In vitro studies of bioaccessibility, intestinal transportation and phases I, II and III metabolism of pentacyclic triterpenes from cultivars of Malus domestica Borkh

Abstract

Pentacyclic triterpenes are widespread in the plant kingdom and they have been known for their remarkable bioactivities and health-promoting properties. Triterpenes occur largely in apple cultivars, which are among the most highly consumed fruits worldwide. Cultivars of Malus domestica Borkh possess different triterpene pattern, which could reflect in bioavailability and health-promoting properties. Only scarce information is available concerning the bioavailability of pentacyclic triterpenes in different databases and there is no complete information about the fate of these compounds that are constituents of medicinal and edible plants. Poor bioavailability reported for isolated triterpenes could be due to low gastrointestinal absorption, extensive metabolic degradation, efficient uptake by other tissues, and/or rapid excretion. The plant extract matrix could also play an important role in triterpene bioaccessibility and absorption. According to the type of transport involved, competition between triterpene constituents of an extract may also take place. The present project aims at carrying out bioaccessibility studies on isolated pentacyclic triterpenes and apple triterpene extracts from different cultivars of Malus domestica Borkh assessing the influence of the conditions of the upper gastrointestinal digestion through the use of an in vitro model developed by the group of Dr. Larondelle. The transport of the digested triterpene solutions across the human intestinal epithelium will then be studied using the Caco-2/TC-7 cell monolayer as a model in the presence and absence of transporters. In vitro assessment of phase I, II and III metabolism of pure triterpenes and extracts will be investigated using the same Caco-2/TC-7 enterocytes, as well as commercial rat and human liver microsomes. The identification of triterpenes and their metabolites will be carried out by using high performance liquid chromatography/high resolution tandem mass spectrometry (Orbitrap-LC-MS/MS). (AU)