It would appear that lupeol shows no toxic effects at reasonable levels in mice. No adverse effects have yet been seen, and research is still at an early stage. We currently have no long term human use studies to base any assumptions on, nevertheless I'm sure we'll start seeing those pretty quickly.
I have to stress that many of the studies on lupeol are conducted either in the lab (in-vitro) or in the murine model (in mice) and don't necceserily mean these effects will be translated into human results. However, the studies are very bullish and the results hugely positive.
Almost all of the studies I have read go on to conclude that lupeol warrents further investigation and mention the very strong possibilities of lupeol