Wilsoniamines A and B: novel alkaloids from the temperate Australian bryozoan, Amathia wilsoni

Two novel alkaloids, wilsoniamines A and B, both possessing a hexahydropyrrolo[1,2-c]imidazol-1-one ring system that has not previously been found in nature, together with a new alkaloid, amathamide H and a known alkaloid, amathamide C were isolated from the temperate Australian bryozoan, Amathia wilsoni. MS and NMR analysis established the structure of the new compounds and indicated that the structure of amathamide C and several related compounds be revised. Amathamides C and H showed moderate anti-malarial and anti-trypanosomal activity.     

Synthesis, characterization and antibacterial properties of multifunctional hindered amine light stabilizers

A series of novel hindered amine light stabilizers containing an N-halamine moiety were designed and synthesized. Their structures were characterized by FT-IR, 1H NMR, and MS. The compounds were tested for antibacterial activity against Candida albicans, Staphylococcus aureus, and Escherichia coll. At a concentration of 0.5 mmol/L, these compounds all exhibited satisfactory antibacterial activity against all the three types of bacteria.     

Synthesis and potent antimicrobial activity of some novel N-(alkyl)-2-phenyl-1H-benzimidazole-5-carboxamidines

A series of 22 novel 1,2-disubstituted-1H-benzimidazole-N-alkylated-5- carboxamidine derivatives were synthesized and evaluated for in vitro antibacterial activity against S. aureus and methicillin resistant S. aureus (MRSA), E. coli, E. faecalis and for antifungal activity against C. albicans. Compound 59 [1-(2,4-dichlorobenzyl)-N- (2-diethylaminoethyl)-1H-benzimidazole-5-carboxamidine], with a 3,4-dichlorophenyl group at the C-2 position, displayed the greatest activity (MIC = 3.12 microg/mL against both some bacteria and the fungus C. albicans).     

New organoselenium compounds active against pathogenic bacteria, fungi and viruses

Different N-substituted benzisoselenazol-3(2H)-ones, analogues of ebselen were designed as new antiviral and antimicrobial agents. We report their synthesis, chemical properties as well as study on biological activity against broad spectrum of pathogenic microorganisms (Staphylococcus aureus, Staphylococcus simulans, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, Aspergillus niger) and viruses (herpes simplex virus type 1 (HSV-1), encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV)), in vitro. Most of them exhibited high activity against viruses (HSV-1, EMCV) and gram-positive bacteria strains (S. aureus, S. simulans), while their activity against gram-negative bacteria strains (E. coli, P. aeruginosa, K. pneumoniae) was substantially lower. Some of tested compounds were active against yeast C. albicans and filamentous fungus A. niger.     

Antifungal metabolites from Blumea balsamifera

The leaves of Blumea balsamifera afforded icthyothereol acetate, cryptomeridiol, lutein, and beta-carotene. The structures of icthyothereol acetate (1) and cryptomeridiol (2) were elucidated by extensive 1D and 2D NMR spectroscopy, while those of lutein and beta-carotene were identified by comparison with literature data. Antimicrobial tests indicated that 1 has moderate activity against the fungi Aspergillus niger, Trichophyton mentagrophytes, and Candida albicans, while 2 has low activity against A. niger, T. mentagrophytes, and C. albicans. Both compounds have no antimicrobial activity against Psuedomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Escherichia coli.     

Antimicrobial activity and pollen composition of honey samples collected from different provinces in Turkey

The antibacterial activity of honey samples from different sources were collected and investigated against Bacillus cereus, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 27736, Morganella morganii, Micrococcus luteus NRRL B-4375, Escherichia coli ATCC 35218, and Candida albicans. Pathogens exhibited different sensitivities towards the honey samples. The results showed that majority of the honey samples (75%) generally inhibitied the bacteria tested. The honey samples which were obtained from Izmir (samples 1 and 2) proved more effective as inhibitors against P. aeruginosa, E. coli, and S. aureus. The honey which was obtained from Mu?la (sample 5) exhibited high anticandidal activity on C. albicans. A comparison of the honey samples on the basis of pollen content revealed that they were heterofloral, and samples which had highest antibacterial activity against P. aeruginosa, E. coli, and S. aureus were dominated by pollen from Chenopodiaceae/Amaranthaceae (sample 1), and Trifolium, Trigonella, Cyperaceae, Zea mays and Anthemis taxa (sample 2). The honey proved more effective on bacteria than antibiotics.     

