Kurzbeschreibung
(Englisch)
|
This proposal is based on the outcomes and questions raised in the previous project, developed and supported in the framework of the former COST Action 837. It is a basic research addressed to key generic questions on the biochemical mechanisms involved in the detoxification of sulphonated aromatic compounds, as well as on their cross talks with secondary metabolism and redox processes, in different plant species, producing and non-producing natural anthraquinones. The specific scientific objectives of the research proposed are thus the following:a) To elucidate if the detoxification mechanisms of sulphonated aromatic compounds are unique and specific to anthraquinone producing plants, and dependent on the way of penetration of the xenobiotics (uptake by root/rhizome versus direct injection into shoot).b) To characterize the response of different plant parts (root/rhizome versus leaf) to penetrated sulphonated xenobiotics at different levels (secondary metabolism, detoxification and redox processes).c) To determine the maximal possible amount of sulphonated aromatic compounds that can be accumulated and detoxified without injury, critical stress or disruption of plant metabolism in the species under investigation. d) To evaluate the effect of the number and position of sulphonated moiety on the metabolic fate of compounds with different substitution types on the aromatic ring. The proposed research will contribute to better understand and control the biochemical mechanisms leading to the detoxification of xenobiotics in higher plants. It is expected to get results of great interest to phytotechnologies. For an efficient phytotreatment actually, the importance of selection of appropriate plants, capable of optimal removal and metabolism of organic pollutants is quite obvious. The outcomes of this research will provide a sound basis for the future implementation of a phytotreatment to remove sulphonated aromatic compounds from contaminated sites and industrial waste
|
Partner und Internationale Organisationen
(Englisch)
|
AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GR, HU, IE, IL, IT, LT, LU, NL, NO, PL, PT, RO, SE, SI, SK, TR, UK
|
Abstract
(Englisch)
|
Sulphonated anthraquinones are precursors of many synthetic dyes and pigments, recalcitrant to biodegradation and thus not eliminated by classical wastewater treatments. In the development of a phytotreatment to remove sulphonated aromatic compounds from dye and textile industrial effluents, it has been shown that rhubarb (Rheum rabarbarum) and common sorrel (Rumex acetosa) are the most efficient plants. Both species, producing natural anthraquinones, not only accumulate, but also transform these xenobiotic chemicals. Even if the precise biochemical mechanisms involved in the detoxification of sulphonated anthraquinones are not yet understood, they probably have cross talks with secondary metabolism, redox processes and plant energy metabolism. The aim of the present study was to investigate the possible roles of cytochrome P450 monooxygenases and peroxidases in the detoxification of several sulphonated anthraquinones. Both plant species were cultivated in a greenhouse under hydroponic conditions, with or without sulphonated anthraquinones. Plants were harvested at different times and either microsomal or cytosolic fractions were prepared. The monooxygenase activity of cytochromes P450 toward several sulphonated anthraquinones was tested using a new method based on the fluorimetric detection of oxygen consumed during cytochromes P450-catalysed reactions. The activity of cytosolic peroxidases was measured by spectrophotometry, using guaiacol as a substrate. A significant activity of P450 was detected in rhubarb leaves, while no (rhizome) or low (petioles and roots) activity was found in other parts of the plants. An induction of this enzyme was observed at the beginning of the exposition to sulphonated anthraquinones. P450 were able to accept as substrate the five sulphonated anthraquinones, with a higher activity toward AQ-2,6-SS and AQ-2-S. An activity of the P450 was also found in the leaves of common sorrel, but no induction of the activity occurred after the exposition to the pollutant. The activity of peroxidases increased when rhubarb was cultivated in the presence of the five sulphonated anthraquinones. Peroxidases activity was also detected in the leaves of common sorrel, but in this plant no significant difference was found between plants cultivated with and without sulphonated anthraquinones. Results suggest the existence in rhubarb and common sorrel of specific mechanisms involved in the metabolism of sulphonated anthraquinones. Further investigation should be performed to unravel the next steps of this detoxification pathway. Besides these promising results for the phytotreatment of sulphonated anthraquinones, it will be of high interest to test an experimental pilot system to determine its efficiency. These results also reinforce the idea that natural biodiversity should be better studied to use the most appropriate species for the phytotreatment of a specific pollutant.
|
