Pathogenic Fungal Strains Research Articles

Synthesis of antimicrobial azoloazines and molecular docking for inhibiting COVID-19.

Diverse new azoloazines were synthesized from the reaction of fluorinated hydrazonoyl chlorides with heterocyclic thiones, 1,8‐diaminonaphthalene, ketene aminal derivatives, and 4‐amino‐5‐triflouromethyl‐1,2,4‐triazole‐2‐thiol. The mechanistic pathways and the structures of all synthesized derivatives were discussed and assured based on the available spectral data. The synthesized azoloazine derivatives were evaluated for their antifungal and antibacterial activities through zone of inhibition measurement. The results revealed promising antifungal activities for compounds 4, 5, 17a,b, 19, and 25 against the pathogenic fungal strains used; Aspergillus flavus and Candida albicans compared to ketoconazole. In addition, compounds 4, 5, 19, and 25 showed moderate antibacterial activities against most tested bacterial strains. Molecular docking studies of the promising compounds were carried out on leucyl‐tRNA synthetase active site of Candida albicans, suggesting good binding in the active site forming stable complexes. Moreover, docking of the synthesized compounds was performed on the active site of SARS‐CoV‐2 3CLpro to predict their potential as a hopeful anti‐COVID and to investigate their binding pattern.

Development of Nano-Antifungal Therapy for Systemic and Endemic Mycoses.

Fungal mycoses have become an important health and environmental concern due to the numerous deleterious side effects on the well-being of plants and humans. Antifungal therapy is limited, expensive, and unspecific (causes toxic effects), thus, more efficient alternatives need to be developed. In this work, Copper (I) Iodide (CuI) nanomaterials (NMs) were synthesized and fully characterized, aiming to develop efficient antifungal agents. The bioactivity of CuI NMs was evaluated using Sporothrix schenckii and Candida albicans as model organisms. CuI NMs were prepared as powders and as colloidal suspensions by a two-step reaction: first, the CuI controlled precipitation, followed by hydrazine reduction. Biopolymers (Arabic gum and chitosan) were used as surfactants to control the size of the CuI materials and to enhance its antifungal activity. The materials (powders and colloids) were characterized by SEM-EDX and AFM. The materials exhibit a hierarchical 3D shell morphology composed of ordered nanostructures. Excellent antifungal activity is shown by the NMs against pathogenic fungal strains, due to the simultaneous and multiple mechanisms of the composites to combat fungi. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CuI-AG and CuI-Chitosan are below 50 μg/mL (with 5 h of exposition). Optical and Atomic Force Microscopy (AFM) analyses demonstrate the capability of the materials to disrupt biofilm formation. AFM also demonstrates the ability of the materials to adhere and penetrate fungal cells, followed by their lysis and death. Following the concept of safe by design, the biocompatibility of the materials was tested. The hemolytic activity of the materials was evaluated using red blood cells. Our results indicate that the materials show an excellent antifungal activity at lower doses of hemolytic disruption.

Antibacterial and Antifungal Activity of Coccinia grandis Leaves’ Extracts against Fish Pathogens

Coccinia grandis is used in India and other parts of the world as a medicinal plant. In the present study an attempt was made to identify the presence of phytochemicals in the Aqueous, Ethanol, Methanol and Petroleum ether extracts of leaves of C. grandis. The qualitative Preliminary phytochemical present of study reveals that alkaloids, phenol, flavonoids, steroids, terpenoids, saponins, tannins, protein, carbohydrates, glycosides, oils, gums, resins and amino acid by adopting standard methods. In this study antibacterial and antifungal activity of leaves extracts of C. grandis were tested against five pathogenic bacterial strains such as Bacillus subtilis, Staphylococcus aureus, Psedomonas aurginia, Escherichia coli and Vibrio anguillarum by agar well diffusion method. C. grandis were tested against four pathogenic fungal strains such as Candida albicans, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus. The ethanol leaves extracts of C. grandis demonstrated higher antibacterial activities against Vibrio anguillarum (31±1.00 mm) in 500 μl concentration. A higher antifungal effect was observed with the ethanol leaves extracts with an inhibitory halo of Aspergillus niger (30.33±1.53 mm) in 500 μl concentration.

