Mutagenicity of paepalantine dimer and glycoside derivatives from Paepalanthus bromelioides

The first isocoumarin isolated from the methylene chloride extract of Paepalanthus bromelioides, named paepalantine (isocoumarin 1), was found to have antimicrobial activity; but, it is mutagenic clastogenic and cytotoxic. Two other isocoumarins, paepalantine-9-O-beta-D-glucopyranoside (isocoumarin 2) and paepalantine-9-O-beta-D-allopyranosyl(1-->6) glucopyranoside (isocoumarin 3) were isolated from the ethanolic extract. A fourth new isocoumarin, also isolated from the methylene chloride extract of the capitula of P. bromelioides, was characterized as an 8-8' dimer of paepalantine and denominated isocoumarin 4. The abilities of isocoumarins 2, 3 and 4 to induce mutations in Salmonella typhimurium strains TA97a, TA98, TA100 and TA102 were investigated. Mutagenic activity was observed in strain TA97a treated with isocoumarin 2 in the presence of S9 mixture. The substitution of H at position 9 by glucose or glucose-allose caused reductions in the mutagenic activities of paepalantine, indicating this to be an important site for these properties. (C) 2003 Elsevier Ltd. All rights reserved.

A new cytotoxic naphthoquinone from Paepalanthus latipes

Quinones constitute an important class of naturally occurring compounds. They are found in plants, fungi and bacteria. Large number of quinones has been associated with antitumor, antibacterial, antimalarial and antifungal activities. In this work we describe the isolation, structure determination and the cytotoxic index of a new 1,4-naphthoquinone isolated from the capitula of Paepalanthus latipes.

Effect of the isocoumarin paepalantine on the luminol and lucigenin amplified chemiluminescence of rat neutrophils

Paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naphto(2,3c)pyran-1-one), a natural isocoumarin isolated from the capitula of Paepalanthus bromelioides (Eriocaulaceae), was assessed for its effect on the respiratory burst (zymosan-stimulated luminol-enhanced chemiluminescence and. PMA-stimulated lucigenin-enhanced chemiluminescence) of polymorphonuclear neutrophils in vitro. Special attention was devoted to establishing the IC50 for neutrophils. Paepalantine was able to decrease luminol and lucigenin chemiluminescence, reflecting an inhibitory effect on the respiratory burst, with an ED50 of 0.44 +/- 0.05 and 0.84 +/- 0.15 mug/ml, respectively. A cell-free system was performed with paepalantine on myeloperoxidase/H2O2 and myeloperoxidase/H2O2/Cl- systems. Paepalantine inhibited luminol oxidation in both systems. This inhibition was related to the interaction of paepalantine-myeloperoxidase and its scavenger effect on HOCl.

In vitro basal and metabolism-mediated cytotoxicity of flavonoids

The purpose of this study was to compare the basal cytotoxicity and metabolism-mediated cytotoxicity of kaempferol, quercetin and rutin. McCoy cells were exposed to various concentrations of the flavonols with and without the S9 system. The neutral red uptake assay was used to determine viability after 24 h at 35-37 degrees C. Dose-response curves were established for each flavonol in the presence and absence of external metabolizing systems. Kaempferol and quercetin were cytotoxic and provoked a dose-dependent decrease in cell viability, without the S9 system. The hepatic S9 microsomal fraction metabolized these compounds to less cytotoxic metabolites. In contrast, rutin at 500 mu g/ml failed to produce any overt signs of toxicity in either assay. (c) 2005 Elsevier Ltd. All rights reserved.

Structure-antimicrobial activity of some natural isocoumarins and their analogues

Three naturally occurring isocoumarins (paepalantine, paepalantine 9-O-beta-D-glucopyranoside and paepalantine 90-beta-D-allopyranosyl(1 -> 6) glucopyranoside) and two semi-synthetic analogues, 9,10-acylated compound and 9-OH-10-methylated compound,. structurally similar to paepalantine, were evaluated for antimicrobial activity using a spectrophotometric microdilution technique. The paepalantine was active against S. aureus, S. epidermidis, and E faecalis. while the other four compounds proved ineffective against all microorganisms tested at concentrations of 500 mu g/ml. Variations in phenolic substitution at OH-9 and/or OH-10 in the paepalantine molecule resulted in compounds without antimicrobial activity. A combination of structural features, two phenolic groups as cathecolic system, forms an oxygenated system arrangement that may reflect the potentially antimicrobial properties of paepalantine. (c) 2004 Elsevier GmbH. All rights reserved.

