Semisynthesis and antimicrobial activity of novel guttiferone-A derivatives

Six derivatives of guttiferone-A (LFQM-79, 80, 81, 82, 113 and 114) were synthesized and evaluated for their antimicrobial activity against the opportunistic or pathogenic fungi Candida albicans (ATCC 09548), Candida glabrata (ATCC 90030), Candida krusei (ATCC 6258), Candida parapsilosis (ATCC 69548), Candida tropicalis (ATCC 750), Cryptococcus neoformans (ATCC 90012), Trichophyton tonsurans, Microsporum gypseum and also against the opportunistic and pathogenic Gram-positive bacteria Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Bacillus cereus (ATCC 11778) and Gram-negative Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 9027), Salmonella typhimurium (ATCC 14028), Proteus mirabilis (ATCC 25933). The antimicrobial activities of derivatives were compared with guttiferone-A and they presented to be more potent than the original molecule and sometimes greater than standard drugs established in therapeutics. The current study showed that derivatives of guttiferone-A possess potent antimicrobial activity and are relatively non-cytotoxic, which reveal these new molecules as promising new drug prototype candidates, with innovative structural pattern.     

Synthesis of egonol derivatives and their antimicrobial activities

Eighteen derivatives of egonol (A-R) were synthesized and evaluated for their antimicrobial activities against Staphylococcus aureus ATCC 29213, Bacillus subtilis ATCC 6633, Candida albicans ATCC 10231 and Escherichia coli ATCC 8739 microorganisms comparing with egonol. The obtained data reported that compound B exhibited improved activities against all tested bacteria than egonol, others have shown different range of activities.     

Studies on antimicrobial activity, in vitro, of Physalis angulata L. (Solanaceae) fraction and physalin B bringing out the importance of assay determination

Complex physalin metabolites present in the capsules of the fruit of Physalis angulata L. have been isolated and submitted to a series of assays of antimicrobial activity against Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, Neisseria gonorrhoeae ATCC 49226, Escherichia coli ATCC 8739; E. coli ATCC 25922, Candida albicans ATCC 10231 applying different methodologies such as: bioautography, dilution broth, dilution agar, and agar diffusion techniques. A mixture of physalins (pool) containing physalins B, D, F, G inhibit S. aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, and N. gonorrhoeae ATCC 49226 at a concentration of 200 mg/microl, using agar dilution assays. The mixture was inactive against P. aeruginosa ATCC27853, E. coli ATCC 8739; E. coli ATCC 25922, C. albicans ATCC 10231 when applying bioautography assays. Physalin B (200 microg/ml) by the agar diffusion assay inhibited S. aureus ATCC 6538P by +/- 85%; and may be considered responsible for the antimicrobial activity.     

Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives

The in vitro antibacterial and antifungal activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated. The in vitro antimicrobial activities were screened against the standard strains: Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 as Gram positive, Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230 and Klebsiella pneumoniae as Gram negative, and Candida albicans as yeast-like fungus. Compounds (3, 5, 6, 7) inhibited the growth of all the test strains at MIC values of 32-512 microg/ml. None of the four compounds (1, 2,4,8) studied showed antimicrobial activity against any of the test strains within the MIC range 0.25-512 micro/ml.     

Synthesis, characterization and antimicrobial activity of new aliphatic sulfonamide

A series of novel aliphatic sulfonamide derivatives (1-7) were synthesized and characterized by elemental analyses, FT-IR, (1)H NMR, (13)C NMR and LC-MS techniques. All the synthesized compounds were evaluated in vitro as antimicrobial agents against representative strains of Gram-positive (Staphylococcus aureus ATCC 25953, Bacillus cereus ATCC 6633 and Listeria monocytogenes ATCC Li6 (isolate), Gram-negative bacteria (Escherichia coli ATCC 11230) and antifungal agent against Candida albicans (clinical isolate) by both disc diffusion and minimal inhibition concentration (MIC) methods. All these bacteria and fungus studied were screened against some antibiotics to compare with our chemicals' zone diameters. Our aliphatic sulfonamides have highest powerful antibacterial activity for Gram-negative bacteria than Gram-positive bacteria and antibacterial activity decreases as the length of the carbon chain increases.     