An antifungal cadinanolide from Pseudoelephantopus spicatus

A new sesquiterpene lactone was obtained from the chloroform extract of Pseudoelephantopus spicatus. Its structure was elucidated by extensive one dimentional (1D) and 2D NMR spectroscopy and mass spectrometry. It was found to exhibit moderate antifungal activity against C albicans and A. niger, and low activity against T. mentagrophytes, S. aureus, E. coli and P. aeruginosa. It was inactive against B. subtilis.     

Synthesis,antimicrobial and anti-inflammatory activities of some novel 5-substituted imidazolone analogs

In view of potent antimicrobial and anti-inflammatory activities exhibited by 5-substituted imidazolones, a variety of novel imidazolone analogs 3a-l were synthesized by the condensation of different substituted oxazolones 1 with various aromatic amines 2. All the synthesized compounds were screened for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Several analogs produced good or moderate activities particularly against the tested Gram-positive bacteria Micrococcus luteus and Gram-negative bacteria Pseudomonas aeruginosa and. Meanwhile, compounds 3b and 3c displayed marked antifungal activity against C. albicans. In addition, the in vivo anti-inflammatory activity of the synthesized compounds was determined using the carrageenin-induced paw oedema method in rats. Two of 5-substituted imidazolone derivatives, 3k and 3d show good anti-inflammatory activity. The structures of all the newly synthesized compounds were elucidated using IR, ¹H NMR and ¹³C NMR.     

Synthesis, biological and computational study of new Schiff base hydrazones bearing 3-(4-pyridine)-5-mercapto-1,2,4-triazole moiety

A series of new Schiff base hydrazones (compounds 1-16) were synthesized by condensation reaction of 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole with various aldehydes and/or dialdehydes. The structure of the prepared compounds was confirmed by means of 1H NMR, 13C NMR, UV-vis, IR and elemental analyses. The all prepared compounds were assayed for antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Candida albicans) activities by disc diffusion method. The results indicate that all tested compounds did not show any antibacterial activity against E. coli, as gram negative bacteria, and antifungal activity against C. albicans. But the compounds 2, 3, 4, 6 and 8 containing 4-Cl, 4-Me, 4-MeO, 2,4-di-Cl and 2-OH substituted phenyl moiety, respectively, showed good inhibition against S. aureus as compare to standard drugs. The structure of all biologically active compounds has also been theoretically studied by ab initio Hartree-Fock (HF) methods.     

Synthesis,antimicrobial, antiquorum-sensing and cytotoxic activities of new series of benzothiazole derivatives

New series of benzothiazole derivatives were designed and synthesized. The newly synthesized compounds were screened for their antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus cereus. Compounds 6j and 6o showed the highest activity against E. coli and S. aureus. The antifungal activity of these compounds was also tested against Candida albicans and Aspergillus fumigatus293. Compounds 4c, 4g and 6j exhibited the highest activity against C. albicans. In addition, compounds4 a and 6j displayed promising activity against A. fumigatus 293. The same compounds were examined for their antiquorum-sensing activity against Chromobacterium violaceum ATCC 12472, whereas compounds4 a, 6j and 6p showed moderate activity. The in vitro cytotoxicity testing of the synthesized compounds was performed against cervical cancer(Hela) and kidney fibroblast cancer(COS-7) cell lines. Results indicated that all tested compounds have IC50 values 50 mmol/L against both cell lines. Molecular properties, toxicities, drug-likeness, and drug score profiles of compounds 4a–c, 5a, 6g,h, 6j, 6l, 6o and7 c,d were also assessed.     

Antimicrobial terpenoids from Pterocarpus indicus

A mixture of loliolide 1 (> 85%) and paniculatadiol 2 (< 15%) was obtained from the ethyl acetate leaf extract of Pterocarpus indicus by silica gel chromatography, while the air-dried flowers afforded lupeol 3 and phytol esters 4. The structures of 1-4 were determined by NMR spectroscopy. Antimicrobial tests on a mixture of 1 and 2 indicated that it has moderate activity against Candida albicans and low activity against Pseudomonas aeruginosa, Escherichia coli, and Aspergillus niger. It was found inactive against Staphylococcus aureus, Bacillus subtilis, and Trichophyton mentagrophytes.     

