Traditional multi-herbal formula in diabetes therapy – Antihyperglycemic and antioxidant potential

Traditional medicinal plants are used as an additional form of type 2 diabetes therapy in which oxidative stress is one of the progression factors. The aim of the study was the evaluation of antihyperglycemic and antioxidant potential of tea mixture registered as food and marketed for treatment of type 2 diabetes mellitus. Chemical profiling of the extracts included quantification of total phenolics and flavonoids, while antihyperglycemic potential was estimated through determination of inhibition potential of α-amylase and α-glucosidase. Additionally, extracts were characterized for specific phenolic compounds by high performance liquid chromatography (HPLC). The in vitro antioxidant activity was estimated by application of DPPH, OH, NO and FRAP tests. The greatest anti-α-amylase potential is attributed to the Phaseoli legumen, while the highest potential to inhibit α-glucosidase was recorded for Olivae folium. Generally, screening of the phenolic compounds enabled us to conclude that a high level of correlation exists between anti-α-amylase potential and the quantified amounts of total phenolics, as well as gallic acid, while the chlorogenic acid is most probably responsible for the inhibition of α-glucosidase activity. Therefore, the high total ratio (40%, m/m) of Olivae folium and Phaseoli legumen in the evaluated tea mixture can be stated as fully justified. However, future in vivo research is required for further understanding of the antihyperglycemic activity mechanisms of secondary metabolites found in specified herbal components, as well as to evaluate their synergistic effect when applied in a form of tea mixture.