Identification of minor nitrosation products of the alkaloid gramine by mass spectrometry.

The nitrosation of gramine, a tertiary amine alkaloid present in barley malt, was carried out by reaction with sodium nitrite in buffered acetic acid (pH 3.4) for 1 hr at room temperature. Following the previous isolation and identification of the major nitrosation products (Ahmad et al. Fd Chem. Toxic. 1985, 23, 841), two minor products were isolated by HPLC and identified as indolin-3-one oxime and indole-3-aldehyde. Identification was based on mass spectrometry. The results give strong support to the hypothesis that gramine does not undergo nitrosation by nitrosative dealkylation.