Antimicrobial activity of 2,5-dihydroxy-3-methyl-1,4-benzoquinone from Embelia schimperi

Chromatographic separation of an ethyl acetate extract from Embelia schimperi led to the isolation of a new compound identified as 2,5-dihydroxy-3-methyl-1,4-benzoquinone (1) on the basis of spectroscopic and physical data. The plant's crude extract and pure compound 1 were assayed for in vitro antimicrobial activity against clinical strains of Salmonella spp., Proteus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Cryptococcus neoformans, Shigella dysentriae and Staphylococcus aureus. Disc diffusion method was used and zones of inhibition, after respective incubation periods, were used to quantify antimicrobial activity. Standard antibiotics namely: augmentin, cotrimoxazole, gentamycin, tetracycline and lyncomycin were used as controls. The crude extract was inactive while the pure compound 1 showed significant activities against Salmonella spp., Proteus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Cryptococcus neoformans, Shigella dysentriae and Staphylococcus aureus with zones of inhibition ranging from 10-20 mm. The most sensitive microorganism was P aeruginosa while C. neoformans was insensitive to both the crude extract and compound 1.     

Synthesis, structure and biological activity of cobalt(II) and copper(II) complexes of valine-derived schiff bases

We have synthesized two cobalt(II) 2 and copper(II) 3 complexes of valine-derived Schiff bases. The obtained complexes were characterized by elemental analysis, FT-IR and X-ray diffraction. Biological studies of complexes 2 and 3 had been carried out in vitro for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi. Compound 3 was proven to be a broad spectrum agent, showed a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodothece glutinis, Saccharomyces cerevisia, Aspergillus spp., Rhizopus nigricans) tested and a moderate activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Enterobacter aerogenes) tested. The in vitro cytotoxicity of compound 3 was evaluated using hemolytic assay, in which the compound 3 was found to be non-toxic to human erythrocytes even at a concentration of 500mug/mL.     

Synthesis of pseudopeptides based L-tryptophan as a potential antimicrobial agent

Four compounds named L-BTrpPA, L-Trp-o-PA, L-Trp-m-PA and L-Trp-p-PA, pseudopeptides constructed from pyridine and tryptophan units, were synthesized and tested against the Gram-positive, Gram-negative strains of bacteria and human pathogenic fungi. L-Trp-o-PA proved to be a broad-spectrum antimicrobial agent, showing a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodotorula glutinis, Saccharomyces cerevisiae, Aspergillus spp., Rhizopus nigricans) tested and activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris, Enterobacter aerogenes) tested. The in vitro cell cytotoxicity of L-Trp-o-PA was evaluated using haemolytic assay, in which the compound was found to have low lytic property, even up to the concentration of 4000 microg/mL, it only lysed 6-7% of erythrocytes, which was 100-fold greater than the MICs (minimum inhibitory concentration).     

Antimicrobial action of Lentinus edodes juice on human microflora

The action of the juice of Shiitake mushroom (L. edodes) on pathogenic and opportunistic microorganisms, detected in cases of considerable dysbiotic changes (Escherichia coli O-114, Staphylococcus aureus, Enterococcus faecalis, Candida albicans), as well as on some bacterial eubiotic producer strains (Escherichia coli M-17, Bifidobacterium spp., Lactobacillus spp.). The juice of this mushroom at a concentration of 5% from the volume of the nutrient medium was found to produce a pronounced antimicrobial effect with respect to C. albicans, S. aureus, E. faecalis, E. coli O-114 and to stimulate the growth of E. coli M-17. Bifidobacteria and lactobacteria exhibited resistance to the action of L. edodes juice.     

Antimicrobial activity of invertebrate-pathogenic fungi in the genera Akanthomyces and Gibellula