Mutagenic and cytotoxic effect of planifolin: A naphthopyranone dimer isolated from Paepalanthus planifolius

A naphthopyranone dimer, named planifolin, was isolated from a methylene chloride extract of the capitula of Paepalanthus planifolius Koern. The molecule (C31H26O10) appeared to be made up of two monomeric portions, semi-vioxanthin and paepalantine (an isocoumarin), linked by an ether bond, and it may possess several kinds of biological activity that can be related to its polyphenolic structure. Short-term tests that detect genetic damage can afford the information needed to evaluate carcinogenic risks of chemicals to humans. The Ames test, recommended for testing the mutagenicity of chemical compounds with potential pharmacological application, was used in the present study. The mutagenic activity was evaluated in Salmonella typhimurium strains TA100, TA98, TA102 and TA97a and the cytotoxic effect in McCoy cells. The in vitro cytotoxicity of planifolin to McCoy cells, tested in microculture with neutral red, showed a significant cytotoxic index (CI50) of 12.83 mu g/mL. Planifolin showed mutagenic activity for TA100, TA98 and TA97a. The results indicate that this new naphthopyranone dimer causes mutations by substitution and by addition and deletion of bases in the sequence of DNA. Moreover, its mutagenic potential was increased by metabolic activation. (c) 2005 Elsevier Ltd. All rights reserved.

Antioxidant activity of isocoumarins isolated from Paepalanthus bromelioides on mitochondria

The isocoumarins (1-50 mu M) paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naptho(2,3c)pyran-1-one), 8,8 '-paepalantine dimer, and vioxanthin isolated from Paepalanthus bromelioides, were assessed for antioxidant activity using isolated rat liver mitochondria and non-mitochondrial systems, and compared with the flavonoid quercetin. The paepalantine and paepalantine dimers, but not vioxanthin, were effective at scavenging both 1,1-diphenyl-2-picrylhydrazyl (DPPH*) and superoxide (O-2(-)) radicals in non-mitochondrial systems, and protected mitochondria from tert-butylhydroperoxide-induced H2O2 accumulation and Fe2+ -citrate-mediated mitochondrial membrane lipid peroxidation, with almost the same potency as quercetin. These results point towards paepalantine, followed by paepalantine dimer, as being a powerful agent affording protection, apparently via O-2(-) scavenging, from oxidative stress conditions imposed on mitochondria, the main intracellular source and target of those reactive oxygen species. This strong antioxidant action of paepalantine was reproduced in HepG2 cells exposed to oxidative stress condition induced by H2O2. (C) 2007 Elsevier Ltd. All rights reserved.

Effects of isocoumarins isolated from Paepalanthus bromelioides on mitochondria: Uncoupling, and induction/inhibition of mitochondrial permeability transition

Isolated mitochondria may undergo uncoupling, and in presence of Ca2+ at different conditions, a mitochondrial permeability transition (MPT) linked to protein,thiol oxidation, and demonstrated by CsA-sensitive mitochondrial swelling; these processes may cause cell death either by necrosis or by apoptosis. Isocoumarins isolated from the Brazilian plant Paepalanthus bromelioides (Eriocaulaceae) paepalantine (9,10-dihydroxy-5,7-dimethoxy-1H-naptho(2,3c)pyran-1-one), 8,8'-paepalantine dimer, and vioxanthin were assayed at 1-50 mu M on isolated rat liver mitochondria, for respiration, MPT, protein thiol oxidation, and interaction with the mitochondrial membrane using 1,6-diphenyl-1,3,5-hexatriene (DPH). The isocoumarins did not significantly affect state 3 respiration of succinate-energized mitochondria; they did however, stimulate 4 respiration, indicating mitochondrial uncoupling. Induction of MPT and protein thiol oxidation were assessed in succinate-energized mitochondria exposed to 10 mu M Ca2+; inhibition of these processes was assessed in non-energized organelles in the presence of 300 mu M t-butyl hydroperoxide plus 500 mu M Ca2+. Only paepalantine was an effective MPT/protein thiol oxidation inducer, also releasing cytochrome c from mitochondria; the protein thiol oxidation, unlike mitochondrial swelling, was neither inhibited by CsA nor dependent on the presence of Ca2+. Vioxanthin was an effective inhibitor of MPT/protein thiol oxidation. All isocoumarins inserted deeply into the mitochondrial membrane, but only paepalantine dimer and vioxantin decreased the membrane's fluidity. A direct reaction with mitochondrial membrane protein thiols, involving an oxidation of these groups, is proposed to account for MPT induction by paepalantine, while a restriction of oxidation of these same thiol groups imposed by the decrease of membrane fluidity, is proposed to account for MPT inhibition by vioxanthin. (c) 2006 Published by Elsevier B.V..

