17177-50-3

Convenient syntheses of rac-glycidaldehyde from rac-but-3-ene-1,2-diol and (R)-glycidaldehyde from D-mannitol are described. (R)-Glycidaldehyde (1) reacts with guanosine in water (pH 4-11, faster reaction at higher pH) to give initially 6(S)-hydroxy-7(S)-(hydroxymethyl)-3-(β-D-ribofuranosyl)-5,6,7- trihydroimidazo[1,2-a]purin-9(3H)-one (7a) and 6(S),7(R)-dihydroxy-3-(β-D-ribofuranosyl)-5,6,73-tetrahydropyrimido[1,2-a] purin-10(3H)-one (8a). The former decomposes to 7-(hydroxymethyl)-5,9-dihydro-9-oxo-3-(β-D-ribofuranosyl)imidazo[1,2-a] purine (3a), 5,9-dihydro-9-oxo-3-(β-D-ribofuranosyl)imidazo[1,2-a]purine (5a, 1,N2-ethenoguanosine), and formaldehyde, while the latter adduct is relatively stable. The position of the hydroxymethyl group on the imidazo ring of 7-(hydroxymethyl)-5,9-dihydro-9-oxo-3-(β-D-ribofuranosyl)imidazo-[1,2-a] purine was proved by 13C NMR analysis of adducts derived from [1-15N]guanosine and [amino-15N]guanosine. At longer reaction times, the adduct 7,7′-methylenebis[5,9-dihydro-9-oxo-3-(β-D-ribofuranosyl)imidazo[1,2- a]purine[ (4a) is formed from guanosine and glycidaldehyde. The structure analysis of this adduct was also aided by 13C NMR analysis of the 15N-labeled adduct derived from [1-15N]guanosine. Analogous adducts were obtained from the reaction between glycidaldehyde and deoxyguanosine. Mechanisms of formation of the adducts from glycidaldehyde and guanosine/deoxyguanosine are proposed and supported by model studies with simple amines. The formaldehyde produced in the reactions described reacts with guanosine to give the known adduct N2-(hydroxymethyl)guanosine (9).

The mutagenicity and carcinogenicity of the important commodity chemical 1,3-butadiene are attributed to the epoxide products. We confirmed our previous work showing that expression of rat glutathione (GSH) transferase 5-5 enhances the mutagenicity of butadiene diepoxide in Salmonella typhimurium TA1535. A GSH-butadiene diepoxide conjugate was isolated and fully characterized by mass spectrometry and nuclear magnetic resonance as S-(2-hydroxy-3,4-epoxybutyl)GSH. The conjugate had a t1/2 of 2.6 h (pH 7.4, 37 °C) and was considerably more mutagenic than butadiene diepoxide or monoepoxide in S. typhimurium. We propose that the GSH conjugate may be a major species involved in butadiene genotoxicity, not a detoxication product.

Three metabolites of 1,3-butadiene, namely butadiene diolepoxide, butadiene monoepoxide and diepoxybutane, were tested in the bacterial mutation assay using Salmonella typhimurium Strain TA100 with and without metabolic activation (S9 mix). All three compounds showed a mutagenic response. The bifunctional epoxide was more effective than the diolepoxide which was more effective than the monoepoxide. Toxicity appeared to follow the ranking of the chemicals for their mutagenic potency. The monoepoxide and the diolepoxide were also tested for induction of micronuclei in mouse bone marrow erythrocytes and for dominant lethal mutation induction in postmeiotic male mouse germ cells. The effects of the diepoxide in both in vivo tests have been published earlier. In the micronucleus assay, the three metabolites gave a positive response whereby the diepoxide was more effective than the monoepoxide which was more effective than the diolepoxide. In contrast to the diepoxide which was positive at a dose as low as 36 mg/kg, the monoepoxide and the diol did not show an induction of dominant lethal effects up to doses of 120 and 240 mg/kg, respectively. It is concluded that the metabolites were mutagenic in bacteria without metabolic activation and clastogenic in mouse bone marrow; only the bifunctional diepoxide, however, was active in postmeiotic male mouse germ cells.

