Showing papers on "Antibacterial activity published in 1998"

Influence of Powder Characteristic of ZnO on Antibacterial Activity

Abstract: The effects of shape, crystallinity and specific surface area of ZnO powder on antibacterial activity were studied by measuring the change in the electrical conductivity with bacterial growth. From the results, it was clarified that the antibacterial activity increased with the increase of powder concentration in the physiological saline. The antibacterial activity against Escherichia coli strongly depended on the specific surface area of the powder; the activity increased with the increase of the surface area, irrespective of the shape and the crystallinity of their powders. In the case of Staphylococcus aureus, however, it was found that there was no difference in the activity according to the characteristic of the powders. The appearance of antibacterial activity was found to be due to the generation of H2O2 from the surface of ZnO powder.

Synthesis and microbiological activity of some novel 5- or 6-methyl-2-(2,4-disubstituted phenyl) benzoxazole derivatives

Abstract: The synthesis of a new series of 5- or 6-methyl-2-(2,4-disubstituted phenyl)benzoxazoles (4, 5) is described in order to determine their antimicrobial activities and feasible structure-activity relationships. The synthesized compounds were tested in vitro against three Gram-positive bacteria, three Gram-negative bacteria and the yeast Candida albicans, in comparison with several control drugs. Microbiological results exhibited that the synthesized compounds possess a broad spectrum of antibacterial activity against the tested microorganisms. The compounds 4b and 4c indicated some antibacterial activity against Staphylococcus aureus having a minimum inhibitory concentration (MIC) of 12.5 μg/ml. Moreover, the compound 5a revealed a significant antibacterial activity against the enterobacter Pseudomonas aeruginosa showing a MIC value of 25 μg/ml, i.e. more potent than the control drugs tetracycline and streptomycin. For the antimycotic activity against the yeast C. albicans, the derivative 4c was found to be more active than the other synthesized compounds with a MIC value of 12.5 μg/ml, but one-fold less potent than the control drugs oxiconazole and haloprogin.

SYNTHESIS AND ANTIBACTERIAL PROPERTIES OF NEW DITHIENYL CONTAINING PYRAN, PYRANO[2,3-b] PYRIDINE, PYRANO[2,3-d]PYRIMIDINE AND PYRIDINE DERIVATIVES

Abstract: Some new pyran 3,8; pyrano[2,3-b]pyridine 4; pyrano[2,3-d] pyrimidine 5,6,7 and 9; pyridine 10–14 derivatives have been prepared. The structure of all the new compounds have been established on the basis of elemental analyses and spectroscopic data. All the synthesized compounds have been screened for their antibacterial activity. Pyranopyrimidinethione 7 and pyridinethione 10 exhibited a good antibacterial activity compared with the standard antibiotic Gentamycin.

Antibacterial temporary filling materials: the effect of adding various ratios of Ag-Zn-Zeolite

Abstract: The effect of a new type of antibacterial temporary filling material was evaluated. Ag-Zn-Zeolite (Bactekiller, Kanebo, Japan) and SiO2 filler were incorporated into urethane acrylate monomer paste in amounts of 5/55, 10/50, 20/40 and 30/30 wt%, respectively. The present study was designed to use a dye penetration test to measure direct inhibition of bacterial growth of four oral bacteria (Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Streptococcus sanguis). The amounts of silver and zinc ions released from these materials were measured by atomic absorption spectrophotometry. The results indicated that the occurrence of marginal leakage was low in all of these materials. These materials exhibited prominent in-vitro antibacterial activity against S. mutans and S. mitis. The Ag-Zn-Zeolite in these materials was able to release very small but detectable amounts of Ag and Zn even 4 weeks after the immersion started. The larger the amounts of Ag-Zn-Zeolite that were incorporated, the greater the release of silver and zinc. However, it appears that increasing antibacterial activity is not promoted by the higher ratio of Ag-Zn-Zeolite.

Structure-activity relationships of protoberberines having antimicrobial activity.