Comprehensive GC-MS and FT-IR Profiling of Coleus zeylanicus essential oil and investigation of its anti-fungal and anti - oxidant activities

To evaluate the leaf volatile constituents of essential oil of Coleus zeylanicus and evaluate their anti-oxidant and anti-fungal activity. The Chemical composition of Coleus zeylanicus essential oil was determined using GC-MS and FT-IR analytical techniques. The antioxidant activity was evaluated using DPPH scavenging assay. The anti-fungal effect was tested against two potential pathogenic fungal strains - Candida albicans and Malassezia furfur using agar well diffusion method. The essential oil was profiled by the presence of sesquiterpene hydrocarbons 90.67% of their total composition followed by oxygenated monoterpenes and monoterpene hydrocarbons as 5.3% and 2.1% respectively. The GC-MS results showed 14 compounds from Coleus zeylanicus leaf EO representing 98.07% of the total oil composition. The major component was identified as a-Gurjunene (35.94%), a-bisabolol (10.82%) and G-selinene (4.26%). EO showed remarkable antioxidant activity values of IC50 = 59.78± 3.21µg/ml by DPPH scavenging assay. The essential oil showed interesting anti-fungal effects against two pathogenic fungal strains. The most sensible strains to Coleus zeylanicus EO was Malassezia furfur (32.00±0.50mm) compared to that of Candida albicans (15.00±1.25mm). Hence, Coleus zeylanicus EO has potential application against fungal infection and oxidative stress-related diseases. However, further investigations are necessary to isolate and investigate the action mechanism of these bioactive compounds.

Evaluation of Bactericidal and Fungicidal Efficacy of Strychno spotatorum Linn. (Nirmali) Seeds

Aim: Diseases due to pathogenic microbes pose a great burden on human health and they have been correlated with socioeconomic, environmental, and ecological factors. The threat due to infectious diseases is further intensified by the continued emergence of new and multidrug resistant microorganisms. This scenario warrants a continuous search for antimicrobial agents preferably of plant origin due to their availability, accessibility, and affordability. The present study was aimed to evaluate the antibacterial and antifungal properties of Strychnos potatorum Linn (Nirmali) seeds using common pathogenic bacterial and fungal strains.
 Methodology: Fresh and matured S. potatorum seeds were used for the present study. The powdered seeds were delipidated with petroleum ether (60-80°C) overnight and the extract was filtered. Soxhalation was performed with 95% ethanol to extract the phyto-ingredients from the seeds. Four Gram positive, four Gram negative, and eight fungal strains were used. The antimicrobial activity was evaluated by disc diffusion and well diffusion methods. The Minimum inhibitory concentration (MIC) Minimum bactericidal concentrations (MBC), Minimum fungicidal concentration (MFC) were assayed.
 Results: The data obtained through the disc diffusion, well diffusion, the minimum bactericidal concentration, and minimum fungicidal concentrations revealed that the ethanolic extract of the seeds possesses significant antibacterial and antifungal activities. The results obtained were compared with standard drugs widely prescribed for antimicrobial therapy.
 Conclusion: The present study provides the scientific rationale for the use of Strychnos potatorum seeds in traditional medicine and a rich source of phytochemicals having significant antimicrobial activities.

