To the Editor,
In Figure 1 of the article of Feng et al. (Citation2007) it is stated that NNK is insoluble in water. However, this is not true. Azzi et al. (Citation2006) state in their abstract: “The water-soluble NNK permeated the membrane rapidly” and in Materials and Methods on page 139: “Saturated solutions of each chemical were prepared by sonicating excess solute in the appropriate solvent for 15 min and then stirring the suspensions for 48 h at 37°C. Aliquots were taken from the stirred solution every 6 h for 48 h, centrifuged and filtered through a 0.2 μ m filter. The saturation concentrations of NNK and B[α]P in the filtrate were measured by HPLC after appropriate sample dilution. The apparent solubility of NNK in saline was found to be 25 mg/ml, and the solubility of B[α]P in 5% Brij–NS was found to be 30 μ g/ml.” This is clear evidence that NNK is well soluble in water and confirms our own long-standing experience working with NNK (e.g., Richter & Tricker, Citation1994).
REFERENCES
- Azzi C., Zhang J., Purdon C. H., Chapman J. M., Nitcheva D., Hebert J. R., Smith E. W. Permeation and reservoir formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) across porcine esophageal tissue in the presence of ethanol and menthol. Carcinogenesis 2006; 27: 137–145
- Feng S., Plunkett S. E., Lam K., Kapur S., Muhammad R., Jin Y., Zimmermann M., Mendes P., Kinser R., Roethig H. J. A new method for estimating the retention of selected smoke constituents in the respiratory tract of smokers during cigarette smoking. Inhal. Toxicol. 2007; 19: 169–179
- Richter E., Tricker A. R. Nicotine inhibits the metabolic activation of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in rats. Carcinogenesis 1994; 15: 1061–1064