Investigation of cytotoxic, genotoxic, mutagenic, and estrogenic effects of the flame retardants tris-(2-chloroethyl)-phosphate (TCEP) and tris-(2-chloropropyl)-phosphate (TCPP) in vitro.

The organophosphorus esters tris-(2-chloroethyl)-phosphate (TCEP) and tris-(2-chloropropyl)-phosphate (TCPP) have been widely used as flame retardants and fire preventing agents, e.g. in polyurethane foams. We investigated the cytotoxic, genotoxic, mutagenic, and estrogenic potentials of TCEP and TCPP, using different in vitro models. Cytotoxic effects were evaluated by neutral red uptake and genotoxicity with the alkaline single cell gel electrophoresis (Comet assay), both in V79 (hamster fibroblasts) cells. Mutagenicity was tested in the Ames assay with Salmonella typhimurium using the strains TA 97 a, 98, 100, 102, 104, 1535, 1537, and 1538, with and without metabolic activation by S9-rat liver homogenate. Estrogenic or anti-estrogenic effects were examined with the recombinant yeast reporter gene assay, and in human endometrial cancer Ishikawa cells by induction of alkaline phosphatase. In V79 cells TCEP was weakly cytotoxic at concentrations above 10 microM in the presence of S9-rat liver homogenate whereas TCPP showed cytotoxicity above 1mM in the presence of S9. Both substances did not induce DNA strand breaks in the alkaline version of the Comet assay neither without an external enzymatic metabolizing system, nor in the presence of S9-mix. Additionally, no mutagenic potential could be detected for TCEP and TCPP in eight Salmonella strains using concentrations up to 1mM in the presence and absence of S9. Hormonal activity shown as induction of estrogenic or anti-estrogenic effects could not be detected in the two in vitro test systems.

Technetium(V) and rhenium(V) complexes for 5-HT2A serotonin receptor binding: structure-affinity considerations.

Starting from the lead structure of ketanserin, a prototypic serotonin (5-HT) antagonist, new oxotechnetium(V) and oxorhenium(V) complexes were synthesized that are able to compete with [3H]ketan-serin in receptor-binding assays. To imitate organic 5-HT2 receptor ligands, fragments of ketanserin were combined with chelate moieties. Neutral compounds of the general formula [MOL1L2] (M = Tc, Re; L1 = HS-CH2CH2-S-CH2CH2-SH, N-(2-mercaptophenyl)salicylideneimine, N-(2-mercaptoethyl)-salicylideneimine, 3-(2-([N,N-bis(2-mercapto-S-ethyl)]-amino)ethyl)-2,4-(1H, 3H)-quinazolinedione and L2 = HS-R with R = subst. alkyl) were prepared by common action of a Tc(V) or Re(V) precursor with a mixture of equimolar amounts of a tridentate ligand L1 and a monodentate thiolate L2 bearing fragments of the lead structure. Lipophilic complexes consisting of a small S4 thiolate/thioether chelate unit, protonable nitrogen-containing spacer, and simple benzyl moiety significantly inhibited the specific binding of [3H]ketan-serin with IC50 values between 10 and 50 nM.

Estrogenic properties of isoflavones derived from Millettia griffoniana.

In most developing countries, 70-80% of the population still resort to traditional medicine for their primary health care. This medicine utilises medicinal plants which are traditionally taken as concoction and infusion. The root and stem bark of Millettia griffoniana (Leguminosae), has been reported to contain isoflavonoids, alkaloids, and diterpenoids. The possible benefit of some bioactive isoflavones derived from M. griffoniana prompted us to screen them for estrogenic activity. Six isoflavones and coumarin derived from M. griffoniana (bail) namely, compound nos. 1-6 (Fig. 1) were tested for their potential estrogenic activities in three different estrogen receptor alpha (ERalpha)-dependent assays. In a yeast-based ERalpha assay, all test substances and 17beta-estradiol as endogenous agonist, showed a significant induction of beta-galactosidase activity. The test compounds at the concentration of 5 x 10(-6) M could achieve 59-121% of the beta-galactosidase induction obtained with 10(-8) M 17beta-estradiol (100%). In the reporter gene assay based on stably transfected MCF-7 cells (MVLN cells), the estrogen responsive induction of luciferase was also stimulated by the M. griffoniana isoflavones. In Ishikawa cells, all substances exhibited estrogenic activity revealed by the induction of alkaline phosphatase (AlkP) activity. The estrogenic activities of isoflavones from M. griffoniana could be completely suppressed by the pure estrogen antagonist, ICI 182,780, suggesting that the compounds exert their activities through ERalpha. Although all substances showed estrogenic effects, 4'-methoxy-7-O-[(E)-3-methyl-7-hydroxymethyl-2,6-octadienyl]isoflavone (7-O-DHF), Griffonianone C (GRIF-C), and 3',4'-dihydroxy-7-O-[(E)-3,7-dimethyl-2,6-octadienyl]isoflavone (7-O-GISO) were found to be the most potent of tested substances. In summary, estrogenic activities of the isoflavones derived from M. griffoniana were described for the first time using reporter gene assays and the estrogen-inducible AlkP Ishikawa model.