Antimicrobial and Antioxidant Activities of Methanolic Extract and Fractions of <i>Epilobium roseum</i> (Schreb.) against Bacterial Strains

Present study aims to evaluate antimicrobial and antioxidant activities of the crude methanolic extract and different fractions of the Epilobium roseum (Schreb). The extract and fractions were used against pathogenic bacteria (Bacillus subtilis, Bacillus atrophaeus, Klebsiella pneumonia and Pseudomonas aeruginosa) and fungal strains (Aspergillus niger and Aspergillus flavus). The methanolic extract and their sub fraction n-hexane showed a prominent inhibition zone against all bacterial strains but inactive against fungal strains. The various extracts of Epilobium roseum (Schreb) from various parts were tested for their antioxidant activity by 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assay. The IC50 of the stem and root of methanolic extract and their sub fraction n-hexane showed best activity ranged between 22.73 ± 6.92, 21.49 ± 6.26 and 14.94 ± 3.54, 13.92 ± 1.04 μg/ml compared to another fraction. The results support that Epilobium roseum can be used as antimicrobial and antioxidant agents. The results support the present study that Epilobium roseum (Schreb) has a potential source of natural antibacterial, antifungal and antioxidant potentials.

Evaluation of the Antimicrobial Activity of Endophytic Fungus Isolated from <i>Cocos nucifera</i> (L.) Cotyledon against Medically-Important Pathogens

The study aimed to evaluate the endophytic fungi isolated from Cocos nucifera (L.) cotyledon for their possible antimicrobial activity. A total of twelve endophytic fungal species were successfully isolated, from which five were selected and presumptively identified, including Aspergillus niger, Raffaelea sp., Aspergillus flavus, Cladosporium sp. and Pseudallescheria spp. based on their macro and microscopic characters. The agar blocks of actively growing pure culture were assessed for antibacterial activity against five human pathogenic bacterial and fungal strains: Escherichia coli (BIOTECH 1634), Bacillus subtilis (BIOTECH 1697), Staphylococcus aureus (BIOTECH 1592), Serratia marcescens (BIOTECH 1748), and Candida tropicalis (BIOTECH 2085). Among the selected five endophytic used for antimicrobial activity screening, the Raffaelea sp. (CN-EF 2) has shown a high zone of inhibition of 11 mm against Bacillus subtilis, 18 mm against Escherichia coli, 15 mm against Staphylococcus aureus, and 11 mm against Candida tropicalis. Correspondingly, Aspergillus niger (CN-EF 1) has shown a zone of inhibition of 16 mm against C. tropicalis. The endophytic fungus Raffaelea sp. was effective against all test organisms except for Serratia marcescens, while Aspergillus niger was only effective for pathogenic fungi C. albicans. Hence, further in-depth studies of the isolated endophytic fungi are needed to determine the mechanisms behind the endophytes’ inhibitory effects.

Synthesis and Antimicrobial Activity of Cyclic Dithiocarbamates Employing Triton-B/CS2 System

An efficient and green methodology to synthesize cyclic dithiocarbamates (compounds 1-11) was developed by reaction of primary amines, CS2 and 1,2-dibromoethane or 1,4-dibromobutane, catalyzed by Triton-B (as PTC)/CS2 system. Mass spectroscopy, elemental analysis and 1H NMR are used for characterization of the synthesized compounds (1-11). This effectual green tactics give good yield of product which entails mild conditions. Compounds (1-11) were found to possess in vitro antimicrobial activities against the pathogenic bacterial and fungal strain. The microbial strains used to screen activities are Escherichia coli, Staphylococcus aureus and Candida albicans.

Triterpenoids and Semisynthetic Derivatives with Antimicrobial Activities from the Leaves of <i>Caloncoba glauca</i> (Flacourtiaceae)

Chemical investigation of the MeOH extract from the leaves of C. glauca yielded nine known triterpenoids (1-9) belonging to the cycloartane and friedelane series. Two of these compounds namely glaucartanoic acid A (1) and 3β,21β-dihydroxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic acid (5) were subjected to chemical derivatizations and afforded five new derivatives: diacetylglaucartanoic acid A (1a), 24-acetylglaucartanoic acid A (1b), glaucartanoic acid A methyl ester (1c), 24-methoxyglaucartanoic acid A methyl ester (1d), and 3β,21β-diacetoxy-30-nor-(D:A)-friedoolean-20(29)-en-27-oic acid (5a). Their structures were assigned based on their NMR and MS data and by comparison with literature values. The MeOH extract, isolated compounds and some new semi-synthetic derivatives were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms, including Gram-positive and Gram-negative bacteria, and fungi using broth microdilution method. The MeOH extract displayed activity towards all the tested pathogenic bacterial and fungal strains with good activity (MIC against Staphylococcus aureus ATCC25923 and Shigella flexneri SDINT. Compounds 3 and 5 showed the most potent antimicrobial effect.

