Intestinal Metabolism of Selected Steroidal Glycoalkaloids in the Pig Cecum Model

Abstract

Due to the presence of the steroidal glycoalkaloid solanine, the potato was chosen as Germany's poisonous plant of the year 2022. Steroidal glycoalkaloids are secondary plant metabolites which have been reported to induce toxic as well as beneficial health effects. Nevertheless, data regarding occurrence, toxicokinetics, and metabolism of steroidal glycoalkaloids is scarce, and substantially more research is required for a proper risk assessment. Therefore, the intestinal metabolism of solanine, chaconine, solasonine, solamargine, and tomatine was investigated using the ex vivo pig cecum model. All steroidal glycoalkaloids were degraded by the porcine intestinal microbiota, releasing the respective aglycon. Furthermore, the hydrolysis rate was strongly dependent on the linked carbohydrate side chain. Solanine and solasonine, which are linked to a solatriose, were metabolized significantly faster than the chaconine and solamargin, which are linked to a chacotriose. In addition, stepwise cleavage of the carbohydrate side chain and the formation of β- and γ-intermediates were detected by HPLC-HRMS. The results provide valuable insights into the intestinal metabolism of selected steroidal glycoalkaloids and help to reduce uncertainties and improve risk assessment.