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KB Cells (kb + cell)
Selected AbstractsAntitumor and antifungal activities in endophytic fungi isolated from pharmaceutical plants Taxus mairei, Cephalataxus fortunei and Torreya grandisFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2001Yaojian Huang Abstract The purpose of this work was to screen the endophytic fungi having antitumor or antifungal activity, which were isolated from the inner barks of three kinds of pharmaceutical plants, Taxus mairei, Cephalataxus fortunei and Torreya grandis, collected from Fujian province, China. Antitumor activity was studied by the MTT assay and antifungal activity was determined by observing fungal growth inhibition. 13.4% of endophytic fungi fermentation broths displayed cytotoxic activity on HL-60 cells at and below a dilution of 1:50, and 6.4% on KB cells. 52.3% of endophytic fungi fermentation broths displayed growth inhibition on at least one pathogenic fungi, such as Neurospora sp., Trichoderma sp. and Fusarium sp. Among all endophytic fungi isolated, the genus Paecilomyces sp. has the highest positive rate of antitumor and antifungal activity. These results indicate that endophytic fungi could be a promising source for antitumor and antifungal bioactive agents. [source] 1H and 13C NMR signal assignments of Paecilin A and B, two new chromone derivatives from mangrove endophytic fungus Paecilomyces sp. (tree 1,7)MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2007Zhiyong Guo Abstract Two new natural products, named paecilin A (1) and B (2), together with two known compounds secalonic acid D (3) and (11)-cytochalasa-6(12),13-diene-1,21-dione-16,18-dimethyl-7-hydroxy-l0-phenyl-(7S*,13E,16S*,18S*) (4), were isolated from the mangrove endophytic fungus, Paecilomyces sp. (tree 1,7) from the South China Sea. 1D and 2D NMR experiments including COSY, HMQC, and HMBC were used for the determination of their structures. In our cytotoxicity assays, secalonic D (3) showed cytotoxicity toward KB cells with IC50 < 1 µg ml,1 and inhibiting human topoisomerase I with IC50 at 0.16 µmol ml,1. 1, 2, and 4 showed no activity to KB cells. Copyright © 2007 John Wiley & Sons, Ltd. [source] Binding of the periodontitis associated bacterium Porphyromonas gingivalis to glycoproteins from human epithelial cellsMOLECULAR ORAL MICROBIOLOGY, Issue 5 2008U. Hallén Introduction:, In the present study we examined the ability of the periodontal pathogen Porphyromonas gingivalis to adhere to glycoconjugates on intact cells and to protein preparations of epithelial cells (KB cells). Methods:, The KB cell protein preparation was separated by sodium dodecyl sulfate,polyacrylamide gel electrophoresis and transferred to nitrocellulose membranes by Western blotting. The membranes were used in overlay assays with labeled P. gingivalis. Flow cytometry was used to analyze attachment of bacteria to intact KB cells. Results:, Glycoconjugate expression on the KB cells and in the protein preparation was confirmed. Binding was detected to several bands on the Western blots. Flow cytometry showed a distinct increase in fluorescence for strain FDC 381. Preincubation of the bacteria with mannose, fucose, N -acetylglucosamine and N -acetylgalactosamine inhibited the binding to KB cells by approximately 30% whereas preincubation with N -acetylneuraminic acid reduced the binding by 60%. Conclusion:, These results indicate that carbohydrate structures are involved in the binding process of P. gingivalis to oral epithelial cells and that neuraminic acid plays a significant role in the adhesion process. [source] Adhesion and invasion to epithelial cells by fimA genotypes of Porphyromonas gingivalisMOLECULAR ORAL MICROBIOLOGY, Issue 6 2006J. E. Umeda Adhesion to and invasion of epithelial cells by the periodontopathogen Porphyromonas gingivalis is promoted by the major fimbriae, encoded by fimA. The microorganism can be classified in six genotypes, based on fimA sequence, and genotype II strains are more prevalent than others in periodontitis patients. This study aimed to determine the adhesive and invasive abilities on KB cells of different fimA allelic variants of P. gingivalis isolates. Twenty-two isolates and six reference strains representing the six fimA genotypes and non-typeable strains were screened for their adhesion and invasion abilities on KB cells, using standard methods. All strains were able to adhere and, except for one, to invade KB cells. However, these properties were not homogeneous among strains belonging to the same genotype. There was no correlation between adhesion and invasion efficiencies. Isolate KdII 865 (fimA genotype II) was the most invasive and the second most adhesive strain, whereas reference strain ATCC 33277 (fimA I) showed a low adhesion ability but was highly invasive. These data indicated that fimA genotypes of P. gingivalis are not related to the adhesion and invasion abilities on KB cells, suggesting that the increased prevalence and proportion of certain genotypes may be attributed to other characteristics besides FimA variation. [source] Two epithelial cell invasion-related loci of the oral pathogen Actinobacillus actinomycetemcomitansMOLECULAR ORAL MICROBIOLOGY, Issue 1 2004L. Li Two invasion-related loci, apiA and the two-gene operon apiBC, were isolated from the oral pathogen Actinobacillus actinomycetemcomitans UT32. apiA encodes a 32.5 kDa protein that migrates on SDS-PAGE as a 101 kDa protein as detected by Western blot analysis or silver staining of an outer membrane-enriched fraction of Escherichia coli transformants. E. coli expressing ApiA have a different phenotype than the host vector, in broth and on solid media, and a colony morphology that resembles that of fresh A. actinomycetemcomitans isolates. These E. coli transformants bound to chicken collagen type II, human collagen type