Abstract
2121
For a long time myosmine was considered to be one of the minor tobacco alkaloids without significant relevance. However, due to its widespread occurrence in food and its high reactivity under nitrosation and peroxidation conditions a better knowledge of its possible toxicological impact is required. As a first step the dose-dependent metabolism of myosmine has been examined in female Wistar rats. After identification of 4-oxo-4-(3-pyridyl)butanoic acid (keto acid) and 3-pyridylacetic acid as the two major and 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) as one of the minor urinary metabolites two additional metabolites have been identified as 3-pyridylmethanol and 3’-hydroxymyosmine (see table). The animals received apple bites contaminated with 3H-myosmine at doses of 0.001, 0.005, 0.5 and 50 μmol/kg body weight (0.5 kBq/rat). Urine and feces were collected in time intervalls up to 48 h. Excretion of radioactivity occurred mainly in urine and was nearly complete after 24 h. The pattern of urinary metabolites was analysed by radio-HPLC using a RP-18 column for metabolite separation. For identification of the metabolites urine was transferred to C18-SPE tubes and successively eluted with CH3CN/H2O (2:98; 4:96; 6:94; 8:92; v/v). The fraction containing 3-pyridylmethanol (CH3CN/H2O 4:96; v/v) was further cleaned-up by 2-dimensional thin layer chromatography. The promising spot was derivatised with pentafluorobenzoyl chloride solution in NMe3/CH2Cl2 (1:1, v/v) and further analysed by GC/MS. 3’-Hydroxymyosmine was located in the urinary fraction eluted with CH3CN/H2O (8:92, v/v). An aliquot of the fraction was transferred on an analytical Kieselgel F254 plate and developed with (CHCl3/MeOH/NH4OH (85:15:2, v/v). The spot with Rf 0.46 was further analysed by LC-MS. The identified metabolites give rise to speculations about their metabolic formation. DNA reactive intermediates cannot be excluded and therefore it is necessary to focus research on revelation of myosmine activation pathways. Supported by a grant of the German Research Foundation (ZWI 59/2-2).
- American Association for Cancer Research
Volume 65, Issue 9 Supplement