Infectious disease caused by antibiotic resistant microorganisms is a global public health problem. There is a need to search for new bioactive compounds from new sources. In this study, we focused on invertebrate-pathogenic fungi infecting spiders. One hundred and sixty-five crude extracts from Akanthomyces (n = 45) and Gibellula (n = 10) were screened for their antimicrobial activity against nine human pathogens. Twenty-one extracts out of 165 (12.73%) from 16 (29.09%) isolates exhibited antimicrobial activity against at least one test strain. The most activity was against Staphylococcus aureus American Type Culture Collection (ATCC 25923) (8.48%) followed by Cryptococcus neoformans ATCC 90112 (3.03%), C. neoformans ATCC 90113 (2.42%), methicillin-resistant Staphylococcus aureus (MRSA) SK-1 (2.42%), Penicillium marneffei (2.42%), Microsporum gypseum (1.21%), Candida albicans ATCC 90028 (1.21%), Pseudomonas aeruginosa ATCC 27853 (0.61%) and Escherichia coli ATCC 25922 (0.61%), respectively. The ethyl acetate extract of mycelia from Gibellula pulchra EPF083 had the strongest broad spectrum antimicrobial activity with a minimum inhibitory concentration (MIC) value of 16 μg/ml against S. aureus ATCC 25923, MRSA SK-1, C. neoformans (ATCC 90112 and ATCC 90113) and P. marneffei and exhibited fungicidal activity against C. neoformans ATCC 90112 and P. marneffei with minimum fungicidal concentration (MFC) values of 16 and 32 μg/ml, respectively. These preliminary data show that invertebrate-pathogenic fungi could be a potential source of antimicrobial agents.     

Essential oil analysis and antimicrobial activity of eight Stachys species from Greece

The volatile composition of eight Stachys species has been studied. The investigated taxa were St. alopecuros (L.) Bentham., St. scardica (Griseb.) Hayek, St. cretica L. ssp. cretica, St. germanica L. ssp. heldreichii (Boiss.) Hayek, St. recta L., St. spinulosa L., St. euboica Rech. and St. menthifolia Vis., growing wild in Greece. The essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus, and their analyses were performed by GC and GC-MS. Identification of the substances was made by comparison of mass spectra and retention indices with literature records. Sesquiterpene hydrocarbons were shown to be the main group of constituents of all taxa. Furthermore, the obtained essential oils were tested against the following six bacteria: Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35210), Bacillus subtilis (ATCC 10907), Bacillus cereus (clinical isolates), Micrococcus flavus (ATCC 10240), Staphylococcus epidermidis (ATCC 2228), as well as against the following five fungi: Aspergillus niger (ATCC 6275), Penicillium ochrochloron (ATCC 9112), Epidermophyton floccosum (clinical isolates), Candida albicans (clinical isolates) and Trichophyton mentagrophytes (clinical isolates). The tested essential oils showed better activity against bacterial species than against fungi. Pseudomonas aeruginosa was the most resistant strain, as none of the essential oils was active against this strain. The essential oil of St. scardica has been proven most active against both bacteria and fungi.     

Modification of lysozyme with oleoyl chloride for broadening the antimicrobial specificity

Lysozyme from egg white was modified by covalent attachment of an oleyl group to the free amino groups of lysozyme. The aim of the chemical modification was to develop an effective antimicrobial lysozyme derivative against both gram-negative and gram-positive bacteria. Lysozyme with various degrees of modification was obtained by changing oleoyl chloride/lysozyme mass ratio. Lysozyme derivatives evidently exhibited an antimicrobial effect against Escherichia coli (ATCC 29998). The modification slightly changed the antimicrobial effect of lysozyme derivative against Staphylococcus aureus (ATCC 121002). Since there was a positive correlation between the modification degree and the antimicrobial effect against E. coli, it was concluded that the change in antimicrobial behavior was due to an increase in hydrophobicity of the enzyme molecule enabling it to penetrate through the bacterial membrane of E. coli. It was also shown that oleoyl chloride with an MIC value of 10?mg/mL was effective against both E. coli and S. aureus.     

Egyptian propolis: 1-antimicrobial activity and chemical composition of Upper Egypt propolis

The antimicrobial activity of four propolis samples collected from Upper Egypt against Staphylococcus aureus; Escherichia coli and Candida albicans was evaluated. There was a variation in the antimicrobial activity according to the propolis origin. Banisweif propolis showed the highest antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans, but Fayoum propolis had moderate activity against all tested pathogens. Propolis collected from Assiut and Souhag gave lower antimicrobial activity. Propolis samples were investigated by GC/MS, 71 compounds were identified, 14 being new for propolis. Banisweif propolis is characterized by the presence of 7 caffeate esters and 4 triterpenoids. Fayoum propolis showed the highest amount of lactic acid and the presence of 3 chalcones. But Assiut propolis is characterized by the presence of 4 prenylated coumarates. Souhag propolis is characterized by the presence of 5 aliphatic dicarboxylic acids and some other new compounds to propolis.     

