Determination of propyl propane thiosulfonate in plasma and tissues by UHPLC-MS/MS orbitrap and analytical pyrolysis (Py-GC-MS)

Garlic and onion contain biologically active substances, including volatile organosulfur compounds (OSCs), which may be responsible for their antimicrobial and antioxidant properties. The isolation of the compound propyl propane thiosulfonate (PTSO) affords a stable, active agent to be used in the food industry. PTSO may be incorporated into an inert commercial alimentary support to produce active packaging. According to the recommendations of the OECD 489 and 474, several methods are necessary to verifying that the compound could reach to the target tissue or general circulation. In this sense, the aim of this study was determinate the presence of PTSO in plasma and tissues (stomach and liver) of rats following oral administration (55 mg/kg bw) for later assessed the genotoxicity. The quantification of PTSO in plasma was performed by UHPLC–MS/MS Orbitrap and its identification and degradation products in tissues (stomach and liver) was performed by analytical pyrolysis (Py-GC–MS). PTSO was not detected at any concentration tested in plasma, and in the stomach six OSCs compounds of PTSO were detected. Among these, dimethyl disulphide and methyl propyldisulphide are likely to have originated from PTSO, which seems to suffer hydrolysis reactions. Signs of the presence of PTSO were also found in liver of treated rats by detecting a single OSC: 2-methyl-2-(methylthio) propane, indicating the influence of distribution and metabolism processes. These results indicate that Py-GC-MS is an adequate technique that provides first evidences of the absorption of PTSO and its presence including metabolites in tissues.