Identification of the major fungitoxic component of cinnamon bark oil

The study was done to identify the most active fungitoxic component of cinnamon bark (Cinnamomum zeylanicum) oil that can be used as a marker for standardization of cinnamon extract or oil based natural preservative of stored seeds. Aspergillus flavus and A. ruber were used as test fungi. The hexane extracted crude oil and the hydro-distilled essential oil from cinnamon bark had complete growth inhibition concentration (CGIC) of 300 and 100 µl/l, respectively. Both oils produced three fractions on preparative thin layer silica-gel chromatography plates. The fraction-2 of either oil was the largest and most active, with CGIC of 200 µl/l, but the fungitoxicity was also retained in the other two fractions. The fraction-1 and 3 of the crude oil reduced growth of both the fungal species by 65%, and those of distilled oil by 45% at 200 µl/l. The CGIC of these fractions from both the sources was above 500 µl/l. The gas chromatography and mass spectrometry (GC-MS) of the fraction-2 of the hexane extract revealed that it contained 61% cinnamaldehyde, 29% cinnamic acid, and two minor unidentified compounds in the proportion of 4% and 6%. The GC-MS of the fraction-2 of the distilled oil revealed that it contained 99.1% cinnamaldehyde and 0.9% of an unidentified compound. The CGIC of synthetic cinnamaldehyde was 300 µl/l and that of cinnamic acid above 500 µl/l. The 1:1 mixture of cinnamaldehyde and cinnamic acid had CGIC of 500 µl/l. The data revealed that cinnamaldehyde was the major fungitoxic component of hexane extract and the distilled essential oil of cinnamon bark, while other components have additive or synergistic effects on total fungitoxicity. It is suggested that the natural seed preservative based on cinnamon oil can be standardized against cinnamaldehyde.

Chemical, biochemical, and microbiological aspects of chitosan quaternary salt as active coating on sliced apples

The biocompatibility of chitosan and chitosan quaternary salt coatings was evaluated for use as edible coatings for sliced apple. Measurement of water loss, color change, and fungal growth appearance were monitored as a function of time. A significant brownish effect was observed on chitosan coated slices, varying greatly from L* = 76.5 and Hue angle = 95.9° (t = 0) to L* = 45.3 and Hue angle = 69.8° (t = 3 days), whilst for TMC coated samples the variation was considerable lower (L* = 74.1; Hue angle = 95.0°) to (L* = 67.0; Hue angle = 83.8°) within the same period. The hydrosoluble derivative N,N,N-trimethylchitosan demonstrated good antifungal activity against P. expansum although highly dependent on the polymer properties such as degree of quaternization. The most efficient formulation was that prepared from derivative having a degree of quaternization of 45%, high solubility, and high viscosity. This formulation restrained fungus spreading up to 30%, while for the control it reached almost 80% of the total assessed surfaces during 7 days of storage.

Fusarium graminearum growth inhibition mechanism using phenolic compounds from Spirulina sp

The application of natural antifungal substances is motivated by the need for alternatives to existing methods that are not always applicable, efficient, or that do not pose risk to consumers or the environment. Furthermore, studies on the behaviour of toxigenic species in the presence of natural fungicides have enabled their safe application in the food chain In this study, Spirulina LEB-18 phenolic extract was assessed for its antifungal activity on 12 toxigenic strains of Fusarium graminearum isolated from barley and wheat. The susceptible metabolic pathways were assessed through the determination of structural compounds (glucosamine and ergosterol) and enzyme activity of the microorganisms' primary metabolism. The results indicate that phenolic extracts reduced the growth rate of the toxigenic species investigated. The IC50 was obtained by applying 3 to 8% (p/p) of phenolic compounds in relation to the culture medium. The use of this natural fungicide proved promising for the inhibition of fungal multiplication, especially in terms of the inactivation of enzymatic systems (amylase and protease) of Fusarium graminearum.

Comparison of in vitro activity of five antifungal agents against dermatophytes, using the agar dilution and broth microdilution methods

The purpose of this study was to compare the agar dilution and broth microdilution methods for determining the minimum inhibitory concentration (MIC) of fluconazole, itraconazole, ketoconazole, griseofulvin and terbinafine for 60 dermatophyte samples belonging to the species Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. The percentage agreement between the two methods, for all the isolates with < 2 dilutions that were tested was 91.6% for ketoconazole and griseofulvin, 88.3% for itraconazole, 81.6% for terbinafine and 73.3% for fluconazole. One hundred percent agreement was obtained for Trichophyton mentagrophytes isolates evaluated with ketoconazole and griseofulvin. Thus, until a reference method for testing the in vitro susceptibility of dermatophytes is standardized, the similarity of the results between the two methods means that the agar dilution method may be useful for susceptibility testing on these filamentous fungi.

Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

Antifungal and antimycotoxigenic activity of essential oils from Eucalyptus globulus, Thymus capitatus and Schinus molle

Abstract Essential oils (EO) of eucalyptus (Eucalyptus globulus L.), thymus (Thymus capitatus L.) pirul (Schinus molle L.) were evaluated for their efficacy to control Aspergillus parasiticus and Fusarium moniliforme growth and their ability to produce mycotoxins. Data from kinetics radial growth was used to obtain the half maximal inhibitory concentration (IC50). The IC50 was used to evaluate spore germination kinetic and mycotoxin production. Also, spore viability was evaluated by the MTT assay. All EO had an effect on the radial growth of both species. After 96 h of incubation, thymus EO at concentrations of 1000 and 2500 µL L–1 totally inhibited the growth of F. moniliforme and A. parasiticus, respectively. Eucalyptus and thymus EO significantly reduced spore germination of A. parasiticus. Inhibition of spore germination of F. moniliforme was 84.6, 34.0, and 30.6% when exposed to eucalyptus, pirul, and thymus EO, respectively. Thymus and eucalyptus EO reduced aflatoxin (4%) and fumonisin (31%) production, respectively. Spore viability was affected when oils concentration increased, being the thymus EO the one that reduced proliferation of both fungi. Our findings suggest that EO affect F. moniliforme and A. parasiticus development and mycotoxin production.

Activity of Tri-N-Butyl Tin maleate in carpets against Staphylococcus aureus and Aspergillus niger, verified through two methodologies: Inhibition Halo (HZ) and Inhibition Surface (Print)

The aim of the present study was to verify the activity of the Tri-N-Butyl Tin maleate compound against Staphylococcus aureus and Aspergillus niger, after its industrial application in 40 samples of carpets of different materials (polypropylene, polyester, polyamide and wool). The qualitative assays were performed through two methodologies: Inhibition Halo (HZ) and Inhibition of Surface (Print). The carpet with the product inhibited 100% of bacterial (Staphylococcus aureus) and fungi (Aspergillus niger) growth, under the conditions of this study. The microbial inhibition was higher in upper portion of carpets. The methodologies employed appear to be adequate to test the bactericide and fungicide activities of the Tri-N-Butyl Tin maleate. The print methodology confirmed the results obtained by the inhibition zone assay. Further studies using the same methodologies are needed to confirm our results.

Sporothrix schenckii COMPLEX: SUSCEPTIBILITIES TO COMBINED ANTIFUNGAL AGENTS AND CHARACTERIZATION OF ENZYMATIC PROFILES

SUMMARY Sporothrix schenckiiwas reclassified as a complex encompassing six cryptic species, which calls for the reassessment of clinical and epidemiological data of these new species. We evaluated the susceptibility of Sporothrix albicans (n = 1) , S. brasiliensis (n = 6) , S. globosa (n = 1), S. mexicana(n = 1) and S. schenckii(n = 36) to terbinafine (TRB) alone and in combination with itraconazole (ITZ), ketoconazole (KTZ), and voriconazole (VRZ) by a checkerboard microdilution method and determined the enzymatic profile of these species with the API-ZYM kit. Most interactions were additive (27.5%, 32.5% and 5%) or indifferent (70%, 50% and 52.5%) for TRB+KTZ, TRB+ITZ and TRB+VRZ, respectively. Antagonisms were observed in 42.5% of isolates for the TRB+VRZ combination. Based on enzymatic profiling, the Sporothrix schenckii strains were categorized into 14 biotypes. Leucine arylamidase (LA) activity was observed only for S. albicans and S. mexicana. The species S. globosaand S. mexicanawere the only species without β-glucosidase (GS) activity. Our results may contribute to a better understanding of virulence and resistance among species of the genus Sporothrixin further studies.

CHEMICAL CHARACTERIZATION AND EVALUATION OF ANTIBACTERIAL, ANTIFUNGAL, ANTIMYCOBACTERIAL, AND CYTOTOXIC ACTIVITIES OF Talinum paniculatum

SUMMARY In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteus and Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosisand Mycobacterium bovisas well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatumshowed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.

Chemical composition, toxicity and larvicidal and antifungal activities of Persea americana (avocado) seed extracts

The present study had the aim of testing the hexane and methanol extracts of avocado seeds, in order to determine their toxicity towards Artemia salina, evaluate their larvicidal activity towards Aedes aegypti and investigate their in vitro antifungal potential against strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis through the microdilution technique. In toxicity tests on Artemia salina, the hexane and methanol extracts from avocado seeds showed LC50 values of 2.37 and 24.13mg mL-1 respectively. Against Aedes aegypti larvae, the LC50 results obtained were 16.7mg mL-1 for hexane extract and 8.87mg mL-1 for methanol extract from avocado seeds. The extracts tested were also active against all the yeast strains tested in vitro, with differing results such that the minimum inhibitory concentration of the hexane extract ranged from 0.625 to 1.25mg L-¹, from 0.312 to 0.625mg mL-1 and from 0.031 to 0.625mg mL-1, for the strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis, respectively. The minimal inhibitory concentration for the methanol extract ranged from 0.125 to 0.625mg mL-1, from 0.08 to 0.156mg mL-1 and from 0.312 to 0.625mg mL-1, for the strains of Candida spp., Cryptococcus neoformans and Malassezia pachydermatis, respectively.

