Component of the oleanane-type triterpene saponins biosynthetic pathway (PubMed:26333142, PubMed:29603041). Oxidosqualene cyclase converting oxidosqualene into beta-amyrin, generating five rings and eight asymmetric centers in a single transformation (PubMed:26333142, PubMed:29603041). (S)-2,3-epoxysqualene = beta-amyrin Secondary metabolite biosynthesis; terpenoid biosynthesis. Belongs to the terpene cyclase/mutase family.