Oxidosqualene cyclase that generates friedelin, a triterpenoid product with the maximum number of rearrangements possible. Friedelin is probably required to coat the leaf exterior as defense compound against pathogens or herbivores. (S)-2,3-epoxysqualene = friedelin Expressed only in the epidermal cells on both sides of the leaf and not in internal leaf tissues. Belongs to the terpene cyclase/mutase family.