Abstract: 13-Alkyl derivatives (2-6 and 8-12) of berberine (1) and palmatine (7) were subjected to in vitro antibacterial activity tests against Bacillus subtilis and Salmonella enteritidis. Antibacterial activity increased as the length of the C-13 aliphatic side chain increased. The effects of the oxygen-substituents on aromatic rings A, C, and D of protoberberinium salts 13-20 on the antimicrobial activity against Staphylococcus aureus, B. subtilis, S. enteritidis, Escherichia coli, and Candida albicans are also discussed. The change in lipophilicity of the protoberberinium salts caused by modification of the substituents appears to influence the antibacterial activity. 13-Hexylberberine (6) and 13-hexylpalmatine (12) exhibited the greatest antibacterial activity.

Antimicrobial activity of 8-alkyl- and 8-phenyl-substituted berberines and their 12-bromo derivatives

Abstract: The 8-alkyl- (3−6), 8-phenyl- (7), 12-bromo- (8), 8-alkyl-12-bromo- (9−12), and 12-bromo-8-phenyl- (13) berberine derivatives were prepared and tested for their antimicrobial activity in vitro to evaluate structure−activity relationships. Introduction of the alkyl or phenyl group and the bromine atom into the C-8 and C-12 positions of berberine (1), respectively, led to significant increases of the antimicrobial activity. In both the 8-alkyl- and 8-alkyl-12-bromo-berberines (3−6 and 9−12, respectively), the antibacterial activity increased as the length of the aliphatic chain increased. The exception was the activity against Candida albicans and Escherichia coli, which did not always increase as the alkyl side chain lengthened. Among the compounds tested, 12-bromo-8-n-hexylberberine (12) was 64, 256, 128, 16, and 32 times more active against Staphylococcus aureus, Bacillus subtilis, Salmonella enteritidis, E. coli, and C. albicans, respectively, in comparison to the clinically used berberine. Compound 12 ...

Study of pyridinium‐type functional polymers. II. Antibacterial activity of soluble pyridinium‐type polymers

Abstract: The antibacterial activity of a series of soluble pyridinium-type polymers with different compositions against Escherichia coli (E. coli) suspended in sterilized distilled water was investigated by a colony count method. The results show that the antibacterial activity of the soluble pyridinium-type polymers is characterized by their activity to kill bacterial cells and this activity can be enhanced as the content of the pyridinium group (Cq) in the polymers increases. The species of the bacteria has a great influence upon the antibacterial activity of the soluble pyridinium-type polymers. The polymers possess a strong ability to kill Gram-positive and Gram-negative bacteria, and yeasts, excepting Bacillus subtilis, having gemmae and fungi. The toxicity of this kind of polymer has also been appraised. In the acute stimulation and allergy experiments, the red maculae, edema, and abnormal phenomena of an allergy on the skin of the tested animals were not observed. The acute toxicity experiment shows that the LD50 of the polymer is 2330 mg/kg, implying that this kind of polymer has only very weak toxicity. This is significant for the application of soluble pyridinium-type polymers. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1761–1768, 1998

Antibacterial composition and antibacterial laminate

Abstract: Since an inorganic and/or organic antibacterial agent and a hydrophilic substance are used in combination in this invention to produce an antibacterial composition, the intrinsic antibacterial activity of the inorganic or organic antibacterial agent is markedly increased, so that the antibacterial agent used even in a low concentration shows a high antibacterial activity. High antibacterial moldings can be obtained at a relatively low cost by laminating the antibacterial composition of the invention on an inorganic or organic substrate.

Antibacterial activity of marine-derived fungi.

Abstract: A total of 227 marine isolates of ubiqituous fungi were cultivated on different media and the secondary metabolite content of the extracts (ethyl acetate/chloroform/methanol 3 : 2 : 1) characterized by HPLC. The fungi were secured from animals, plants and sediments of Venezuelan waters (0–10 m) including mangroves and lagoonal areas. The extracts were tested for antibacterial activity. A total of 7 were active towards Vibrio parahaemolyticus and 55 towards Staphylococcus aureus, representing 18 different fungal species from 8 ascomycetous genera. For 61 strains of Penicillium citrinum antibacterial activity correlated well with content of secondary metabolites as measured by HPLC. Thirteen isolates of Penicillium steckii produced very similar profiles of secondary metabolites and 6 of these had activity against either V. parahaemolyticus or S. aureus or both.