Prospect of Endophytic Fungal Entomopathogens for Pest Management

Endophytic fungal entomopathogens could offer a number of benefits to their host plants, which include protection against the primary pests, resistance against microbial pathogens, stimulation of growth, or increase of heavy metal or drought tolerance. However, all reports, so far, indicate that colonization of some plants by entomopathogenic fungi seemly confer only certain benefits to their hosts or else only one parameter was examined. Our study underscores the practicability of introduction of specific insect fungal pathogen strains into host plants as endophytes that could simultaneously promote host plant growth and offer plant protection against microbial pathogens, and/or insect pests, which highlights the prospect of endophytic fungal entomopathogens for pest management. Here, we further commented on the study-involved issues and the factors that possibly affect colonization by fungal entomopathogens and the benefits to the host plant offered by the endophytes. Moreover, we put forward the possible link of some plant morphological changes and/or stimulation of some plant defense pathways with the resistance of the host plants against insect/ microbial pathogens, although the underlying mechanism remains somewhat of a mystery that should be uncovered in the future.

Synthesis, characterization and applications of Organomecury(II) pyrrolidine-N-thiohydrazide complexes

The complexes of organomercury(II) with pyrrolidine-N-thiohydrazide of the type RHg(L)Cl where[R=C 6 H 5 (phenyl), p-ClC 6 H 4 (p-chlorophenyl), p-BrC 6 H 4 (p-bromophenyl), o-, p-HOC 6 H 4, (o-,p-hydroxyphenyl) , L = pyrrolidine-N-thiohydrazide, have been synthesized and characterized by elemental analysis, IR, 1 H-NMR and electronic spectral analysis. Thermogravimetric and differential thermal analytical curves are used to calculate thermodynamic parameters and variations in these parameters have been correlated with complex structural parameters. All complexes were tested in vitro for their antibacterial activity against Gram-negative bacteria, namely, Escherichia coli , Zymomonas mobilis and against two pathogenic fungal strains, namely, Aspergillus niger and Cerveleria.

Evaluation of purity, viability, stability and biochemical characteristics of clinical fungal isolates preserved by three different methods

Introduction: In era of organ transplants and immunocompromised patients, systemic mycosis has emerged as a major cause of morbidity and mortality among these patients. Research on these clinical fungal isolates is the key to the development of antifungal diagnostics and therapeutic agents. Mycology laboratories has to preserve these pathogenic fungal strains for various experiments. These laboratories requires a preservation method that ensures purity, viability, stability and biochemical characteristics of the fungal isolates during the storage period. Objectives: To determining the purity, viability, stability and biochemical characteristics of clinical fungal isolates subjected to three different, but simple and inexpensive preservation methods. Materials and Methods: A total of 50 clinical isolates of yeast and mold were subjected to different preservation Methods: All the isolates were evaluated for purity, viability, stability and biochemical characteristics before storage and after 6 months and one year. Stability testing was based on antifungal susceptibility testing as recommended by CLSI. Results: All the three preservation methods, ensured survival of all the fungal strains for one year duration. Periodic subculture method on agar slope demonstrated mild colony morphological changes in 2 molds and high contamination rate. Water culture technique and oil overlay technique, demonstrated protection of purity, viability, stability and biochemical characteristics of all the fungal isolates up to one year of storage. Conclusion: Comparison of different fungal storage methods suggested that both water technique and oil overlay technique can be utilized as a simple, effective and inexpensive methods for long term preservation of clinical fungal isolates. Keywords: Preservation, Storage, Yeast, Molds, CLSI.

