Interestingly, despite the chemical composition of S. nitens extract, the toxic activity of flavonoid could be inhibited by the presence of other compounds present in this natural product. Preparations obtained from plants provide a complex mixture of different chemicals, which can act synergistically or antagonistically in the induction of cytotoxic- ity and other biological activities. Human red blood cells can also be used as tools in the toxicity studies of the compounds, because their membrane properties are well known, and their lysis can be easily monitored by measuring the release of hemoglobin