Epoxybutanediol is one of the epoxide metabolites of butadiene (BD). A pair of diastereomeric N-1-adenine adducts were formed by reacting epoxybutanediol with deoxyadenosine 5'-monophosphate (5'-dAMP). These two N-1-adenine adducts rearranged in a base-catalysed reaction to an N6-trihydroxybutyl-adenine adduct, which was characterized by UV and mass spectroscopy. Using the 32P-postlabelling/HPLC assay the same adducts were detected in diepoxybutane (DEB)-treated DNA in vitro and in liver DNA samples from rats exposed to BD by inhalation. Adenine adducts of epoxybutanediol are probably suitable for monitoring BD exposure. Copyright (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.

Possible routes for the preparation of 2,3,4-trihydroxybutylarsonic acid, a key compound for the synthesis of novel arsonolipids, were experimentally evaluated. The best substrate was found to be 3,4-epoxybutane-1,2-diol. Its reaction with alkaline sodium arsenite, "Na3AsO3," gave the arsonic acid in 50% yield, as two pairs of diastereoisomers, each pair being a racemic mixture. Copyright Taylor & Francis Group, LLC.

Differences in the metabolism of 1,3-butadiene (Bd) in rats and mice may account for the observed species difference in carcinogenicity. Previous studies of the metabolic fate of Bd have identified epoxide formation as a key metabolic transformation which gives 1,2-epoxy-3-butene (BMO), although some evidence of aldehyde metabolites is reported. In this study, male Sprague-Dawley rats and male B6C3F1 mice received single doses of [4- 14C]BMO at 1, 5, 20, and 50 mg/kg of body weight (0.014, 0.071, 0.286, and 0.714 mmol/kg of body weight). Analysis of urinary metabolites indicated that both species preferentially metabolize BMO by direct reaction with GSH when given by ip administration. The excretion of (R)-2-(N-acetyl-L-cystein-S- yl)-1-hydroxybut-3-ene (IIa), 1-(N-acetyl-L-cystein-S-yl)-2-(S)-hydroxybut- 3-ene (IIb), 1-(N-acetyl-L-cystein-S-yl)-2-(R)-hydroxybut-3-ene (IIc), and (S)-2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene (IId) accounted for 48- 64% of urinary radioactivity in rats and 46-54% in mice. The metabolites originating from the R-stereoisomer of BMO (IIc and IId) predominated over those arising from the S-stereoisomer (IIa and IIb) in both species. IIc was formed preferentially in mice and IId in rats. The corresponding mercaptoacetic acids, S-(1-hydroxybut-3-en-2-yl)mercaptoacetic acid (IIf) and S-(2-hydroxybut-3-en-1-yl)mercaptoacetic acid (IIg), were identified only in mouse urine (ca. 20% of the recovered radioactivity). 4-(N-Acetyl-L-cystein- S-yl)-1,2-dihydroxybutane (Ia), a metabolite derived from hydrolysis of BMO, accounted for 10-17% of the radioactivity in rat and 6-10% in mouse urine. 4- (N-Acetyl-L-cystein-S-yl)-2-hydroxybutanoic acid (Ib), 3-(N-acetyl-L-cystein- S-yl)propan-1-ol (Ic), and 3-(N-acetyl-L-cystein-S-yl)propanoic acid (Id), also derived from the hydrolysis of BMO, were only present in the rat. Metabolites of 1,2,3,4-diepoxybutane (DEB) were not detected after administration of BMO in rat or mouse urine. This study showed both quantitative and qualitative differences in the metabolism of BMO with varying doses and between species. The data aid in the safety evaluation of Bd and contribute to the interpretation of mathematical models developed for quantitative risk assessment and extrapolation of animals to humans.

Reaction of guanosine (1a) with racemic glycidaldehyde (2) in aqueous medium at pH 10 gives 5,9-dihydro-9-oxo-3-β-D-ribofuranosylimidazopurine (1,N2-ethenoguanosine) (3c), its 7-hydroxymethyl derivative (3a), and methylene-7,7'-bis-5,9-dihydro-9-oxo-3-β-D-ribofuranosylimidazopurine (5); the structures of adducts (3a) and (5) were deduced from 13C n.m.r. analysis of 15N labelled adducts derived from guanosine (1b) and guanosine (1c).