ANTIFUNGAL AND ANTIBACTERIAL ACTIVITY OF ALOE VERA PLANT EXTRACT

Aloe vera is a well-known medicinal plant used in many therapeutic purposes. Naturally it is composed of many useful compounds that have ability to use for treatment of many diseases. The active compounds reported in this plant are saponins, sugar, enzymes, vitamins, aloesin, aloeemodin, aloin, acemannan aloemannan, aloeride, methylchromones, flavonoids, naftoquinones, sterols, minerals, anthraquinones, amino acids, lignin and salicylic acid and other different compounds including fat-soluble and water-soluble vitamins, enzymes, minerals, simple/complex sugars, organic acid and phenolic compounds. In this study aloe vera is used for antibacterial and antifulgal activity against different strains of bacteria and pathogenic fungal strains. Ethanol extract of Aloe vera leaves and roots is applied on these bacterial and fungal strains in different concentrations (15, 20, 25, 30µl). Bacillus cereus, Bacillus subtitis, Bacillus megaterium, Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and some other bacterial strains are used for this study. Escherichia coli and Agrobacterium tumefacins shows zone of inhibition around 18mm which consider as good result. Bacillus subtitis and Bacillus megaterium also shows good result around 16mm. Proteus mirabilis and Pseudomonas aeruginosa shows minimum zone of inhibition which is around 11mm. among all used fungal strains (fuserium oxysporum, Candida albicans, Aspergillus fumigatus, Aspergillus niger) fuserium oxysporum and Aspergillus niger shows excellent results around 19mm both against root extract and leaves extract.

Investigation of antagonistic activities of actinomycetes isolated from Cuc Phuong and Ba Be National Parks against four plant pathogenic fungi

Fungal diseases are a huge problem in agriculture, causing serious damage to annual crop yields worldwide. In order to control fungal pathogens in plants, using antagonistic microorganisms is a common approach, especially actinomycetes, as biocontrols considered to be very potential and safe for the environment. With the advantage of high levels of biodiversity, Vietnamese actinomycetes are of a valuable resource for finding strains that are capable of biocontrolling fungal pathogens in plants. Thus, in this study, 70 actinomycete strains were isolated from Cuc Phuong and Ba Be National Parks by four different isolation methods including rehydration centrifugation, sodium dodecyl sulfate – yeast extract, dry heating and dilution methods. Of these, 29 strains (41.4%) belong to rare actinomycete genera including Actinoplanes, Acrocarpospora, Dactylosporangium, Kineosporia, Micromonospora, Nocardia, Nocardiopsis and Pseudonocardia, which are rarely studied in Vietnam. Subsequently, 70 actinomycete strains were subjected to antagonistic activity assays against four highly pathogenic fungi in plants including Alternaria sp., Botrytis cinerea, Colletotrichum gloeosporioides and Phytophthora capsici. The results showed that 80.5% of Streptomyces and 31% of rare actinomyces could inhibit the growth of at least one of the four pathogenic fungal strains. Moreover, ten actinmomycete strains were found to be able to inhibit three types of tested fungal pathogens, simutaneously. Especially, four actinomycete strains (VTCC-A-828, VTCC-A-671, VTCC-A-605, and VTCC-A-69), having the highest antagonistic activity against four fungal pathogens Alternaria sp., Botrytis cinerea, Colletotrichum gloeosporioides and Phytophthora capsici, respectively, were selected. The results in this study indicate the great potential application for Vietnam's microorganisms in the field of plant protection.

Assessment of the Sensitivity of Some Plant Pathogenic Fungi to 6-Demethylmevinolin, a Putative Natural Sensitizer Able to Help Overcoming the Fungicide Resistance of Plant Pathogens.

