Effects of hexachlorophene on the metabolism of glucose and glutamate in rat brain

In vitro kinetics of the rat brain succinate dehydrogenase inhibition by hexachlorophene

Brain succinate dehydrogenase (SDH) activity was inhibited by in vitro hexachlorophene (HCP) with a half inhibitory concentration (IC50) of 0.65 x 10(-3) M. The HCP exerted noncompetitive inhibition at 0.5 mM (<IC50), uncompetitive inhibition at 0.65 mM (= IC50), and mixed-type inhibition at 0.8 mM (>IC50) on SDH activity. The brain SDH demands more energy of activation (deltaE) in the presence of HCP. The ionizable groups of SDH such as the sulfhydral group of cysteine and alpha-amino groups of cysteine were not altered qualitatively in the presence of HCP.

Patterns of mid-to-term placental enzymes in rats treated with magnesium sulphate

1. Pregnant rats were injected daily with 150 mg/kg b.w. of magnesium sulphate (MgSO4) starting at the 5th day gestation and sacrificed at the 13th, 15th, 19th or the 21st day of pregnancy. 2. The profiles of LDH, G-6-PD, HK and Ala-T activities in mid-to-term placentae were not changed by the drug. 3. Placental PK was strongly activated by MgSO4 in 13-19 day pregnant rats, whereas Asp-T was more severely depressed at the final phase of pregnancy. 4. Although mild to moderate changes in the flow of substrates should be predictable by the results, it seems unlikely that these could account for the reported deleterious effects of MgSO4 on rat offsprings.

Effects of chlorinated bisphenols on torula yeast glucose-6-phosphate dehydrogenase

Chlorinated bisphenol antibacterial and antifungal agents are potent inhibitors of torula yeast glucose-6-phosphate dehydrogenase (G6PD). Several compounds were tested, including hexachlorophene [HCP; 2,2'-methylenebis(3,4,6-trichlorophenol)]; 2,2'-oxybis(tetrachlorophenol); 2',4-dihydroxy-2,3,3',5,5',6-hexachlorodiphenylmethane; 2,2'-methylenebis(3,4-dichlorophenol) (3,4-TCP); bithionol [2,2'-thiobis(4,6-dichlorophenol)]; 2,2'-methylenebis(3,5-dichlorophenol); 2,2'-dihydroxy-3,3',5,6,6'-pentachlorodiphenylmethane; 2,2'-methylenebis(4-chlorophenol) (DCP); 2,2'-methylenebis(4,6-dichlorophenol); and the related uncoupler 2,4-dinitrophenol. The relative inhibitory activity of the chlorinated bisphenols tended to increase with degree of chlorination of the aromatic rings. the concentrations of the bisphenols that caused 50% inhibition ranged from 2.5 micrometers for 2,2'-oxybis(tetrachlorophenol) to 40 micrometers for 2,2'-methylenebis(4,6-dichlorophenol) under comparable assay conditions. More detailed kinetic analysis showed that, as with HCP, the inhibition of G6PD by 3,4-TCP and DCP followed noncompetitive kinetics. Calculations from the kinetic data gave apparent inhibition constant (Ki) values for 3,4-TCP of 267 micrometers with G6P and 308 micrometers with NADP, and for DCP of 697 micrometers with both G6P and NADP.