungal infections. Furthermore, there are a restricted arsenal of antifungals available and an increase in the development of resistance to antifungal drugs. Because of these disadvantages, the search for new antifungal agents in natural sources has increased. The development of these new antifungal drugs involves various steps and methodologies. The evaluation of the in vitro antifungal activity and cytotoxicity are the first steps in the screening. There is also the possibility of antifungal combinations to improve the therapy and reduce toxicity. Despite that, the application of the new antifungal candidate could be used in association with photodynamic therapy or using nanotechnology as an ally. In vivo tests can be performed to evaluate the efficacy and toxicity using conventional and alternative animal models. In this work, we review the methods available for the e...
Cheminform, 2003
Two novel antifungal compounds, 1 (SCH 466457), and 2 (SCH 466456), active in a "cell wall" assay, were isolated from the fermentation broth of an unidentified fungus. The active compoundswere separated from the broth filtrate by adsorption on a macroreticular resin and were purified on reverse phase HPLC.Detailed mass spectrometric and NMRexperiments and degradative studies helped in elucidating the structures of these compounds. The compounds were identified to be peptides containing amino acids such as alanine, aminoisobutyric acid, proline, leucine, valine, glycine and a previously identified /3-keto acid, 2-methyl 3-oxotetradecanoic acid.5) Both compounds were active against Candida, dermatophytes and
Evaluation of the antimicrobial activity of some fungal secondary metabolite
EurAsian Journal of BioSciences, 2020
The inhibitory effect of the prepared secondary metabolite against pathogenic bacteria subjected during the present study compared with antimicrobial standard agent Chloramphenicol on bacterial growth was studied using Agar well diffusion method. The results show inhibitory activity against subjected bacterial isolates when compared with Chloramphenicol. The results of statistical analysis revealed significant differences between concentrations against bacterial isolates. Staphylococcus aureus was the most sensitive to the secondary metabolite in the study while the three subjected bacteria show a different mode of inhibition related to the high activity of the applied, compound also the results show that the secondary metabolite show high inhibitory effects especially in the 150mg/ml concentrations, the inhibitory activity increase with the increase of secondary metabolite concentration. The statistical analysis of the results showed of the inhibitory effect of Trichoderm koningii secondary metabolite on the growth of Trichophyton mentagrophytes , Microsporum canis, and T. verrucosum, there are significant differences below the level of probability (P<0.05) between the inhibitory effects of Trichoderm koningii secondary metabolite studied different concentrations, compared with the standard antifungal fluconazole. The secondary metabolite of the Trichoderm koningii gave higher inhibition impact compared with the inhibitory effect of antifungal fluconazole at the concentration 100%, The statistical analysis of the results showed the inhibitory effect of Trichoderm viride secondary metabolite on the growth of Trichophyton mentagrophytes , Microsporum canis, and T. verrucosum, Diameter average of inhibition at concentrations of 75% was (30, 27, 29)mm, respectively, and diameter average of inhibition at the concentrations of 50% (24, 22, 26) mm, respectively, whereas diameter average of inhibition at the concentrations 25% (22, 20, 23) mm of fungal genera respectively.
Early State Research on Antifungal Natural Products
Molecules, 2014
Nosocomial infections caused by fungi have increased greatly in recent years, mainly due to the rising number of immunocompromised patients. However, the available antifungal therapeutic arsenal is limited, and the development of new drugs has been slow. Therefore, the search for alternative drugs with low resistance rates and fewer side effects remains a major challenge. Plants produce a variety of medicinal components that can inhibit pathogen growth. Studies of plant species have been conducted to evaluate the characteristics of natural drug products, including their sustainability, affordability, and antimicrobial activity. A considerable number of studies of medicinal plants and alternative compounds, such as secondary metabolites, phenolic compounds, essential oils and extracts, have been performed. Thus, this review discusses the history of the antifungal arsenal, surveys natural products with potential antifungal activity, discusses strategies to develop derivatives of natural products, and presents perspectives on the development of novel antifungal drug candidates.
Journal of Applied Pharmaceutical Science
The current study was carried out to isolate and identify marine fungi from the coastal region of Mumbai and assess their antibacterial potential. Aspergillus fumigatus, Histoplasma capsulatum, Cladosporium cladosporioides, Cladosporium pseudocladosporioides, Trichophyton rubrum, Penicillium chrysogenum, Alternaria alternate, Neoscytalidium dimidiatum and Aspergillus terreus were isolated and identified. The metabolite extraction was carried out by broth fermentation and extraction of dry mycelium using organic solvents like chloroform, ethyl acetate, and ethanol. Antibacterial potential of fungal metabolites was assessed by well diffusion method. Different concentrations (2-150 µg/ml) of extracts of broth and dry mycelia were tested against organisms like Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Klebsiella pneumonia, Bacillus subtilis, and Staphylococcus aureus. Results revealed that chloroform and ethanolic extracts (2 µg/ml) from C. cladosporioides broth fermentation exhibit 100% growth inhibition of test organisms. Mycelium ethanolic extract of A. fumigatus, ethyl acetate extract of C. cladosporioides and chloroform extract of C. pseudocladosporioides exhibited maximum (100%) growth inhibition against all test organisms at 2 µg/ml. The study confirms the antibacterial potential of fungal metabolites and therefore paves a way for further identification of the active principles.