In vitro assay of the antimicrobial activity of kephir against bacterial and fungal strains

Kephir is a fermented carbonated refreshing milk, with a slightly acidic aromatic taste and creamy foam composition which contains lactobacilli, leuconostocci, acetic acid bacteria, lactostreptococci and yeasts. Recent studies have demonstrated its antibacterial, immunostimulating, antitumoral and cholesterol-lowering activities.

Purpose

The purpose of this study was to investigate the antimicrobial activity of kephir against Bacillus subtilis spp. spizizenii ATCC 6633, Staphylococcus aureus ATCC 6538, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 8739, Salmonella enteritidis ATCC 13076, Pseudomonas aeruginosa ATCC 9027 and Candida albicans ATCC 10231. The kephir fermented for 24 h and 48 h, as well and after 7 days preservation at 4–8 °C was tested by in vitro disk diffusion method. The intensity of the antimicrobial activity was interpreted by comparison with two antibiotics, i.e. ampicillin and neomycin.

Results

The antimicrobial activity of 24 h as well as 48 fermented kephir, fresh or after 7 days preservation at 4–8 °C was similar and observed against B. subtilis, S. aureus, E. coli, E. faecalis and S. enteritidis. For E. coli, E. faecalis and S. enteritidis the antimicrobial activity was superior to both tested antibiotics and for B. subtilis and S. aureus to one antibiotic. The tested products exhibited no activity against P. aeruginosa and C. albicans.

Conclusion

Kephir is exhibiting large spectrum and strong antibacterial activity probably due to the complex viable probiotic strains association producing antimicrobial substances.     

Synthesis and antimicrobial studies of novel 1-benzhydryl-piperazine sulfonamide and carboxamide derivatives

A series of novel substituted 1-benzhydryl-piperazine sulfonamide 8(a-f) and benzamides 9(a-h) were synthesized and their antimicrobial activities evaluated in vitro by paper disc diffusion and micro dilution method against standard strains of Gram-positive (Staphylococcus aureus ATCC 25953, Staphylococcus epidermis 25212, Bacillus cereus 11778, Bacillus substilis 6051) and Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2853, Proteus vulgaris ATCC 2853 and Salmonella typhi ATCC 9484) bacteria. Among the synthesized new compounds 8d, 8e, 9c, 9e, 9f and 9 h showed potent antimicrobial activities compared to the standard drug streptomycin.     

The Diversity and Antimicrobial Activity of Preussia sp. Endophytes Isolated from Australian Dry Rainforests

Limited knowledge currently exists regarding species diversity and antimicrobial activity of endophytic isolates of Preussia within Australia. This report describes endophytic Preussia species that were identified through molecular analysis of the internal transcribed spacer region. Screening for antimicrobial secondary metabolites was determined by testing crude ethyl acetate (EtOAc) extracts derived from fungal mycelia against a panel of ATCC type strains which included Bacillus cereus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Serratia marcescens, methicillin-resistant Staphylococcus aureus (MRSA) and the opportunist yeast pathogen Candida albicans. Subsequently, high-performance liquid chromatography generated fractions of bioactive EtOAc extracts which were subject to confirmatory testing using the Clinical and Laboratory Standards Institute reference microdilution antimicrobial activity assay. A total of 18 Preussia were isolated from nine host plants with 6/18 having a <97 % sequence similarity to other known species in Genbank, suggesting that they are new species. In preliminary screening, 13/18 Preussia isolates revealed antimicrobial activity against at least one of the microbes tested, whilst 6/18 isolates, including 4/6 putative new species showed specific antimicrobial activity against MRSA and C. albicans. These results highlight the antimicrobial potential of Australian Preussia spp. and also the importance of Australian dry rainforests as an untapped repository of potentially significant bioactive compounds.     