Antimicrobial activity of bergenin from Endopleura uchi (Huber) Cuatrec

Endopleura uchi (Huber) Cuatrec. is an Amazon species traditionally used as treatment for inflammations and female disorders. Bergenin was isolated from ethyl acetate fraction of bark of E. uchi by using column chromatography over sephadex LH-20 and then silica gel 60 flash. Its structure was identified on the basis of its NMR spectra. The antimicrobial activity of bergenin and fractions of methanol extract of E. uchi were evaluated against ATCC microorganisms (Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Candida albicans, C. guilliermondii, Aspergillus flavus, A. nidulans). Clinically isolated strains of all of these microorganisms, along with C. tropicalis, A. niger, Shigella sonnei, Serratia marcenses and Klebsiella pneumoniae were also evaluated. The growth inhibition caused by bergenin, extracts and fractions of E. uchi against ATCC microorganisms were similar to the inhibition to microorganisms clinically isolated. The ethyl acetate fraction and the isolate bergenin inhibit the growth of the yeasts C. albicans, C. tropicalis, and C. guilliermondii, but present lower activity against filamentous fungi Aspergillus flavus, A. nidulans, A. niger, and did not inhibit the Gram positive and Gram negative bacteria. The activity of the ethyl acetate fraction and bergenin are in agreement wit its high concentration found in bark extract of E. uchi. Moreover, the selective activity against three Candida species helps to understand its traditional use against infections that affect women.

Antimicrobial activity of honeys from two stingless honeybee species and Apis mellifera (Hymenoptera: Apidae) against pathogenic microorganisms

Honeys are described possessing different properties including antimicrobial. Many studies have presented this activity of honeys produced by Apis mellifera bees, however studies including activities of stingless bees honeys are scarce. The aim of this study was to compare the antimicrobial activity of honeys collected in the Amazonas State from Melipona compressipes, Melipona seminigra and Apis mellifera against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Chromobacterium violaceum, and Candida albicans. Minimum inhibitory concentrations were determined using the agar dilution method with Müller-Hinton agar (for bacteria) or Saboraud agar (for yeast). Staphylococcus aureus and E. faecalis were inhibited by all honeys at concentrations below 12%, while E. coli and C. violaceum were inhibited by stingless bee honeys at concentrations between 10 and 20%. A. mellifera honey inhibited E. coli at a concentration of 7% and Candida violaceum at 0.7%. C. albicans were inhibited only with honey concentrations between 30 and 40%. All examined honey had antimicrobial activity against the tested pathogens, thus serving as potential antimicrobial agents for several therapeutic approaches.

Screening of Brazilian basidiomycetes for antimicrobial activity

A total of 103 isolates of basidiomycetes, representing 84 species from different Brazilian ecosystems, were evaluated for their antifungal and antibacterial activity in a panel of pathogenic and non-pathogenic microorganisms. Tissue plugs of the fruiting bodies were cultivated in liquid media and the whole culture extracted with ethyl acetate. Crude extracts from Agaricus cf. nigrecentulus, Agrocybe perfecta, Climacodon pulcherrimus, Gloeoporus thelephoroides, Hexagonia hydnoides, Irpex lacteus, Leucoagaricus cf. cinereus, Marasmius cf. bellus, Marasmius sp., Nothopanus hygrophanus, Oudemansiella canarii, Pycnoporus sanguineus, Phellinus sp., and Tyromyces duracinus presented significant activity against one or more of the target microorganisms. Eight isolates were active only against bacteria while three inhibited exclusively the growth of fungi. Two extracts presented wide antimicrobial spectrum and were active against both fungi and bacteria. Differences in the bioactivity of extracts obtained from isolates from the same species were observed.

Antimicrobial activity of wax and hexane extracts from Citrus spp. peels

Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin) from C. limon.

Screening of Amazonian plants from the Adolpho Ducke forest reserve, Manaus, state of Amazonas, Brazil, for antimicrobial activity

Tropical forests are species-rich reserves for the discovery and development of antimicrobial drugs. The aim of this work is to investigate the in vitro antimicrobial potential of Amazon plants found within the National Institute on Amazon Research's Adolpho Ducke forest reserve, located in Manaus, state of Amazonas, Brazil. 75 methanol, chloroform and water extracts representing 12 plant species were tested for antimicrobial activity towards strains of Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, Streptococcus oralis, Staphylococcus aureus and Candida albicans using the gel-diffusion method. Active extracts were further evaluated to establish minimum inhibitory concentrations (MIC) and antimicrobial profiles using bioautography on normal-phase thin-layer chromatography plates. Diclinanona calycina presented extracts with good antimicrobial activity and S. oralis and M. smegmatis were the most sensitive bacteria. D. calycina and Lacmellea gracilis presented extracts with the lowest MIC (48.8 µg/ml). D. calycina methanol and chloroform leaf extracts presented the best overall antimicrobial activity. All test organisms were sensitive to D. calycina branch chloroform extract in the bioautography assay. This is the first evaluation of the biological activity of these plant species and significant in vitro antimicrobial activity was detected in extracts and components from two species, D. calycina and L. gracilis.