Search results for "BIOTRANSFORMATION"

The fate aspects of pharmaceuticals in the environment : biotransformation, sedimentation and exposure of fish

2012

BIODEGRADACJA ZWIĄZKÓW FOSFONOWYCH PRZEZ GRZYBY

2020

Phosphonates are the group of organophosphorus compounds, which are characterized by the presence of covalent bond(s) between carbon and phosphorus atom in their structure. Both; the natural and synthetic phosphonic compounds, are encountered in various ecosystems, however because of their wide range of applications, the latter ones are considerably more frequently discussed. Regarding the broad spectrum of biological activity, capability to chelate metal cations and environmental stability of direct carbon to phosphorus bond under physiological conditions, phosphonic compounds found a variety of applications e.g. as pesticides, drugs, anticorrosive agents, additives to surfactants and flam…

Transport, stability, and biological activity of resveratrol

2011

Numerous studies have reported interesting properties of trans-resveratrol, a phytoalexin, as a preventive agent of several important pathologies: vascular diseases, cancers, viral infections, and neurodegenerative processes. These beneficial effects of resveratrol have been supported by observations at the cellular and molecular levels in both cellular and in vivo models, but the cellular fate of resveratrol remains unclear. We suggest here that resveratrol uptake, metabolism, and stability of the parent molecule could influence the biological effects of resveratrol. It appears that resveratrol stability involves redox reactions and biotransformation that influence its antioxidant properti…

Radioactive labeling of defined HPMA-based polymeric structures using [18F]FETos for in vivo imaging by positron emission tomography.

2009

During the last decades polymer-based nanomedicine has turned out to be a promising tool in modern pharmaceutics. The following article describes the synthesis of well-defined random and block copolymers by RAFT polymerization with potential medical application. The polymers have been labeled with the positron-emitting nuclide fluorine-18. The polymeric structures are based on the biocompatible N-(2-hydroxypropyl)-methacrylamide (HPMA). To achieve these structures, functional reactive ester polymers with a molecular weight within the range of 25,000-110,000 g/mol were aminolyzed by 2-hydroxypropylamine and tyramine (3%) to form (18)F-labelable HPMA-polymer precursors. The labeling procedure…

The impact of Pleurotus ostreatus on organic matter transformation processes.

2012

This study showed the effect of Pleurotus ostreatus on the external organic matter (OM) transformation processes. The kinetics of these changes were determined. The experiment was conducted as 42-day pot experiment done in four combinations (with four replications). The four combinations of different substrates were: (1) organic, (2) composted hay, (3) organic soil + composted hay, (4) organic soil + composted hay + lead. The study results showed that P. ostreatus had the ability to transform external OM as well as metal–organic complexes. These transformations were reflected in the constant rate of characterized changes and correlation coefficients. The study also indicated the direction o…

Reduction of benzo(a)pyrene mutagenicity by dihydrodiol dehydrogenase

1979

THE enigma of how inert chemicals can exert potent mutagenic, carcinogenic, allergenic and cytotoxic effects has been much debated. It has been learned that such compounds are metabolically converted to chemically reactive species1. In the case of aromatic or olefinic compounds, monooxygenases located in the membranes of the cell can transform these compounds into epoxides2–5 which by virtue of electrophilic reactivity can bind chemically to cellular macromolecules such as DNA, RNA and proteins, thereby disturbing biochemical control mechanisms and leading to the above mentioned toxic effects. The same membranes in which such epoxides are produced possess an enzyme, epoxide hydratase, which…

Natural products and enzymes from plant cell cultures

1995

Plants represent an unlimited source of natural products. Many of the recently detected phytochemicals exhibit remarkable bioactivities, ranging from anticancer activity, phosphodiesterase inhibition to cytotoxicity against HIV-infected cells. Cultivated plant cells produce at their unorganized, dedifferentiated stage secondary metabolites, but in very different amounts in so far as new compounds are concerned. In fact, more than 140 novel natural products are presently known from plant cell cultures, which also include new metabolites formed by biotransformation. The biotransformation capacity of suspended cells is described and recent high yielding transformations, like the formation of a…

Unsaturated fatty acid bioconversion by apple pomace enzyme system. Factors influencing the production of aroma compounds

1996

Productions of volatile compounds (hexanal and 2,4-decadienal) obtained from polyunsaturated fatty acids by action of specific apple pomace enzyme system were quantitatively improved by increasing substrate and enzyme concentrations in the reaction medium. The importance of an exogenous supply of oxygen during bioconversion was also shown. Some physico-chemical factors involved in the pomace enzyme system expression were screened. A temperature of 25°C was favourable to the bioconversion. The control of alkaline or acidic conditions in the reaction medium may orientate the reaction preferentially to the production of one or other aldehyde.

Infiuence of Foreign Compounds on Formation and Disposition of Reactive Metabolites

2008

Many toxic compounds are unreactive and need biotransformation in order to exert their toxic effects. Several enzymes control the formation or disposition of reactive metabolites. Especially well studied is the group of enzymes responsible for the control of reactive epoxides. Such epoxides may bind spontaneously to DNA, RNA and protein. These alterations of critical cellular macromolecules may disturb the normal biochemistry of the cell and lead to cytotoxic, allergenic, mutagenic and carcinogenic effects. Whether these effects will be manifested depends on the chemical reactivity as well as on other properties (geometry, lipophilicity) of the epoxide in question. Enzymes controlling the c…

Genetically engineered V79 Chinese hamster cells metabolically activate the cytostatic drugs cyclophosphamide and ifosfamide.

1990

V79 cells, genetically engineered to express active cytochromes P450IIB1 and P450IA1, were used to study the cytotoxicity and mutagenicity of cyclophosphamide and ifosfamide. Cyclophosphamide, tested up to a concentration of 2 mM, was not cytotoxic in V79 nor in the P450IA1-expressing V79-derived cell line XEM2. Pronounced cytotoxicity was, however, observed in the P450IIB1-expressing V79-derived cell line SD1. Induction of gene mutations (acquisition of 6-thioguanine resistance) was observed in SD1 cells as well, but the effects were weak. Ifosfamide was inactive in V79 cells, but was cytotoxic in SD1 cells. Ifosfamide mustard, an active metabolite of ifosfamide, was equally cytotoxic and …