First examples of tetracyclic triterpenoids with a D:B-friedobaccharane skeleton. A tentative biosynthetic route 

 -  Tetrahedron Letters, 45, p.7367-7370, 2004 .
<br/><br/> Baruol (1)and Leonal (2), first examples of tetracyclic triterpenes possessing a D:B-friedobaccharane skeleton, were isolated from Maytenus blepharodes and M. chiapensis, respectively. Their structures were established by spectroscopic analysis, molecular modeling studies and biogenetic background. The implication of the D:B-friedobaccharenyl cation in the biosynthetic route of baccharane and shionane skeletons is discussed. Baruol exhibited b-glucuronidase inhibitory activity, a target in the search for hepatoprotective agents.