Study of the enantioselective elimination of four toxaphene congeners in rat after intravenous administration by high resolution gas chromatography negative ion mass spectrometry

Temperature and Congener Structure Affect the Enantioselectivity of Toxaphene Elimination by Fish

“…Moreover, the ratios of Penta-1 and -2 were invariant in all three t ) 0 samples (data not shown). A similar effect was described by Skopp et al, who reported no enantioselectivity associated with the elimination of 2,2,5-endo,6-exo,8,9,10-heptachlorobornane (B7-515 or P-32), a nonpersistent CTT, in rats (14). Thus, it appears that, for certain lower chlorinated homologues, elimination rates not associated with enantioselective processes (e.g., passive diffusion via the gills) greatly exceed those that are enantioselective (i.e., biotransformation) and those of higher chlorinated homologues.…”

“…In the later stages of the cold experiment, the activation barrier for E1, the more persistent and only remaining enantiomer, was apparently not exceeded, resulting in immeasurable elimination once temperatures decreased below 15 °C (g40 d, Figure 2). This theory can explain the behavior of other CTTs, e.g., pentachloro-CTTs (this study), B7-515 (14), and non-toxaphene organochlorines such as PCB 95 and R-HCH (13). In our model, CTTs can be classified into four groups (Table 3).…”

“…Of particular interest are studies of toxaphene that have characterized enantioselectivity of uptake and elimination processes by model organisms (12)(13)(14). Recently, we observed that fish (Fundulus heteroclitus) from an area contaminated with weathered toxaphene eliminated 2-exo,3endo,6-exo,8,9,10-hexachlorobornane (B6-923, Figure 1) within a few days (t1/2 ) 7 d) under controlled, uncontaminated conditions (12).…”

Chirality as an Environmental Forensics Tool

“…Thus, it is highly likely that transport of a-HCH across the blood-brain barrier in rats and the other mammals is highly stereoselective. In contrast, rats exposed to several toxaphene congeners showed rapid nonenantioselective elimination of the B7-515 congener, but stereoselective elimination of B8-1413, B9-1679, and B9-1025 with EFs that did not significantly differ among tissues of brains, adipose, and livers [271]. Thus, no stereoselective blood-brain barrier transport was evident for chlorobornanes, unlike the case with a-HCH.…”