Radical scavenging activity of steviol glycosides and steviol glucuronide

A radical scavenging activity for hydroxyl radicals of steviol glycosides and steviol glucuronide has been demonstrated in vitro. The activity was measured by the decrease of the fluorescence of hydroxyterephthalate that is formed from terephthalate in the presence of hydroxyl radicals (excitation at 315 nm, emission at 420 nm). Stevioside, rebaudioside A and rubusoside have about the same scavenging activity and were much better (20 x) than glucose or sucrose. It was demonstrated that steviol glucuronide, the excretion product in urine, also has strong ROS ((OH)-O-center dot) scavenging activity (14 x better than sugar). This activity might explain most of the beneficial pharmacological effects of oral stevioside on ROS related diseases, such as high blood pressure, type 2 diabetes, insulin resistance, atherosleroris, inflammation and certain forms of cancer, as well as certain brain diseases like Parkinson or Alzheimer. More research is still required on this interesting topic.