Synthetic analogs of anoplin show improved antimicrobial activities

We present the antimicrobial and hemolytic activities of the decapeptide anoplin and 19 analogs thereof tested against methicillin‐resistant Staphylococcus aureus ATCC 33591 (MRSA), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), vancomycin‐resistant Enterococcus faecium (ATCC 700221) (VRE), and Candida albicans (ATCC 200955). The anoplin analogs contain substitutions in amino acid positions 2, 3, 5, 6, 8, 9, and 10. We use these peptides to study the effect of altering the charge and hydrophobicity of anoplin on activity against red blood cells and microorganisms. We find that increasing the charge and/or hydrophobicity improves antimicrobial activity and increases hemolytic activity. For each strain tested, we identify at least six anoplin analogs with an improved therapeutic index compared with anoplin, the only exception being Enterococcus faecium, against which only few compounds are more specific than anoplin. Both 2Nal⁶ and Cha⁶ show improved therapeutic index against all strains tested. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Derivatization does not influence antimicrobial and antifungal activities of applanoxidic acids and sterols from Ganoderma spp

Applanoxidic acids and sterols, isolated from Ganoderma spp., were acetylated and/or methylated. The antibacterial activity against Escherichia coli and Staphylococcus aureus and the antifungal activity against Candida albicans and Trichophyton mentagrophytes of the derivatives were investigated by a microdilution method, and compared with those of the natural products. Both natural and modified compounds exhibited comparable antibacterial and antifungal activities in a range of 1.0 to > 2.0 mg/ml minimal inhibitory concentration.     

Lactic acid bacteria from healthy oral cavity of Thai volunteers: inhibition of oral pathogens

The aims of the present study were to screen and characterize the antimicrobial lactic acid bacteria which were isolated from healthy oral cavities of Thai volunteers, and to characterize their inhibiting substances. Among 3790 isolates (suspected to be lactic acid bacteria) from 130 volunteers, five showed an appreciable effect against Sarcina lutea ATCC 9341, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Streptococcus mutans DTMU 1, Strep. salivarius DTMU 1, Strep. sanguis DTMU 1, Candida albicans ATCC 13803 and C. albicans DTMU 2, as well as the oral pathogens. These antimicrobial isolates included L17 and N14 which showed the antibacterial activity, D14 which showed the anticandidal activity, and D6 and N8 which showed both the antibacterial and anticandidal activities. The isolates were later found to be facultative anaerobic, Gram-positive, non-spore-forming, non-capsule-forming and catalase-negative bacilli. They could utilize casein but could not hydrolyse starch, and they produced hydrogen peroxide and bacteriocins. Their antimicrobial potentials were found to be affected by pH, catalase, proteolytic enzymes and temperature. The activity was partially inactivated after catalase treatment, significantly declined at pH > or =9.0 or after trypsin and pepsin treatments, and also reduced after heating at > or =100 degrees C. However, the antimicrobial activity of these five isolates was somewhat resistant to heat. When the isolates were tested for their antimicrobial sensitivity, they were shown to be sensitive to a number of antimicrobial agents. The final identification revealed that D6, D14 and N14 were Lactobacillus paracasei subsp. paracasei, and L17 and N8 were Lact. rhamnosus.     

Antimicrobial and antiviral screening of novel indole carboxamide and propanamide derivatives

A few series of indole derivatives were screened for antimicrobial, antifungal and anti-HBV activities. The compounds were tested for their in vitro antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and for their antifungal activity against Candida albicans using a disc diffusion method, which measures the diameter of the inhibition zone around a paper disc soaked in a solution of the test compounds. The antimicrobial activity results showed that all compounds are as a active as the standard compound ampicillin against Staphylococcus aureus. It was also found that indole carboxamide derivatives, substituted at 3-position with several benzyl groups, showed better inhibition of Bacillus subtilis than their congeners substituted at 2-position. Activity patterns of the compounds against Escherichia coli and Staphylococcus aureus were found slightly different by the same method. In this case, there was no correlation between structure and activity of the compounds. The antifungal activity of carboxamide derivatives was found higher compared to that of the propanamide derivatives. The minimum inhibitory concentration (MIC) values of some indole derivatives were also determined by the tube dilution technique. The MIC values of the compounds were found nearly 20- to 100-fold smaller compared to the standard compounds ciprofloxacin and ampicillin (1.56-3.13 microg/ml and 1.56-12.5 microg/ml, respectively) against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The MIC values of the tested compounds showed that these are better inhibitors for Candida albicans. Indole derivatives were screened by the anti-HBV susceptibility test. No compound showed good inhibition against the HBV virus.