Effects of medicinal plants on radiolabeling and biodistribution of diagnostic radiopharmaceuticals: A systematic review

Radiopharmaceuticals are drugs that contain radioisotopes used for diagnostic and therapeutic purposes. There are evidences that medicinal herbs and their constituents can modify the radiolabeling, biodistribution, and pharmacokinetics of radiopharmaceuticals through drug interaction. To have an overview of the effects and the underlying mechanisms of medicinal plants on the radiolabeling and bioavailability of radiopharmaceuticals, we conducted this study to summarize the current findings in this field. The scientific literature was systematically collected from databases and analyzed. Studies showed that medicinal plants and their constituents can alter radiolabeling and biodistribution via several mechanisms. Interactions with proteins in red blood cells at the same sites, chelating action of stannous and pertechnetate ions, antioxidant action impeding or decreasing stannous ion oxidation, direct oxidation of stannous ions, generation of reactive oxygen species (ROS) which oxidize stannous ions and damage induced in the cell membrane. Most the medicinal plants can decrease the radioactivity of radiopharmaceuticals, but some of them like Peumus boldus, Punica granatum, Nectandra membranacea, Mentha crispa, Rosmarinus officinalis and derivatives such as eugenol and epigallocatechin gallate have increasing effects. In addition, altering feature in some of them is tissue dependent