Tissue distribution and excretion of myosmine after i.v. administration to Long–Evans rats using quantitative whole-body autoradiography

Isolation of Nicotinic Acid (Vitamin B3) and N-Propylamine after Myosmine Peroxidation

The alkaloid myosmine (3-(1-pyrroline-2-yl)pyridine) is widespread in biological matrixes including foodstuffs and tobacco products. Some in vitro tests in cellular systems showed mutagenic activity for myosmine. Myosmine activation including peroxidation mechanism employs unstable oxazirane intermediates. The formation of minor metabolite 3-hydroxymethyl-pyridine in rat metabolism experiments as well as in in vitro peroxidation assays suggests its further oxidation to nicotinic acid and possible concomitant formation of n-propylamine. A sensitive high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed for the direct analysis of n-propylamine in the peroxidation assay solution of myosmine employing derivatization with 3,5-dinitrobenzoyl chloride. Additionally, during peroxidation procedures, formation of 3-pyridylmethanol to nicotinic acid, the essential vitamin B3, was observed and characterized using HPLC-UV and gas chromatography/mass spectrometry. This new reaction pathway may present further contribution to our knowledge of myosmine's significance in human food including its activation in human organism, foodstuffs, and biological systems.

Effects of Myosmine on Antioxidative Defence in Rat Liver

Myosmine [3-(1-pyrrolin-2-yl) pyridine] is an alkaloid structurally similar to nicotine, which is known to induce oxidative stress. In this study we investigated the effects of myosmine on enzymatic and non-enzymatic antioxidative defence in rat liver. Wistar rats received a single i.p. injection of 19 mg kg-1 of myosmine and an oral dose of 190 mg kg-1 by gavage. Nicotine was used as a positive control. Through either route of administration, myosmine altered the hepatic function by decreasing the levels of reduced glutathione, superoxide dismutase, and glutathione peroxidase activities on one hand and by increasing malondialdehyde, catalase, and glutathione reductase activity on the other. Compared to control, both routes caused significant lipid peroxidation in the liver and altered hepatic enzymatic and non-enzymatic antioxidative defences. The pro-oxidant effects of myosmine were comparable with those of nicotine.

Analysis of myosmine, cotinine and nicotine in human toenail, plasma and saliva

Myosmine is a minor tobacco alkaloid with widespread occurrence in the human diet. Myosmine is genotoxic in human cells and is readily nitrosated and peroxidated yielding reactive intermediates with carcinogenic potential. For biomonitoring of short-term and long-term exposure, analytical methods were established for determination of myosmine together with nicotine and cotinine in plasma, saliva and toenail by gas chromatography-mass spectrometry (GC/MS). Validation of the method with samples of 14 smokers and 10 non-smokers showed smoking-dependent differences of myosmine in toenails (66 +/- 56 vs 21 +/- 15 ng g(-1), p <0.01) as well as saliva (2.54 +/- 2.68 vs 0.73 +/- 0.65 ng ml(-1), p <0.01). However, these differences were much smaller than those with nicotine (1971 +/- 818 vs 132 +/- 82 ng g(-1), p <0.0001) and cotinine (1237 +/- 818 vs <35 ng g(-1)) in toenail and those of cotinine (97.43 +/- 84.54 vs 1.85 +/- 4.50 ng ml(-1), p <0.0001) in saliva. These results were confirmed in plasma samples from 84 patients undergoing gastro-oesophageal endoscopy. Differences between 25 smokers and 59 non-smokers are again much lower for myosmine (0.30 +/- 0.35 vs 0.16 +/- 0.18 ng ml(-1), p <0.05) than for cotinine (54.67 +/- 29.63 vs 0.61 +/- 1.82 ng ml(-1), p <0.0001). In conclusion, sources other than tobacco contribute considerably to the human body burden of myosmine.