In vitro evaluation of the bioactivity and bioaccessibility of Hypericum olympicum L.

The genus Hypericum has been utilized in traditional medicine in several parts of the world since ancient times. The utmost activities have been associated with the natural pharmaceuticals prepared from Hypericum species due to their unique chemical profile. In the present study, Hypericum olympicum L. extracts before and after being processing in an in vitro simulated digestion system were submitted to in vitro anti-diabetic assays, i.e., α-glucosidase and α-amylase inhibition assays and antiglycation assay. The formation of advanced glycation end products (AGEs) is one of the most precursor molecules for the complications of diabetes mellitus. In oxidative stress conditions, reactive oxygen species (ROS) and AGEs production increase significantly inside the cells. Furthermore, mechanistically different antioxidant assays, including free radical scavenging and metal-reducing activities, and the total antioxidant capacity assay were conducted. Major flavonoid glycosides (rutin, hyperoside and isoquercitrin) and the main phenolic acid (chlorogenic acid) in the extracts and their bioaccessibilities were also determined by high performance thin layer chromatography (HPTLC). The results indicated that amounts of all phenolic compounds analyzed in this study increased throughout in vitro simulated gastric system in comparison with non-digested fraction. Moreover, the results demonstrated that anti-diabetic activity and antioxidant capacity of the extract increased remarkably following the simulation process.