The effect of N-acetylhomocysteine and its thiolactone on the distribution and excretion of mercury in methyl mercuric chloride injected mice

Chelation therapy for methylmercury(II) poisoning. Synthesis and determination of solubility properties of MeHg(II) complexes of thiol and dithiol antidotes

Methylmercury(II) complexes of the most widely studied antidotes for mercury poisoning have been prepared, and both the water solubility and 1-octanol/water partition coefficients determined for these complexes and the L-cysteine complex. New complexes of N-acetyl-D,L-penicillamine, 2-mercaptosuccinic acid, meso-dimercaptosuccinic acid, and Unithiol have been synthesized and characterized, and are found to have the formulations MeHgSCMe2CH(NHCOMe)CO2H, MeHgSCH(CO2H)CH2CO2H, MeHgSCH(CO2H)CH(CO2H)SHgMe, and Na[MeHgSCH2CH-(SHgMe)CH2SO3], respectively. Trends in octanol/water partition coefficients are consistent with reported studies of the effectiveness of antidotes for MeHg(II) poisoning and redistribution of MeHg(II) on administration of antidotes, particularly for British anti-Lewisite, Unithiol, and meso-dimercaptosuccinic acid.

H nmr study of the effectiveness of various thiols for removal of methylmercury from hemolyzed erythrocytes

The effectiveness of eight thiol ligands for removing methylmercury (CH3Hg(II)) from its glutathione and hemoglobin complexes in hemolyzed erythrocytes has been studied by 1H nuclear magnetic resonance spectroscopy. These complexes are the predominant methylmercury species in human erythrocytes. The effectiveness was determined from the exchange-averaged chemical shift of the resonance for the proton on the alpha-carbon of the cysteinyl residue and from the intensity of the resonance for the methylene protons of the glycine residue of reduced glutathione (GSH), both of which provide a measure of the amount of glutathione in the CH3Hg(II)-complexed form. The thiol ligands were found to release GSH from its CH3Hg(II) complex in the order 2, 3-dimercaptosuccinic acid greater than mercaptosuccinic acid greater than cysteine greater than mercaptoacetic acid greater than D-penicillamine greater than 2,3-dimercaptopropanesulfonic acid greater than N-acetyl-D,L-penicillamine greater than D,L-homocysteine.

Early indices of methyl mercury toxicity and their use in treatment evaluation

Mercury distribution, food consumption, body weight, and in vivo protein synthesis were compared as criteria for evaluating the efficacy of D-penicillamine (DPA) in treating experimental methyl mercury (MM) intoxication. Female rats were orally administered MM hydroxide at 40 mg/kg and, after a 7- to 8-d latency period, displayed characteristic neurological signs of MM intoxication. Within 24 h of MM exposure food consumption decreased 75% causing a 12-g drop in body weight, and synthesis of whole blood and kidney protein increased. Protein synthesis in liver was increased 39% by MM after 3 d, and that in cerebellum was decreased 15% after 7 d. Treatment with DPA (1.2 g/kg.d sc on d 2, 3, and 4) prevented the appearance of neurological signs. DPA lowered the Hg content of all tissues; restored food consumption of control levels; increased the onset and amount of body weight gain; returned synthesis of blood, liver, and kidney proteins to control levels; and prevented the decrease in protein synthesis in cerebellum. By itself, DPA produced a transitory decrease in both food consumption and body weight, which could be prevented with vitamin B6. Vitamin B6 antagonized DPA's reversal of MM's action on protein synthesis. Furthermore, DPA and/or vitamin B6 had a variety of effects on protein synthesis in control rats. Thus it was not possible to use protein synthesis to predict the efficacy of the combination of DPA and vitamin B6 as found for the parameters of food consumption, body weight, and Hg distribution. Since changes in body weight and food consumption were the earliest and most pronounced and consistent responses to MM and effective DPA treatment, they were considered the best criteria for evaluating treatment efficacy in experimental MM poisoning in rats.