II, III, V and fibronectin. apiB and apiC encode proteins of 130.1 and 70.6 kDa, respectively. ApiBC conferred on E. coli a slightly enhanced ability to bind to collagen type III. ApiA- and ApiB-deficient mutants were constructed in A. actinomycetemcomitans. The ApiB-mutant had 4-fold diminished invasion of KB cells; the ApiA-mutant had increased invasion. Both loci were found in all A. actinomycetemcomitans strains, although polymorphism was detected only for apiBC. The deduced sequences of these invasion-related proteins are homologous to members of the YadA adhesin/invasin family. [source] Green Tea Phenol Extracts Reduce UVB-induced DNA Damage in Human Cells via Interleukin-12,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2008Agatha Schwarz Green tea chemoprevention has been a focus of recent research, as a polyphenolic fraction from green tea (GTP) has been suggested to prevent UV radiation-induced skin cancer. Recently, it was demonstrated that GTP reduced the risk for skin cancer in a murine photocarcinogenesis model. This was accompanied by a reduction in UV-induced DNA damage. These effects appeared to be mediated via interleukin (IL)-12, which was previously shown to induce DNA repair. Therefore, we studied whether GTP induction of IL-12 and DNA repair could also be observed in human cells. KB cells and normal human keratinocytes were exposed to GTP 5 h before and after UVB. UVB-induced apoptosis was reduced in UVB-exposed cells treated with GTP. GTP induced the secretion of IL-12 in keratinocytes. The reduction in UV-induced cell death by GTP was almost completely reversed upon addition of an anti-IL-12-antibody, indicating that the reduction of UV-induced cell death by GTP is mediated via IL-12. The ability of IL-12 to reduce DNA damage and sunburn cells was confirmed in "human living skin equivalent" models. Hence the previously reported UV-protective effects of GTP appear to be mediated in human cells via IL-12, most likely through induction of DNA repair. [source] Effect of Ring Methylation on the Photophysical, Photochemical and Photobiological Properties of cis -Dichlorobis(1,10-Phenanthroline)Rhodium(III)Chloride,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006Devanesan Loganathan ABSTRACT Methylated analogues of cis -dichlorobis(1,10-phenanthroline)-rhodium(III)chloride (BISPHEN) have been prepared in order to increase the hydrophobicity of the parent compound, and thus create octahedral rhodium (III) complexes suitable for use as anticancer and antiviral agents that can be photo-activated. The parent complex has been shown in earlier work to be unable to cross through cell membranes. Octamethylation, as in the case of cis -dichlorobis(3,4,7,8-tetramethyl-1,10-phenanthroline)rhodium(III)chloride (OCTBP), provides enough hydrophobicity to be taken up by KB tumor cells. It also provides a higher level of ground-state association with double-stranded DNA and increases the quantum efficiency of photoaquation by greater than 10-fold, relative to BISPHEN. OCTBP forms covalent bonds to deoxyguanosine when irradiated with the nucleoside, as has been seen with the parent complex. Irradiation of OCTBP in the presence of the KB or M109 tumor cell lines using narrow-band UVB (,= 311 nm) irradiation initiates a considerable amount of phototoxicity. There is evidence that OCTBP acts as a prodrug (i.e. after passing through the cell membrane the metal complex is photolyzed to cis -chloro aquo OCTBP, which may be the active phototoxic agent). OCTBP and the tetramethyl analogue cis -dichlorobis(4,7-dimethyl-1,10-phenanthroline)rhodium(III)chloride (47TMBP) also show photoaquation upon excitation with visible light (, > 500 nm), and indeed, some phototoxicity of KB cells is observed at these wavelengths as well. This is attributed to direct population of photoactive triplet-excited states. These results, together with our earlier studies of cis -dichloro[dipyrido(3,2-a: 2,,3,-c)phenazine (1,10-phenanthroline)rhodium(III)chloride (DPPZPHEN) demonstrate that such octahedral rhodium complexes are viable "photo-cisplatin" reagents. [source] Antimalarial compounds from Kniphofia foliosa rootsPHYTOTHERAPY RESEARCH, Issue 6 2005Abraham Abebe Wube Abstract During the course of screening Ethiopian medicinal plants for their antimalarial properties, it was found that the dichloromethane extract of the roots of Kniphofia foliosa Hochst. (Asphodelaceae), which have long been used in the traditional medicine of Ethiopia for the treatment of abdominal cramps and wound healing, displayed strong in vitro antiplasmodial activity against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum with an ED50 value of 3.8 µg/mL and weak cytotoxic activity against KB cells with an ED50 value of 35.2 µg/mL. Five compounds were isolated from the roots and evaluated for their invitro antimalarial activity. Among the compounds tested, 10-(chrysophanol-7,-yl)-10-(,)-hydroxychrysopanol-9-anthrone and chryslandicin, showed a high inhibition of the growth of the malaria parasite, P. falciparum with ED50 values of 0.260 and 0.537 µg/mL, respectively, while the naphthalene derivative, 2-acetyl-1-hydroxy-8-methoxy-3-methylnaphthalene, exhibited a less significant antimalarial activity with an ED50 value of 15.4 µg/mL. To compare the effect on the parasite with toxicity to mammalian cells, the cytotoxic activities of the isolated compounds against the KB cell line were evaluated and 10-(chrysophanol-7,-yl)-10-(,)-hydroxychrysopanol-9-anthrone and chryslandicin displayed very low toxicity with ED50 values of 104 and 90 µg/mL, respectively. This is the first report of the inhibition of the growth of P. falciparum by anthraquinone-anthrone dimers and establishes them as a new class of potential antimalarial compounds with very little host cell toxicity. Copyright © 2005 John Wiley & Sons, Ltd. [source] | ||||||||||