Cysteamine 5-methyl

The radioprotective action of 3,5-diamino-l,2,4-thiadiazole, its 3-toluene-p-sulfonyl derivative, and the corresponding 5-methyl-amino- and 5-anilino analogs has been determined.218 Administration of the parent compound results in 69% survival in mice after 900 r whole body X-radiation, a result that compares favorably with the effects of such established protectors as AET ([Pg.202]

Dihydrogen evolves from vanadium(II)-cysteine at pH6.0-9.5. This reduction is first order in V11 and independent of pH in the range 7.5-8.5. If cysteamine or cysteine methyl ester is used, dihydrogen is still evolved. The reaction with serine is 1000 times slower than with cysteine even though the half wave potentials are comparable.156 This reaction may be explained by a hydride pathway similar to that proposed for catechol complexes or alternatively Scheme 8. 

In an initial step, 2-chloroacetic acid ethyl ester is reacted with formamide to give 5-methylimidazole-4-carboxylic acid ethyl ester. Then sodium in ammonia is used to convert that to 4-hydroxymethyl-5-methylimidazole-hydrochloride. Cysteamine HCI (HSCH2CH2NH2-HCI) is then reacted to give 4-(2-aminomethyl)-thiomethyl-5-methyl-imidazole dihydrochloride. Then N-cyanamido-5,5-dimethyl-dithio-carbonate (from cyanamid, KOH, CS2 and ((CH3)2S04) is reacted to give a further intermediate which is finally reacted with methylamine to give cimetidine. 

Trace quantities of formaldehyde and methyl glyoxal in aqueous and food samples were determined by a newly developed method. Formaldehyde and methyl glyoxal were reacted with cysteamine in aqueous medium or food sample to give thiazolidine and 2-acetylthiazolidine, respectively, at pH 6 and 8. Thiazolidine derivatives formed from formaldehyde and methyl glyoxal were extracted with dichlorometh-ane or chloroform and subsequently analyzed by a gas chromatograph equipped with a fused silica capillary column and a thermionic detector. Seventeen commercial food items were analyzed for formaldehyde and methyl glyoxal. The quantities of formaldehyde and methyl glyoxal varied from 0 to 17 ppm and from 0 to 620 ppm, respectively. 

Since direct analyses for formaldehyde and methyl glyoxal are difficult with gas chromatography (GC) or any other methods, we attempted to determine levels of formaldehyde and methyl glyoxal in various food samples using their derivatives thiazolidine and 2-acetylthiazolidine, respectively. The proposed mechanism of thiazolidine formation from cysteamine and corresponding aldehydes is shown in Figure 1. 

Materials. Cysteamine hydrochloride, formaldehyde (37% in water), methyl glyoxal (40% in water), and N-methylacetamide were purchased from the Aldrich Chemical Co., Milwaukee, WI. The extraction solvents (dichloromethane and chloroform) were obtained commercially and used without further treatment. Standard fatty aldehydes were obtained from reliable commercial sources. 

GC analysis of volatile aldehyde standards. A mixture of formaldehyde, acetaldehyde, propionaldehyde, isobutyl aldehyde, isovaleraldehyde, methyl glyoxal, and furfural (0.1 mg each) were added to 20 ml of cysteamine solution (6g/1 liter of deionized water). The pH of the solution was adjusted to 8 with 6 N NaOH solution. The reaction proceeded promptly to formm thiazolidine derivatives. The reaction mixture was then extracted with 2 ml of dichloromethane, and an aliquot of the extract was injected in the GC. A gas chromatoram of the extract is shown in Figure 2. 

Reaction temperature. The same molar ratio of methyl glyoxal and cysteamine was reacted at 0, 25, and 100°C. The results are shown in Table III. The reaction at room temperature (20°C) gave the best results for 2-acetylthiazolidine formation. 

Table III. Relative ratio of products from the reaction of methyl glyoxal and cysteamine at various temperature...

The effect of molar ratio of methyl glyoxal and cysteamine. This was examined at room temperature and the results are shown in Table IV. When the molar ratio of cysteamine and methyl glyoxal was 1000 at pH 8, 2-acetylthiazolidine was produced exclusively. On the other hand, formation of 2-acetylthiazolidine remained constant pH 6. Therefore, cysteamine was reacted with samples of interest at 25°C and in a quantity to exceed 1000 fold the estimated amount of methyl flyoxal in the following experiments, when experiment was cunducted at pH 8. 

Preparation of calibration curve for methyl glyoxal analysis. The calibration curve for methyl glyoxas was prepared using N-methylacetamide as an internal standard. N-Methylacetamide was added to each standard reaction mixture of methyl glyoxal (1.0-7.5 mg) and 0.75 g of cysteamine in 70 ml of dichloromethane at pH 6. 

Methyl glyoxal has never been reported in soy sauce or soy bean paste prior to this study. Certain aldehydes (acetaldehyde, n-propanal, 2-methylpropanal, and 3-methylbutanal) were found in soy sauce previously (32). A gas chromatogram of the extract from cysteamine-treated soy sauce and untreated soy sauce are shown in Figures 7 and 8. 

Materials. All reagents were obtained from Aldrich Chemical Co (Milwaukee, WI). Purities were as follows Formaldehyde, 37 wt % Acetaldehyde, 99.5% Butanal, 99% Propanal, 97% 2-Methyl-1-propanal, 99% Pentanal, 99% 3-Methyl-1-butanal, 97% Hexanal, 98% Heptanal, 95% Octanal, 99% Nonanal, 95% 2,4,5-trimethylthiazole (IS), 98%, 2-aminoethanethiol (cysteamine), 98%. Chloroform (Optima Grade, Fisher Scientific, Fair Lawn, NJ) was the extracting solvent. 

Stiefel et al. (97, 98) have shown that modified cysteamine ligands give [Mo 02] complexes with the unusual skew trapezoid bipyrami-dal stereochemistry (21). They suggest that structure 19 would result in unfavorable steric interactions between the methyl groups on the N atoms of the cysteamine ligands. A noteworthy feature of 21 is the... 

The distribution of AET in the organs has been observed tumors showed the lowest concentration " Cysteamine-S-phospha"te was found to give significant concentrations of MEA in 13 of 15 tissues observed, including tumor tissue whereas its methyl ester remained uncleaved in vivo. 

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