Agricultural fungicides contaminate the environment and promote the spread of fungicide-resistant strains of pathogenic fungi. The enhancement of pathogen sensitivity to these pesticides using chemosensitizers allows the reducing of fungicide dosages without a decrease in their efficiency. Using Petri plate and microplate bioassays, 6-demethylmevinolin (6-DMM), a putative sensitizer of a microbial origin, was shown to affect both colony growth and conidial germination of Alternaria solani, A. alternata, Parastagonospora nodorum, Rhizoctonia solani, and four Fusarium species (F. avenaceum, F. culmorum, F. oxysporum, F. graminearum) forming a wheat root rot complex together with B. sorokiniana. Non- or marginally toxic 6-DMM concentrations suitable for sensitizing effect were determined by the probit analysis. The range of determined concentrations confirmed a possibility of using 6-DMM as a putative sensitizer for the whole complex of root rot agents, other cereal pathogens (A. alternata, P. nodorum), and some potato (R. solani, A. solani) and tomato (A. solani) pathogens. Despite the different sensitivities of the eight tested pathogens, 6-DMM lacked specificity to fungi and possessed a mild antimycotic activity that is typical of other known pathogen-sensitizing agents. The pilot evaluation of the 6-DMM sensitizing first confirmed a principal possibility of using it for the sensitization of B. sorokiniana and R. solani to triazole- and strobilurin-based fungicides, respectively.

Bioactive Constituents from the Bryophyta Hypnum plumaeforme.

Chemical investigation of the secondary metabolites of the whole plant of bryophyte Hypnum plumaeforme Wilson led to the isolation of a new pimarane-type diterpenoid, momilactone F (1), along with seventeen known compounds. Their chemical structures were elucidated based on massive spectroscopic data. The allelopathic and antifungal properties were evaluated. Among them, momilactone F (1), acrenol (2),[11] momilactones A (3) and B (4) showed significant allelopathic activity against Samolus parviflorus Raf. and Lactuca sativa L. var. angustana Irish, as well as selected antifungal property against crop pathogenic fungi strains. On the other hand, 8(14)-podocarpen-13-on-18-oic acid (8) exhibited strong promoting activity on the growth of L. sativa L. var. angustana Irish. The present investigation provided new insights for developing of H. plumaeforme for further application as a potential agricultural tool.

Rotating and stacking genes can improve crop resistance durability while potentially selecting highly virulent pathogen strains

Rotating crop cultivars with different resistance genes could slow the evolution of virulent strains of fungal pathogens, but could also produce highly virulent pathogen strains. We present a new model that links polycyclic pathogen epidemiology and population genetics in order to predict how different strategies of rotating cultivars with different resistances will affect the evolution of pathogen virulence and the breakdown of crop resistance. We modelled a situation where there were four different resistance genes that can be deployed within each crop cultivar, and four virulence genes that may be present within the pathogen. We simulated four different rotational management strategies: (i) no rotation; (ii) a different gene every year; (iii) a different gene every 5 years; and (iv) a different combination of two stacked genes each year. Results indicate that rotating cultivars can lead to longer periods of disease suppression but also to the selection of highly virulent strains. The efficacy and relative advantage of different resistant cultivar rotation strategies depended on the fitness penalties, initial virulence allele frequencies, and ability of non-virulent pathogen genotypes to grow and reproduce on resistant cultivars. By capturing the essential processes involved, our model provides a useful new tool for investigating the evolutionary dynamics of pathogen virulence and crop resistance breakdown.

Eucalyptus camaldulensis gum as a green matrix to fabrication of zinc and silver nanoparticles: Characterization and novel prospects as antimicrobial and dye-degrading agents

