Substrate specificites of cytosolic glutathione-S transferases in five different species of the aquatic macrophyte Myriophyllum

We report about the general biotransformation activity based on the activities of glutathione S-transferases (GST's; EC 2.5.1.18) on different model substrates, of five species of the macrophyte genera Myriophyllum (M. hippuroides, M. mattogrossense, M. aquaticum, M. quitense, M. verticillatum), under controlled conditions of water quality, temperature and photoperiod. The model substrates for the GST's we employed were 1-chloro-2,4-dinitrobenzene (CDNB), 4-nitrophenyl-2-nitro-4-trifluoromethyl phenyl ether (Fluorodifen, FL), 2,4-dichlor-1-nitribenzene (DCNB), para-nitrobenzoylchloride (pNBC), 1,2-epoxy-3-(4-nitrophenoxy)propane (EPNP) and ethacrynic acid (EA). All species showed response to all GST conjugating substrates in the cytosol, except M. hippuroides and M. verticillatum wich showed no conjugation reaction with DCNB. The use of different model substrates give an insight on basic biotransformation capacity of the different macrophyte species. This might indicate wich species may have enhanced ability to handle xenobiotics of different molecular structure. Under maintenance in our standard testing medium and conditions the biotransformation profile of all analyzed species show that highest GST-activities were measured using ethacrynic acid and fluorodifen as conjugating substrates. This suggests that they are well equipped to conjugate xenobiotics of different structures.