Indoor Air quality related to occupancy at an air-conditioned public building

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Screening for antimicrobial activity of natural products using a microplate photometer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxicity of chlorhexidine digluconate to murine macrophages and its effect on hydrogen peroxide and nitric oxide induction

Chlorhexidine, even at low concentrations, is toxic for a variety of eukaryotic cells; however, its effects on host immune cells are not well known. We evaluated in vitro chlorhexidine-induced cytotoxicity and its effects on reactive oxygen/nitrogen intermediate induction by murine peritoneal macrophages. Thioglycollate-induced cells were obtained from Swiss mice by peritoneal lavage with 5 ml of 10 mM phosphate-buffered saline, washed twice and resuspended (10(6) cells/ml) in appropriate medium for each test. Cell preparations contained more than 95% macrophages. The cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay and the presence of hydrogen peroxide (H2O2) and nitric oxide (NO) by the horseradish peroxidase-dependent oxidation of phenol red and Griess reaction, respectively. The midpoint cytotoxicity values for 1- and 24-h exposures were 61.12 ± 2.46 and 21.22 ± 2.44 µg/ml, respectively. Chlorhexidine did not induce synthesis or liberation of reactive oxygen/nitrogen intermediates. When macrophages were treated with various sub-toxic doses for 1 h (1, 5, 10, and 20 µg/ml) and 24 h (0.5, 1, and 5 µg/ml) and stimulated with 200 nM phorbol myristate acetate (PMA) solution, the H2O2 production was not altered; however, the NO production induced by 10 µg/ml lipopolysaccharide (LPS) solution varied from 14.47 ± 1.46 to 22.35 ± 1.94 µmol/l and 13.50 ± 1.42 to 20.44 ± 1.40 µmol/l (N = 5). The results showed that chlorhexidine has no immunostimulating activity and sub-toxic concentrations did not affect the response of macrophages to the soluble stimulus PMA but can interfere with the receptor-dependent stimulus LPS.

Antitumor and immunomodulatory effects of the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ascorbic acid potentiates the cytotoxicity of the naphthoquinone 5-methoxy-3,4-dehydroxanthomegnin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Viability of human fibroblasts in coconut water as a storage medium

P>AimTo evaluate the effectiveness of a new storage medium for avulsed teeth, coconut water, in maintaining the viability of human fibroblasts.MethodologyCell viability after different time periods was evaluated in the following storage media: coconut water, coconut water with sodium bicarbonate, milk, saline and still mineral water. Human fibroblasts were seeded in Eagle's minimal essential medium (EMEM) supplemented with 7.5% foetal calf serum. After trypsinisation, 100 mu L of culture medium containing approximately 10(4) cells mL(-1) were collected and pipetted into the wells of 96-well plates, which were incubated overnight in 5% CO(2) and 95% air mixture at 37 degrees C. EMEM was then replaced by the storage media and the plates were incubated at 37 degrees C for 1, 2 and 4 h. Cell viability was determined using the neutral red assay. The proportions of viable cells after exposure to the storage media were analysed statistically by anova and the least significant difference (LSD) test (alpha = 5%).ResultsMilk had the greatest capacity to maintain cell viability (P < 0.05), followed by coconut water with sodium bicarbonate and saline. Coconut water was significantly worse at maintaining cell viability compared to milk, coconut water with sodium bicarbonate and saline. The smallest number of viable cells was observed for mineral water (P < 0.05).ConclusionCoconut water was worse than milk in maintaining human fibroblast cell viability.

Cytotoxicity of two novel formulations of calcium phosphate cements: A comparative in vitro study

The purpose was to evaluate the cytotoxicity of two novel formulations (alpha and beta) of calcium phosphate cements. Positive control, represented by a commercial hydroxyapatite cement, and negative control were included for comparative purposes. A continuous lineage of fibroblastic cells was used, and the effect of the tested materials on both cell proliferation and viability was assessed by counting cell number on hemocytometer and by the trypan blue exclusion test, respectively. Study design attempted to simulate clinical use by allowing direct and indirect contact of cells and cements. Results were analyzed by the Kruskal-Wallis test and indicated that the beta formulation was extremely cytotoxic (P < 0.001), because this material induced the greatest reduction on cell proliferation and viability. The alpha formulation behaved similarly to the positive control regarding its effect on cell proliferation and viability. Thus, it is concluded that alpha formulation has promise for further evaluation of its behavior in vivo.