EVALUATION OF THE TOXICITY OF GUARANA WITH IN-VITRO BIOASSAYS

A natural stimulant, Paullinia cupana, commonly called guarana, was te sted for its ability to induce in vitro toxicity in Chinese hamster ov ary (CHO) cells and bacterial cells (Photobacterium phosphoreum). The cytotoxic effects of aqueous guarana extracts were evaluated by three endpoint systems: neutral red (NR) uptake assay, total protein content [kenacid blue (KB)] assay, and tetrazolium (MTT) assay. The Microtox test as also used. Results indicated that the lowest concentration of guarana tested was not toxic and that the IC50 values calculated with the IVR, KB, and MTT assays were lower than the highest concentration tested (40 mg/ml). There was no significant difference in cytotoxicity between the three test systems. The EC50 values obtained with the Mic rotox assay were consistent with these data. The present in vitro anal ysis suggests that the concentration of guarana is of critical importa nce in its cytotoxic activity and high doses could be harmful to human health, (C) 1998 Academic Press.