Bioaccesibility, uptake and transport mechanisms of monotropein and monotropein esters from Gaultheria berries

Iridoids are a group of secondary metabolites that can be found in berries from Gaultheria genus [1]. Monotropein (MT) has demonstrated health promoting properties in vitro and in vivo [2]. Scarce information about the bioavailability of MT can be found in literature. The aim of this study was to determine the uptake and transport mechanism of MT and MT esters, namely: cinnamate (MT-Cin) and coumarate (MT-Cou) ([Fig. 1]), which are secondary plant metabolites present in G. phillyreifolia and G. poeppigii berries [3]. Berries, as well as the isolated esters and the commercial standard of MT were submitted to a simulated digestion model. After digestion, micelles were isolated, and the uptake and transport of the parent compound and esters was studied using differentiated Caco-2 cells. Under our assay conditions, the food matrix stabilized the compounds during digestion, but interfered with the micellization, resulting in a lower percentage of bioaccesible compounds. MT-Cin presented the highest uptake and transport, with a Cmax of 0.46 nmol/mg protein at a Tmax of 180 min, and an apparent permeability (Papp) of 0.050x10 – 6 cm/s. The presence of bromosulphalein, a known OATPB2B1 inhibitor, decreased the uptake of MT-Cin by 74.3%, while phlorizin, a known SGLT inhibitor, delayed the Tmax to 240 min. In the same line, both inhibitors induced significant changes in the Papp of both esters. In conclusion, the esters of MT have better physicochemical properties that lead to higher uptake rates and Papp compared to MT. However, the mechanism of transport through membranes remains to be clarified.

Fig. 1 

Publikationsverlauf

Artikel online veröffentlicht:
12. Dezember 2022

• References

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