Green biosynthesis of nanoparticles (NPs) has gained much significance due to cost-effectiveness, time-efficiency, biocompatibility, and environmentally friendliness. Herein, we report the fabrication of zinc (ZnNPs) and silver nanoparticles (AgNPs) using Eucalyptus camaldulensis (EC) gum extract as a low-cost and green bio-matrix. The as-fabricated EC-ZnNPs and EC-AgNPs were comprehensively characterized by UV–visible spectroscopy, Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and scanning electron microscopy (SEM) techniques. Specific characteristic peaks of synthesized NPs were scrutinized through UV–visible and FTIR. The synthesized NPs revealed irregular shape and size with an increase in roughness of the surface. A delay in the rate of weight loss indicated the stable nature of EC-ZnNPs at high temperatures. Similarly, an increase in the crystallinity nature of EC-ZnNPs and EC-AgNPs was evidenced through XRD analysis. As compared to gum samples, the green fabricated EC-ZnNPs and EC-AgNPs performed an admirable inhibitory activity against a pathogenic bacterium (Escherichia coli) and fungal strain (Schizophyllum commune). Mutagenicity and cytotoxicity activities determined through Ames and haemolytic tests affirmed the non-mutagenic and non-toxic attributes of the gum samples and their derived EC-ZnNPs and EC-AgNPs. Finally, the EC-AgNPs and EC-ZnNPs showed a high photocatalytic potentiality towards the degradation of methylene blue dye under sunlight irradiation. In conclusion, the findings manifest excellent antimicrobial and dye degradation potentialities of gum-based EC-ZnNPs and EC-AgNPs, representing its putative perspective as a novel nano-antibiotic against pathogenic bacterial and fungal isolates, and for environmental mitigation. The present method is eco-friendly, clean and did not require any toxic/hazardous reductants.

Comparative evaluation of antifungal and antibacterial activities of crude extracts of Pleurotus sajor-caju, Pleurotus tuber-regium and Lentinus squarrosulus (Basidiomycota, Pleurotaceae, Lentinaceae) from Cameroon

Antifungal and antibacterial activities of crude extracts of 3 tropical mushrooms including Pleurotus sajor-caju, Pleurotus tuber-regium and Lentinus squarrosulus were investigated on eleven species of bacterial and three of fungal human pathogens. For the pathogenic fungi, the Minimal Inhibitory Concentration (MIC) of carpophore extracts ranged from 0.39 mg/mL to 6.25 mg/mL for Candida albicans, 0.78 mg/mL to 6.25 mg/mL for Aspergillus fumigetus, and 1.56 mg/mL to 6.25 mg/mL for Aspergillus ochraceus. For bacteria, the MIC values ranged from 6.25 mg/mL to 12.5 mg/mL on most Gram positive strains including Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus and Mycobacterium smegmatis. This MIC value was the same (12.5 mg/mL) for the 3 crude extracts tested on Staphylococcus epidermidis for the Gram positive strains. Gram negative bacteria were generally less sensitive to crude extracts with higher MIC values ranging from 6.25 mg/mL to 12.5 mg/mL for Escherichia coli and Enterobacter cloacae and the same (12.5 mg/mL) for Proteus vulgaris, Klebsiella oxytoca, Klebsiella aerogenes and Proteus mirabilis. Based on the above mentioned figures, it appears that strains of pathogenic fungi tested are generally much more sensitive to crude extracts than strains of bacteria. In fact, antimicrobial activities of the 3 crude extracts tested are stronger on human pathogenic fungi than bacteria. These results are evidence that carpophores of the 3 mushrooms species could be a source of new molecules potentially more effective than synthetic products against some human pathogenic fungi and bacteria.

Nano-sized formazan analogues: Synthesis, structure elucidation, antimicrobial activity and docking study for COVID-19

Three series of nanosized-formazan analogues were synthesized from the reaction of dithiazone with various types of α-haloketones (ester and acetyl substituted hydrazonoyl chlorides and phenacyl bromides) in sodium ethoxide solution. The structure and the crystal size of the new synthesized derivatives were assured based on the spectral analyses, XRD and SEM data. The antibacterial and antifungal activities were evaluated by agar diffusion technique. The results showed mild to moderate antibacterial activities and moderate to potent antifungal activities. Significant antifungal activities were observed for four derivatives 3a, 3d, 5a and 5g on the pathogenic fungal strains; Aspergillus flavus and Candida albicans with inhibition zone ranging from 16 to 20 mm. Molecular docking simulations of the synthesized compounds into leucyl-tRNA synthetase editing domain of Candida albicans suggested that most formazan analogues can fit deeply forming stable complexes in the active site. Furthermore, we utilized the docking approach to examine the potential of these compounds to inhibit SARS-CoV-2 3CLpro. The results were very promising verifying these formazan analogues as a hopeful antiviral agents.