6 research outputs found
Glutaraldehyde exposed Pseudomonas fluorescens: a case of biofilm persistence?
From the assessment of the recovery capability of pseudomonas
fluorescens atcc 13525t after exposure to several glutaraldehyde (gta)
concentrations (100, 200 and 400 mg/l) and exposure times (1 and 2
hours), it was found that, for gta concentrations above 100 mg/l,
whatever the exposure time, bacterial cells presented different
growth patterns in solid media. after this statement, the recovered
cells were initially characterized using api ne20 strips and species
identification was obtained using the api database. the type culture
and the cells obtained after treatment with concentrations below
200 mg/l were identified as p. fluorescens. conversely, the identification
of cells exposed to higher concentrations of gta failed. the
electrophoretic profiles of both the type culture and the cells
exposed to gta were obtained by pcr, using the primer t3b. the
results showed identical profiles for the type culture and the cells
exposed to low gta concentrations, and a totally different pattern for
cells exposed to gta concentrations above 200 mg/l. sequencing of
the 16s rdna gene is under way in order to further clarify the
differences observed. the p. fluorescens atcc 13525 (used as control)
and the cells treated with 200 mg/l of gta during 2 hours were
selected for further studies. a comparative study was carried out
between the above referred cells in terms of morphological
structure, surface properties, respiratory activity, biofilm formation ability and susceptibility to gta. the results showed that the cells
treated with 200 mg/l of gta presented an elongated structure, were
about 30 times less active in terms of respiratory activity and were
more hydrophilic. concerning biofilm formation, both tested cells
presented biofilm formation ability, but the gta treated cells
produced about 2 times more mass of biofilm. however, this
biofilm had a specific respiratory activity 3 times less than the one
formed by the control culture. the biofilm behaviour immediately
after exposure to 200 mg/l of gta during 2 hours, was similar for
both situations studied, since a low biofilm removal and inactivation
was achieved. however, 7 hours after gta exposure, only 55% of the
biofilm formed by the control culture remained attached to the
surface, while for the biofilms formed by the treated cells all the
deposit remained attached to the surface.
the results obtained in this work indicate that cells submitted to gta
treatment may give rise to biofilms harder to remove and consequently
more persistent, than non-treated cells. therefore, care must
be taken in the selection and application of biocides in industrial
biofilms
Phytotoxicity of alkaloids, coumarins and flavonoids isolated from 11 species belonging to the Rutaceae and Meliaceae families
Meliaceae and Rutaceae families are known for the high diversity of their secondary metabolites, which include many groups that represent a rich source of structural diversity, and are good candidates as sources of allelochemicals that could be useful in agriculture. In the work described here the bioactivity profiles were evaluated for 3 alkaloids (1â3), 12 coumarins (4â15), 2 phenylpropanoic acid derivatives (16 and 17) and 14 flavonoids (18â31) from 11 species belonging to the Meliaceae and Rutaceae families. All compounds were tested in the wheat coleoptile bioassay and those that showed the highest activities were tested on the STS (Standard Target Species) Lepidium sativum (cress), Lactuca sativa (lettuce), Lycopersicon esculentum (tomato), and Allium cepa (onion). Most of the isolated compounds showed phytotoxic activity and graveoline (3), psoralen (8), and flavone (18) were the most active, with bioactivity levels similar to that of the commercial herbicide Logran1. The results indicate that these compounds could be involved as semiochemicals in the allelopathic interactions of these plant species
Exploitation of new chalcones and 4H-chromenes as agents for cancer treatment
Chalcone and chromene derivatives were synthesized in good yield through simple and effective reactions using innocuous solvents such as water and ethanol and high yielding aldol condensations. Generally, the reactions were performed at room temperature, leading to the isolation of highly pure compounds. These compounds were tested on breast cancer cells (MCF-7 and Hs578T) and breast non-neoplastic cells (MCF-10A). After determination of IC50 value, specific assays were performed to analyze the potential of these compounds, and those bearing halogenated substituents presented enhanced activity comparing to methoxyl or methyl groups. More specifically, the bromine atom was often present in the bioactive molecules that proceeded to the final assays and showed to be promising candidates for further studies. The selected chromene acted as a cell migration inhibitory agent and triggered regulated cell death associated with G2/M cell-arrest and microtubule destabilization. For chalcones, the results suggest an anti-proliferative activity. Also, results for combination-therapy potentiated the antitumor effect of doxorubicin and reduced cytotoxicity in MCF-10A cells.We acknowledge the financial support from University of
Minho, Fundaçao para a Ci ~ encia e a Tecnologia and FEDER- ^
COMPETE for financial support through Centro de QuĂmica (UID/
QUI/00686/2013 and UID/QUI/0686/2016), and for the postdoctoral grants awarded to Marta Costa (SFRH/BPD/79609/2011) and Belem
Sampaio-Marques (SFRH/BPD/90533/2012), PhD grants of Filipa
Santos (SFRH/BD/87139/2012) and OlĂvia Pontes (SFRH/BD/128850/
2017). The confocal microscope Olympus FV1000 acquired under
the financial support of PPBI-POCI-01-0145-FEDER-022122. The
NMR spectrometer Bruker Avance III 400 is part of the National
NMR Network (RNRMN) and was purchased within the framework
of the National Program for Scientific Re-equipment, contract
REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT.
This work was also developed under the project NORTE-01-0145-
FEDER-000013, by the Northern Portugal Regional Operational
Program (NORTE 2020), through the European Regional Development Fund (FEDER) and the Competitiveness Factors Operational
Program (COMPETE) and by National funds, through the Foundation for Science and Technology (ref. POCI-01-0145-FEDER007038)
INIBIDORES DO FOTOSSISTEMA II: UMA PERSPECTIVA ALELOQUĂMICA
The process of photosynthesis involves the absorption of light energy by photosynthetic pigments found in the thylakoid membrane of chloroplasts in order to produce chemical energy. In the presence of photosynthetic inhibitors, plant development is affected mainly by the reduction of the electron chain, which leads to growth inhibition. In this context, chlorophyll a (Chl a) fluorescence is an important technique used to identify the effects of inhibitors on the photosynthetic apparatus employing the JIP-test, which correlates the Chl a fluorescence transient to biophysical parameters, providing valuable information about the efficiency of photosystems I and II. Natural products have been highlighted as photosynthesis inhibitors due to the continued use of synthetic herbicides, which leads to the development of invasive plants resistant to these pesticides, in addition to the toxicity caused to humans and the environment. Thus, this review describes the main applications of extracts and isolated secondary metabolites obtained from plants and microorganisms in the investigation of electron transport inhibition on photosystem II