6-Methylsulfinylhexyl Isothiocyanate and Its Homologues as Food-originated Compounds with Antibacterial Activity against Escherichia coli and Staphylococcus aureus

Abstract: Cruciferae plants, banana and coriander each showed antibacterial activity. The highest activity among the foodstuffs tested was found in the stems of wasabi. An ethereal extract from wasabi stems had potent antibacterial activity and we isolated the active compound from the extract. Instrumental analysis identified the compound as 6-methylsulfinylhexyl isothiocyanate. Some homologues of 6-methylsulfinylhexyl isothiocyanate were also active against Escherichia coli and Staphylococcus aureus.

Comparative antibacterial effects of novel Pelargonium essential oils and solvent extracts

Abstract: The scented leaves of a number of Pelargonium (Geraniaceae) species and cultivars were extracted using steam distillation, petroleum spirit and methanol. The extracts were assessed for their antibacterial activity in vitro against Staphylococcus aureus, Proteus vulgaris, Bacillus cereus and Staph. epidermidis. The results indicated substantial antibacterial activity and suggested that Pelargonium essential oils could be used as novel antibacterial agents. The methanolic and petroleum spirit extracts were more potent antibacterial agents than the steam-distilled volatile samples. The results suggest that Pelargonium essential oils and solvent extracts could be used as novel food or cosmetic antimicrobial agents.

4-Hydroxy-3-nitrophenylacetic and Sinapic Acids as Antibacterial Compounds from Mustard Seeds.

Abstract: A methanol extract from yellow mustard seeds had antibacterial activity against Escherichia coli, Salmonella enteritidis, and Staphylococcus aureus. Two compounds with such activity were isolated from the extract. By instrumental analysis, the compounds were identified as 4-hydroxy-3-nitrophenylacetic and sinapic acids. Examination of the structure-activity relationship showed that the hydroxyl and nitro groups of the first compound were involved in the activity against all three species. The two methoxyl groups and the hydroxyl group in sinapic acid were effective against E. coli and all of the substituents of the benzene ring were effective against S. enteritidis. The presence of the propenoic group of the second compound was effective against S. aureus.

Anhydrolide macrolides. 1. Synthesis and antibacterial activity of 2,3-anhydro-6-O-methyl 11,12-carbamate erythromycin A analogues.

Abstract: A series of 3-descladinosyl-2,3-anhydro-6-O-methylerythromycin A 11,12-carbamate analogues have been synthesized and evaluated for antibacterial activity. These compounds were found to be potent antibacterial agents against Gram-positive organisms in vitro, many having MIC values below 1 μg/mL for the macrolide-susceptible Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae, as well as improved activity compared to erythromycin A against the inducibly MLS (macrolide, lincosamide, and streptogramin B)-resistant organisms. Structure−activity studies revealed that arylalkyl carbamates with two and four carbon atoms between the aromatic moiety and carbamate nitrogen have the best in vitro activity. All of the C-10 epi analogues evaluated were found to have substantially less activity than the corresponding natural C-10 isomer. Several analogues demonstrated moderate antibacterial activity against the constitutively resistant S. aureus A-5278, S. pneumoniae 5979, and S. pyogenes 930. Ho...

Antibacterial activity of medicinal plants from the philippines

Abstract: Aqueous extracts of 36 plant species were screened for antibacterial activity against Erwinia carotovora pv carotovora, Xanthomonas camprestris pv capestris and Pseudomonas solanacearum. Twenty-one of the plant species showed antibacterial activity, with Allium cepa, A. porrum, A. sativum, Euphorbia tirucalli, and Piper betel being active against all test pathogens.

Isolation and characterization of a new pyrano[4',3':6,7]naphtho[1,2-b]xanthene antibiotic FD-594.

Abstract: During our screening of microbial metabolites for effective drugs against tumor cell lines, we discovered a new pyrano[4′, 3′:6, 7]naphtho[1, 2-b]xanthene derivative, FD-594 from the fermentation broth of Streptomyces sp. TA-0256. FD-594 shows moderate activity against tumor cell lines, comparative to that of adriamycin, as well as antibacterial activity against some Gram-positive bacteria.