Further exploration of antimicrobial ketodihydronicotinic acid derivatives by multiple parallel syntheses

A synthetic reexamination of a series of ketodihydronicotinic acid class antibacterial agents was undertaken in an attempt to improve their therapeutic potential. A convenient new synthesis was developed involving hetero Diels-Alder chemistry producing 74 new analogs in a multiple parallel synthetic manner and these were examined in vitro for their antimicrobial potential. Several compounds demonstrated significant broad-spectrum activity against clinically derived bacterial strains but previously known 1-(2,4-difluorophenyl)-6-(4-dimethylaminophenyl)-4-pyridone-3-carboxylic acid (7) remained the most potent compound in this class. Cross-resistance with ciprofloxacin supported a commonality of mode of action. Permiabilization of Escherichia coli cells by polymyxin B significantly enhanced potency with these agents suggesting that poor cellular uptake was primarily responsible for the disappointing activity against bacteria that some of the analogs exhibited.     

Secondary metabolites from Tectona philippinensis

The air-dried leaves of Tectona philippinensis, an endemic and endangered Philippine medicinal plant, afforded 5-hydroxy-3,7,4'-trimethoxyflavone (1), 5,4'-dihydroxy-3,7-dimethoxyflavone (2), squalene (3), a mixture of lupeol (4a) and beta-amyrin (4b), chlorophyllide a (5), and hydrocarbons. Antimicrobial tests on 1 and 2 indicated low antifungal activity against the fungi, Candida albicans and Trichophyton mentagrophytes. Compound 1 was also found to have low antibacterial activity against Escherichia coli and Pseudomonas aeruginosa.     

Synthesis and antimicrobial activity of some benzoxazinoids derivatives of 2-nitrophenol and 3-hydroxy-2-nitropyridine

Benzoxazinoids (BXs), alkaloids frequently found in Gramineae species, are natural defensives that can potentially be exploited to the development of novel antimicrobial agents. Here, BXs analogs were synthesized from 2-nitrophenol (benzoxazinone series) and 3-hydroxy-2-nitropyridine (pyridoxazinone series) and tested against fungal and bacteria of medical interest. The starting materials were submitted to adequate nucleophilic substitution in order to functionalize of analogs, followed by a reductive cyclization catalyzed by palladium on carbon. Next, the biological assays showed that pyridoxazinone serie has a good antibacterial activity, especially against Enterococcus faecalis (Minimum inhibitory concentration—MIC: 7.8-15.6?μg.mL^?1) and Acinetobacter baumannii (MIC 31.25-125?μg.mL^?1). Antifungal activity, in turn, was related to compound 2e which showed a MIC of 62.5?μg.mL^?1 against Candida albicans, Candida glabrata, and Candida tropicalis. All analogs complied with Lipinski's rules and were predicted to have a low toxicity.     

Quorum sensing in Candida albicans: probing farnesol's mode of action with 40 natural and synthetic farnesol analogs

The dimorphic fungus Candida albicans produces extracellular farnesol (3,7,11-trimethyl-2,6,10-dodecatriene-1-ol) which acts as a quorum-sensing molecule (QSM) to suppress filamentation. Of four possible geometric isomers of farnesol, only the E,E isomer possesses QSM activity. We tested 40 natural and synthetic analogs of farnesol for their activity in an N-acetylglucosamine-induced differentiation assay for germ tube formation (GTF). Modified structural features include the head group, chain length, presence or absence of the three double bonds, substitution of a backbone carbon by S, O, N, and Se heteroatoms, presence or absence of a 3-methyl branch, and the bulkiness of the hydrophobic tail. Of the 40 compounds, 22 showed QSM activity by their ability to reduce GTF by 50%. However, even the most active of the analogs tested had only 7.3% of the activity of E,E-farnesol. Structure-activity relationships were examined in terms of the likely presence in C. albicans of a farnesol binding receptor protein.     

Study on the synthesis and antimicrobial activity of novel cationic porphyrins

A novel series of quaternary ammonium cationic derivatives based on tetrapyridyl-porphyrin was synthesized.All the compounds were evaluated for their in vitro antibacterial activities against S.aureus,E.coli and P.aeruginosa,and antifungal activities against C.albicans,where microorganisms were exposed and unexposed to the irradiation.The results revealed that some of these compounds,especially,3a and 4a displayed satisfactory antibacterial activity against Gram-positive bacteria S.aureus and moderate an...     

Antimicrobial activities of single aroma compounds

Commercially available aroma samples were evaluated for their olfactory quality by professional perfumers and tested for their antimicrobial activity. Agar diffusion and agar-dilution were used as test methods and a set of two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and four Gram-negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris G, Klebsiella pneumoniae and Salmonella abony) and a yeast, Candida albicans, were the test microorganisms. All the investigated compounds were active against Gram-positive bacteria, especially beta-caryophyllene against Enterococcus faecalis (MIC 6 ppm), but only few substances showed activity towards Gram-negative bacteria, except for cinnamic acid, which was active against all (MIC 60 ppm) and Candida albicans, against which cinnamic acid and caryophyllene oxide showed high activity (MIC < 60 ppm).     

Synthesis and in vitro antimicrobial screening of new pyrano[4,3-b]pyrane derivatives of 1H-pyrazole

A new series of pyrano[4,3-b]pyrane 4a-l bearing 1H-pyrazole has been synthesized by one pot base catalyzed cyclocondensation reaction of 1H-pyrazole-4-carbaldehyde la-1,malononitrile 2 and 4-hydroxy-6-methylpyrone 3.All the synthesized compounds were screened against six bacterial pathogens,namely B.subtilis,C.tetani,S.pneumoniae,S.typhi,V.cholerae, E.coli and antifungal activity against,two fungal pathogens,A.fumigatus and C.albicans using broth microdilution MIC method. Some of the compounds are found to be equipotent or more potent than that of commercial drugs,against most of employed strains.     

Synthesis and biological activity of peptide derivatives of iodoquinazolinones/nitroimidazoles

Two substituted quinazolinyl/imidazolyl-salicylic acids 5, 6 were synthesized by the reaction of 6-iodo-2-methylbenzoxazin-4-one/5-nitroimidazole with 5-aminosalicylic acid (5-ASA). Coupling of compounds 5 and 6 with different amino acid ester hydrochlorides, dipeptide and tripeptide methyl esters yielded novel quinazolino/imidazolopeptide derivatives 5a-f and 6a-g. The chemical structures of all newly synthesized compounds were confirmed by means of FT-IR, (1)H- and (13)C-NMR, MSand elemental analysis. Selected peptide ester derivatives were further hydrolyzed by using lithium hydroxide (LiOH) to afford the corresponding acid derivatives 5ba-da and 6e(a)-g(a). All peptide derivatives were assayed for antimicrobial and anthelmintic activities against eight pathogenic microbes and three earthworm species. Among the tested compounds, 5e,5d, 6e and their hydrolyzed analogs 5d(a) and 6e(a) exhibited higher antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans, and 5(a),6g and 6g(a) displayed better antifungal activity against the dermatophytes Trichophyton mentagrophytes and Microsporum audouinii. Moreover, 6f and its hydrolyzed derivative6f(a) showed good anthelmintic activity against Megascoplex konkanensis, Pontoscotex corethruses and Eudrilus eugeniea at dose of 2 mg mL(-1).     

A New Sphingolipid and Furanocoumarins with Antimicrobial Activity from <i>Ficus exasperata</i>

From the methanol extract of the stem bark of Ficus exasperata, a new sphingolipid named Ficusamide, (2S,3S,4R,11E)-2-[(2',3'-dihydroxyhexacosanoylamino)]-11-octadecene-1,3,4-triol (1), along with three known furanocoumarins, (S)-(－) oxypeucedanin hydrate (2), (R)-(+) oxypeucedanin hydrate (3), bergapten (5-methoxypsoralen) and six other known compounds, were isolated. Their structures were characterized basing on spectroscopic methods and chemical evidence. Compounds (1-3) were analyzed for their antimicrobial activity. Ficusamide (1) showed wick activity (minimal inhibitory concentration (MIC)=312.5?μg/mL) against Escherichia coli, while the furanocoumarins (2) and (3) showed significant activity (MIC=9.76?μg/mL) against Bacillus cereus, Candida albicans and Microsporum audouinii.